| Whole grain foods is a typical representative of the nutritional health food,containing dietary fiber,vitamins,minerals,antioxidants and other functional components.The bioactive substances are mainly enriched in the exodermis of the grain,and produce a variety of health function through the synergistic interaction of "whole grain nutrition package".With black-grained wheat as the research object,feruloylated oligosaccharides(FOs)were prepared from black-grained wheat bran insoluble dietary fiber by xylanase treatment.The hydrolyzate was isolated by activated carbon column chromatography.The composition and structure of enzymatic hydrolysis were analyzed by ion chromatography and high performance liquid chromatography.Adding FOs to the black-grained wheat whole grain products,with extrusion puffing technology,the formula was studied in the grain wheat extrusion puffing food,to develop a kind of whole grain wheat food with good-tasted,the best nutrition and strengthening FOs,to provide the theoretical basis for the comprehensive utilization of black-grained wheat,and to provide guidance for practical production.The insoluble dietary fiber was hydrolyzed by xylanase to release feruloylated oligosaccharides(FOs).The content and composition of FOs were analyzed by UV wavelength and HPLC,combining with dual-wavelength method and thin layer chromatography(TLC).Based on the single factor experiments of enzyme dosage,reaction time,pH,and temperature,with FOs concentration as response value,the process for enzymatic production of FOs was optimized by using response surface methodology employing a four-level,three-variable central composition rotatable design.The optimum reaction conditions were as follows:preparing for 22 h at 46?,with enzyme concentration of 15.5 mg/L and pH 4.8.Under the conditions,FOs content of the product was 0.4913 mmoL/L.The results of UV wavetenth and HPLC showed that the oligosaccharides of hydrolyzate containing ferulic acyl group which was feruloylated oligosaccharides.The enzymatic hydrolysate was separated and purified with activated carbon column chromatography to get water washing oligosaccharides(WO)and different concentrations of ethanol washing oligsaccharides(EO).The oligosaccharide,monosaccharide composition and ferulic acid group of the fractions were analyzed by HPLC and ion chromatography.The results showed that the degree of polymerization of WO was higher with 4-7,and the degree of polymerization of different concentration of EO was mainly 2-4 witch content was increasing with the increase of ethanol concentration.WO with bound ferulic acid was feruloylated oligosaccharides,in witch the content of ferulic acid was 42.78 mg/g.EO was arabino-xylooligosaccharides without the bound ferulic acid.The oligsaccharides of WO and EO were mainly composed of arabinose and xylose.The branching degree of WO(A/X=0.53)was higher than that of EO(A/X=0.33),witch also provided more substitution sites for the connection of the ferulic acid group.The enzymatic hydrolysate was treated with high pressure 10-30 min,the content of FOs increased with the treatment time.This showed that the effect of the high temperature and high pressure could promote the high degree of polymerization(DP)of dietary fiber to low DP of FOs transformation.The addition of FOs had a certain improvement effect on the quality of whole grain puffed food of black-grained wheat,including the expansion rate and the sensory evaluation.Based on the single factor experiments of the addition of soybean protein,soy lecithin and sugar,with comprehensive score as response value,the additions of these were optimized by using response surface methodology employing a three-level,three-variable central composition rotatable design.The optimum additions were as follows:3.3%of soybean protein,0.4%of soy lecithin,8.3%of sugar and 7%of FOs.Under these conditions,the comprehensive score of the whole grain extrusion puffing product of black-grained wheat was 4.16. |
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