Research on the production process of candied orange slices product

INTRODUCTION

Research rationale

Vegetables and fruits are essential components of the human diet, providing vital nutrients that support growth, enhance the immune system, and help prevent diseases such as cardiovascular issues and strokes They are rich sources of important vitamins and minerals, including vitamin C and dietary fiber In Vietnam, fruits and vegetables not only serve as a crucial food source but also contribute significantly to the economy by creating jobs and boosting agricultural exports As of mid-March 2017, Vietnam's export turnover for fruits and vegetables reached nearly $543 million, marking a 26.7% increase from the previous year and demonstrating the country's growing influence in the global market.

Vietnam's tropical monsoon climate features four distinct seasons: Spring, Summer, Autumn, and Winter, along with rainy and dry seasons This diverse climate supports a variety of fruit trees, including litchi, jackfruit, avocado, oranges, tangerines, apples, and durian Notably, oranges thrive in regions such as Tuyen Quang, Bac Giang, Ha Giang, Hanoi, Hung Yen, Vinh, and Nghe An Rich in vitamin C, fiber, and low in calories, oranges offer numerous health benefits, including improved cardiovascular health However, fresh oranges face significant post-harvest losses of 15-30% due to physiological activities, biochemical changes, and microorganisms during transportation and storage To mitigate quality loss, implementing effective post-harvest processing techniques is crucial in Vietnam.

The market offers a variety of trusted orange products, including orange candy, juice, syrup, and jam However, candied orange slices remain underexplored due to the complex production process, which involves careful preparation of fresh orange slices, reduction of bitterness, and the addition of sugar and honey for enhanced flavor while ensuring health safety This method not only preserves the fruit but also extends its shelf life to up to one year, resulting in a distinct product compared to fresh oranges While dried fruit jams made from other fruits like pineapple, bananas, and apples are widely available, candied orange slices are scarce, with limited research on large-scale production.

This study aims to process candied orange slices from various nutritious and sensory-rich orange varieties in Vietnam, enhancing product diversity in the market and boosting income for orange growers.

“ Research on the production process of candied orange slices ” at the laboratory of The faculty of Biotechnology and Food Technology.

Research’s objectives

Set up a process of candied orange slices products with high nutritional value, convenience, safety in use, and contributing to the diversification of orange products on the market

- To determine the effects of the bitter elimination method on product quality

- To determine the ratio of mixing orange and sugar on product quality

- To determine the effects of temperature and drying time on product quality

- Evaluate the quality of the product candied orange slices finished product

- Establish a process for processing the product's candied orange slices.

Research questions and hypotheses

-Do we use salt water to remove all bitter taste of orange peel?

-Can we use other types of sugar add-in?what are other types of sugar?

-What is the effect of honey on the final product?

-What is the appropriate drying temperature?

-If we use 5% salt water, then candied orange slices will be de-bitter

-If we choose the ratio of oranges and sugar is 2:1, then the candied orange slices product will have a pertinent sweet taste

-If choosing the temperature for drying is 55 o C in 24h, then the product will be safe humidity

Limitations

-The research is implemented in the laboratory, the equipment and machines are limited, cannot be done on a large scale and modern equipment such as the factory

-This is a new product that has never been studied before, so it takes time to research and experiment.

Definitions

Candied orange slices are a delightful treat made from crispy dried orange pieces that are coated in sugar and dehydrated at high temperatures, resulting in a product with approximately 90% dry matter.

LITERATURE REVIEW

The scientific basis of the thesis

Oranges, scientifically known as Citrus sinensis, are part of the citrus family and come in various sizes depending on their variety These ripe fruits are characterized by their sweet and slightly sour flavor, making them a popular choice for many.

The origins of citrus fruits, particularly oranges, are debated, with evidence suggesting they were cultivated in China as early as 2200 BC, while others claim their native roots lie in the Himalayas of India Oranges gained popularity in India before spreading to East and Southeast Asia By the 3rd century BC, orange trees made their way to Europe, flourishing in Mediterranean regions Christopher Columbus introduced orange trees to America, leading to their cultivation across Australia and Africa in subsequent years Today, orange trees are widely grown in numerous countries around the globe.

Figure 2.1 Sanh orange and Vinh orange Structure of orange trees:

-Stems and branches of orange: Stems of woody type, semi-bush, with 4-6 main branches, 2 - 3m tall trees, low branches Spike direction, sparse, horizontal branching

-Orange leaves: Staggered leaves, longleaf, dark green, oval, 5-10cm long, 2.5-5cm wide, with a thin tooth edge; petioles with wings, 4-10mm wide Leaves with small ears [96]

Orange flowers bloom in spring, showcasing numerous small, white blooms that are typically clustered together Despite the abundance of flowers, only a few will ultimately develop into fruit These flowers emit a light, pleasant aroma, adding to the charm of orange trees during their flowering season.

Orange roots, similar to those of woody plants, effectively absorb water and mineral salts Their root system is characterized by a shallow, broad, and dense structure, which is primarily found in topsoil and porous soils The most vigorous growth occurs in February and September, with the roots thriving particularly well during the first eight years of the plant's life.

- The oranges fruits are spherical, with a thin rind, orange-yellow when ripe, sweet, or slightly acidic [20]

Some varieties of oranges are grown in Vietnam:

Vinh orange, a citrus fruit native to Vinh in Nghe An, Vietnam, is known for its round shape and succulent texture Characterized by a vibrant yellow hue mixed with green, these oranges are popular for their unique flavor There are several varieties of oranges available today, including Xa Doai, Van Du, Song Con, and Navel oranges.

Xa Doai orange (Citrus sinensis 'XA DOAI') is a Spanish-origin orange variety cultivated in Vietnam, characterized by its two distinct shapes: high fruit and oval (flat) forms With an average diameter of 6.8-7.8 cm and weighing between 200-250 grams, each fruit typically contains 10-12 segments The oranges are known for their juiciness, featuring 2-3 cm thick peels that turn a vibrant yellow upon ripening.

• Song Con oranges imported by a French plantation owner planted on Dao Nguyen production hill (today's Song Con Farm) should be named "Song Con oranges"

Song Con oranges feature a thin skin, are juicy, sweet, and aromatic These oranges begin to bear fruit after 3-4 years and are known for their high productivity They exhibit strong resistance to pests and diseases, making them ideal for cultivation in various mountainous midland regions.

The Van Du orange, imported to the Van Du orange farm in 1947, was developed through a meticulous selection process to ensure high quality This variety features a robust tree with a broad canopy and large, dark green leaves Van Du oranges yield medium-sized fruits that are juicy and seed-filled, offering a unique flavor profile that combines a deep sweetness with a subtle bitterness that dissipates quickly after consumption.

Navel oranges, also referred to as umbilical oranges, are native to California and were introduced to Vietnam in 1937, where they can still be found in various farms These oranges typically weigh around 230 grams, with some reaching up to 290 grams, and have an approximate diameter of 7.6 cm When ripe, the fruit exhibits a yellowish-gray color and contains 11 to 12 segments filled with dark yellow pulp.

Hai Duong oranges, primarily cultivated in Thanh Ha and Tu Ky districts of Hai Duong, are renowned for their large size, with individual fruits weighing between 300 to 700 grams and measuring about 10 cm in diameter Characterized by their striking red-yellow skin, these oranges contain white cloves and feature 20-30 large, flat seeds per fruit They are known for their distinct sour and bitter flavor, making them a unique variety in the region.

+ Sanh orange (C reticulata x C Sinensis: king mandarin)

The Sanh orange, known for its thick, bright green skin, is the most popular orange variety in Vietnam Its flesh is dark orange and sweet, making it a favorite among fruit lovers.

Typical of king mandarin: Bo Ha oranges, Ha Giang, Tuyen Quang, Yen Bai,

Bo Ha oranges are grown in Bo Ha, Yen The district, Bac Giang province Bo Ha orange is suitable with mountainous midland, cool and humid climate

Ha Giang, Tuyen Quang, and Yen Bai are renowned for their high-quality oranges, primarily grown in the northern provinces of Vietnam These oranges are typically harvested during the Tet holiday, making them a seasonal delicacy Among these, the Ham Yen orange from Tuyen Quang province stands out for its exceptional taste and quality, solidifying the region's reputation for delicious citrus fruits.

