Study On The Determination And Extraction Of Soybean Isoflavones From Soy Sauce Residue

Soy sauce residue is a byproduct from the ancient production of soy sauce.It occurs in the process of the soy sauce' s extraction completion.After the soy sauce is extracted,a large number of soy paste are reserved as a byproduct.The residues in the lower layer can be processed into soy sauce.However,the others in the upper layer are not further processed and utilized due to existence of dust and impurities from long term exposure in outside air.In order to reuse wastes and improve the economic benefits of soy sauce production and taking the production of Xiamen Gulong Food Co.,Ltd as an example,this paper studies the determination and extraction of soybean isoflavones from soy sauce residue.Firstly,the basic physical and chemical characteristics of soy sauce residue are identified after the sample preparation.Through dehydration,soxhlet extraction,kjeldahl determination of nitrogen,titration and other means,the characteristics of soy sauce residue in 60 ? are as follows.The dehydration rate is 44.60 g/100 g,the fat,protein,chloride and reducing sugar content of dehydrated soy sauce residue are 18.55 g/100 g,11.08 g/100 g,22.68 g/100 g and 0.91 g/100 g,respectively.The physical and chemical characteristics of soy sauce residue are uncovered through the analysis.Secondly,the content of soybean isoflavones in soy sauce residue is determined by high performance liquid chromatography(HPLC)-electrospray mass spectrometry(EMS).Through taking three kinds of glycoside(daidzin,glycitin and genistin)and three kinds of aglycone(daidzein,glycitein,genistein)as the standard substance,the qualitative ion pairs,quantitative ion pairs,mass spectrometric parameters and chromatographic conditions of each monomer are optimized.By the standard reference,mass spectrometric characteristic ion pair and chromatographic peak retention time,the isoflavones in soy sauce residue are qualitatively analyzed and the content of isoflavones in soy sauce residue is quantified by peak area.The results show that the content of genistein is the highest,up to 240 ?g/mL and low in the others.The total content of these six isoflavones is 632.8 ?g/mL,of which genistein takes 37.9%.Finally,the extraction technology of isoflavones from soy sauce residue is studied.Effects of ethanol volume fraction,solid-liquid ratio,ultrasonic extraction time and ultrasonic extraction temperature on the extraction rate of soybean isoflavones from soy sauce residue are determined by single factor analysis.It turned out that the factors rank solid-liquid ratio,ethanol volume fraction,extraction time and extraction temperature from the strong to weak.Furthermore,the extraction conditions are optimized by orthogonal experiment.The finial extraction conditions are as follows.70% alcohol is used as the extractant,the ratio of material to liquid is 1:20,the extraction temperature is 60 ?,the extraction time is 4 hours,ultrasonic assisted extraction is adopted,ultrasonic working frequency and ultrasonic electric power are respectively 40 KHZ and 150 W.Under these conditions,the total amount of the isoflavones extracted from soy sauce residue is 10.9 mg/g,among which the genistein is 4.15 mg/g.