33A-19 |
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C. PÉREZ-ALONSO1, J. G. Báez-González1, J. P. Pérez-Orozco2, C. I. Beristain3, and E. J. Vernon-Carter4. (1) IPH, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco # 186, Mexico City, 09340, Mexico, (2) IPH and DIQBQ, Universidad Autonoma Metropolitana e Instituto Tecnológico Zacatepec, Zacatepec, Mexico, (3) Instituto de Ciencias Básicas, Univ. Veracruzana, Apartado Postal #575, Xalapa, Veracruz, 91000, Mexico, (4) IPH, Universidad Autónoma Metropolitana Iztapalapa, San Rafael Atlixco No. 186, Col. Vicentina, Mexico City, 09340, Mexico Moisture sorption isotherms are useful thermodynamic tools for determining interactions of water and food substances, and provide information useful for assessing food processing operations such as drying, mixing, packing, and storage. Sorption isotherms can also be used to investigate structural features of a food product, such as specific surface area, pore size distribution and crystallinity. Such data can be used for selecting appropriate storage conditions, and packaging systems that optimize or maximize retention of aroma, color, texture, nutrients and biological stability. The objective of this work was to develop a methodology based on the use of the thermodynamic properties to recommend the best conditions of storage (moisture content, and water activity (aw)) of microcapsules of natural colorants by means of the sorption process of biopolymers as wall materials. In this work, vapor sorption isotherms were determined at 25, 35, and 40 °C for the gum arabic (GA), mesquite gum (MG) and a blend of gums and maltodextrin DE-10 (MD) (GA17%-MG66%-MD17% wt). The experimental sorption data were fitted to GAB’s model and the thermodynamic parameters (enthalpies and entropies, differential and integral) were determined by the Claussius-Clapeyron method. The minimum integral entropy can be considered as the point maximum stability where strong bonds between adsorbate and adsorbent occur, and therefore, water is less available to participate in spoilage reactions. In our experiments the point of maximum stability was found between 12.24 and 14.68 kg H2O/100 kg d.s. and its corresponding aw(0.32 to 0.57) for gum arabic, 12.12 - 14.27 kg H2O/100 kg d.s. (aw=0.33- 0.55) for mesquite gum, and 11.37-13.84 kg H2O/100 kg d.s. (aw=0.28-0.55) for the biopolymer blend in the range of temperatures studied.
Session 33A, Carbohydrate: General
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