+ Sweet orange (Citrus sinensis L.Osbeck)

Oranges typically weigh around 100g and feature a thin skin that can be yellow, red, or dark red, making them easy to peel and segment There are three primary varieties of oranges: Canh orange from Hanoi, Dong Du oranges from Hai Phong, and Ngoc Cuc and Hanh Thien oranges from Nam Ha Additionally, Bu oranges and Sour oranges, known for their slightly sour taste, are commonly found in Huong Son (Ha Tinh) and Tuyen Hoa (Quang Binh) Another notable type is the Voi orange, a hybrid between Bu and grapefruit, which produces larger fruits weighing between 300g to 350g and is cultivated in Tuyen Hoa (Quang Binh).

The composition of an orange consists of the following:

The outermost layer, known as the flavedo, varies in color from orange to blue depending on the breed and is rich in essential oil sacs, contributing a robust flavor akin to that of orange pulp.

The white part of the rind (albedo): contains pectin and cellulose, has nearly the same amount of vitamin C as the flesh and other nutrients [139], [20]

Carpels with juicy vesicles: the inside contains, the orange cloves are cell fluids

A section of an orange: in it cure the orange cloves and the cell fluid

Orange seeds: hold sprout, include endosperm, embryo, seed coat [96]

Central column: The part located in the center of the orange, containing pectin and cellulose[96]

Table 2.1 Physical parameter of a sweet orange fruit [26]

1 Fruit color Yellow, orange, green

5 The average number of segment 10

9 The thickness of flavedo (mm) 1.8

Citrus is a valuable fruit tree on the international market, being one of the most traded fruits Moreover, this is a fruit with high nutritional value

Table 2.2 The nutritional composition of fresh orange (USDA) [33]

Nutritional composition of orange per 100 gram

Fresh oranges are primarily composed of carbohydrates and water, with minimal amounts of fat and protein The sweetness of these fruits comes from sugars like glucose, fructose, and sucrose Despite their relatively high sugar content, oranges have a low glycemic index, ranging from 31 to 51, indicating they are beneficial for health Foods with a glycemic index below 55 are considered low glycemic index foods, offering numerous health advantages.

The importance of the orange industry to people and the economy

2.2.1 The importance of the orange industry to people

Oranges are a nutrient-dense fruit packed with vitamin C, fiber, folate, and antioxidants, while being low in calories and sugar, making them an excellent choice for daily consumption to support overall health.

Orange juice, as noted by M.D Nguyen Thi Hang, Vice Chairman of the Department of Eastern Medicine at the Vietnam Academy of Traditional Medicine, is rich in flavonoids and hesperidin antioxidants that promote health Additionally, its high vitamin C content can help lower blood pressure, while its nutrients function as a diuretic, aiding the kidneys in excreting excess salt and water, thereby boosting resistance and combating fatigue.

Consuming orange juice with a pinch of salt after intense exercise is an effective way to quickly restore hydration and energy The high fructose content and 85% water in oranges allow for rapid absorption, providing a refreshing boost and enhancing overall recovery.

Enhance eyesight: Orange is rich in carotenoids and vitamin A These substances help enhance eyesight, especially good for women who have problems with macular degeneration [34]

Anti-cancer: Scientists have recently published the results of the prevent-cancer effects of orange juice It contains flavonoid substances like hesperidin and naringenin

Laboratory studies have shown that orange juice reduces childhood leukemia, as well as combating breast, liver, and colon cancers [31]

Reducing the risk of cardiovascular disease: Studies have shown that orange juice can help reduce the risk of heart disease because it can help improve blood circulation [34]

Oranges are rich in beta-carotene, a potent antioxidant that safeguards skin cells from damage, combats free radicals, and helps prevent the visible signs of aging.

Weight-loss support: A large orange contains 4 grams of fiber and only 87 calories Therefore, eating oranges helps you to prevent hunger, limit junk food habits

In addition, oranges are also rich in mineral vitamins to help you always feel healthy, full of energy [31]

To strengthen your immune system and reduce the risk of viral infections, incorporate foods high in polyphenols into your diet Oranges, in particular, are abundant in polyphenols, which offer numerous health benefits, including antiviral, anti-inflammatory, anti-allergic, anti-carcinogenic, and anti-proliferative properties.

2.2.2 The importance of the orange industry to people and the economy

Orange trees thrive in tropical climates and are relatively easy to cultivate, making them a popular choice among farmers Varieties like gourmet oranges are particularly lucrative, offering high returns By implementing advanced techniques for off-season flowering, farmers can enhance the selling price of citrus fruits, significantly boosting their income.

The expansion of both domestic and international markets is generating jobs, boosting farmers' incomes, and enhancing their economic conditions, while also increasing export turnover and revenue With just 1.5 hectares of land, farmers can achieve impressive yields of over 80 tons per crop.

Orange trees play a vital role in enhancing the economic development of farmers To ensure sustainable efficiency in this agricultural model, it is essential for the relevant sectors to establish favorable conditions that enable farmers to access advanced techniques, secure quality seed sources, and maintain a stable market for their produce This support will allow gardeners to focus confidently on their production efforts.

The situation of orange production and consumption in Vietnam and worldwide

2.3.1 The situation of orange production and consumption in Vietnam

Figure 2.6 Area planted oranges in Vietnam from 2005 to 2018

Based on the chart, we can see that the area of oranges growing from 2013 to

Since 2018, the area dedicated to orange cultivation in Vietnam has expanded significantly, growing from 75,000 hectares to over 120,000 hectares within five years This increase reflects Vietnam's commitment to investing in orange farming, which not only enhances productivity but also plays a vital role in the country's economic development.

Formatted: Centered, Space After: 0 pt, Line spacing: 1.5 lines, Tab stops: 0 cm, Left + 0.95 cm, Left + 1.27 cm, Left+ 3.81 cm, Left

Figure 2.7 Orange production in Vietnam

From 2005 to 2013, the area dedicated to orange cultivation decreased; however, orange production continued to rise and stabilize, indicating improved productivity per area Since 2013, there has been a significant expansion in the area planted with oranges Notably, in 2016, orange production saw a 10.9% increase compared to 2015, followed by an impressive 18.7% rise in 2017.

2016, an increase of 151 thousand tons [35]

Cao Phong District in Hoa Binh Province is renowned for its substantial orange production, making it one of the largest suppliers in Northern Vietnam As of February 2017, the district boasts 2,080 hectares dedicated to citrus cultivation, with oranges covering 1,367 hectares Over 900 hectares are actively producing, yielding more than 23 million tons of oranges in 2016, and prices range from 25,000 to 35,000 VND per kilogram This thriving orange industry significantly contributes to the income of local farmers The annual harvest season typically runs from August to May, featuring various orange varieties that mature early, as well as main and late crops.

Sanh orange is cultivated across more than 7,000 hectares in 13 communes, involving over 4,000 households, with an average annual production of 80,000 to 100,000 tons and a market price of 40,000 to 50,000 VND per kg, yielding an estimated annual value exceeding 650 billion VND In 2007, Sanh orange received a product branding and trademark certificate from the National Office of Intellectual Property, earning its place among the "Top 50 famous Vietnamese specialty fruits," "Top 10 famous brands in Vietnam," and the "Vietnam Agricultural Gold Brand." Additionally, Vinh orange is grown in Nghe An's Quy Hop region, covering over 2,000 hectares, with an average yield of 27 tons per hectare, and some areas achieving productivity over 45 tons per hectare annually.

In Vietnam, orange products are crafted with a focus on food hygiene and safety, ensuring that every part of the fruit is utilized to minimize waste and provide additional income for growers These products, including orange peel jam, cough syrup, and essential oils, offer numerous health benefits such as mental refreshment, fever relief, and skin beauty enhancement Additionally, items like orange wine and jam significantly boost the value of the Vietnamese orange brand.

