Study On The Preparation Of Fermented Chili Sauce With Dried Chili

Fermented pepper products have a broad consumer market in China.In actual production,it is difficult to achieve year-round and large-scale production by directly using fresh pepper to make sauce due to the seasonal ripening of fresh pepper and the difficulty in storage.Moreover,the loss of nutrients and the pollution of high-salt waste liquid will be caused by using salted pepper preform to make sauce.It is not only convenient to harvest,transport and store the raw materials but also can avoid a series of problems caused by the salting process if the dry pepper is used as raw material to produce the fermented chili sauce.Therefore,this study aims to screen lactic acid bacteria inoculated dry pepper to make fermented chili sauce,study the growth characteristics of fermentation strains,optimize the pretreatment process conditions of dry pepper and the fermentation process conditions of chili sauce,and finally analyze the change rules of basic physical and chemical indexes and sensory flavor indexes in the fermentation process of sauce made from different raw materials.It is expected to provide reference for the research and development of dried pepper fermented sauce.The main research contents and results are as follows:(1)Screening of excellent lactic acid bacteria.Twenty strains with large calcium-soluble circles were isolated from the naturally fermented pickle juice samples.Combined with the results of Glan staining microscopic examination,14 strains were preliminarily identified as lactic acid bacteria.Then,six strains with strong acid-producing capacity were obtained from the middle and primary screening for 16S r DNA identification.Strains PC4,PC8,PC13,PC14and PC17 were further identified as Lactobacillus plantarum and MK1-3 as Lactobacillus paracasei.The growth characteristics of five lactic acid bacteria strains PC4,PC8,PC13,PC17 and MK1-3 showed similar growth trends,and the OD₆₀₀ value of Lactobacillus paracasei MK1-3 was significantly lower than that of other strains after entering the stable stage(P<0.05).When the p H value was 3,Lactobacillus plantarum PC8 and PC13 showed good acid resistance.Under 10%Na Cl concentration,Lactobacillus plantarum PC8 showed good salt tolerance.The degradation rate of sodium nitrite was more than 80%,and the degradation rate of Na NO₂ by Lactobacillus plantarum PC4 was the highest,which reached95.37%.Considering the above results,Lactobacillus plantarum PC8 was selected to inoculate and ferment the subsequent fermented chili sauce.(2)Optimizing the pre-treatment process conditions of dry chili blanching.The results showed that:dried peppers were fully rehydrated after being pretreated for 5 min under the conditions of 100?and 1:4 ratio of material to liquid.The color saturation was significantly higher than that of the control group(P<0.05)and the Vc content reached 105.48%of the original content.The pretreatment effectively reduces the background microbial content of dried peppers and reduces the risk of bacterial contamination during the fermentation process.(3)The optimal fermentation process conditions were determined.Based on the single-factor experiment,the response surface test was designed and combined with the fuzzy mathematics evaluation method,and the optimal fermentation process conditions were obtained as follows:fermentation temperature 33?,salt addition amount 3.6%,sucrose addition amount 5.6%.Verification of this condition shows that the average sensory score of fermented chili sauce under this condition is 83.49 points.(4)Research on the quality of dried and fresh chili sauce.Dried chili and fresh chili were used to make sauces,and the differences in total acid content,p H value,amino acid nitrogen content,reducing sugar content,sensory score,color ratio,organic acid content,and volatile compound content of the two fermented sauces were compared.The test results showed that at the end of fermentation,the total acid content and reducing sugar content of the dried chili sauce reached 91.5%and 87.71%of the fresh chili sauce,respectively,and the p H difference between the two was not significant(P>0.05);the color of the dried chili sauce was better and its color ratio and amino acid nitrogen content are significantly higher than that of fresh chili sauce(P<0.05);The sensory scores of the dry and fresh chili sauces are 77.8 and 79.8 points respectively;The main organic acids are lactic acid,citric acid and succinic acid.At the end of fermentation,the content of lactic acid and citric acid in the dry chili sauce reached 53.03%and 64.52%of the fresh chili sauce,respectively.The succinic acid content was significantly higher than that in the fresh chili sauce during the whole fermentation process(P<0.05)and the content reaches 0.7467 mg/m L at the 5 th day of fermentation;Through the electronic nose analysis,the volatile compounds of the two chili sauces are similar,with the most abundant terpenes and nitrogen and oxygen compounds;PCA analysis can effectively distinguish different chili sauces and their fermented sauces.The clustering effect is good,indicating that the characteristic flavors of the two chili sauces are different.Further through the GC-MS detection,the content of each aroma component in the dry chili sauce from high to low is:alcohols>alkanes>esters>terpenes>acids>ketones>aldehydes>others,fresh chili sauce they are:esters>alcohols>terpenes>alkanes>ketones>aldehydes>acids>others.OAV analysis shows that 2-methoxy-3-isobutylpyrazine,linalool,and(+)-limonene,which are shared by dried and fresh chili sauce,are the three characteristic aroma components that contribute the most to aroma sensory.Nonanoic acid,methyl decanoate,methyl 2-methylbutanoate,2-heptanone,acetaldehyde,2-hexenal,4-methyl-1-pentanol,3-pentanol are the characteristic aroma components of dried chili paste give the dried chili paste its unique herbal aroma,nutty aroma and mature fat aroma.?-ocimene,pentyl 2-methyl butyrate,hexyl hexanoate,folic aldehyde,leaf alcohol,2-hexenol,mushroom alcohol,dimethyl sulfide are the unique characteristic aroma component of fresh chili sauce,which gives the fresh chili sauce a stronger spicy smell and fresh fruit aroma.The characteristic aromas of the two chili sauces are different obviously.