STRUCTURAL RELAXATION OF BINARY FOOD SYSTEMS LIU YETING (B. Appl. Sc. (Hons, 2nd Upper), NUS) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY FOOD SCIENCE AND TECHNOLOGY PROGRAMME C/O DEPARTMENT OF CHEMISTRY NATIONAL UNIVERSITY OF SINGAPORE 2009 ACKNOWLEDGEMENTS I would like to thank my supervisors Prof. Dr. Zhou Weibiao and Prof. Dr. Bhesh Bhandari for their insightful guidance and warm encouragement through the whole research project. Without them, this project could not succeed. Furthermore, they are also my mentors in the life. I also would like to thank my father Mr. Liu Quanda, my mother Ms. Zhang Juying, my sister Ms. Liu Yiping, and my girlfriend Miss Li Linglu for their unconditional love and support to my PhD study, without which I may not survive these years. During the PhD study, there are numerous kind people who provided me their help, including Ms. Lee Chooi Lan, Ms. Lew Huey Lee, Ms. Maria Chong, Mr. Abdul Rahaman Bin Mohd Noor, Dr. Yu Bin, Mr. Sam Yeo, Mr. Tan Choon Wah and etc. I also had many great students who assisted me to try new ideas. They are Miss Jiang Bin, Ms. Geradine Lim, Mr. Yu Pengcheng, Miss Kuah Huixin, Miss Nguyen Hai Duong, and Miss Yip Pei Jun. Many friends and postgraduate fellows also gave me their encouragement. I am very thankful to all of them. Last not least, I want to thank National University of Singapore for providing me the research scholarship and research grant (R-143-000-216-112). i TABLE OF CONTENTS SUMMARY VII LIST OF PUBLICATIONS . X LIST OF TABLES .XII LIST OF FIGURES . XIII 1. 2. INTRODUCTION 1.1. BACKGROUND .1 1.2. AIMS AND OBJECTIVES .3 1.3. THESIS OUTLINE .3 LITERATURE ENTHALPY REVIEW: RELAXATION GLASS OF TRANSITION AMORPHOUS AND FOOD SACCHARIDES 2.1. INTRODUCTION .6 2.2. AMORPHOUS SOLIDS .7 2.2.1. Concept of Amorphous State 2.2.2. Molecular Arrangement of Amorphous Solids 2.2.3. Amorphous Food Solid Materials 11 2.3. GLASS TRANSITION .12 2.3.1. Concept of Glass Transition 12 2.3.2. Molecular Mobility at Glass Transition Temperature .16 2.3.3. Physical Property Changes at Glass Transition Temperature 18 ii 2.3.4. Measurement of Glass Transition Temperature of Food Saccharides 25 2.3.5. Models for Prediction of Glass Transition Temperature .30 2.3.6. Influence of Glass Transition on Food Stability 35 2.4. ENTHALPY RELAXATION .38 2.4.1. Concept of Enthalpy Relaxation 38 2.4.2. Kinetics of Enthalpy Relaxation .45 2.4.2.1. Non-exponentiality 45 2.4.2.2. Non-linearity 47 2.4.3. Influence of Enthalpy Relaxation on Food Stability 49 2.5. 3. CONCLUSION .51 EFFECT OF GSS ADDITION ON GLASS TRANSITION AND ENTHALPY RELAXATION OF AMORPHOUS SUCROSE BASED MIXTURES 52 3.1. INTRODUCTION .52 3.2. MATERIALS AND METHODS 52 3.2.1. Sample Preparation .52 3.2.2. Thermal Analysis .54 3.3. 3.2.2.1. Unaged Experiments 55 3.2.2.2. Aging Experiments 56 RESULTS AND DISCUSSION 56 3.3.1. Glass Transition .56 3.3.2. Enthalpy Relaxation .59 3.4. CONCLUSION .72 iii 4. EFFECT OF WATER ADDITION ON GLASS TRANSITION AND ENTHALPY RELAXATION OF SUCROSE-GSS MIXTURES .74 4.1. INTRODUCTION .74 4.2. MATERIALS AND METHODS 76 4.2.1. Sample Preparation .76 4.2.2. Thermal Analysis .78 4.2.3. Mathematical Modeling .79 4.3. RESULTS AND DISCUSSION 80 4.3.1. Moisture Absorption 80 4.3.2. Glass Transition .82 4.3.3. Enthalpy Relaxation .88 4.4. 5. CONCLUSION .101 INDEPENDENCE OF Β VALUE IN KWW EQUATION ON AGING TEMPERATURE 103 6. 5.1. INTRODUCTION .103 5.2. THEORETICAL CONSIDERATION OF Β VALUE FOR DIFFERENT TA 105 5.3. MATERIALS AND METHODS 111 5.4. RESULTS AND DISCUSSION 111 5.5. CONCLUSION .117 EFFECT OF STARCH ADDITION ON GLASS TRANSITION & ENTHALPY RELAXATION OF SUCROSE BASED MIXTURES 120 6.1. INTRODUCTION .120 6.2. MATERIALS & METHODS 122 6.2.1. Sample Preparation .122 iv 6.2.2. Thermal Analysis .124 6.3. RESULTS & DISCUSSION .124 6.3.1. Glass transition 124 6.3.2. Enthalpy Relaxation .130 6.4. 7. CONCLUSION .134 EFFECT OF WATER ADDITION ON GLASS TRANSITION AND ENTHALPY RELAXATION OF SUGAR-STARCH MIXTURES .136 7.1. INTRODUCTION .136 7.2. MATERIALS & METHODS 138 7.3. RESULTS & DISCUSSION .139 7.3.1. Moisture Absorption 139 7.3.2. Glass Transition .141 7.3.3. Enthalpy Relaxation .144 7.4. 8. CONCLUSION .151 PRELIMINARY STUDY ON TEXTURE CHANGES OF TABLET AND CANDY SYSTEMS 153 8.1. INTRODUCTION .153 8.2. MATERIALS AND METHODS 155 8.2.1. Sample Preparation for Tablet 155 8.2.2. Structural Relaxation of Tablet 155 8.2.3. Sample Preparation for Candy 156 8.2.4. Structural Relaxation of Candy .158 8.3. RESULTS AND DISCUSSION 159 8.3.1. Sucrose-Starch Based Tablet .159 v 8.3.2. Sucrose-GSS Based Candy 161 8.4. 