88C-28 |
Changes of the physico-chemical properties of onion powders during storage |
K. R. YOON1, J. W. Lee2, and K. H. Park1. (1) Dept. of Food Science & Technology, Chung-Ang University, San 40-1 Naeri Daedug, Ansung, 456-756, South Korea, (2) Research Center, Tae Kyung Nong San Co., Ltd., 305 Kusuri Meeyangmun, Ansung, 456-840, South Korea Since onions in form of dried powders have several problems such as caking, color and flavor losses during storage, microencapsulation with different coating agents is applied to minimize the quality degradation. The objective was to determine the optimum processing condition for the onion powders by evaluating the physico-chemical properties of them prepared with different processing methods and coating materials. Three different methods, coating and blending, vacuum drying and spray drying were used to prepare the onion powders. Maltodextrin, cyclodextrin, and modified starch and gum Arabic were used as wall materials for spray drying. The change of moisture content, water activity, total pyruvate, color difference and physical properties were measured for five weeks, and the properties were tested by anti-oxidative stability, photographed by microscope and QDA chart by sensory evaluation. The moisture content of coating and blending (CB) was the highest (5.38 to 7.62%) and the lowest (1.70 to 3.22%) was in spray drying with maltodextrin (SD) during storage. In water activity, the maximum value was 0.2 to 0.26 of vacuum drying while the minimum was 0.03 to 0.16 of SD. The content of pyruvate was decreased from 0.917 to 0.496 mg/g in CB. The density of all samples steadily decreased during storage. After five weeks, powders made by CB and vacuum drying were agglomerated with their particles and spray dried products showed better rheological properties than others. The results of anti-oxdative stability showed that onion components were well encapsulated in SD and were exposed to the surface of powder in CB. For sensory evaluation, coating and blending was changed to the most different pattern while spray drying was changed to the minimum among samples during that period. These results suggest that the spray drying with cyclodextrin was the best way for the processed onion powders to increase stability during storage.
Session 88C, Food Engineering: Physical and Chemical Properties
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