Study On The Technology Of Semi-solid Fermentation Of Zhenji Mushroom By Lactobacillus Plantarum MG-1

Hypsizygus marmoreus is a kind of edible mushroom rich in various nutrients.Af ter harvest,due to strong respiration,physiological metabolic activities,loss of bacteri al water and microbial infestation,its storage period is shorter,Resulting in lower va lue of their goods.The main consumer variety of Hypsizygus marmoreus in the marke t is fresh food.The domestic research on fermented Hypsizygus marmoreus is rarely reported in the literature,and there is no relevant research report abroad.The charact eristics of Lactobacillus plantarum can be used for semi-solid vacuum fermentation of Hypsizygus marmoreus.avoiding the secondary pollution caused by the division and packaging after the fermentation is matured,reducing the nitrite content and avoiding the preservative to the body.The harm,prevent the production of toxic metabolites,improve their flavor and texture,extend the shelf life of the product,and increase t he added value of the Hypsizygus marmoreus.In this experiment,Lactobacillus Plant arum MG-1 preserved in laboratory was used in the fermentation of Hypsizygus mar moreus.Different inoculation amount,salt addition amount,fermentation temperature,fermentation time and water content were taken as single factors,and the content of nitrite,total acid,free amino acid and sensory quality were taken as weighted compr ehensive indexes to screen.and the composite fermentation conditions were optimized by the same weighted index.Finally,the sterilization method of fermented Hypsizygu s marmoreus were studied.The main findings are as follows:Different inoculation amount,salt addition amount,fermentation temperature,fermentation time and water content were used as single factors,and the nitrite content,total acid content,free amino acid and sensory quality were evaluated as weighted comprehensive indicators.The test results were as follows:The weighted comprehensive score of 5%inoculation volume was 0.984;8%salt concentration was 0.988;the weighted comprehensive score of fermentation temperature was 0.975;the weighted comprehensive score of fermentation time was 0.967;and the weighted comprehensive score of 92%water content was 0.907 in CK group.The results showed that the inoculation amount was 5%,the salt concentration was 8%,the fermentation temperature was 31?and the fermentation time was 10 days.The results of single factor experiment showed that inoculation amount,salt concentration,fermentation temperature and fermentation time had great influence on the quality of fermented Hypsizygus marmoreus.Therefore,based on the single factor experiment,the four factors of inoculation size,salt concentration,fermentation temperature and fermentation time were used.As independent variables,the nitrite content,total acid content,free amino acid and sensory quality were evaluated as weighted comprehensive indicators.According to the response surface optimization experiment,the optimal fermentation combination was obtained:inoculum volume 5%,salt concentration 7.7%,fermentation The temperature was 31?and the fermentation time was 10 days.Under these conditions,repeated verification experiments showed that the nitrite content decreased by86.3%and the total acid content increased by 16.4%and the free amino acid content increased by 40.3%,respectively,compared with natural fermentation.sensory score increased by 18.4%,hardness increased by 15.2%,color difference decreased by 3.5%;,nitrite content is lower than the nitrite limit standard in pickles(?20mg/kg),the total acid content is lower than the limit of total acid content in pickle(?1.5g/100g),the flavor is better and obviously better than natural fermentation.The effects of high pressure steam sterilization(121?),atmospheric pressure ste am sterilization(100?),pasteurized water bath sterilization and steam sterilization(85?),microwave sterilization(800W)on the quality of fermented Hypsizygus marmor eus products.The results showed that 800W-180s in the microwave sterilization grou p could completely kill microorganisms,which could significantly reduce the nitrite c ontent(0.033mg/kg),the total acid content(0.78%),and reduce the free amino acid l oss(2223.mg/100g);can better maintain the color(14.60)and hardness(4.3kg/cm~2)o f the true mushroom,so that it maintains a good appearance and flavor(81.5points);compared with other sterilization methods in the test,The action time is short,the sterilization temperature is low,the action efficiency is high,the nitrite content can b e reduced,the free amino acid loss can be reduced,and the quality of Hypsizygus marmoreus can be better maintained;the nitrite content is much lower than the nitrit e limit in the pickled vegetables.The standard(?20mg/kg),the total acid content is l ower than the limit of total acid content in pickle(?1.5g/100g),Microbial indicators meet food hygiene requirements.Therefore,800W-180s is the most suitable sterilizati on method of true mushroom.