• Culinary science and hospitality research
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• v.20 no.6
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• pp.235-244
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• 2014

The purpose of this study was to investigate the effect of freezing and thawing rate on the physical properties of soybean sprouts to improve the quality of processed soybean sprouts during distribution and storage. Cooked soybean sprouts were frozen by air-blast freezing (ABF) system at $-45^{\circ}C$ or natural air convection freezing (NCF) system at $-24^{\circ}C$, then thawed using microwave oven by varying output power (0, 400, 800 and 1,000 W) until $75^{\circ}C$. The quality of soybean sprouts was measured by the water content, hardness and springiness. In addition, the internal microstructure of soybean sprouts was observed by optical microscope. For results, water content of soybean sprouts thawed by 1,000 W in a microwave showed the lowest value after natural air convection freezing. Springiness of soybean sprouts thawed by all amounts of output power was decreased in comparison with control. Hardness was increased only in soybean sprouts thawed by 1,000 W after air-blast freezing. However the gaps between springiness and hardness were relatively small with control at 1,000 W thawing, after air-blast freezing. Internal microstructure of the soybean sprouts was more damaged as freezing and thawing time were increased. In conclusion, high freezing and thawing rate might improves the quality of soy bean sprout, and IQF freezing and 1,000 W of microwave thawing appears to be the optimum condition for frozen HMR production. From the results freezing and thawing process parameters might can be use as quality control parameters as various type of sprout products processing.