2.3.2 The situation of orange production and consumption worldwide

Figure 2.8 Orange production worldwide from 2012/2013 to 2018/2019

(in million metric tons) (M Shahbandeh, 2019)

From 2012 to 2019, global orange production experienced notable fluctuations, starting at 49.85 million metric tons in the 2012/2013 period and rising significantly to 54.28 million metric tons by 2018/2019.

Figure 2.9 Leading orange producing countries worldwide in 2018/2019

In the marketing year 2018/2019, Brazil emerged as the world's leading orange producer, yielding an impressive 20.16 million metric tons This accounted for a significant portion of the global orange production, which totaled 54.28 million metric tons that year.

Brazil account for about 37% of oranges production worldwide [36]

Following by Food and Agriculture Organization of the United Nations,

Statistical Bulletin, 2016; production of oranges of all countries in the world from

2008 to 2016, in the Northern Hemisphere, countries with a large production of oranges such as the USA, Mediterranean Region included Italy, Spain, Egypt, Turkey,

Mexico, China, India, Indonesia, Islamic Republic of Iran, Pakistan, in the Southern

Hemisphere have Brazil, South Africa [22], [36].

Products made from oranges

Orange juice: It has bright colors and a refreshing flavor extracted from fresh oranges and concentrated fresh orange juice and pasteurized to further retard spoilage

We can use orange juice to adds to drinks, candies and sweets

Orange peel extract is elaborated with orange peel and orange core The product is the perfect options for beverages, soft drinks, or food applications

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Not at 0 cm + 0.95 cm + 1.27 cm + 3.81 cm

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Dry orange juice powder is a versatile ingredient that can enhance a variety of products, including ready-made meals, jams, syrups, and flavorings It is also popular in orange-flavored tea and serves as a flavorful addition to cookies, icings, and cakes.

Orange syrup is primarily used in soft drinks and beverages, but its versatility extends to the production of ice creams, dairy products, baked goods, ready meals, jams, and other syrups This syrup typically has a brix level ranging from 41.0 to 44.0, making it a flavorful ingredient in various culinary applications.

Orange Essential Oil is a natural extract derived from the peels of various Citrus Sinensis fruits This oil is produced using a cold-pressed mechanical process that avoids thermal treatments, ensuring the preservation of its beneficial properties To maintain its quality, the oil is immediately packaged in drums following extraction.

Fruit jams are products made from fresh or semi-prepared fruits cooked with sugar to dryness of 65-70% Featured jam products are sweet, naturally pure aroma of berries

Many people enhance the natural sugar content of fruit by adding extra sugar when making fruit jams Additionally, jams with high acidity levels effectively inhibit the growth of microorganisms, ensuring better preservation.

Most fruit jams require pectin, a natural coagulant found in fruit, to achieve the desired texture Over time, jam may begin to separate, starting with surface moisture before spreading throughout the product Storing jam at low temperatures, maintaining a pH below 2.8, or exposing it to impurities and mechanical disturbances can accelerate its decomposition.

Jam classification: according to the state of product structure

- Processing from juice or fruit pure

- Create gel coagulated with pectin or agar

- There are 3 types: Jelly, Jam, Marmalade

- The dry matter content is about 60-65%

- Soft, slightly wet, no more sugar syrup around the product

- Outside there is a sugar coat crust

Candied orange slices are a delicious treat made by combining orange pieces with sugar and drying them at high temperatures This process results in a product that contains approximately 90% dry matter, offering a crispy texture reminiscent of dried jam.

General process of producing candied orange slices

Flow chart 1 General process of producing candied orange slices

The research titled "Research on Greening Disease Prevention and Trial Planting of New Orange Varieties in Ham Yen, Tuyen Quang Province, Vietnam" outlines a comprehensive procedure for producing high-quality oranges This procedure includes steps for effective disease prevention, selection of resilient orange varieties, and the implementation of trial planting methods to ensure optimal growth and yield.

Raw materials used to produce products must be of good quality, achieve maturity, a state of hardness and no defects, no smashing, meeting the standards of TCVN 1873: 2014

The fruits after selection and classification are washed to remove all impurities and microorganisms adhering to the crust

After washing, cut off the stem, the fruit is cut into thin slices, remove the seed, remove broken orange, and unsatisfactory orange piece to prepare for the next step

Soaking in lime water helps to increase the firmness of the product and removes some of the bitter substance in the orange peel

-Put the orange pieces into the prepared lime water and soak for 10 hours

-Rinse with clean water after soaking

Adding sugar to products not only enhances sweetness but also extends their shelf life Incorporating orange peels can boost flavor and improve preservation, but it's essential to treat the peels beforehand to minimize bitterness, which can negatively impact the quality of candied orange slices.

Soaking the sugar will help the orange pieces to soak into the sugar, while the melted sugar will avoid localized burning when concentrated

-Put the sugar into orange after draining

- After mixing sugar, let stand for 12 hours for the orange to soak into the sugar and dissolve

-Concentrate orange slices on low heat to avoid burning the product due to caramelized

-During the concentration process, stir well and do gently to avoid broken orange pieces

- Orange pieces after concentration will be uniform yellow, dry sugar will stick around

The drying process of product works to lose some of the water in the product, the product is drier, flexible, does not drain, and preserves longer

Procedure: The drying stage is used by specialized dry ovens

- Spread the orange pieces after concentrating on the drying tray

- Put the drying tray into the oven

Purpose: To continue releasing the remaining steam in the product, and to lower the temperature of the product, helping to prevent water when packaging

Procedure: After drying, remove the tray from the oven Cooling the product in two ways is a natural cooling and forced cooling:

+ Natural cooling: A method to cool after drying in the room and slowly

+ Forced cooling: As a fan-cooling method, this cooling method has advantages over natural cooling which is faster cooling time, the product is less changed

Purpose: To help the product is isolated from the outside environment, prolong the time of storage and use of the product

+ Prepare packaging: Can use PE bags or glass jars, plastic jars to contain products

Fully print product information on the package including product name, net weight, ingredients, production date, expiry date, instructions for use, address of the manufacturer, etc

+ In the bag: Need to seal the mouth of the bag (PE bag) or tighten the cap tightly (glass and plastic vials)

To extend the shelf life of high-sugar products, it is essential to store them in cold conditions at temperatures between 3 to 7°C While the storage process may not prevent water leakage, proper refrigeration on a small scale can effectively preserve the product's quality.

CONTENTS AND METHODS

Material

Raw oranges, primarily Chanh Orange and ripe oranges sourced from Thai Nguyen city, must adhere to specific technical ripeness standards The fruits should be free from rot and damage, possessing a natural aroma, and meeting the criteria outlined in TCVN 1873 - 2014.

- Sugar of Thanh Hoa company reaches TCVN 6959:2001, salt of Van Ninh company reaches TCVN 9639:2013

- Lime has been purchased at Thai market - Thai Nguyen City

3.1.2 Research instruments, equipment, and chemicals

Table 3.1 Research instruments and equipment

A dehydrator machine effectively dries fresh fruits while preserving their essential nutrients It is also utilized in the production of candied orange slices, significantly reducing processing time compared to traditional sun-drying methods By using a dehydrator, manufacturers can achieve higher quality products that meet food safety and hygiene standards.

3.1.3 The location and duration of research

- Location: Faculty of Biotechnology and Food Technology – Thai Nguyen

University of Agriculture and Forestry

Methods

3.2.1.1 Research on choosing the bitter elimination method of fresh orange

Table 3.3 Research on choosing the brine solution to the bitter elimination method of fresh orange

Formula Salt (ratio salt/water (%) Fixed factor

- Soaking time in lime water: 10h

Assessing the structure, flavor, taste, and color of the product, we used the sensory evaluation method After sensory evaluation, we have the result, and using the

The use of SPSS software for statistical analysis has determined the optimal ratio of salt to water and soaking time for processing orange jam Key index values obtained from the experiment include color at 0.8, taste at 1.2, and both flavor and structure at 1 The significant impact of salt in eliminating bitterness has resulted in taste being the highest valued index, underscoring its importance in enhancing the final product's flavor.

