| With the improvement of living standard and health care consciousness,vinegar has not only been positioned as a traditional condiment,its medicinal and health care functions are increasingly concerned.Naked oats(Avena nuda L.)are rich in protein,starch,β-glucan,vitamins,polyphenols,and flavonoids.They are high-quality whole grains and have broad processing prospects.However,at present,the deep processing depth of oats is insufficient,the types of processed oat products are few,and the added value is low.The functional characteristics of oat have not been effectively reflected in the existing products.Research on brewing vinegar with oats as raw materials has been rarely reported.In this paper,naked oat was used as raw material,the brewing technology of oat vinegar was studied from the aspects of strengthening of dominant strains,application of commercial enzymes,and optimization of fermentation conditions.The changes of polyphenols and flavonoids in the process of oat vinegar alcoholation and vinegarization were discussed,and the antioxidant activity of oat vinegar was compared and analyzed.The main contents and conclusions are as follows:(1)Single factor and response surface were used to optimize the oat vinegar saccharification and wine brewing process,and the optimal process of oat saccharification was determined as follows: α-amylase was added at 900 U/g,liquefaction temperature 67°C,liquefaction 57 minutes,protease was added at 450 U/g,and saccharifying enzyme was added at 3200 U/g,the content of polyphenols in oat mash can reach 2.80 mg / m L.The optimization result of alcoholization stage was that the total inoculation amount of lactic acid bacteria L17 and yeast Y13 was 6.2%,the inoculation ratio was 3: 3,and the closed fermentation period was 8.5 days.The alcohol and non-volatile acid contents of oat wine mash were relatively high,with the alcohol content reaching 10.6% vol and the non-volatile acid content reaching 1.60g/100 m L.(2)Through the optimized brewing process,the oat raw vinegar contains total acid 6.18 g / 100 m L,non-volatile acid 1.73 g / 100 m L,polyphenol 4.48 mg / m L,flavonoid 137.2 mg / 100 g,amino nitrogen 0.21 g / 100 m L,reducing sugar 1.87 g / 100 m L and total esters 2.21 g / 100 m L.The oat vinegar has a uniform body shape,black and bright color,soft aroma,strong acidity,pure flavor,excellent quality,and good commerciality.It can provide technical support and theoretical basis for the industrial production of oat vinegar.(3)The antioxidant properties of oat vinegar were investigated using the self-made Shanxi vinegar,commercially available white vinegar fermented with edible alcohol and ascorbic acid as controls.The results show that oat vinegar has higher DPPH,ABTS,O2-free radical scavenging capacity,up to 83.2%,74.5% and 36.8%,respectively.The scavenging capacity of oat vinegar to DPPH is 1.29 times that of Shanxi vinegar,and 4.95 times that of commercially available white vinegar.The scavenging capacity of O2-is 1.39 times,2.63 times,and 4.0 times that of Shanxi vinegar,white vinegar,and ascorbic acid,respectively.The ABTS free radical scavenging ability is greater than commercially available white vinegar,and the reducing ability is also higher than Shanxi vinegar and white vinegar. |
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