| Black garlic is a new health food prepared by processing fresh garlic(Allium sativum L.)at high temperature(60?–90 ?)and high humidity(60%–80%)for 60-90 days.Black garlic not only has soft tissue,sweet taste,eliminates the spicy taste of fresh garlic,but also has the characteristics of anti-aging,anti-virus,improving immunity,anti-tumor,protecting liver,reducing blood lipid and blood pressure,and was favored by consumers.Black garlic products were relatively simple and could not meet the market demand,so it was urgent to develop new black garlic products to meet the needs of different people.In this study,the commercial black garlic was processed into black garlic powder and black garlic extract,and the preparation process was optimized.In addition,L.plantarum,L.rhamnosus and their mixed bacteria were used to ferment the black garlic extract,and various analytical methods were used to analyze its components.The main research results were as follows:1.To optimize the processing technology of black garlic products,and to detect the change of composition content and antioxidant activity.The commercial(multi-petal)black garlic was processed into black garlic powder and black garlic extract.The single factor experiments and single factor combined with response surface methodology were used to optimize the process of black garlic powder and black garlic extract.The best technological parameters of black garlic powder were as follows:heated temperature,100 ?;heated time,30 min;crushed for 3 min to obtain peeled black garlic,then heated temperature,160 ?;heated time,2 h;crushed time 3 min to prepare black garlic powder,and added 1%microcrystalline cellulose to enhance the anti-coagulation property of black garlic powder.The best technological parameters of black garlic extract were as follows:the extraction temperature of peeled black garlic,99.96 ?;the solid-to-liquid ratios,1:4.38 g/m L(m/v);and the extraction time,2.72 h;and the black garlic extract with the highest soluble solids content could be obtained.The content of K in black garlic powder was the highest,about 667.93±0.33 mg/100 g.Seventeen amino acids,crude polysaccharides,reducing sugars,polyphenols and 5-hydroxymethylfurfural(5-HMF)could be detected in all three products.The results showed that the antioxidant activity of black garlic powder was stronger than that of black garlic and black garlic extract.2.Effects of L.plantarum,L.rhamnosus and their mixed bacteria fermentation on physical and chemical properties of black garlic extract.The results showed that the number of viable Lactobacillus increased exponentially in a short time(0-2 days),and then decreased.The pH and 5-HMF content of fermentation broth decreased significantly with the extension of fermentation time.While the contents of total acid,amino nitrogen,total polyphenols and total flavonoids increased gradually.Probiotic fermentation has become an effective new method to reduce 5-HMF.3.The sensory evaluation method and metabonomics analysis system of black garlic fermented products were established.The method of comprehensive evaluation of black garlic fermentation broth by artificial sensory evaluation combined with electronic sensory evaluation for the first time;L.plantarum 1 d fermentation broth(S2),L.rhamnosus 2 d fermentation broth(S3),and mixed bacteria 1 d fermentation broth(S4)scored higher in overall sensory evaluation.The fermentation broth of black garlic was analyzed by GC-MS and LC-Q-TOF-MS/MS,and which were identified 96volatile substances and 108 non-volatile substances.After fermentation,the content of components with bad baking flavor was reduced,and pleasant aroma substances was increased;In addition,the content of functional components such as lactic acid,Gly-Pro-Glu,sorbose,?-CEHC and?-tocotrienols increased.In a word,black garlic fermented by Lactobacillus can improve its quality. |
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