15D-22 |
Quality characteristics of Yakju between heat treatment and membrane filtration during storage |
K. H. Park and S. K. ROH. Department of Food Science & Technology, Chung-Ang University, San 40-1 Naeri Daedug, Ansung, 456-756, South Korea In order to extend shelf-life of Yakju, Korean rice wine, a heat treatment method has been used in Yakju industry. But it is difficult to inactivate microorganisms completely due to their heat resistance and thus it causes some problems to Yakju quality such as off-flavors. To minimize quality loss and flavor change of Yakju, a nonthermal method could be considered for the removal of spoilage microorganisms. Therefore, this study was to evaluate effects of treatment methods on the quality of Yakju by measuring the changes among non-sterilized, heat-treated and membrane-filtered rice wine during storage. The proximate components, survival of microorganisms and flavor compounds were analyzed during stored at 25C. Yakju was heated at 69C for 1 min. for heat treatment while it was filtered by hollow fiber membrane with cut-off molecular weight of 100,000. Acidity and turbidity increased in non-sterilized Yakju whereas they did not change in both heat-treated and membrane-filtered ones. The viable cell numbers of total microorganisms and lactic bacterium of non-treated Yakju were increased exponentially during storage, but they were not detected in treated wines. The burnt off-flavor compounds such as pyrazines were detected in heat-treated Yakju. It implies that flavors of Yakju are deteriorated by heat while fresh-like flavors are remained in membrane-filtered Yakju. Consequently, these results indicate that the ultrafilration of Yakju has potential to remove microorganisms more effectively while keeping fresh-like quality than conventional heat treatment.
Session 15D, Food Microbiology: Fruits and vegetables
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