9. CONCLUSION .167 CONCLUSIONS AND RECOMMENDATIONS .169 9.1. EFFECT OF ANTI-PLASTICIZER ADDITION 169 9.2. EFFECT OF PLASTICIZER ADDITION .171 9.3. MACRO AND MICRO LEVEL STRUCTURAL RELAXATION .173 9.4. RECOMMENDATIONS FOR FUTURE RESEARCH 174 10. REFERENCES .176 vi SUMMARY This thesis advanced the study of structural relaxation into binary and tertiary food systems. It studied the effect of anti-plasticizers glucose syrup solid (GSS) and starch addition on sucrose based amorphous mixtures. It also studied the effect of plasticizer water addition on these two binary systems. Furthermore, it attempted to reveal the relationship between micro and macro level structural relaxations. Meanwhile, β value in Kohlrausch-Williams-Watts (KWW) equation was theoretically proved to be independent of sub-Tg aging temperature. In the sucrose-GSS system, increase of GSS generally did not elevate its Tg until its addition was more than 50% (w/w). A eutectic-like effect was found on Tg of S75G25. GSS addition increased relaxation time spectrum and reduced relaxation speed for enthalpy relaxation In sucrose-GSS-water system, the plasticization effect of water addition on glass transition was straightforward. Its addition showed complicated effects on the enthalpy relaxation. No clear relationship between β and water addition was found. Its initial addition from anhydrous state reduced enthalpy relaxation speed. But its further addition increased enthalpy relaxation speed (only for sucrose and GSS in this study). An exceptional case was found for S75G25 with an initial acceleration effect followed by retardation effect. vii In sucrose-starch system, increasing starch content did not increase Tg of the mixtures dramatically. It slightly reduced relaxation spectrum but dramatically reduced relaxation speed. In sucrose-starch-water system, water addition had a straightforward plasticization effect on glass transition. But it had different componentspecific effects on the enthalpy relaxation. There was no clear relationship between β values and water addition. Water had a retardation effect on the enthalpy relaxation speed by its initial addition from anhydrous state followed by an acceleration effect for further addition. However, its initial retardation effect was absent in Su20St80 and Su60St40. During the sub-Tg storage of the sucrose-starch tablets at 10˚C below their corresponding Tg, a sudden increase of Young’s modulus (E) was found in the first days during which a fast enthalpy relaxation took place. The Young’s modulus fell back to its previous level after this period and remained similar while a slow enthalpy relaxation took place. The sucrose-GSS based candy system was aged at three temperatures with different distance below their corresponding Tg in different humidity environments. The relationship between enthalpy relaxation and texture change depended on the stage of the enthalpy relaxation. There was an initial rapid stage of the enthalpy relaxation followed by a slow stage. In the initial rapid stage, there was no definite relationship between them. In the later slow stage, no definite relationship could be found between them either. However, viii when the enthalpy relaxation transited from the rapid stage to the slow stage, a sudden increase of breaking force was observed. In this thesis, the value of β was proved to be independent of aging temperatures for a glass, which means β should be the same for a glass at all aging temperatures. Mathematical modeling using same β for all aging temperatures and Matlab programming produced results with clearer trends and good model quality. ix further addition of water. Meanwhile, different plasticization effectiveness was found for different amorphous samples, for example, 1% addition of water could decrease the Tg by around 7ºC for GSS, around 4ºC for the sucrose-GSS mixtures of 25% GSS, around 8~10ºC for all sucrose-starch mixtures. In contrast to the straightforward plasticization effect of water addition on Tg, a complicated and component-specific relationship between the enthalpy relaxation and water addition was found for both sucrose-GSS mixtures and sucrose-starch mixtures. This is contradictive to the theoretical predication. In both mixtures, there was no clear relationship between β value and water