Study on the effect of freezing pretreatment and endogenous fermentation on the quality and processing time of black shallots using moist heat treatment method

Black shallots are new products made by processing fresh shallots (Allium ascolanicumL.) under controlled temperature and humidity conditions without the use of additives. The purpose of this study was to determine suitable freezing pretreatment and endogenous fermentation conditions (treatment temperature, treatment time) to break down the cell structure in raw materials, to promote reactions caused by enzyme (hydrolysis reaction of polysaccharides, proteins, reaction of converting polyphenol compounds in bound form to free form...), improving the content of nutritional ingredients and active ingredients in black shallotproducts and shorten fermentation time. The results have determined that the suitable freezing pretreatment condition at a temperature of -20oC for 30 hours and the suitable endogenous fermentation condition at a temperature of 45oC for 2 days. Under these conditions, the black shallotproducts achieved good quality, corresponding to the total fermentation time shortened to 17 days compared to the control which was 24 days. This research initially gave feasibility for black shallotproduction on an industrial scale.