Production Technology And Physicochemical Properties Of Fermented Vinegar With Tofu Yellow Pulp

Tofu yellow syrup is a by-product produced in the process of forming tofu after soaking,refining,and spotting soybeans.In the production of tofu,every 100 kg of soybeans used on average can produce 5-7 times as much tofu yellow syrup.Tofu yellow syrup is often regarded as "waste water",most of which is directly discharged and rarely reused,which causes environmental pollution on the one hand and leads to waste of resources on the other.In fact,tofu yellow syrup is rich and diverse in nutrients.In the process of making tofu from soybeans,many water-soluble albumin,amino acids,flavonoids,vitamins,minerals and other ingredients are included in it,which facilitate the growth of fermentation microorganisms such as yeast and acetic acid bacteria.Growth.Vinegar is brewed with tofu yellow syrup as raw material,which can "turn waste into treasure".Yellow syrup water vinegar produced is different from traditional food manufacturing and is a seasoning rich in amino acids,flavonoids and other functional ingredients.This has very good theoretical and practical research value for the development of new foods and new resources.At the same time,it explores new ways and new methods for the reuse of tofu yellow water.In this paper,acetic acid bacteria strains suitable for fermenting vinegar in tofu yellow syrup have been selected,and the process conditions of alcohol fermentation and acetic acid fermentation have been optimized,and the amino acids,organic acids,aroma substances,phenolic substances and other nutrients in the fermentation broth have been analyzed and studied.The change trend of these nutrients determines the antioxidant capacity of the vinegar and the best clarification method.The test results are as follows:1.It is determined that the pH of the tofu yellow syrup is 5.6,3.2%soluble solid content,1.13 g/100mL reducing sugar,0.24 g/100g crude fat,0.73 g/100g protein,0.51 g/100g ash,14.58 mg/100mL Ca content,0.07 mg/100mL Fe,0.04 mg/100mL Zn,5.74 mg/100mL Mg.2.To the existing 6 bacterial strain acetic acid bacteria（LB）,Acetobacter pasteurii（BS）and acetic acid bacteria S-1,S-2,S-3 and S-4 isolated from tomato vinegar,red jujube vinegar,apricot vinegar,and persimmon vinegar which are vigorously fermented with acetic acid.After expanding culture and domestication,it is found that BS can ferment the most acid in the fermented tofu yellow syrup fermentation broth,and the growth of acetic acid bacteria is also the best.Therefore,the best acetic acid bacteria strain for fermenting tofu yellow water vinegar.3.Through single factor test and response surface optimization design,the most effective process parameters of tofu yellow syrup water-alcohol fermentation and acetic acid fermentation were determined.（1）The optimal process parameters of alcohol fermentation are:11%initial sugar content,3%yeast inoculation amount and fermentation temperature of 32℃;（2）The optimal process conditions for acetic acid fermentation:the acetic acid bacteria inoculation amount is 8%,and the initial acidity is 1.9 g/100mL,the initial alcohol content is 8%（v/v）,the fermentation temperature is 30℃,the acidity of the vinegar liquid is 5.88 g/100mL,the acidity is moderate,the mouthfeel is soft,and there is a slight bean aroma.4.After the tofu yellow syrup is fermented into vinegar liquid,the amino acid content increases from 2.415 g/kg to 3.544 g/kg,and the aromatic and sweet amino acid content increases to 0.393 g/kg and 1.055 g/kg,respectively,in the vinegar liquid the content of six organic acids including succinic acid,acetic acid,malic acid,tartaric acid,citric acid and lactic acid has increased,while oxalic acid and fumaric acid have been greatly reduced;the amount of many aroma substances in the yellow syrup vinegar is also increasing,and the quality of the vinegar liquor was significantly improved.5.In the process of tofu yellow syrup water fermentation,due to the action of fermenting microorganisms,the total phenols,total flavonoids,and isoflavones in the fermentation broth have increased on different level,DPPH·,ABTS+·,·OH scavenging rate are both increased,the reducing capacity is improved,and the overall antioxidant capacity of the fermentation broth is significantly improved.6.The effect of tofu yellow syrup water vinegar liquid which is clarified with 0.2 g/L chitosan is obvious.