Study On Multi-cereal Mixed Flours Of Steamed Bread

This study was based on the principle of dietary nutrient supply quantity and balance per day, which is commended by Chinese Nourishment Academic Association. China is rich in varieties of coarse cereals and these grains are full of some nutrients absent in main food grains like wheat. Chinese people have made staple steamed bread as one of their main foods for long time. However, the current species of staple steamed bread are monotony and nutrient deficiency, and the coarse cereals are not well developed. Our aim was to develop a new kind of nutrition balance flour for special staple steamed bread by mixing wheat with corn, millet, buckwheat, and oat and the relevant effects was researched.The appearance and taste of product can be improved by milling raw materials, these four kinds of coarse cereals were micronized by vibration mill. Under the milling process, we found that buckwheat was the easiest to mill, followed by millet and corn, and the hardest was oat. According to our test, the optimum milling times for buckwheat, corn and millet were 15 min, and the average particle sizes of these tree grains were 31.6μm, 31.6μm and 26.9μm, respectively. However, the time of oat was 25 min and the average particle size was 46.2μm.Effects of adding four grains and milling on wheat dough rheology and staple steamed bread quality were studied. Both farinograph property and stretching property were improved after milling. However, these properties were not good as these of wheat dough yet. Adding these four grains made qualities bad, and the extent of effects of these four grains were, micronized oat powder> micronized buckwheat powder> micronized millet powder> micronized corn powder; coarse buckwheat powder> coarse oat powder> coarse corn powder> coarse millet powder. It was unreasonable of only using conventional standard of wheat flour farinograph property and stretching property to evaluate the dough, so we introduced combining with steamed bread cooking experiment to estimate the dough. According to mending standard, the ratio of adding four kinds of grains should be controlled lower than 40%, and the best additions were micronized millet powder 30%,micronized corn powder 20%, micronized buckwheat powder 20%, micronized oat powder 20%, respectively.Contents of amino acid in five kinds of grains proteins were analyzed, and the results were, as follows EAAI value of oat was the highest 90.23, the corn powder's was the lowest 61.35, other materials were wheat powder 65.33, millet powder 82.59, and buckwheat powder 77.06. Optimum formula of multiple grains steamed bread flour was determined by orthogonal experiment that was wheat powder 68.0%, millet powder 8.0%, corn powder 5.0%, oat powder 9.0%, and buckwheat powder 10.0%. In this optimum condition, dietary fiber content of this four was 2.1g/100g and 2.5 times more than wheat flour, comprehensive score of steamed bread was 81, and composition of essential amino acids was closer to FAO/WHO, and EAAI value was 8.1% higher than wheat flour.Five kinds of enzymes including fungusα-amylase, glucose oxidase, pentosanase, maltogenic amylase and transglutaminase were used to improve the sensory quality of multiple grains steamed bread. Except transglutaminase other four enzymes can surely get effective improvement. The result of Orthogonal experiment showed that: adding complex formulation of fungusα-amylase, glucose oxidase, pentosanase, and maltogenic amylase into multiple grain steamed bread could obviously improve sensory quality of multiple grain steamed bread. And the optimum complex was fungusα-amylase 10 mg/kg, pentosanase 10 mg/kg, glucose oxidase 15 mg/kg, maltogenic amylase 50 mg/kg. Effect of single enzyme on anti-aging of multiple grain steamed bread in terms of hardening rate and renaturation change value was studied, result showed anti-aging effect of maltogenic amylase on multiple grain steamed bread was the biggest, fungusα-amylase, glucose oxidase, pentosanase, transglutaminase followed ordinally. The optimum anti-ageing effect of complex of enzymes was optimized by response surface method, and the result was that maltogenic amylase 51.46 mg/kg, fungusα-amylase 41.15 mg/kg, and glucose oxidase 19.38 mg/kg. In the optimum condition, the hardening rate of steamed bread was 6.18 g/h, and change value of springiness was 4.93 and hardening rate was 87.4% lower than blank sample, and changed value of springiness decreased by 69.2%.