| Dietary fibre refers to those carbohydrate-based macromolecules which can not easily be digested by body, it contains cellulose, hemicellulose, lignin, resin, pectin and so on. Dietary fibre is indispensable to healthy diet, and is called"The seventh nutriment"for body. Dietary fibre has special Physical and Chemical Properties and physiological function, it can prevent many diseases and play an important role in maintaining human health. Corn is one of the most widely distributed food crops, our country is a big maize production country, rank the second place in the world's total annual output of corn. Corn bran is a by-product of corn processing, and is rich in high-quality dietary fibre. Its major components are cellulose, hemicellulose and so on. China's annual production of corn bran up to 2 million tons, most of which have not been fully utilized, mainly be used as feed, and some even be used as rubbish thrown away in vain, resulting in a great waste of resources. China's current development and use of corn bran is more rare, the studies of using corn bran to prepare dietary fibre with high activity are few. In this paper, we use corn bran as raw material, use enzymatic method to prepare dietary fibre, and treat the dietary fibre obtained with many functional activation methods, and investigate its in vitro adsorption and blood lipid-lowering activity, finally we determine the optimal method of maintaining its stability.Firstly, we use enzymatic method to prepare corn bran dietary fibre. Through some single factor experiments we optimized the reaction times of amylase, lipase and protease, the experimental results show that: the optimum reaction time of amylase is 15min, and the best reaction time of lipase and protease is 25min. We make further use of cellulase to prepare soluble and insoluble dietary fibre, carry on a three factors, three-level orthogonal experiment which is based on the single factor experiments, and get the optimal reaction conditions of cellulase were: reaction time 3h, enzyme dosage 0.4μL / g, reaction temperature 50℃.Secondly, we treat corn bran dietary fibre which is prepared by the above enzymatic method with many functional activation methods, and ultimately get the best functional activation method: 0.6% NaOH with high temperature and pressure. This method allows swelling force up to 14.5 mL/g and water holding capacity up to 20.31%, significantly increased 4.3 times of the swelling force and 2.7 times of the water holding capacity. Scanning electron microscopy results show that, 0.6% NaOH with high temperature and pressure activation destroy the regular fibrous structure of corn bran dietary fibre and turn it into irregular small granules. The decrease of granularity and the increased surface area make the increase of swelling force and water holding capacity. Infrared spectroscopy results showed, 0.6% NaOH with high temperature and pressure treatment results in an decrease in the amount of carbonyl and an increase in the number of hydroxy. Hydroxy, as the side-group in chemical structure of dietary fibre makes dietary fibre has a function as weak acid cation exchange resin which has strong ion-exchange capacity and adsorption capacity.Thirdly, we study the in vitro adsorptive activity of corn bran dietary fibre. The result of nitrite adsorption of corn bran showed that in simulated gastric environment, corn bran has obvious absorptive function on nitrite. Further results of maximum adsorption on 2000μmol/L nitrite and the adsorption on different concentrations of nitrite show that compared with HCB, HDF and IDF, the maximum adsorption capacity and the average adsorption rate on 2000umol/L nitrite within 5h of AHDF are the largest, were 13.41mg / g and 24.96 mg / L * h, respectively. The maximum adsorption of AHDF on 400μmol/L, 600μmol/L, 800μmol /L, 1000μmol/L nitrite is amount of 100%, the average adsorption rate within 3h is 23.00 mg / L * h, and the adsorption stability is high. Thus, in a simulated gastric environment (pH2.5), the activated corn bran dietary fibre which is treated by alkali, high temperature and pressure has a very strong adsorptive activity on nitrite. The result of adsorption on glucose shows that in both the intestinal environment or the stomach environment, the activated corn bran dietary fibre has no significant adsorption on glucose. The activated corn bran dietary fibre has obvious adsorption on 10mmol / L calcium ions, the maximum absorption rate is about 49.4mg / g.Fourthly, we study the blood lipid lowering function of the activated corn bran dietary fibre which is treated by alkali, high temperature and pressure. Through successfully constructing hyperlipidemia model to Wistar rats, re-grouping and feeding the corresponding food, we find that feeding the activated corn bran dietary fibre can very significantly reduce 41.4% TC and 56.5% LDL-C, significantly reduce 20.7% TG and slightly reduce 2.8% HDL-C of hyperlipidemic rats, so the activated corn bran dietary fibre has a very effective blood lipid lowering function. Its blood lipid lowering activity is significantly higher than the dietary fibre which is produced by Aotefu company from Shanxi.Finally, we study the method of maintaining the stability of the activated corn bran dietary fibre, we determine the optimal method: adding 1.25% ascorbic acid powder and vacuum packaging.
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