Study On The Quality Improvement Of Black Wheat Bran By Steam Explosion Pretreatment And Its Application

Black wheat has become an important black food resource due to its high nutritional value.As the main by-product of black wheat processing,black wheat bran contains most of the nutrients in black wheat.However,due to its high insoluble dietary fiber content,easy oxidative deterioration,poor processing suitability,and palatability,the application of wheat bran in food is limited,resulting in a waste of resources.How to modify wheat bran to reduce or eliminate its adverse effects in food processing has become a hot research topic in recent years.As the most promising pretreatment method for biomass resource conversion,steam explosion(SE)has the advantages of short reaction time,low energy consumption,high efficiency,no pollution,and adaptation to industrialization.In this thesis,steam explosion technology was used to modify the black wheat bran.The effects of steam explosion on the nutritional quality and physicochemical properties of black wheat bran were systematically studied.The effects of modified wheat bran on the quality of whole wheat flour and whole wheat noodles were explored.The whole wheat flour and whole wheat noodles products were developed to provide some theoretical support and scientific guidance for the application of steam explosion technology in food processing and the development of whole wheat food.The main results of this thesis are as follows:(1)Effects of steam explosion pretreatment on physicochemical properties and nutritional quality of black wheat bran.The process parameters of SE pretreatment of black wheat bran were optimized under different pressure(0.5 MPa,1.0 MPa,and 1.5MPa)and different pressure times(30 s,60 s,and 90 s).The results showed that SE reduced the internal structural strength of black wheat bran,made the structure of wheat bran lose,significantly increased water holding capacity and swelling capacity,and increased the content of soluble dietary fiber and free active components.The modification effect was the most significant when the pressure was 1.0 MPa and the compression time was 90 s(P<0.05).Under this condition,the content of soluble dietary fiber in wheat bran increased by 53.63%.The total contents of polyphenols,anthocyanins,and flavonoids increased by 90.65%,40.89%,and 92.90%,respectively.DPPH,ABTS,and FRAP in antioxidant activity increased by 57.36%,41.62%,and43.95%,respectively,while the bitterness value and phytate content decreased by10.76% and 64.12%,respectively.(2)Effects of steam explosion modified black wheat bran(SEWB)on whole wheat flour properties and dough quality.Steam explosion modified whole wheat flour(SEWF)was prepared by adding 5%,10%,15%,20%,25%,and 30% SEWB to black wheat flour.The results showed that with the increase of SEWB,the moisture content of SEWF decreased,while the water holding capacity,oil holding capacity,and swelling capacity increased.When the additional amount of wheat bran was 5%～30%,SEWF had a lower viscosity value and stronger thermal stability than whole wheat flour(WWF)prepared from unmodified wheat bran.At the same time,the fatty acid value,acid value,and peroxide value of SEWF were significantly lower than those of WWF(P<0.05),indicating that SE could significantly inhibit the oxidative rancidity of fat in whole wheat flour,improve the storage performance of whole wheat flour,and effectively prolong the shelf life.When the additional amount of wheat bran was 0%～20%,compared with WWF,SEWF had higher elastic modulus G’ and viscous modulus G" but lower loss factor(tanδ value),indicating that SE could improve the viscoelasticity of whole wheat flour dough.(3)Formulation optimization and quality improvement of black wheat whole wheat noodles.The formula of whole wheat noodles was optimized by a single-factor test and response surface test design.The optimal formula of black wheat noodles was black wheat modified wheat bran 13.60%,gluten 12.87%,resistant starch 13.00%,and water addition 48.75%.The effects of four factors on the evaluation of black wheat whole wheat noodles were: modified black wheat bran > resistant starch > gluten > water.Under this formula,the sensory score of the product was 83.55 measured by fuzzy mathematics sensory score,and the noodles were crisp and non-sticky.The e GI value was 54.93 by in vitro digestion model,which was low GI food.There was a correlation between the texture characteristics(hardness,chewiness,shear force,tensile force,elasticity,resilience),cooking characteristics(broken rate,water absorption,cooking loss rate),and sensory quality of the noodles.Through principal component analysis and correlation analysis,the comprehensive evaluation model of black wheat whole wheat noodles was constructed as F=2.517F1+1.667F2+1.233F3.Using the comprehensive evaluation model to evaluate the quality of black wheat whole wheat noodles can save manpower and time cost,and has certain feasibility.