Study On The Preparation Of Breakfast Cereal Powder With High Dietary Fibre From Jujube

In recent years, as the refined diet can cause a lot of health problems, as well as healthconsciousness has been widespread, people gradually realized that the important role ofdietary fiber in daily diet and are increasingly looking forward to food with high dietary fibercontent. In addition, jujube residue, rich in dietary fiber and with some physiologicalfunctionality, is a by-product of date from food production. As a reinforcing material to cerealbreakfast flour, jujube residue can increase the dietary fiber content to a large extent. In thepresent study, the formulation, processing procedures and brewing of cereal breakfast weremainly studied in order to increase the dietary fiber content of cereal breakfast and improve itsreconstituted property.Firstly, the formulation was determined. Rice was selected as the main raw material, fulljujube residue as dietary fiber resources, dates as the main flavor material and as well as anadditive to improve the dietary fiber content of the product, while red bean and lotus wereapplied to increase the protein content. And the effects of various materials on physicalproperties and sensory score of cereal breakfast were studied. The results are as following:with the increase of jujube residue content, water absorption index, wetting ability, anddispersion index would increase while the expansion degree, gelatinization degree,water-soluble ability, and in-vitro protein digestibility would decrease. For example, when thejujube residue content increased to5%, the wetting time would decrease to3s，and dispersionindex would be about95%; with the increase of red bean/rice ratio of content, the expansionratio, gelatinization degree, and water-soluble ability would decline, whereas bulk density andwater absorption index would improve; moreover, when the ratio of pitted date/rice contentwas1:5or the pitted date content of the product was10%, the highest sensory scores wereobtained, respectively; by further orthogonal experiment, the optimum formulation of thebreakfast cereal was established: red bean/rice content ratio being1:5,10%of pitted dates,5%total residues of jujube,5%of lotus,15%of sugar, and8.9%of dietary fiber content.Through this new formulation, the dietary fiber content of the product was greatly improved.Secondly, optimum processing procedure was established. Effects of different processingparameters on the product properties were studied. The results showed that: decrease both intemperature and in moisture content of the feed would be beneficial for improving theexpansion degree. And at a relatively temperature (140℃) of the end zone, feed moisturecontent of20%, the expansion degree reached the maximum value of2.0; moreover, it wasalso demonstrated that extrusion cooking was able to efficiently modify the dietary fiber, thusremarkably reducing the IDF and increasing the content of SDF. In the optimum procedure,the ratio of SDF to IDF of the product increased from0.40to0.62, thus achieving the goal ofmodification of dietary fiber; furthermore, in the condition of medium moisture of feed,medium end zone temperature (135℃), and medium screw speed, gelatinization degree reaches its highest value, while the feeding rate had no significant effect on the expansionratio. On the basis of these single-factor experiments, central composite study was carried outto determine the optimum processing procedure to establish a regression model usingresponse surface analysis: feed moisture content of20%, the end zone at135℃, a screwspeed being100r/min, feeding rate being2.0r/s.Furthermore, the adequate percentage of small-size particles was determined to solve theproblem of product’s poorly reconstituted property. Wetting ability, dispersion index, andpasting index were chosen as the evaluation indexes, and the effects of particle size ofrelevant grain, temperature of water, and water/powder ratio on the reconstituted propertywere studied. The results showed that: the product with small particle size (with aparticlediamite smaller than125μm) had the most poorly reconstituted property under allreconstituted conditions which can be improved by changing water tempareture orwater/powder ratio.However, compared with the cereal breakfast product of larger particlesize, the pasting property of that with small particle size was better. Therefore, when thecontent of the part with small particle size in the overall product was around30%—whichwas considered as the most adequate percentage, dispersion index could reach95%, andwetting index was less than30s. As a result, by controlling the particle size distribution of theproduct, the reconstituted property could be remarkably improved.