| In this paper,barley malt was used as raw material to produce malt vinegar by fermentation to provide a theoretical basis for the brewing of malt vinegar.Firstly,conditions of alcohol fermentation and acetic acid fermentation were optimized in shake flask test,secondly,the pilot-scale test of acetic acid fermentation was studied.thirdly,the clarification process of malt vinegar was investigated,finally,the chemical composition of the product were analyzed and compared.The main results were as follows:?1?Based on the comparative experiment of the alcoholic fermentation between the laboratory Optional yeast Y-21,Y-23,and the Angel high active dry yeast,the laboratory Optional yeast Y-21 was screened as the test strain for the alcoholic fermentation on the wort.Under the condition that the initial sugar 20°Bx,the inoculum size 11%,the liquid volume 50%,amount of sulfur dioxide 88mg·L-1,and the fermentation time9d,the alcohol content of the malt liquor was 8.37%?V/V?.?2?Through the comparative experiment of the alcoholic fermentation between the laboratory optional acetic acid bacteria A-4,A-168,and the acetic acid bacteria AS1.41,the laboratory Optional acetic acid bacteria A-4 was screened as the test strain or the acetic acid fermentation on the malt liquor.Under the condition that alcoholicity 5%,the liquid volume 100mL/500mL,fermentation temperature 32?,p H 4.0,shaking speed120r/min,the inoculum size 9%,and the fermentation time 10d,the rate of transferring from alcohol was96.78%.?3?Using 50L fermentor,under the condition that ventilation volume of prophase?metaphaseand anaphase were 1.5 m3/h?2.0 m3/h and 1.5 m3/h,the agitation speed of prophase?metaphaseand anaphase were100r/min?150r/min and 100r/min,incipient alcoholicity 5%?v/v?,incipient pH 4.0,the inoculum size9%,the liquid volume 50%?v/v?,pressure of tank 0.2kg/cm2,fermentation temperature 32?,and the fermentation time60h,finally,the net content of acetic acid was 4.64g/100mL.?4?Using diatomite,bentonite,chitosan,PVPP?cross-linked polyvinylpyrrolidone,also known as crospovidone?,gelatin five single clarifier,and sodium alginate-sodium carbonate,PVPP-gelatin two kinds of complex clarifier,comparative experiments were carried out on the clarification effect of the malt vinegar.The result showed that the clarification effect of bentonite was best,under the condition that the bentonite addition20%,the clarification time 5h,the clarification temperature 40?,transmittancy was 93.5%,and requirements of clarification was reached.?5?After alcoholic and acetic acid fermentation,according to determine,the content of protein,reducing sugar,total sugar in malt liquor and malt vinegar was showing a downward trend,finally,the content was1.35g/100mL,0.48g/100mL,0.75g/100mL respectively;Using the amino acid automatic analyzer,17 kinds of free amino acids were detected from the wort,malt liquor and malt vinegar,including six kinds of essential amino acids,essential amino acid was 40.79%of the total amino acids in the wort,22.58%of the total amino acids in the malt liquor,and 45.01%of the total amino acids in the malt vinegar;In addition,applying GC-MS,aroma components in the wort,malt liquor and malt vinegar were analyzed,70 compounds were isolated and identified,there were 9 kinds in the wort,39 kinds in the malt liquor,and 22 kinds in the malt vinegar.There was high proportion of essential amino acids in the malt vinegar,From the perspective of the nutritional value of products,malt vinegar was better than wort and malt liquor;There was more kinds of aroma components in the malt liquor,From the perspective of the aroma of products,malt liquor was better than wort and malt vinegar.Therefore,in general,the wort after alcoholic fermentation and acetic acid fermentation,nutritional value and flavor had been greatly elevated and improved. |
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