addition. In the sucrose-GSS mixtures, water had an anti-plasticization (retardation) effect on the enthalpy relaxation speed (i.e. increase of τ values) by its initial addition from anhydrous state in most of the samples. Among those samples, only for sucrose and GSS, further addition of water was found to have an expected plasticization (acceleration) effect on the enthalpy relaxation speed (i.e. decrease of τ values). And the threshold value of water addition for its plasticization effect was different between sucrose and GSS. Meanwhile, an exceptional case was found for the sucrose-GSS mixture with 25% GSS, in which the initial addition of water from anhydrous state had a plasticization effect on the enthalpy relaxation speed, and further addition of water had an anti-plasticization effect. Different component specific effects of water addition were also found in the sucrose-starch mixtures. Water had an anti-plasticization (retardation) effect on the enthalpy relaxation speed by its initial addition from anhydrous state 172 followed by a plasticization effect for further addition, in some samples including sucrose, Su80St20, and Su40St60. However, the anti-plasticization effect by the initial addition was absent in Su20St80 and Su60St40, in which only plasticization effect was found for water addition. Complex mechanism such as “hole-filling” and “cold-relaxation” behind the effect of water addition could exist due to the small size of water molecule. The effect of water addition on the enthalpy relaxation deemed to be specific to individual samples and an ad-hoc approach is suggested for such studies. The effect of water addition into an amorphous material also requires an understanding of the nature of their molecular interactions. In this study, the effect of water addition was quite straightforward on the glass transition but component specific on the enthalpy relaxation. When the addition level was low, either an anti-plasticization effect or a plasticization effect could take place depending on the molecular interaction between them. However, its further addition would have a plasticization effect in most of the samples. 9.3. Macro and Micro Level Structural Relaxation The relationship between macro- and micro-level structural relaxation was studied using a sucrose-starch based tablet system and a sucrose-GSS based candy system. During the sub-Tg storage of the sucrose-starch tablets at 10˚C below their corresponding Tg, a sudden increase of Young’s modulus (E) was found in the first days during which a fast enthalpy relaxation took place. 173 Young’s modulus fell back to its previous level after this period and remained similar while a slow enthalpy relaxation took place. The sucrose-GSS based candy system was aged at different temperatures and also in different humidity environments. The samples were aged at three temperatures with different distance below their corresponding Tg, so that different enthalpy relaxation kinetics could be associated with different subTg relaxation conditions. It was found that the relationship between the enthalpy relaxation and texture change depended on the stage of the enthalpy relaxation. For the enthalpy relaxation, there was an initial rapid stage followed by a slow stage. In the initial rapid stage, no clear relationship could be found between them, e.g. in the candy samples with 50% GSS in the first days and the candy samples with 75% GSS in the entire observation period of 28 days. In the later slow stage, no clear relationship could be found between them either, e.g. in the candy samples with 25% GSS after days and the candy samples with 50% GSS after days. However, when the enthalpy relaxation transited from the rapid stage to the slow stage, a sudden increase of the breaking force was observed in the candy samples with 50% GSS. 9.4. Recommendations for Future Research This project has advanced the study of structural relaxation to binary and tertiary food systems. Furthermore, it has attempted to reveal the relationship between micro and macro level structural relaxation. However, due to the complex nature of food materials such as GSS and starch, many of the 174 findings demands further understanding of fundamental issues, particularly on the molecular mobility and interactions. It may be a good idea to study the enthalpy relaxation of some simple mixtures before advancing to complex materials. Taking glucose, maltose, maltotriose, and