Extraction And Preparation Of Raffinose From Defatted Wheat Germ

The preparation of raffinose from defatted wheat germ (DWG) and the optimization of conditions in the procedure were studied in this paper. The product obtained was analyzed by MS, FT-IR, NMR, X-ray diffraction and it can be confirmed to be raffinose. The physical and chemical properties were tested according to national standards.The raffinose extraction process was studied. Single-factor experiments were used to select experimental factors and levels influencing the rate of extraction, then the method of orthogonal test with four factors and three levels was adopted. The factors influencing the technological parameters were determined by ANOVA. The better operating conditions were as follows: concentration of ethanol solution 75%, extraction temperature 50℃, ratio of DWG to solvent 1︰13 (w/v) and extraction time 2.5 h. The extraction rate of 83.65% was obtained under the optimized processing conditions.The decolorization conditions of activated charcoal (AC) were optimized in the water system and the alcohol system respectively . The decolorization effects of AC in the two systems under optimized conditions were compared in order to determine the appropriate system. The determination of the best decolorization conditions in alcohol system: experimental factors and levels influencing the rate of decolorization were first selected by single-factor experiment then the method of response surface analysis (RSA) with three factors and three levels was adopted and the factors influencing the technological parameters were determined by means of regression analysis. The better operating conditions were as follows: the amount of AC 4% (w/v), temperature 50℃, pH 5.0, adsorption time 2 h. The best decolorization rate can be reached under these conditions.The determination of the best decolorization conditions in water system: the alcohol extraction was concentrated to remove ethanol, then different proportion of water was added to determine the optimum amount of water addition, then the amount of AC was investigated also the decolorization temperature, pH, decolorization time on the decolorization rate and the rate of sugar loss. The better operating conditions in water system were as follows: the amount of AC 1% (w/v), pH 4.5, temperature 50℃, adsorption time 1.5 h. The best decolorization rate can be reached under these conditions. The decolorization effects of AC in the two systems under optimized conditions were compared. The result showed that both in water system and alcohol system good decolorization effect can be achieved, the alcohol system was selected considering the complexity of the process.Crystallization was used to separate raffinose from the decolorized solution. The decolorized solution was concentrated and a certain percentage of ethanol was added then the mixture was set to crystallize at low temperature. Most of the crude raffinose can be gotten through this procedure. The crude raffinose was heated and dissolved in 70% ethanol to recrystallize at low temperature. A procedure to get raffinose from DWG contains extraction, decolorization, crude crystallization and recrystallizaiton. The purity of the product obtained under this procedure can reach 99% and the yield (as opposed to raw DWG) was 2.3%. The characteristics of the product were analyzed with MS, FT-IR, NMR, X-Ray and all the spectras of the product met closely with those of raffinose standard. The results showed the product was raffinose. The physical and chemical properties were tested according to national standards.