Isolation Of The Soybean Molasses And The Microbiological Purification Of The Oligosaccharide

Soy molasses is a byproduct obtained from processing of soybean protein consentrate, which contains high proportion of soy oligosaccharide. The paper relates to analyzing and identifying the molasses's components, removing fat and gum from it, decolouring soy syrup and preparing modified soy oligosaccharide by fermentation with S.cerevisiae.In order to analyze the composition of the soy molasses, the material was separated into 6 parts by solvent extraction. The major components were determined :sugar 54.64%(which comprise sucrose 32.17%,raffinose 4.27%,stachyose 17.54%),fat 18%,steroid glycoside 3.06%,phospholipid 8.79%,protein 8.71%,ash 8.69%.Steroid glycoside,phospholipid,neutral fat and oligosaccharide were determined by IR,HPLC,and LC-MS.Four isoflavones and one saponin were identified.Fatty substances in the soy molasses were removed by organic solvent extraction and it was found that 69.9% of the fat could be eliminated by a mixture of n-hexane and ethanol (2:1).Then the maximum deposit at pH2.4 by phosphonic acid,which comprise sugar 9.1%,fat 8.4%,protein 19.0%,material 4.6% saponin 22.0%,isoflavone 6.4%,others 30.5%.and the best condition for clarifying soy molasses were obtained.which is that the pH of molasses is 3.0 modulated by phosphoric acid,then adjusted to pH 7.2 by calcium hydroxide.and heats up to 90℃. Compared with other macroporous resins,the D290 has better decolouring efficiecy,but employing it alone cann't decolor soy molasses very well.By the singular factor analysis, the best condition was determined for decoloring with D290 and active carbon.D290:room temperature,pH 4-6 and time 12 h;Active carbon: powder,the amount 4%,the time 80min,the temperature 55℃ and pH 4.0. under the condition,the removal rate of the impurities at 260nm wavelength are:D290 83.5%,active carbon 76.5%. D290 94% and active carbon 85.5% at 420nm wavelength.when D290 and active carbon powder were combined to decolor, the carbon amount is only 2.5%,the removal of the impurities at 260nm wavelength is 85.5%, 95.9% at 420nm wavelength.The syrup after decoloring is composed of sucrose 70.88%,raffinose 6.21%,stachyose 22.91% analyzed by HPLC.And the last,there is the conclusion that the S.cerevisiae C is the best one for consuming sucrose by measuring the weight of thalli when S,cerevisiae A,B,C ferment the molasses using glucose,sucrose,raffinose and stachyose as their carbon sources.The best condition for fermentation is determined by singular factor analysis: the temperature 30℃.,the quantity of inoculation 3%,the original pH value 6.5,the original content of the carbohydrates 6% under which conditions the removal rate of sucrose is 93.26%,the remainder rate of raffinose and stachyose are 92.98%,95.71% respectively.It means that the content of sucrose in soya oligosaccharide has been decreased remarkably.