3.2.1.2 Research on choosing the ratio of orange and sugar to product quality Table 3.4 Research on choosing the ratio of orange and sugar to product quality

Formula 1 1.5:1.0 - Soaking time in lime water: 10h

- Ratio of Salt and water: was selected in experiment 1

In Experiment 2, three formulas with varying ratios of orange and sugar were tested, revealing that formula 2 exhibited distinct characteristics with a color score of 1.2, taste score of 1.2, flavor score of 0.8, and structure score of 0.8 The results indicated that sugar significantly impacts both the taste and color of the final product; excessive sugar leads to an overly sweet flavor and a brown hue post-drying, while insufficient sugar results in a bland taste Following a thorough evaluation and scoring, the optimal orange-to-sugar ratio will be selected for subsequent experiments.

3.2.1.3 Research on choosing drying temperature on product quality

Table 3.5 Research on choosing drying temperature on product quality

Formula Temperature (ᴼC) Fixed factor

Formula 1 50 - Soaking time in lime water: 10h

- Ratio of salt and water: was selected in experiment 1

- Ratio of Orange and Sugar: was selected in experiment 2

In this experiment, key indices were established: color (1.2), taste (0.8), flavor (0.8), and structure (1.2) The most critical factors in selecting the optimal drying temperature and time are the color and structure, which have the highest importance scores After thorough evaluation and scoring, we will determine the best drying temperature to finalize the production process effectively.

3.2.1.4 Evaluate the quality of the product candied orange slices finished product

- Determination of the moisture content by the method of drying to constant weight (TCVN 10788:2015);

- Determination of soluble dry matter content by refractometer (TCVN 4414:1987);

- Determination of vitamin C content in the product by the titration method of 0.01N iodine (Nguyễn Văn Mùi (2001))

- Determination of total organic acid content by the neutralization method with NaOH 0.1N (TCVN 4589:1988);

- Determination of total sugar content by Bertrand method (TCVN 4074-2009)

3.2.2 Physical and chemical analysis methods for evaluating the quality of the product candied orange slices finished product

3.2.2.1 Determining the moisture content by drying method to constant weight according to TCVN 10788:2015 [15]

- Principle: Use heat to evaporate the water contained in the sample From the mass difference before and after drying, the moisture content of the orange sample is calculated

3.2.2.2 The method of determining the content of soluble solids by refractometer according to TCVN 4414 – 1987 [13]

Light refraction occurs when light transitions from the atmosphere into a liquid medium, causing the light rays to bend, particularly in water-soluble solutions By analyzing the degree of this light deviation, we can assess the concentration of dissolved solids The refractometer provides a direct reading of the percentage concentration at a temperature of 20°C.

3.2.2.3 Methods of determining vitamin C content [5]

- Principle: Ascorbic acid has strong reducing is oxidized with iodine solution with the indicator is a starch solution:

In a solution containing vitamin C, I3 - is converted to iodide ion Once all the vitamin C is oxidized, iodine and I3 - appear in the solution, reacting with starch to produce a dark blue color, which indicates the endpoint of the titration.

3.2.2.4 Method of determining total organic acid according to TCVN 4589:1988

Organic acids dissolve readily in water, allowing for a straightforward titration process By using sodium hydroxide solution and phenolphthalein as an indicator, the quantity of organic acid present in a sample can be accurately determined.

3.2.2.5 The method for determining the total sugar content by the method Bertrand according to TCVN 4074-2009 [12]

The principle involves extracting total sugar from a sample using hot water, followed by hydrolyzing the sugar into glucose with hydrochloric acid (HCl) The glucose is then quantified through reactions with Fehling solution, iron (III) sulfate, and potassium permanganate.

3.2.3 Evaluating sensory quality by the method of the quality scoring (TCVN

The sensory quality of the product was evaluated during production testing using the scoring method outlined in TCVN 3215-79 This assessment focused on the product's structure, flavor, taste, and color, employing a comprehensive sensory evaluation approach.

In a controlled environment designed to minimize distractions, seven trained individuals participated in sensory tests where uniform lighting and water for rinsing were provided after each sample All testing conditions were standardized, and the presentation order of samples was randomized Prior to testing, unique codes for each sample were prepared, and the results were subsequently recorded and analyzed using SPSS software (Khetra, Y., Kanawjia, S K., & Puri, R (2016)) The sensory evaluation adhered to Vietnamese standards (TCVN 3215 - 79), which employ a systematic approach to sensory points.

20 points built on a unified system scale of 6 steps (from 0 to 5) and a score 5 is the highest for an indicator [11], [20], [23]

Following the sensory evaluation, results were analyzed using SPSS software A univariate analysis of variance was employed to statistically assess the data from the sensory evaluation of each sample, incorporating fixed factors and dependent variables.

We use the analysis of variance (ANOVA) to analyzed all scores of the sensory evaluation, to determine whether there were significant differences between means for each variable [23].

RESULTS

Research on choosing the bitter elimination method of fresh orange to product

To develop a market-responsive product that delivers economic efficiency, it is essential to identify the optimal mixing ratio of raw materials.

Experimental study the effect of the orange peel elimination method, we used brine with different concentrations to perform, included 0%, 2.5%, 5.0%, and 7.5%

According to TCVN 9639:2013, quality assurance salt was dissolved in water at varying concentrations for experimentation Oranges were soaked in the saltwater solution for 10 hours, while other parameters remained consistent as outlined in Table 3.3 The sensory evaluation results are presented in Table 4.1.

Table 4.1 Results for research on choosing the bitter elimination method of fresh orange to product quality

The ratio of salt/water (%) Formula 1 (0%) Formula 2 (2.5%) Formula 3 (5%) Formula 4 (7.5%)

(Note: Values in the same row with different exponents have significant differences at α = 0.05)

Table 4.1 highlights the significant impact of bitter taste on the aroma and flavor of dried orange jam, with the bitterness being influenced by the salt concentration used to soak 10 kg of oranges in each experiment At salt ratios ranging from 0% to 2.5%, the jam retained a bitter flavor However, using a 7.5% salt solution in Formula 4 resulted in the least bitterness, although the saltiness overpowered the overall taste, leading to a soft and crushed texture of the oranges In contrast, Formula 3, with a 5% salt ratio, produced a slight bitterness while enhancing the product's color and distinctive aroma.

The time to soak oranges in brine solution was determined during the experiment of 10

In our study, we discovered that oranges effectively reduced bitterness while preserving some beneficial properties of the peel Additionally, Formula 3 received the highest sensory evaluation score, excelling in four key sensory attributes: color, taste, flavor, and texture.

To ensure optimal product quality, the research identified an ideal mixing ratio of 1 kg of salt dissolved in 20 liters of water for every 10 kg of fresh oranges Soaking the oranges for 10 hours proved to be the most effective method before proceeding to the next experiment.

Research on choosing the ratio of orange and sugar to product quality

In our study, we first assessed the salt concentration, determining that a 5% brine solution effectively neutralized the bitter taste of fresh oranges Following this, we conducted a second experiment to find the optimal sugar-to-orange ratio, testing combinations of 1.5:1.0, 2.0:1.0, and 2.5:1.0 to enhance the flavor profile.

1.0 The addition of sugar aims to create an attractive aromatic sweetness, facilitating processing and storage After that, oranges continue to be concentrated in a sugar solution soaked earlier to help sugar soak into oranges This process should avoid excessive heating, resulting in a burning sugar that affects the color, taste, and structure of the orange The sensory evaluation result of the proportion of materials was presented in Table 4.2:

Table 4.2 Result for research on choosing the ratio of orange and sugar to product quality

The ratio of orange: sugar (kg:kg) Formula 1 (1.5:1.0) Formula 2 (2.0:1.0) Formula 3 (2.5:1.0)

Table 4.2 demonstrates that the average sensory criteria across various formulas differ significantly at the α = 0.05 level Formula 2 achieved the highest quality scores for color, flavor, taste, and structure, while Formula 3 showed a decline, resulting in the lowest scores overall.