other maltodextrin components with similar chemical structure as an example, study of some binary mixtures containing components chosen from this group could help to better reveal the relationship between the effect of plasticizer/anti-plasticizer addition and the enthalpy relaxation kinetics. Meanwhile, the experimental design for studying the relationship between the micro and macro structural relaxation in this thesis was still preliminary. More studies need to be conducted on this subject to better understand their relationship. Other physical properties such as gas permeability of thin film may better represent the macro structural relaxation. Study between them and the enthalpy relaxation kinetics may show clearer quantitative relationship between the macro- and micro-level structural relaxation. 175 10. REFERENCES 1. Broadhead, J.; Rouan Edmond, S. K.; Rhodes, C. T., The spray drying of Pharmaceuticals. Drug Dev. Ind. Pharm. 1992, 18, 1169-1206. 2. Bhandari, B.; Howes, T., Implication of Glass Transition for the Drying and Stability of Dried Foods. Journal of Food Engineering 1999, 40, 71-79. 3. Hancock, B. C.; Zografi, G., Characteristics and significance of the amorphous state in pharmaceutical system. Journal of Pharmaceutical Science 1997, 86, (1), 1-12. 4. Kim, J. Y.; Suzuki, T.; Hagiwara, T.; Yamaji, I.; Takai, R., Enthalpy Relaxation and Glass to Rubber Transition of Amorphous Potato Starch Formed by Ball-Milling. Carbohydrate Polymers 2001, 46, (1-6). 5. Le Meste, M.; Champion, D.; Roudaut, G.; Blond, G.; Simatos, D., Glass transition and food technology: A critical appraisal. Journal of Food Science 2002, 67, (7), 2444-2458. 6. Yu, L., Amorphous pharmaceutical solids: preparation, characterization and stabilization. Advanced Drug Delivery Reviews 2001, 48, (1), 27-42. 7. Simatos, D.; Blond, G.; Perez, J., Physical Aspects of Glass Transition. In Food Preservations by Moisture Control: fundamentals and applications, Barbosa-Canovas, Q. V.; Welti-Chanes, J., Eds. Technomic Publishing Co. Inc: Lancaster, PA, 1995; pp 1-31. 8. Champion, D.; Le Meste, M.; Simatos, D., Towards an improved understanding of glass transition and relaxations in foods: molecular mobility 176 in the glass transition range. Trends in Food Science & Technology 2000, 11, (2), 41-55. 9. Kim, J. Y.; Hagiwara, T.; Kawai, K.; Suzuki, T.; Takai, R., Kinetic process of enthalpy relaxation of glassy starch and effect of physical aging upon its water vapor permeability property. Carbohydrate Polymers 2003, 53, (3), 289-296. 10. Dmowski, W.; Fan, C.; Morrison, M. L.; Liaw, P. K.; Egami, T., Structural changes in bulk metallic glass after annealing below the glasstransition temperature. Materials Science and Engineering: A 2007, 471, (1-2), 125-129. 11. Yoshida, H., Relationship between enthalpy relaxation and dynamic mechanical relaxation of engineering plastics. Thermochimica Acta 1995, 266, 119-127. 12. Bhandari, B.; Hartel, R., Phase transitions during food powder production and powder stability. In Encapsulated and Powdered Foods, Onwulata, C., Ed. Taylor and Francis: New York, 2005; pp 262-291. 13. Rahman, M., Glass Transition and Other Structural Changes in Foods. In Handbook of Food Preservation, Rahman, M. S., Ed. Marcel Dekker: New York, 1999; pp 75-93. 14. Bidault, O.; Assifaoui, A.; Champion, D.; Le Meste, M., Dielectric spectroscopy measurements of the sub-Tg relaxations in amorphous ethyl cellulose: a relaxation magnitude study. Journal of Non-Crystalline Solids 2005, 351, (1167-1178). 177 15. Perez, J., Theories of Liquid-Glass Transition. In Water in Foods, Fito, P.; Mulet, A.; Mc Kenna, B., Eds. Elsevier Applied Science: New York, 1994; pp 89-114. 16. Johari, G. P.; Goldstein, M., Viscous Liquids and the Glass Transition II Secondary Relaxation in Glasses of Rigid Molecules. Journal of Chemical Physics 1970, 53, 2372-2388. 17. Johari, G. P., Effects of Annealing on Secondary Relaxations in Glasses. Journal of Chemical Physics 1982, 77, 4619-4626. 18. Fennema, O. R., Water and Ice. In Food Chemistry, 3rd ed.; Fennema, O. R., Ed. Marcel Dekker: New York, 1996; pp 17-94. 19. Chung, H. J.; Chang, H. I.; Lim, S. T., Physical aging of glassy normal and waxy rice starches: Effect of crystallinity on glass transition and enthalpy relaxation. Carbohydrate Polymers 2004, 58, (2), 101-107. 20. Schmidt, S. J., Water and solids mobility in foods. Advances in Food and Nutrition Research 2004, 48, 1-101. 