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

Abstract

Black shallots are new products made by processing fresh shallots (Allium ascalonicum L.) 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 enzymes (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 shallot products and shorten fermentation time. The results have determined the suitable freezing pretreatment condition at a temperature of -20^oC for 30 hours and the suitable endogenous fermentation condition at a temperature of 45^oC for 2 days. Under these conditions, the black shallot products 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 shallot production on an industrial scale.