In the quality assessment of the formulas, Formula 1 received low scores for color (3.0/5.0) and taste (3.86/5.0), indicating insufficient sweetness and a less appealing color after drying compared to other formulas Although Formula 3 outperformed Formula 1, it still fell short of Formula 2, with scores of 3.43/5 for color, 3.42/5 for flavor, 3.5 for taste, and 3.79/5 for structure, suggesting a moderate acceptance among sensory evaluators The 2.5:1.0 ratio of oranges to sugar in Formula 3 contributed to an overly sweet flavor, overshadowing the essence of orange peels, while the excessive sugar on the surface diminished the product's fresh orange characteristics.

We also find that formula 2 with the mixing ratio of 2.0 / 1.0 was assessed the highest sensory sensitivities, color reached 4.36 score, taste reached 4.5score, flavor reached

4.21 score, structure reached 4.36 score The product has a characteristic orange color, harmonious taste, light fragrance

Therefore, we selected the most appropriate ratio of orange and sugar mixing in formula 2 was 2: 1 to do the next experiments.

Research on choosing temperature on product quality

Drying is a method used to dry material to safe moisture to stabilize product quality and prolong shelf life The drying temperature was studied in the range of 50 -

60oC until the product reaches the required humidity, then evaluating the sensory quality of the product Sensory evaluation results are obtained in Table 4.3:

Table 4.3 Results for research on choosing the temperature and drying time on product quality

(Note: Values in the same roww column with different exponents have significant differences at α = 0.05)

According to Table 4.3, drying temperature affected product quality At the temperature of 50 o C-60 o C, when drying to a safe humidity, the sensory quality was

The study found that Formula 2 achieved the highest total score among the three formulas, with Formula 1 following closely and Formula 3 ranking the lowest Increasing the drying temperature to 60°C effectively reduced moisture content due to enhanced moisture loss At a drying temperature of 55°C, the product maintained a safe moisture level similar to that at 50°C, while also benefiting from a quicker drying time, which reduces implementation costs Both Formula 1 and Formula 2 exhibited favorable sensory scores in terms of color and structure, preserving the product's characteristics, whereas Formula 3 resulted in an unsatisfactory dark brown color and dry texture.

Based on Table 4.3, we selected formula 2 with the drying temperature of 55 o C to complete the product.

Evaluate the quality of the product candied orange slices finished product

After finalizing the production parameters for candied orange slices, the product is packaged in high-heat-sealed tin zip bags, weighing between 200-500g each A quality assessment conducted after six months of storage at normal conditions (20-25°C) is detailed in Table 4.4.

Table 4.4 The content of nutrients and microbiological criteria in candied orange slices products

Total dry matter content ( o Brix) 81.82 c 74.85 b 69.40 a

Moisture content is crucial for yeast and mold growth, with high humidity facilitating mold spore germination Mold growth is minimal at 20% relative humidity but accelerates significantly at 75%, becoming noticeable within weeks Our analysis revealed that the moisture content of the product was low (14-19%), effectively inhibiting mold growth for up to one year Additionally, the high sugar content (50.20 - 62.28%) in candied orange slices further prevents microorganism growth After six months, these candied orange slices maintained their flavor and successfully inhibited mold growth We also assessed the vitamin content in the product.

The vitamin C content of candied orange slices ranges from 16.85 to 28.83 mg%, with an average of 28.83 mg%, meeting 32.03% of the daily value (DV) requirements Additionally, the total organic acid content is between 164.35 and 203 mg%, while the total dry matter content is between 69% and 81% These findings indicate that candied orange slices maintain their nutritional value and flavor even after six months of storage With high quality and nutritional value, these products can be expected to preserve well for up to one year.

Establish a process for processing product candied orange slices

Based on the above experiments, we propose the technology procedure for producing candied orange slices as shown in the below:

The production process of candied orange slices (10kg fresh orange)

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Flow chart Figure 24 2 1.: The flow chart of the production process of candied orange slices

4.5.2 Description of the production process of candied orange slices

Figure 4.1 The main materials: Chanh orange and Sugar

The fruits after selection and classification are washed to remove all impurities and microorganisms adhering to the crust by clean water

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Step 3 Cutting the orange into slices orange

- After washing, cut off the stalk, the fruit is cut across the citrus into thin slices (about 0.5cm to 0.6cm) from the stem to the bottom

- Getting all the seeds out

- Remove the pieces of orange torn, unsatisfactory

Figure 4.3 Cutting slices orange and remove the seed

Step 4 Soaking the sliced orange in brine water

- Soak the orange pieces in 20 liters of 5% brine solution

- Purpose: To eliminate a part of bitter substance in orange skin

+ Put the orange pieces in the prepared saline and soak for 10 hours

+ Rinse with clean water 2-3 times to remove residual salt

+ Drain and make the process of soaking in lime water

Figure 4.4 Soaking the sliced orange in brine water

Step 5 Soaking in lime water

- Soaking the orange with the rate of 10kg of fresh oranges in 20l of freshly prepared lime water

- Purpose: to increase the crispy of the product

- Rinse with clean water from 2-3 times to remove all lime water

Figure 4.5 Soaking in lime water Step 6 Mixing with sugar

- The mixing ratio between oranges and sugar is 10kg of fresh oranges and 5kg of sugar

- Purpose: Soaking the sugar will help orange pieces to soak into the sugar, and melting sugar will avoid local sugar melting when concentrated

+ Pour sugar into orange after draining, can mix sugar in brass or pan

+ After mixing sugar, let stand for 10-12 hours to infuse orange pieces

+ Concentrate the slices orange on low heat to avoid burning the product due to caramelization

To ensure a smooth concentration process without breaking the orange pieces, gently stir the mixture using a chopstick in each hand Additionally, incorporate 20ml of honey to enhance the fragrance of the final product.

+ Orange pieces will gradually turn yellow

+ Orange pieces after concentration will be uniform yellow, have a thin layer of sugar surrouding the orange pieces

Figure 4.7 Concentrate by boiling sugar solution Step 8 Drying by drying oven

- Purpose: The drying process of orange jam has the effect of losing a quantity of water in the product, the jam is drier, flexible, not watery, and preserved for longer

- Procedure: The drying step is used by drying ovens

+ Spread the orange pieces after concentrating on the drying tray

+ Put the drying tray into the oven, the number of trays according to the design of the oven

+ Close the oven door and set up a time to dry for 24 hours

Figure 4.8 Drying orange pieces bt đ rying oven Step 9 Cooling

- Purpose: To continue releasing the remaining steam in the product, and to lower the temperature of the product, helping to prevent steam when packaging

- Procedure: After drying, remove the tray from the oven Cooling the product in two ways is a natural cooling and forced cooling:

Natural cooling is an effective method for reducing the temperature of a product after the drying process By allowing the product to cool at room temperature, its temperature can decrease from 55°C to the ambient temperature This technique ensures optimal cooling without the need for additional energy consumption.

+ Forced cooling: As a fan-cooling method, this cooling method has advantages over the natural cooling method which is faster cooling time, the product is less changed

- Purpose: To help the product is isolated from the outside environment, prolong the time of storage of the product

+ Prepare packaging: we use PE bags to contain products

Fully print information on the packaging, including product name, net weight, ingredients, production date, expiry date, instructions for use, address of the manufacturer,

+ In the bag: sealing of the bag PE bag

Figure 4.9 Packaging the candied orange slices product

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Despite their high sugar content, these products have low water levels, which can lead to leakage during storage To prolong their shelf life, it is essential to store them at a cold temperature of 3-5°C For smaller quantities, keeping jam in the refrigerator is an effective storage solution.

CONCLUSION AND RECOMMENDATIONS

Conclusion

Research conducted at the Faculty of Biotechnology and Food Technology, Thai Nguyen University of Agriculture and Forestry, has yielded significant findings on the processing of candied orange slices The experiments led to valuable conclusions regarding the production methods and quality of these products.

Soaking fresh oranges in a 5% saltwater solution effectively reduces the bitterness of the orange peel, resulting in a milder flavor while preserving the inherent taste of the fruit.

