| In this experiment,. Millet Bran was taken as raw material, and the extraction process of dietary fiber from Millet Bran was investigated. The dietary fiber and mono-polysaccharide contents of Millet bran dietary fiber extracted was analyzed. And the physico-chemical and functional properties of the dietary fibre was also studied. It is important for Millet Bran to realize its comprehensive utilization and develop its economic value. The results are as follows:1.we studied the technology for extracting the dietary fibre from Millet Bran by the combined chemical and enzymatic method. Firstly, the enzymes were used to degrade starch, afterwards the NaOH was used to degrade protein, fat. By this method, the dietary fibre with high purity were obtained. The technical parameters were optimized by using singal factor and four-factor and two-dimensional revolving orthogonal combinatorial design. The result showed that the best process parameters for waxy Millet Bran were the amount of mixing enzyme (a-amylase:glucoamylose=1:3)1.5%, temperature 57℃,treatment time 90min, and NaOH concentration 3.6%, temperature 76℃,treatment time 96min, and the best process parameters for Normal Millet Bran were the amount mixing enzyme (a-amylase:glucoamylose=1:4) 4%, temperature 65℃,treatment time 100min, and NaOH concentration 5%, temperature 100℃, treatment time 70min.2. The monosaccharide composition and content of DF for waxy Millet Bran is xylose, mannose, glucose. The monosaccharide composition and content of DF for waxy Millet Bran is arabinose, xylose, mannose, glucose, galactose. For the two samples, the high content of monosaccharide is xylose, this is because the main composition of hemicellulose in Millet bran is almostarabinoxylan. For the normal Millet Bran, the galactose content in the monosaccharide composition is also very high, almost accounting for 26%, we can infered the branched-chain of this polysaccharides is much less. The glucose contents in the two samples are both low, while glucose is mainly from starch and cellulose, it showed that the products prepared by Milleet bran have little starch and cellulose polysaccharide.3.Condition temperature and granularity of DF had significantly influence on the property of DF.The swelling capacity, water holding capacity, oil holding capacity would increase as the granularity became smaller, but excess comminution would make them descend; in addition, water binding capacity decreased as the granularity became smaller. The swelling capacity and water holding capacity went up along with the temparature are increase, but oil hodling capacity and water binding capacity were reverse.4.The dietary fiber had obvious absorption of cholesterol, and with the increase of dietary fiber addition, the effect of its adsorption went higher. Although this test was taken by in vitro test method which simulated in vivo metablic processes, the results showed that the dietary fibre could absorb cholesterol effectivly.5.The dietary fibre had significant scavenging effect on NO2-in the pH values of 2 and 3.In the pH=2, the adsorption amount of the waxy and non-waxy millet bran dietary fiber on NO2-was 17.66μmol/g,17.01μmol/g, respectively, in the system absorption rate of NO2-was 80.3%, 77.3% separately, but in pH=3,the adsorption capacity decreased significantly, only 9.06μmol/g, 7.93μmol/g, absorption rate was 41%,36%, respectively, while in the pH=5 and 7, with the time increasing, the concenttration of NO2-has not been changed obviously, basically it did not appear adsorption effect.6. In these two dietary fibres, the contents of IDF were as high as 91.35%, and 89.55%, while the starch and non-fibre carohydrate content were low, so the dietary fibres meeted the quality requirements.7. When the dietary fibre replaced part of the flour, the physical properties of bread were changed. These changes were two-sides, on the one hand, it increased the water-holding capacity of bread and made bread more elasticity, on the other hand, dietary fiber prevented the formation of gluten dough, it produced a certain bad influence on the fermentation performance. At the same time, when we add 4% of DF, it is found that the extent of deterioration of bread was not obvious; it is because dietary fibre could improve the water absorption of the dough, it might delay the stale of the bread. In a centain extent, although it had adverse effect on the specific volume and taste of bread, its comprehensive quality has been enhanced. So the added amount of DF in bread-making should be kept about 4%.
|
PDF Full Text Request