21. Orford, P. D.; Parker, R.; Ring, S. G., Aspects of the Glass-Transition Behavior of Mixtures of Carbohydrates of Low-Molecular-Weight. Carbohydrate Research 1990, 196, 11-18. 22. Wungtanagorn, R.; Schmidt, S. J., Thermodynamic properties and kinetics of the physical ageing of amorphous glucose, fructose, and their mixture. Journal of Thermal Analysis and Calorimetry 2001, 65, (1), 9-35. 23. Wungtanagorn, R.; Schmidt, S. J., Phenomenological study of enthalpy relaxation of amorphous glucose, fructose, and their mixture. Thermochimica Acta 2001, 369, (1-2), 95-116. 178 24. Schmidt, S. J.; Lammert, A. M., Physical aging of maltose grasses. Journal of Food Science 1996, 61, (5), 870-875. 25. Saleki-Gerhardt, A.; Zografi, G., Nonisothermal and isothermal crystallization of sucrose from the amorphous state. Pharmaceutical Research 1994, 11, (8), 1166-1173. 26. Shamblin, S. L.; Zografi, G., Enthalpy relaxation in binary amorphous mixtures containing sucrose. Pharmaceutical Research 1998, 15, (12), 18281834. 27. Roos, Y. H.; Karel, M., Water and Molecular-Weight Effects on Glass Transitions in Amorphous Carbohydrates and Carbohydrate Solutions. Journal of Food Science 1991, 56, (6), 1676-1681. 28. Genin, N.; Rene, F., Analysis of the Role of Glass-Transition in Food- Processing. Journal of Food Engineering 1995, 26, (4), 391-408. 29. Williams, M. L.; Landel, R. F.; Ferry, J. D., The temperature dependence of relaxation mechanisms in amorphous polymers and other glassforming liquids. Journal of American Chemists Association 1955, 77, 37013707. 30. Angell, C. A.; Bressel, R. D.; Green, J. L.; Kanno, H.; Oduni, M.; Sarre, E. J., Liquid fragility and glass transition in water and aqueous solutions. In Water in Foods, Fito, P.; Mulet, A.; Mc Kenna, B., Eds. Elsevier Applied Science: New York, 1994; pp 115-142. 31. Angell, C. A., Formation of Glasses from Liquids and Biopolymers. Science 1995, 267, (5206), 1924-1935. 32. Crowley, K. J.; Zografi, G., The use of thermal methods for predicting glass-former fragility. Thermochimica Acta 2001, 380, (2), 79-93. 179 33. Liu, Y.; Bhandari, B.; Zhou, W., Glass transition and enthalpy relaxation of amorphous food saccharides: A review. Journal of Agricultural and Food Chemistry 2006, 54, (16), 5701-5717. 34. Roos, Y. H., Characterization of Food Polymers Using State Diagrams. Journal of Food Engineering 1995, 24, (3), 339-360. 35. Shamblin, S. L.; Taylor, L. S.; Zografi, G., Mixing behavior of colyophilized binary systems. Journal of Pharmaceutical Sciences 1998, 87, (6), 694-701. 36. Gordon, M.; Taylor, J. S., Ideal co-polymers and the second-order transitions of synthetic rubbers 1. Non-crystalline co-polymers. . Journal of Applied Chemistry 1952, 2, 493-500. 37. Simha, R.; Boyer, R. F., On a general relation involving the glass temperature and coefficients of expansions of polymers. Journal of Chemical Physics 1962, 37, 1003-1007. 38. Truong, V.; Bhandari, B. R.; Howes, T.; Adhikari, B., Analytical model for the prediction of glass transition temperature of food systems. In Amorphous food and pharmaceutical systems, Levine, H., Ed. Royal Society of Chemistry: Cambridge, 2002; pp 31-47. 39. Kalichevsky, M. T.; Jaroszkiewicz, E. M.; Blanshard, J. M. V., A Study of the Glass-Transition of Amylopectin Sugar Mixtures. Polymer 1993, 34, (2), 346-358. 40. Shamblin, S. L.; Huang, E. Y.; Zografi, G., The effects of co- lyophilized polymeric additives on the glass transition temperature and crystallization of amorphous sucrose. Journal of Thermal Analysis 1996, 47, (5), 1567-1579. 180 41. Lopez, E. C.; Champion, D.; Blond, G.; Le Meste, M., Influence of dextran, pullulan and gum arabic on the physical properties of frozen sucrose solutions. Carbohydrate Polymers 2005, 59, (1), 83-91. 42. Gabarra, P.; Hartel, R. W., Corn syrup solids and their saccharide fractions affect crystallization of amorphous sucrose. Journal of Food Science 1998, 63, (3), 523-528. 43. Kets, E. P. W.; Ijpelaar, P. J.; Hoekstra, F. A.; Vromans, H., Citrate increases glass transition temperature of vitrified sucrose preparations. Cryobiology 2004, 48, (1), 46-54. 44. Kilburn, D.; Claude, J.; Mezzenga, R.; Dlubek, G.; Alam, A.; Ubbink, J., Water in glassy carbohydrates: Opening it up at the nanolevel. Journal of Physical Chemistry B 2004, 108, (33), 12436-12441. 45. Bizot, H.; LeBail, P.; Leroux, B.; Davy, J.; Roger, P.; Buleon, A., Calorimetric evaluation of the glass transition in hydrated, linear and branched polyanhydroglucose compounds. Carbohydrate Polymers 1997, 32, (1), 33-50. 