Effect Of Yam Flour Addition On Properties Of Dough And Qualities Of Bread

Yam is one of the traditional Chinese medicine of medicine food homology,contains a variety of active components and has high edible and medicinal value.Mixing the yam flour with wheat flour can not only improve the processing performance of yam flour,but also achieve complementary nutrition and improve the nutritional value of bread.In this study,the yam flour was added to wheat flour to study its effect on dough characteristics and bread quality,aiming to provide a theoretical basis for the application of yam flour in bread.The main results were as follows:(1)The active components of yam flour were analyzed:the total polyphenols content was 0.81 mg/g,total flavonoids content was 1.16 mg/g,polysaccharides 53.56 mg/g,allantoin content was 5.29 mg/g.Adding yam flour increased the water holding capacity of the mixed flour whereas decreased the oil holding capacity.(2)Effect of the addition of yam flour on the characteristic of yam-wheat mixed dough by rapid viscosity analyzer(RVA),farinograph,extensograph,rheometer and texture analyzer.The results showed that the addition of yam flour changed mixed dough properties.With the increase in the percentage of yam flour,the pasting temperature,breakdown,water absorption,softness,elasticity modulus(G')and viscosity modulus(G”)decreased whereas the peak time,peak viscosity,minimum viscosity,final viscosity,setback,developing time,stability time,stretching energy,extensibility increased.As the percentage of yam flour in mixed flour was increased,the hardness,springiness,gumminess and chewiness of mixed dough decreased first then increased.(3)With the increase in the percentage of yam flour,the wet gluten content of mixed flour decreased,the microstructure of dough and gluten was destroyed,and the proportion of relatively stable structure in protein secondary structure decreased.(4)Addition of yam flour decreased L~*value,specific volume,hardness and springiness of bread.The addition of the yam flour increased the scavenging ability of DPPH free radicals of bread and improved the antioxidant activity of bread.The content of total polyphenols,total flavonoids,polysaccharides and allantoin in bread increased with the increase of the amount of yam flour,which improved the nutritional value of bread,and the sensory quality of bread is better when the amount of yam flour not more than 15%.