The Effect Of Pre-enzymatic Hydrolysis-drum Drying Process On The Quality And Storage Stability Of Whole Wheat Flakes

Increasing whole grains in food consumption is becoming a modern fashion of healthy diet.Whole wheat flour is a typical whole grain,which contains higher nutrients and health benefits than refined wheat flour.Oatmeal is a kind of nutritious and convenient food made from wheat flour as the raw material and processed by drum drying.Compared with refined wheat flour,whole wheat flour is rich in nutrients.However,the digestibility and brewing characteristics of the product are poor under the conditions of traditional oatmeal processing technology caused by its rich dietary fiber and other ingredients,which make it difficult to meet the needs of consumers.Therefore,it is necessary to improve its processing technology.In addition,there are some defects in the whole cereal,such as single product type,less data of storage stability and so on.In view of the above problems,whole wheat flour was used as raw material in this paper.We used different enzymes for pre-enzymolysis,and then prepare whole cereal through the drum drying process.The effect of the pre-enzymolysis and drum drying process on the quality characteristics of whole cereal was discussed,and the processing conditions were optimized.Furthermore the effects of dietary fiber from different sources on the quality characteristics of whole cereals were compared and studied;and the changes of the sensitive index content of whole cereals under different storage conditions were clarified.The main findings are as follows:(1)Optimization of pre-enzymolysis and drum drying process of whole cereal:In this paper,whole wheat flour was used as raw material.We used different enzymes for pre-enzymolysis,and then prepare whole cereal through the drum drying process.The effects of different enzymes(cellulase,?-amylase and their complex enzymes)were studied on the physical and chemical properties of whole-grain starch digestibility,dispersibility,etc.,and the types of pre-enzymatic hydrolysis were determined.Then,we analyzed the effects of enzyme addition,roller temperature,roller speed and material concentration on the starch content of the whole-grain quickdigestion.The research results show that the optimal process conditions for pre-enzymatic hydrolysis are: the addition amount of cellulase was 0.4%(2000 U/g),and the addition amount of high-temperature alpha amylase was 0.5 U/g.The best process conditions for drum drying are: the whole wheat mass fraction was 25%,the drum speed is 10 Hz,and the drum temperature was 150 ?.Under this process condition,the yield of whole cereal was higher,with a starch digestibility of up to40%,a water solubility index of about 70%,and a water absorption index of about 3.5,and the brew ability was good.(2)The effect of pre-enzymolysis and drum drying process on the quality of whole cereal:We used whole wheat flour as raw material,?-amylase,cellulase and its compound enzymes were used for pre-enzymolysis and drum drying to prepare whole cereal: whole-meal flakes were dried directly without pre-enzymolysis treatment,?-amylase-drum Dried instant whole wheat flakes,cellulase-drum dried instant whole cereals,?-amylase-cellulase-drum dried instant whole wheat flakes,and direct-drum dried refined oatmeal prepared from refined wheat flour.Then,rehydration rate,caking rate,water solubility index,water absorption index,gelatinization degree,viscosity,color,starch,reducing sugar,dietary fiber,phytic acid content,starch and protein digestion characteristics,polyphenols,flavonoid content,dispersion stability and other indicators were determined.The effect of pre-enzymatic hydrolysis-drum drying on the quality characteristics of whole cereal were compared and analyzed.The research results showed that the pre-enzymatic hydrolysis and drum drying treatment can significantly improve the whole cereal's brew ability.Among them,the DWG sample had the lowest rehydration rate and the DWGAC had the highest rehydration rate.Compared with the control sample DWG,The agglomeration rate of DWGA,DWGC,and DWGAC was significantly reduced.The water solubility index of DWGA,DWGC,and DWGAC were 4.98,2.07 and 5.04 times higher than that of DWG.Pre-enzymolysis and drum drying significantly reduced the attenuation valueand regeneration value(P<0.05),and the thermal stability was good.At the same time,the starch and phytic acid content of the whole cereal decreased significantly(P<0.05),the reducing sugar content and gelatinization degree increased significantly(P<0.05),and