Processing Technology And Quality Research Of Fermented Whole Wheat

In recent years,fermented whole grain products with high nutritional value and special functional properties,is catching the attention of global food industry and health organizations.Whole wheat is a highly nutritious food processing raw material.After fermentation,its nutritional compositions and physical and chemical properties undergo great changes.The fermented whole wheat is made from whole wheat after soaking,cooking and fermentation.It is a typical traditional flavor food with Chinese characteristics.It has unique nutritional value and physiological functions.Therefore,it is very important to study and further enhance the quality of fermented whole wheat.The aim of this paper is to study the effect of different processing methods on the quality of fermented whole wheat,and to provide a scientific basis for the processing technology and quality control of fermented whole wheat.The effects of cooking and fermentation on the starch and protein in whole wheat were investigated,which provided scientific basis for the functional properties and marketing of fermented whole wheat.1.Effect of partial peeling treatment on the processing technology of fermented wheatThe effects of partial peeling treatment on the processing technology of fermented whole wheat were studied by investigating sugar content,acidity,sugar-acid ratio and sensory score.The optimal ranges for steaming time,rice leaven amount,fermentation temperature and fermentation time were optimized by single factor experiment.Then,the orthogonal experiment was carried out by single factor analysis of variance(ANOVA),and the optimum conditions were as follows:the partial peeled wheat kernel was soaked in water for 6 h at 25?;the steaming time was 45 min;the rice leaven amount was 0.5%;the fermentation temperature was 30?;the fermentation time was 42 h.Compared with the original fermented process for whole wheat,soaking time and fermentation time is shortened,and steaming time is longer.The fermented partial peeled wheat kernel treated by this fermenting process tastes sweet and less rough compared with the fermented whole wheat.2.Determination of ethanol content in fermented whole wheatA combination methond including solid-phase microextraction(SPME)and gas chromatography(GC)was developed to determine the ethanol content in fermented whole wheat.The effects of SPME on ethanol extraction were studied systematically.The optimum conditions were determined as follows:A portion of 0.1 g of smashed or mashed sample was diluted with 5 m L of ultrapure water in 10 m L headspace vial,and then sodium chloride was added to get a concentration of 40%(w/v).The mixture was incubated at 50?for 5 min with magnetic stirring.A hydroxy-terminated silicone oil/divinyl benzene fiber was inserted and kept extraction for 10 min.After extraction,the fiber was transferred to the GC injection port for desorption.The proposed method has the advantages such as simple operation,rapid determination,less sample consumption,high sensitivity,good accuracy and repeatability.The method was linear in the range of 100?200000?g/g with a coefficient of 0.999(R~2).The limit of detection was 11.92?g/g.The ethanol recoveries were 96.51%?103.48%at 200,2000and 20000?g/g spiking levels with the relative standard deviations less than 9%.The method had been successfully used to determine ethanol in fermented whole wheat during fermentation process.It is suitable for determination of ethanol content in many kinds of fermented grains.3.Effect of cellulase treatment on the processing technology of fermented whole wheatThe optimum conditions for fermented cellulase-treated whole wheat were determined by the evaluation of sugar content,acidity,sugar-acid ratio,alcohol content,texture(hardness,elasticity,viscosity and chewiness)and sensory characteristics.The optimum technological parameters were as follows:the cooking time was 45 min,the rice leaven amount was 1.0%,the fermentation time was 48h,and the cellulase amount was 0.5%.Compared with the original processing technology for fermented whole wheat,the processing conditions for fermented cellulase-treated whole wheat changed greatly,and the cooking time was longer and the rice leaven amount increased.The fermented cellulase-treated whole wheat shows yellow color,delicious and special taste,much less coarser mouthfeel and perfectly balances the hardness and softness of kernel.4.Effects of partial peeling treatment and cellulase treatment on the quality of fermented whole wheatThe effects of fermentation,partial peeling and cellulase treatment on the quality of fermented whole wheat were evaluated by sensory evaluation,texture characteristics,flavor,physical and chemical properties,and functional nutrients in whole wheat.The results showed that in the three kinds of fermented wheat,the fermented cellulase-treated whole wheat had moderate sugar-acid ratio,alcohol,hardness,and resilience,better chewiness,and the best quality.Furthermore,the physical and chemical indexes of fermented whole wheat treated by cellulase reached the industry standard of rice wine.In addition,the contents of three types of dietary fiber,total phenolics,lignans and vitamin E in the whole wheat increased by different treatments,and the contents of these components in the fermented whole wheat treated by cellulase were significantly higher than the contents in non-fermented whole wheat and partial peeling treated wheat kernel.In summary,cellulase treatment on the fermented whole wheat can improve the quality of fermented whole wheat.5.Effects of key procedures on starch and protein in whole wheatThe microstructures,physicochemical properties and in vitro digestibility of starch in whole wheat were studied by morphological properties,X-ray diffraction,particle size distribution,apparent amylose content,thermal properties,solubility and swelling power and pasting properties.Scanning electron micrographs revealed that the shapes of starch after being fermented were irregular oval,spherical and polygonal and crack appeared on the surface of starch compared with the native whole wheat starch(NS)and the cooked whole wheat starch(CS).Besides,the crystalline structure maintained an A-type and the relative crystallinity of the fermented whole wheat starch(FS)was higher than that of the CS.After fermentation,the apparent amylose content,range of gelatinization temperature,gelatinization enthalpy,solubility and pasting temperature increased,however,the swelling power decreased.It was found that the digestibility of starch in the whole wheat changed significantly during processing.Fermentation reduced rapidly digestible starch(RDS)and slowly digestible starch(SDS)but increased the content of resistant starch(RS)in the CS.The digestibility of protein in the stomach and gastrointestinal areas of unfermented whole wheat and fermented whole wheat were compared by gastric-small intestine-large intestine three-step method.The results showed that the in vitro digestibility of protein in whole wheat was higher than that in unfermented whole wheat both in the stomach and the gastrointestinal tract.Studies have shown that the addition of cellulase to the fermented whole wheat can not only improve the taste of fermented whole wheat,but also enhance the quality of the product.Therefore,the fermented cellulase-treated whole wheat has a good market development potential.