46. Peleg, M., Description of Mechanical Changes in Foods at Their Glass Transtion Region. In Food Preservations by Moisture Control: fundamentals and applications, Barbosa-Canovas, Q. V.; Welti-Chanes, J., Eds. Technomic Publishing Co. Inc: Lancaster, PA, 1995; pp 659-671. 47. Fotheringham, U.; Muller, R.; Erb, K.; Baltes, A.; Siebers, F.; Wei, E.; Dudek, R., Evaluation of the calorimetric glass transition of glasses and glass ceramics with respect to structural relaxation and dimensional stability. Thermochimica Acta 2007, 461, (1-2), 72-81. 181 48. Adam, G.; Gibbs, J. H., On the temperature dependence of cooperative relaxation properties in glass-forming liquids. Journal of Chemical Physics 1965, 43, 138-146. 49. Montes, H.; Mazeau, K.; Cavaille, J. Y. In The mechanical beta relaxation in amorphous cellulose, 3rd International Discussion Meeting on Relaxations in Complex Systems, Vigo, Spain, Jun 30-Jul 11, 1997; Vigo, Spain, 1997; pp 416-421. 50. Urbani, R.; Sussich, F.; Prejac, S.; Cesaro, A., Enthalpy relaxation and glass transition behaviour of sucrose by static and dynamic DSC. Thermochimica Acta 1997, 305, 359-367. 51. Truong, V.; Bhandari, B.; Howes, T.; Adhikari, B., Physical Aging of Amorphous Fructose. Journal of Food Science 2002, 26, (8), 3011-3018. 52. Moynihan, C. T.; Easteal, A. J.; Debolt, M. A., Dependence of fictive temperature of glass on cooling rate. J. Am. Ceram. Soc. 1976, 59, 12-16. 53. Montserrat, S., Physical Aging Studies in Epoxy-Resins .1. Kinetics of the Enthalpy Relaxation Process in a Fully Cured Epoxy-Resin. Journal of Polymer Science Part B-Polymer Physics 1994, 32, (3), 509-522. 54. Surana, R.; Pyne, A.; Rani, M.; Suryanarayanan, R., Measurement of enthalpic relaxation by differential scanning calorimetry - effect of experimental conditions. Thermochimica Acta 2005, 433, (1-2), 173-182. 55. Hancock, B. C.; Shamblin, S. L.; Zografi, G., Molecular mobility of amorphous pharmaceutical solids below their glass-transition temperatures. Pharmaceutical Research 1995, 12, (6), 799-806. 56. Lammert, A. M.; Lammert, R. M.; Schmidt, S. J., Physical aging of maltose glasses as measured by standard and modulated differential scanning 182 calorimetry. Journal of Thermal Analysis and Calorimetry 1999, 55, (3), 949975. 57. Chung, H. J.; Lim, S. T., Physical aging of glassy normal and waxy rice starches: thermal and mechanical characterization. Carbohydrate Polymers 2004, 57, (1), 15-21. 58. Hodge, I. M., Enthalpy Relaxation and Recovery in Amorphous Materials. Journal of Non-Crystalline Solids 1994, 169, (3), 211-266. 59. Slobodian, P.; Riha, P.; Rychwalski, R. W.; Emri, I.; Saha, P.; Kubat, J., The relation between relaxed enthalpy and volume during physical aging of amorphous polymers and selenium. European Polymer Journal 2006, 42, (10), 2824-2837. 60. Lourdin, D.; Colonna, P.; Brownsey, G. J.; Noel, T. R.; Ring, S. G., Structural relaxation and physical ageing of starchy materials. Carbohydrate Research 2002, 337, (9), 827-833. 61. Hu, C.-C.; Fu, Y.-J.; Hsiao, S.-W.; Lee, K.-R.; Lai, J.-Y., Effect of physical aging on the gas transport properties of poly(methyl methacrylate) membranes. Journal of Membrane Science 2007, 303, (1-2), 29-36. 62. Surana, R.; Pyne, A.; Suryanarayanan, R., Effect of aging on the physical properties of amorphous trehalose. Pharmaceutical Research 2004, 21, (5), 867-874. 63. Vyazovkin, S.; Dranca, I., Effect of physical aging on nucleation of amorphous indomethacin. Journal of Physical Chemistry B 2007, 111, (25), 7283-7287. 64. Gunawan, L.; Johari, G. P.; Shanker, R. M., Structural relaxation of acetaminophen glass. Pharmaceutical Research 2006, 23, (5), 967-979. 183 65. Shamblin, S. L.; Hancock, B. C.; Pikal, M. J., Coupling between chemical reactivity and structural relaxation in pharmaceutical glasses. Pharmaceutical Research 2006, 23, (10), 2254-2268. 66. Poirier-Brulez, F.; Roudaut, G.; Champion, D.; Tanguy, M.; Simatos, D., Influence of sucrose and water content on molecular mobility in starchbased glasses as assessed through structure and secondary relaxation. Biopolymers 2006, 81, (2), 63-73. 67. Vanhal, I.; Blond, G., Impact of melting conditions of sucrose on its glass transition temperature. Journal of Agricultural and Food Chemistry 1999, 47, (10), 4285-4290. 