Determining the ratio of mixing orange and sugar was 2.0:1.0 The resulting product was a harmonious sweet taste and a slight aroma

Determining the drying temperature was 55°C for 24 hours to create a product with a safe humidity of 7.5%, the yellow color of the product

During a six-month storage period, significant changes were observed in the product's composition After processing, the product exhibited moisture content of 14.06%, dry matter content at 81.82 o Brix, total sugar content of 62.28%, vitamin C content at 203 mg%, and total organic acid content of 28.83% After three months, these values shifted to 16.70% moisture, 74.85 o Brix dry matter, 55.46% total sugar, 186.00 mg% vitamin C, and 21.10% total organic acids By the end of six months, the product's moisture content increased to 18.85%, dry matter decreased to 69.40 o Brix, total sugar dropped to 50.20%, vitamin C reduced to 164.35 mg%, and total organic acids fell to 16.85%.

Set up a production process of household-sized candied orange slices product with all accompanying technology parameters.

Overall objectives

Set up a process of candied orange slices products with high nutritional value, convenience, safety in use, and contributing to the diversification of orange products on the market.

Specific objectives

- To determine the effects of the bitter elimination method on product quality

- To determine the ratio of mixing orange and sugar on product quality

- To determine the effects of temperature and drying time on product quality

- Evaluate the quality of the product candied orange slices finished product

- Establish a process for processing the product's candied orange slices

Research questions

-Do we use salt water to remove all bitter taste of orange peel?

-Can we use other types of sugar add-in?what are other types of sugar?

-What is the effect of honey on the final product?

-What is the appropriate drying temperature?

Research hypotheses

-If we use 5% salt water, then candied orange slices will be de-bitter

-If we choose the ratio of oranges and sugar is 2:1, then the candied orange slices product will have a pertinent sweet taste

-If choosing the temperature for drying is 55 o C in 24h, then the product will be safe humidity

-The research is implemented in the laboratory, the equipment and machines are limited, cannot be done on a large scale and modern equipment such as the factory

-This is a new product that has never been studied before, so it takes time to research and experiment

Candied orange slices are a delightful treat made from fresh orange pieces that are coated in sugar and dried at high temperatures This process results in a product with approximately 90% dry matter, offering a crispy texture reminiscent of dried jam Enjoy the sweet and tangy flavor of these delicious snacks!

The origin of orange

Oranges, scientifically known as Citrus sinensis, are part of the citrus family and come in various sizes based on their variety These ripe fruits are characterized by their sweet and slightly sour flavor, making them a popular choice for many.

The origins of citrus fruits, particularly oranges, are debated, with evidence suggesting they have existed since 2200 BC in China, while some believe they are native to the Himalayas in India Oranges gained popularity in India before spreading to East and Southeast Asia By the 3rd century BC, orange trees made their way to Europe, flourishing in Mediterranean regions Christopher Columbus later introduced orange trees to America, and in subsequent years, they were cultivated in Australia and Africa Today, orange trees are widely grown across many countries worldwide.

Figure 2.1 Sanh orange and Vinh orange Structure of orange trees:

-Stems and branches of orange: Stems of woody type, semi-bush, with 4-6 main branches, 2 - 3m tall trees, low branches Spike direction, sparse, horizontal branching

-Orange leaves: Staggered leaves, longleaf, dark green, oval, 5-10cm long, 2.5-5cm wide, with a thin tooth edge; petioles with wings, 4-10mm wide Leaves with small ears [96]

Orange trees typically bloom in the spring, producing numerous small, white flowers that are clustered together and emit a light, pleasant aroma However, only a limited number of these flowers will develop into fruit.

Orange roots, similar to those of woody plants, efficiently absorb water and mineral salts Their root system is characterized as shallow, broad, and dense, primarily occupying the topsoil and porous soils This root system exhibits its most vigorous growth during February and September, thriving particularly well in the initial eight years of the plant's life.

- The oranges fruits are spherical, with a thin rind, orange-yellow when ripe, sweet, or slightly acidic [20]

Some varieties of oranges are grown in Vietnam:

Vinh orange, a citrus fruit native to Vinh in Nghe An, Vietnam, is characterized by its round shape and succulent texture, featuring a vibrant yellow color with hints of green This popular fruit comes in various varieties, including Xa Doai, Van Du, Song Con, and Navel oranges, each offering unique flavors and characteristics.

Xa Doai orange (Citrus sinensis 'XA DOAI') is a Spanish-origin orange variety cultivated in Vietnam, characterized by its two distinct shapes: high fruit and oval The average diameter of the fruit ranges from 6.8 to 7.8 cm, with each orange weighing between 200 to 250 grams and typically containing 10 to 12 segments Known for its juiciness, the fruit has a thick rind measuring 2-3 cm, and when ripe, it boasts a vibrant yellow peel.

• Song Con oranges imported by a French plantation owner planted on Dao Nguyen production hill (today's Song Con Farm) should be named "Song Con oranges"

Song Con oranges feature a thin skin, are juicy, sweet, and aromatic After 3-4 years of growth, they begin to yield high productivity and demonstrate excellent resistance to pests and diseases, making them ideal for various mountainous midland regions.

The Van Du orange, introduced to the Van Du orange farm in 1947 through a meticulous selection process, has become renowned for its exceptional quality This robust tree features a broad canopy and large, dark green leaves, producing medium-sized fruits that are juicy but contain numerous seeds The unique flavor profile of the Van Du orange is characterized by a rich sweetness with a hint of bitterness that quickly dissipates after consumption, making it a distinctive choice among orange varieties.

Navel oranges, also referred to as umbilical oranges, are native to California and were introduced to Vietnam in 1937, where they can still be found in various farms These oranges typically weigh around 230g, with some reaching up to 290g, and have a diameter of approximately 7.6 cm When ripe, the fruit displays a yellowish-gray color and contains 11 to 12 segments filled with dark yellow pulp.

Hai Duong oranges, predominantly cultivated in Thanh Ha and Tu Ky districts, are known for their significant size, with individual fruits weighing between 300 to 700 grams and measuring up to 10 centimeters in diameter These striking red-yellow oranges feature white cloves and contain 20 to 30 large, flat seeds, offering a unique flavor profile that balances sourness with a hint of bitterness Commonly referred to as Thanh Ha oranges or Dong Dinh oranges, they are a distinctive agricultural product of the Hai Duong region.

+ Sanh orange (C reticulata x C Sinensis: king mandarin)

Sanh orange, the most popular orange variety in Vietnam, is easily identifiable by its thick, bright green skin Its flesh is dark orange, sweet, and juicy, making it a favorite among locals.

Typical of king mandarin: Bo Ha oranges, Ha Giang, Tuyen Quang, Yen Bai,

Bo Ha oranges are grown in Bo Ha, Yen The district, Bac Giang province Bo Ha orange is suitable with mountainous midland, cool and humid climate

Ha Giang, Tuyen Quang, and Yen Bai are renowned for their high-quality oranges, primarily grown in the northern provinces of Vietnam, with peak harvest occurring during the Tet holiday Among these, Ham Yen oranges from Tuyen Quang province stand out for their exceptional taste, making this region particularly famous for its delicious citrus fruits.

+ Sweet orange (Citrus sinensis L.Osbeck)

Oranges are an average of 100g, featuring a thin skin that can be yellow, red, or dark red, making them easy to peel and divide There are three primary types of oranges: Canh oranges from Hanoi, Dong Du oranges from Hai Phong, and Ngoc Cuc and Hanh Thien oranges from Nam Ha Additionally, Bu oranges and Sour oranges, known for their slightly sour taste, are commonly found in Huong Son (Ha Tinh) and Tuyen Hoa (Quang Binh) The Voi orange, a hybrid of Bu and grapefruit, is notable for its large size, weighing between 300-350g, and is primarily cultivated in Tuyen Hoa (Quang Binh).

Characteristics of orange fruit

The composition of an orange consists of the following:

The flavedo, the outermost layer of the fruit, varies in color from orange to blue depending on the breed This layer is rich in essential oil sacs, contributing a robust flavor that closely resembles that of the orange pulp.

