Study On High Hydrostatic Pressure Combined Heating Treatment On Microbial Inactivation In Pickled Chili

Pickled chili is one of the typical representatives of Sichuan pickled vegetables, it keeps the form of fresh chili, brittleness, spicy and color and luster, but also appears the unique flavor, aroma, and health care function in fermentation. But pickled chili belongs to the microbial fermented foods, including corruption bacteria easing to cause deterioration, which affect the quality and edible safety of pickled chili.This research adopts the heat synergy ultrahigh pressure processing on sterilization pickled chili, and evaluates the quality of pickled chili in storage period. The pickled chili is prepared with direct fermentation way; Further pressure, holding time, temperature of single factor experiment to determine the best level; Then use center composite design test (BBD) identify the best combination of temperature, pressure, holding time of sterilization process; Finally the best sterilization processing pickled chili storage under 25℃ for 30d, with color and lustre, pH, total acid, aerobic bacterial count, mould yeast for indicators, to measure heat synergy ultrahigh pressure processing on pickled chili quality in storage period, and compare with not processing, ultra-high pressure processing (400 mpa,20 min), heat treatment (80℃,20 min) at the same time. The main conclusions of this study are as follows:(1) During fermentation, salinity increased gradually with the extension of fermentation time, and salinity reached 5.65% after the mature; pH with the extension of fermentation time in gradually reduce, and the final pH was 3.86; Total acid has also been gradually increasing and eventually total acid content was 0.49%; 1-6d in the initial stages of fermentation, mainly harmful microorganisms coliform bacteria and aerobic mould with reducibility in vegetables will reduce nitrate to nitrite, resulting in nitrite peak in early fermentation process, along with the fermentation, lactic acid bacteria multiplying, lactic acid content increasing, can effectively inhibit the growth of miscellaneous bacteria breeding, and prevent the reduction reaction and nitrite peak appearing, and inhibit the growth of the coliform bacteria breeding.(2) Response surface experiments optimize high hydrostatic pressure combined heating sterilization process, and get best sterilization process conditions for temperature 52℃, pressure 385 MPa, the holding time 22 min, the fatality rate of aerobic bacterial count prediction is 6.07, the fatality rate of Mould and yeast prediction is 6.14; The best sterilization process was validated, obtaining the actual aerobic bacterial count death rate is 6.04, mould yeast count was 6.12.(3) Stored at 25℃ for 30d and compared with other sterilization methods, slightly color change after high hydrostatic pressure combined heating treatment, showing that high hydrostatic pressure combined heating treatment can effectively delay the browning; Variations of pH and total acid were smaller, showing that temperature on microbial death has obvious promoting effect and can prevent the excessive breeding of lactic acid bacteria producing excessive acid, improving the taste of products; Microbial propagation speed during storage is slow, and microbial numbers of high hydrostatic pressure treatment sample has obvious increased trend in the late storage, so the high hydrostatic pressure combined heating treatment is more prominent.