68. Christensen, K. L.; Pedersen, G. P.; Kristensen, H. G., Physical stability of redispersible dry emulsions containing amorphous sucrose. European Journal of Pharmaceutics and Biopharmaceutics 2002, 53, (2), 147153. 69. Bhandari, B.; Hartel, R., Kinetics of enthalpy relaxation in corn-syrup– sucrose mixtures. . Personal communication 2006. 70. Hancock, B. C.; Zografi, G., The relationship between the glass- transition temperature and the water-content of amorphous pharmaceutical solids. Pharmaceutical Research 1994, 11, (4), 471-477. 71. Seow, C. C.; Cheah, P. B.; Chang, Y. P., Antiplasticization by Water in Reduced-Moisture Food Systems. Journal of Food Science 1999, 64, (4), 576581. 72. Pittia, P.; Sacchetti, G., Antiplasticization effect of water in amorphous foods. A review. Food Chemistry 2008, 106, (4), 1417-1427. 184 73. Wolkers, W. F.; Oliver, A. E.; Tablin, F.; Crowe, J. H., A fourier- transform infrared spectroscopy study of sugar glasses. Carbohydrate Research 2004, 339, (6), 1077-1085. 74. Makower, B.; Dye, W. B., Equilibrium moisture content and crystallization of amorphous sucrose and glucose. Agricultural and Food Chemistry 1956, 4, (1), 72-77. 75. Roos, Y.; Karel, M., Plasticizaing effect of water on thermal behavior and crystallizaiton of amorphous food models. Journal of Food Science 1991, 56, (1), 38-43. 76. Roberts, G. E.; White, E. F. T., Relaxation processess in amorphous polymers. In The physics of glassy polymers, Haward, R. N., Ed. Applied Science Publishers: London, 1973; pp 153-222. 77. Butzbach, G. D.; Wendorff, J. H., Polycarbonate-poly(methyl methacrylate) blends: the role of molecular interactions on miscibility and antiplasticization. Polymer 1991, 32, 1155-1159. 78. Ngai, K. L.; Rendell, R. W.; Yee, A. F.; Plazek, D. J., Antiplasticization effects on a secondary relaxation in plasticized glassy polycarbonates. Marcomolecules 1991, 24, 61-67. 79. Benczedi, D.; Tomka, I.; Escher, F., Thermodynamics of amorphous starch-water systems. 1. Volume fluctuations. Macromolecules 1998, 31, (9), 3055-3061. 80. Liu, Y.; Roy, A. K.; Jones, A. A.; Inglefiled, P. T.; Ogden, P., An NMR study of plasticization and antiplasticization of a polymeric glass. Macromolecules 1990, 23, 968-977. 185 81. Johari, G. P., Structural changes and molecular mobility during aging of glasses. Journal de Physique Colloques 1985, 46, C8, 567-572. 82. Kawai, K.; Hagiwara, T.; Takai, R.; Suzuki, T., Comparative investigation by two analytical approaches of enthalpy relaxation for glassy glucose, sucrose, maltose, and trehalose. Pharmaceutical Research 2005, 22, (3), 490-495. 83. Haque, M. K.; Kawai, K.; Suzuki, T., Glass transition and enthalpy relaxation of amorphous lactose glass. Carbohydrate Research 2006, 341, (11), 1884-1889. 84. Truong, V.; Bhandari, B.; Howes, T.; Adhikari, B., Physical Aging of Amorphous Fructose. Journal of Food Science 2002, 26, (8), 3011-3018. 85. Wungtanagorn, R.; Schmidt, S. J., Thermodynamic properties and kinetics of the physcial ageing of amorphous glucose, fructose, and their mixture. Journal of Thermal Analysis and Calorimetry 2001, 65, 9-35. 86. Orford, P. D.; Parket, R.; Ring, S. G., Aspects of the glass transition behavior of mixtures of carbohydrates of low macular weight. Carbohydrate Research 1990, 196, 11-18. 87. Wungtanagorn, R.; Schmidt, S. J., Phenomenological Study Enthalpy Relaxation of Amorphous Glucose, Fructose, and Their Mixture. Thermochimica Acta 2001, 369, 95-116. 88. Cowie, J. M. G.; Ferguson, R., Physical aging studies in polyvinyl methyl-ether) .1. Enthalpy relaxation as a function of aging temperature. Macromolecules 1989, 22, (5), 2307-2312. 186 89. Howarth, J. A. K., Ready-to-Eat Breakfast Cereals. In Shelf-life Evaluation of Foods, 2nd ed.; Man, C. M. D.; Jones, A. A., Eds. Aspen Publishers: Gaithersburg, MD, 2000; p 183. 90. Carvalho, C. W. P.; Mitchell, J. R., Effect of sucrose on starch conversion and glass transition of nonexpanded maize and wheat extrudates. Cereal Chemistry 2001, 78, (3), 342-348. 91. Mezreb, K.; Goullieux, A.; Ralainirina, R.; Queneudec, M., Effect of sucrose on the textural properties of corn and wheat extrudates. Carbohydrate Polymers 2006, 64, (1), 1-8. 92. Liu, Y.; Selomulyo, V. O.; Zhou, W., Effect of high pressure on some physicochemical properties of several native starches. Journal of Food Engineering 2008, 88, (1), 126-136. 187 [...]