The white part of the rind (albedo): contains pectin and cellulose, has nearly the same amount of vitamin C as the flesh and other nutrients [139], [20]

Carpels with juicy vesicles: the inside contains, the orange cloves are cell fluids

A section of an orange: in it cure the orange cloves and the cell fluid

Orange seeds: hold sprout, include endosperm, embryo, seed coat [96]

Central column: The part located in the center of the orange, containing pectin and cellulose[96]

Table 2.1 Physical parameter of a sweet orange fruit [26]

1 Fruit color Yellow, orange, green

5 The average number of segment 10

9 The thickness of flavedo (mm) 1.8

Citrus is a valuable fruit tree on the international market, being one of the most traded fruits Moreover, this is a fruit with high nutritional value

Table 2.2 The nutritional composition of fresh orange (USDA) [33]

Nutritional composition of orange per 100 gram

Fresh oranges are primarily composed of carbohydrates and water, with minimal amounts of fat and protein The sweetness of these fruits comes from their natural sugars, including glucose, fructose, and sucrose Despite their relatively high sugar content, oranges have a low glycemic index, ranging from 31 to 51, which is classified as low (below 55) according to The University of Sydney's glycemic index scale This low glycemic index is associated with various health benefits.

Oranges are a rich source of dietary fiber, including pectin, cellulose, hemicellulose, and lignin, which significantly enhance digestive health and support beneficial gut bacteria Packed with essential vitamins and minerals, particularly vitamin C, thiamin, folic acid, and potassium, regular consumption of oranges contributes to overall well-being Additionally, the flavonoid hesperidin found in oranges is effective in preventing heart disease and promotes vascular health Studies indicate that drinking orange juice can lead to improved blood thinning and lower blood pressure While oranges are not high in iron, their vitamin C content aids in the absorption of iron, helping to combat anemia.

C, citric acid, etc, which enhances the absorption of iron from the digestive tract Therefore combining daily oranges supplements will help to prevent anemia [34]

The chemical composition of orange peel

Cellulose is a vital polymeric polysaccharide found in plant cells, characterized by its lack of sugar properties This insoluble substance can absorb water, swelling to hold about 7-8% of its weight in moisture.

Hesperidin C28H34O5 is abundant in citrus peels, has no bitter taste, has vitamin P activity

Naringin C27H32O14, both in the skin and in the citrus juices, when the fruit is green, naringin causes a bitter taste

Table 2.3 Summary of the composition, percentage, nutritional value, and pharmacological effects of each orange composition

(%) Nutritional value and pharmacological effects

Outer skin 19-21 Curing cough, asthma, dyspepsia, hernia pain, stomach pain

Inner skin 18-19 Anti-stomach ulcer, anti-coagulation, lowering blood pressure Fruit juice 59-61 Curing vitamin C deficiency

Seeds 1-2 Hemostasis can be used in medicine

According to TCVN 1873:2014, we have the following requirements for the quality of the oranges to produce candied orange slices as follows:

- Not crushed or damaged to the extent that it is unsuitable for use;

- Clean, virtually no foreign matter visible to the naked eye;

- Almost no insects that affect the appearance of the product;

- Hardly damaged by the pest;

- Do not experience abnormal moisture outside the enclosure, unless condensed due to release from the cold storage environment;

- Without any strange smell and / or taste;

- Not damaged by low temperatures and / or high temperatures;

- There is no sign of dry porosity inside;

- Virtually no bruises and / or many healed cuts;

- Fresh oranges must achieve appropriate growth and maturity.

Sugar

In the process of processing these products, people often add sugar to adjust the taste and sensory value of the product

Added sugar must meet standards, sucrose is extracted from sugarcane or sugar beets Sugar is white or yellow crystals, very soluble in water, and the solubility increases with temperature

The technical requirements of the sugar are as follows (TCVN 6959: 2001):

Table 2.4 Sensory indicators of sugar

Texture White crystals, relatively uniform in size, dry, no lumps

Taste Sugar crystals or sugar solution in water has a sweet taste, no strange smell

White crystals When diluted sugar in distilled water to make a clear solution

Ivory - white to white crystals When we mixed sugar with distilled water, the solution is relatively clear

Salt (sodium chloride)

Most commercially available jams, including apple, strawberry, and papaya varieties, do not require salt during production However, the presence of flavonoids, pectin, and citric acid in orange peel can impart a bitter flavor to orange jam To mitigate this bitterness and ensure consumer safety, incorporating natural ingredients along with a small amount of salt is beneficial.

According to TCVN 9639:2013, sensory indicators of salt must conform to the requirements specified in the following table:

Table 2.5 Sensory requirements of sodium chloride [ 518 ]

3 taste The solution has 5% of pure salt taste typical of salt, no strange taste

Lime water [37]

Lime water, with the chemical formula Ca(OH)2, is created by dissolving powdered lime (CaO) in water, resulting in a milky solution After allowing the mixture to settle, the clear water on top is collected for use.

Lime water is widely utilized in food preparation for its ability to enhance texture, making products crispy, chewy, and clear, ultimately contributing to an exceptional flavor While lime water is safe for consumption, achieving the ideal balance in its usage is essential for producing the best results.

Honey

Honey is a natural sweetener produced by bees, consisting primarily of carbohydrates such as fructose, glucose, and sucrose Its composition also includes water, minerals, nitrogen compounds, alkaloids, biological stimulants, plant antibiotics, enzymes, organic acids, essential oils, and antioxidants, which contribute to its potential health benefits, including cancer prevention.

Due to its sweetness and distinctive aroma, honey is utilized as an auxiliary ingredient in the production of candied orange slices, enhancing the overall quality of the product Given the high cost of honey, it is used sparingly and must be pure, free from any additives or mixtures To maintain its natural composition and quality, honey is neither heated nor processed, adhering to the standards set by TCVN 12605: 2019.

Table 2.6 Sensory requirements of honey (TCVN 12605: 2019)

1 color Honey comes in a variety of colors from almost colorless to dark brown color

2 smell The characteristic aroma of honey

3 taste From light sweet to strong sweet

4 texture From viscous liquid to crystalline

2.2 The importance of the orange industry to people and the economy

The importance of the orange industry to people

Oranges are a nutrient-dense fruit packed with vitamin C, fiber, folate, and antioxidants, while being low in calories and sugar Incorporating oranges into your daily diet can significantly nourish your body and support overall health.

Orange juice, as highlighted by M.D Nguyen Thi Hang, Vice Chairman of the Department of Eastern Medicine at the Vietnam Academy of Traditional Medicine, is rich in flavonoids and hesperidin antioxidants that promote health Additionally, its high vitamin C content can help lower blood pressure, while the diuretic properties of orange juice aid the kidneys in excreting excess salt and water, enhancing the body's resistance and reducing fatigue.

After intense exercise and sweating, consuming orange juice with a pinch of salt can effectively help restore fitness The fructose content and 85% water in oranges are rapidly absorbed by the body, providing a refreshing boost and enhancing overall recovery.

Enhance eyesight: Orange is rich in carotenoids and vitamin A These substances help enhance eyesight, especially good for women who have problems with macular degeneration [34]

Anti-cancer: Scientists have recently published the results of the prevent-cancer effects of orange juice It contains flavonoid substances like hesperidin and naringenin

Laboratory studies have shown that orange juice reduces childhood leukemia, as well as combating breast, liver, and colon cancers [31]

Reducing the risk of cardiovascular disease: Studies have shown that orange juice can help reduce the risk of heart disease because it can help improve blood circulation [34]

Oranges are rich in beta-carotene, a potent antioxidant that safeguards skin cells from damage and shields the skin against free radicals, helping to prevent the visible signs of aging.

Weight-loss support: A large orange contains 4 grams of fiber and only 87 calories Therefore, eating oranges helps you to prevent hunger, limit junk food habits

In addition, oranges are also rich in mineral vitamins to help you always feel healthy, full of energy [31]

To prevent viral infections, it's beneficial to consume foods high in polyphenols, which can enhance your immune system Oranges, in particular, are rich in polyphenols and offer various health benefits, including antiviral, anti-inflammatory, anti-allergic, anti-carcinogenic, and anti-proliferative properties.

