Study On Rheological Properties Of Dough With Whey Powder And The Bread Process Optimization

Whey powder is the product of whey from cheese(or casein)via sterilizing,concentrating,drying and other processes.Whey powder is rich in lactose,whey protein and various minerals and vitamins,which has high nutritional values and functional properties.The applications of whey powder in bakery food not only improve the quality of products but also promote the utilizations of whey.In this paper,different proportions of sweet whey powder were added into high-gluten flour to make bread,during which the effect of sweet whey powder on the physicochemical and rheological properties of dough was explored,the formulations and process conditions of bread with sweet whey powder were also optimized.Furthermore,the volatile flavor compounds and storage characteristics of bread with sweet whey powder were analyzed.The main results were given as follows:(1)Analysis of the basic ingredients of whey powder and high-gluten flour showed that the main components of high-gluten flour were starch(71.30%),water(14.30%)and protein(12.03%),whereas main components of whey powder were lactose(72.86%),protein(13.35%)and ash(8.19%).Compared with high-gluten flour,sweet whey powder was relatively yellow.The pasting properties of high-gluten flour were changed with the addition of whey powder,during which the peak viscosity,trough,breakdown,final viscosity and setback of high-gluten flour showed a decreased tendency with the addition of sweet whey powder,while the pasting temperature showed an increased tendency.The starting temperature and enthalpy of high-gluten flour with addition of 3.0% sweet whey powder obviously rose compared with control high-gluten flour(without sweet whey powder).These results suggested that sweet whey powder had a positive effect on improving thermodynamic and anti-retrogradation ability of high-gluten flour.(2)The water absorption and development time of dough decreased with addition of sweet whey powder,whereas stability time and farinograph quality number increased.The extension energy,resistance to extension and R/E number showed an increased tendency with increasing amount of sweet whey powder while the extensibility decreased.In general,the addition of sweet whey powder to high-gluten flour enhanced gluten strength and improved the farinograph and extensograph properties of dough.(3)Formulation and process conditions of bread with sweet whey powder were optimized through single factor design and orthogonal experiments.The optimized parameters were as follows: based on the weight of high-gluten flour,sweet whey powder 3.0%,water 50%,yeast 2.0%,sugar 10.0%;mixing time 40 min,fermentation time 70 min,proofing time 60 min,baking time 30 min.(4)Bread made with sweet whey powder were more yellow compared with the control group,giving the bread an attractive color.58 kinds of volatile flavor compounds were detected in two breads,including 54 kinds in bread with sweet whey powder and 40 kinds in the control group bread,leading the enrichment of bread flavor with addition sweet whey powder.Besides,the addition of sweet whey powder reduced the hardness and staling enthalpy of bread during the same storage period,indicating that sweet whey powder could reduce the hardening rate and delay the staling of bread.