the color of the whole cereal decreased properly.Compared with the control sample of DWG,the content of IDF in the sample of pre enzymolysis and roller drying decreased significantly(P<0.05),and the content of SDF in the sample increased by 35.83%,53.39% and 69.49%,respectively.In addition,pre-enzymolysis and drum drying significantly increased the proportion of fast digested starch in the whole cereal,and the content of fast digested starch increased by 22.34%,34.84% and46.59% respectively compared with the control,among which DWGAC had the highest content of fast digested starch;protein digestion rate in vitro was accelerated,and protein digestion rate in vitro was increased by 0.33,0.25 and 0.26 times,respectively.Compared with the DRG,the total phenol content of the four groups was higher,and the difference reached a significant level(P<0.05).There was no significant difference in flavonoid content.There were significant differences in the dispersion stability of five different cereals,among which the precipitation thickness of DWGC was the smallest and that of DWG was the largest.By comparing the TSI value of DWGAC,the TSI value of DWGAC was the smallest and the system was the most stable.(3)The effect of dietary fiber from different sources on the quality characteristics of whole cereal:Using whole wheat flour as raw material,dietary fiber from different sources(bamboo shoot fiber,corn fiber,sugarcane fiber)was added in the proportion of 30%,40% and 50% respectively.High dietary fiber oats were prepared directly by drum drying.The WAI,WSI,caking rate,gelatinization characteristics(peak viscosity,minimum viscosity,final viscosity,attenuation value,regeneration value),dispersion stability and sensory evaluation were measured.And the effects of dietary fiber addition from different sources on the quality characteristics of whole cereal werecompared and analyzed.The results showed that the WSI of three kinds of dietary fiber increased significantly(P<0.05).When the proportion was 30%,the WSI of bamboo fiber whole wheat,corn fiber whole wheat and sugarcane fiber whole wheat were 3.12 times,4.77 times and 2.41 times higher than that of common whole wheat;while WAI decreased significantly(P<0.05).With the increase of dietary fiber proportion to 50%,the caking rate of three kinds of high fiber whole cereal decreased significantly(P<0.05).With the increase of dietary fiber proportion,the B * value of whole wheat samples decreased significantly,the L * value increased,and the a *value decreased significantly,resulting in a certain color difference.The retrogradation value and attenuation value of the whole cereal with dietary fiber decreased significantly,indicating that the thermal stability was better,and the quality of the whole cereal with corn fiber was better.Among the three kinds of high fiber whole oats,the TSI value of corn fiber whole oats was the lowest,which indicates that its dispersion stability was the best,and the best adding proportion was 30%.(4)Study on the stability of whole cereal under different storage conditions:The whole cereals were stored for 30 days at different temperature(4 ?,25?,25?,45?).The indexes of active ingredients(vitamin A,vitamin E),fatty acid value,peroxide value,moisture content and acid value of whole cereal were measured under different storage temperature,light condition and storage time.Then the mathematical models of quality indexes changing with time were established,and the sensitive indexes in the storage process were analyzed based on the dynamic equation.The results showed that the fatty acid value increased significantly(P<0.05),the content of vitamin A and vitamin E decreased slightly,and the peroxide value did not change significantly(P<0.05)with the increase of time.Compared with the 25 ? light condition,the storage moisture content,peroxide value,fatty acid value,vitamin A,e decay rate and other stability indexes of the whole cereal under the 25 ? dark condition had significant differences,which showed that the storage stability of the whole cereal was significantly reduced by the light.However,under the condition of45 ? high temperature,after 30 days storage,the moisture content decreased significantly,with the peroxide value increasing significantly,the fatty acid value increasing gradually,the decay rate of vitamin A reaching 34.78%,which was 2.55 times of that at 4 ° C.In this case,the decay rate of vitamin E reached 71.56%.According to the fitting results of dynamic analysis,the stability was better under the condition of low temperature and dark storage.