The importance of the orange industry to people and the economy

Orange trees thrive in tropical climates and are relatively easy to cultivate and care for compared to other varieties Popular orange varieties, such as gourmet oranges, provide farmers with high income potential By implementing techniques for off-season flowering, farmers can enhance their selling prices, resulting in a significant boost to their income.

The expansion of both domestic and international consumption markets is generating job opportunities and boosting farmers' incomes, thereby enhancing their economic well-being This growth is also contributing to increased export turnover, which serves as a significant revenue source With just 1.5 hectares of land, it is estimated that farmers can achieve yields exceeding 80 tons per crop.

Orange trees play a vital role in enhancing the economic development of farmers To ensure sustainable efficiency in this model, it is essential for the functional sector to facilitate farmers' access to advanced techniques, quality seed sources, and stable markets for their produce, allowing them to focus confidently on their production efforts.

The situation of orange production and consumption in Vietnam and

2.3.1 The situation of orange production and consumption in Vietnam

Figure 2.6 Area planted oranges in Vietnam from 2005 to 2018

Based on the chart, we can see that the area of oranges growing from 2013 to

Since 2018, the area dedicated to orange cultivation in Vietnam has expanded significantly, rising from 75,000 hectares to over 120,000 hectares within five years This growth indicates Vietnam's commitment to investing in orange farming, which not only boosts productivity but also plays a vital role in the country's economic development.

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Figure 2.7 Orange production in Vietnam

Between 2005 and 2013, the area dedicated to orange cultivation decreased; however, orange production experienced a steady increase, indicating improved yield per area Since 2013, the area planted with oranges has significantly expanded Notably, in 2016, orange production rose by 10.9% compared to 2015, and in 2017, it further increased by 18.7%.

2016, an increase of 151 thousand tons [35]

Cao Phong District in Hoa Binh Province is renowned for being one of the largest orange producers in Northern Vietnam, boasting 2,080 hectares of citrus fruit as of February 2017, with oranges covering 1,367 hectares During the business period, over 900 hectares are dedicated to orange cultivation, yielding more than 23 million tons in 2016, with prices ranging from 25,000 to 35,000 VND per kilogram This significant production provides a vital source of income for local farmers The orange harvest season in Cao Phong typically spans from August to May of the following year, featuring early, main, and late-ripening varieties.

Sanh orange is cultivated across more than 7,000 hectares in 13 communes, involving over 4,000 households, with an annual production of 80,000 to 100,000 tons and a market price of 40,000 to 50,000 VND per kilogram, resulting in an estimated annual value exceeding 650 billion VND In 2007, it received a certificate for product branding and trademark recognition from the National Office of Intellectual Property, earning accolades such as being listed among the "Top 50 Famous Vietnamese Specialty Fruits," "Top 10 Famous Brands in Vietnam," and recognized as a "Vietnam Agricultural Gold Brand." Additionally, Vinh orange is primarily grown in Nghe An's Quy Hop region, covering over 2,000 hectares, with an average yield of 27 tons per hectare, and some areas achieving over 45 tons per hectare annually.

In Vietnam, orange specialties are processed with a focus on food hygiene and safety, ensuring that every part of the fruit, from skin to pulp, is utilized to minimize waste and provide additional income for orange growers Products derived from oranges, such as orange peel jam, cough syrup, and essential oils, offer significant health benefits, including mental refreshment and skin beauty, while also aiding in the treatment of colds and fevers Additionally, items like orange wine and jam enhance the value of the Vietnamese orange brand, showcasing the versatility and health advantages of these products.

2.3.2 The situation of orange production and consumption worldwide

Figure 2.8 Orange production worldwide from 2012/2013 to 2018/2019

From 2012 to 2019, global orange production experienced notable fluctuations In the 2012/2013 period, the production reached 49.85 million metric tons, while by 2018/2019, it had significantly risen to 54.28 million metric tons.

Figure 2.9 Leading orange producing countries worldwide in 2018/2019

In the 2018/2019 marketing year, Brazil emerged as the world's leading orange producer, generating an impressive 20.16 million metric tons This accounted for a significant portion of the global orange production, which totaled 54.28 million metric tons that year.

Brazil account for about 37% of oranges production worldwide [36]

Following by Food and Agriculture Organization of the United Nations,

Statistical Bulletin, 2016; production of oranges of all countries in the world from

2008 to 2016, in the Northern Hemisphere, countries with a large production of oranges such as the USA, Mediterranean Region included Italy, Spain, Egypt, Turkey,

Mexico, China, India, Indonesia, Islamic Republic of Iran, Pakistan, in the Southern

Hemisphere have Brazil, South Africa [22], [36]

Orange juice: It has bright colors and a refreshing flavor extracted from fresh oranges and concentrated fresh orange juice and pasteurized to further retard spoilage

We can use orange juice to adds to drinks, candies and sweets

Orange peel extract is elaborated with orange peel and orange core The product is the perfect options for beverages, soft drinks, or food applications

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Not at 0 cm + 0.95 cm + 1.27 cm + 3.81 cm

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Dry orange juice powder is a versatile ingredient that can enhance a variety of products, including ready-made meals, jams, syrups, and flavorings It is also commonly used to create orange-flavored tea and can be added to baked goods such as cookies, icings, and cakes for an extra burst of citrus flavor.

Orange syrup is primarily used in soft drinks and beverages, but its versatility extends to the production of ice creams, dairy products, bakery items, ready meals, jams, and various other syrups This syrup typically has a brix level ranging from 41.0 to 44.0, making it a flavorful ingredient for a wide array of culinary applications.

Orange Essential Oil is a natural product extracted from the peels of various Citrus Sinensis fruits This oil is obtained through a cold-pressed mechanical process that avoids any thermal treatments, ensuring the preservation of its beneficial properties To maintain its quality, the oil is promptly packed in drums immediately after extraction.

Fruit jams are products made from fresh or semi-prepared fruits cooked with sugar to dryness of 65-70% Featured jam products are sweet, naturally pure aroma of berries

Many people enhance the sweetness of fruit by adding significant amounts of sugar, despite the natural sugar already present in the fruit Additionally, fruit jams with high acidity levels can effectively inhibit the growth of microorganisms.

Most fruit jams require pectin, a natural coagulant found in fruit, for proper consistency Over time, jam can begin to separate, initially affecting its surface before spreading throughout the product If stored at low temperatures, with a pH below 2.8, or exposed to impurities and mechanical disturbances, the jam is more likely to deteriorate further.

Jam classification: according to the state of product structure

- Processing from juice or fruit pure

- Create gel coagulated with pectin or agar

- There are 3 types: Jelly, Jam, Marmalade

- Soft, slightly wet, no more sugar syrup around the product

- Outside there is a sugar coat crust

Candied orange slices are a delightful treat made by drying orange pieces with sugar at high temperatures, resulting in a product that contains approximately 90% dry matter These crispy, sweet snacks offer a unique blend of flavor and texture, making them a popular choice for both snacking and baking.

2.5 General process of producing candied orange slices

Flow chart 1 General process of producing candied orange slices

The research titled "Research on Greening Disease Prevention and Trial Planting of New Orange Varieties in Ham Yen, Tuyen Quang Province, Vietnam" outlines a comprehensive procedure for producing our product This procedure includes steps for preventing greening disease while effectively trialing new orange varieties to enhance agricultural output in the region.

Raw materials used to produce products must be of good quality, achieve maturity, a state of hardness and no defects, no smashing, meeting the standards of TCVN 1873: 2014

The fruits after selection and classification are washed to remove all impurities and microorganisms adhering to the crust

After washing, cut off the stem, the fruit is cut into thin slices, remove the seed, remove broken orange, and unsatisfactory orange piece to prepare for the next step

Soaking in lime water helps to increase the firmness of the product and removes some of the bitter substance in the orange peel

-Put the orange pieces into the prepared lime water and soak for 10 hours

-Rinse with clean water after soaking

Adding sugar to products enhances sweetness and extends shelf life Incorporating orange peels boosts flavor and preserves the product, but it's essential to process the peels beforehand to minimize bitterness, ensuring high-quality candied orange slices.