... studies on the enthalpy relaxation of food materials were limited only to several single food compounds such as sucrose, fructose, glucose, maltose, and starch This thesis extended the study of structural 3 relaxation into binary and tertiary food systems Two binary food model systems were studied including sucrose-starch syrup solid system and sucrosestarch system The effect of GSS addition on the... enthalpy relaxation of sucrose-GSS based amorphous systems; 3 to study the effect of starch addition on glass transition and enthalpy relaxation of sucrose-based amorphous systems; 4 to study the effect of water addition on glass transition and enthalpy relaxation of sucrose-starch based amorphous systems; 5 to study the relationship between micro and macro level structure relaxation during sub-Tg relaxation, ... towards the more stable state This kind of change is called structural relaxation Structural relaxation is commonly named as enthalpy relaxation when enthalpy is monitored or volume relaxation when free volume is monitored Both enthalpy relaxation and volume relaxation are categorized as micro-level structural relaxation, because it is believed that structural relaxation is also accompanied by changes... macro-level structural relaxation In the field of synthetic polymer, the micro level structural relaxation (enthalpy relaxation) is recognized as an important factor related to changes in the physical properties of polymer, because the rate of enthalpy relaxation is estimated as the molecular motion at temperature below Tg (11) Due to 2 limited information on the enthalpy relaxation kinetics of food materials,... molecular mobility and food stability is largely unexplored 1.2 Aims and Objectives This research project intended to advance the knowledge of structural relaxation into binary and tertiary food systems with the below objectives: 1 to study the effect of GSS (glucose syrup solid) addition on glass transition and enthalpy relaxation of sucrose-based amorphous systems; 2 to study the effect of water addition... addition on the glass transition and enthalpy relaxation of sucrose-based binary mixtures are presented in Chapter 3, and the effect of starch addition on the glass transition and enthalpy relaxation of sucrose-based binary mixtures are discussed in Chapter 6 The effect of water addition on the glass transition and enthalpy relaxation of the above two binary systems are presented in Chapter 4 and Chapter... independent of aging temperature in Chapter 5 Besides the glass transition and enthalpy relaxation, this thesis attempted to reveal the relationship between micro level and macro level structural relaxations, i.e enthalpy relaxation and texture changes during sub-Tg storage, which will be discussed in Chapter 8 This thesis aims to advance the fundamental knowledge of structural relaxation to binary food systems. .. by using experimental data 67 Table 5-1: Value of β in KWW expression for enthalpy relaxation of selected food saccharides .104 Table 8-1: Sample information of three types of candy (n=6) 157 xii LIST OF FIGURES Figure 2-1: Illustration of formation of amorphous solids by rapid cooling 8 Figure 2-2: The structure of an amorphous solid In the amorphous solid, the micro-heterogeneity...LIST OF PUBLICATIONS 1 Liu, Y., Bhandari, B., & Zhou, W (2006) Glass transition and enthalpy relaxation of amorphous food saccharides: A review Journal of Agricultural and Food Chemistry, 54(16), 5701-5717 2 Liu, Y., Bhandari, B., & Zhou, W (2007) Study of glass transition and enthalpy relaxation of mixtures of amorphous sucrose and amorphous tapioca starch... properties Enthalpy relaxation is important for food materials stored below the glass transition temperature, in consideration of the stability of the physical and chemical properties of the materials In this chapter, all the above topics are discussed with emphasis on food saccharides, one of the most important major components of processed foods Section 2.2 covers the concept of amorphous solids, . STRUCTURAL RELAXATION OF BINARY FOOD SYSTEMS LIU YETING (B. Appl. Sc. (Hons, 2 nd Upper), NUS) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY FOOD SCIENCE. enthalpy relaxation of selected food saccharides 104 Table 8-1: Sample information of three types of candy (n=6) 157 xiii LIST OF FIGURES Figure 2-1: Illustration of formation of amorphous. vii SUMMARY This thesis advanced the study of structural relaxation into binary and tertiary food systems. It studied the effect of anti-plasticizers glucose syrup solid (GSS) and