Study On Flavor And Safety In The Fermentation Of Superior Vinegar

Vinegar fermentation contains a series of biochemical reaction producing abundant flavor compounds, nutrient substance and hazard compounds. Therefore, it is necessary to research the whole process of vinegar fermentation in order to improve the flavor and limit the production of hazard compounds.Pure solid-state fermentation technology was carried out in this study.The specific process was as follows:the ratio of rice and sorghum was3:1, The bran inoculation of Aspergillus niger was5%of the raw materials, the inoculation of yeast was9.3×105cfu/mL, the inoculation of acetic acid bacteria was1.6%of the volume of fermented grains, the fermentation temperature of alcohol and acetic acid was33℃and28℃. Moreover, the total acid was6.33g per100g culture. Formaldehyde nitrogen was0.32g per100g culture. Dissoluble saltless substance was15.6g per100g culture. Further, pH firstly decreased and then maintained to3.10.HS-SPME-PA and DSE which attached to the GC-MS were used to extract the aromatic compounds. The result indicated that esters accumulated to the maximum on12-14th days and reduced later; alcohols increased a lot during the ethanol fermentation, and reduced to a low level because of csterification in the acetic acid fermentation; acids was mainly produced in the acetic acid fermentation and phenols increased to the maximum on16th day. The contents of organic acids reached6.79g/100g sample finally, and succinic acid (1.00g/100g sample), malic acid (0.77g/100g sample) and lactic acid (0.40g/100g sample)were the main organic acids. When the fermentation was over, the content of amino acid was501.52mg/L. three times than the sample of ethanol fermentation. The content of sweet amino acid was from28.97mg/L to256.12mg/L, and the proportion was from23%up to51%. However, the bitter amino acid was from69%down to43%. In other words, the acetic acid fermentation was good for the increase of sweet amino acid.Histamine and cadaverine were mainly produced in the acetic acid fermentation.In the later period of the fermentation, the contents of the two biogenic amines increased to the maximum5.71mg/L and8.67mg/L, respectively. Tyramine decreased in the later period and spermidine appeared in the acetic acid fermentation which reached3.76mg/L. In addition, propanediol methyl ether was found during the aromatic compounds. More effective and exact methods should be set up to detect propanediol methyl ether.