Effect Of Microwave On Millet Quality And Starch Structure And Properties

Millet is rich in nutrition,starch,protein,vitamins and various minerals.It is one of the indispensable food crops in China.Microwave treatment can stabilize millet and improve its quality.Taking millet as raw material and taking lipase activity,gelatinization characteristics,polyphenol content,DPPH radical scavenging rate,color and cooking quality as indicators,this paper studied the effects of microwave treatment time,initial moisture content of millet and microwave dose on millet quality.The effects of microwave treatment on the structure and properties of starch in millet under different conditions were studied.The research results are as follows:After microwave treatment,the content of protein,fat and lipase activity of millet decreased.Microwave time and microwave dose treatment increased the peak viscosity and setback value of millet,but the breakdown value of millet did not change significantly.Microwave treatment also affected the scavenging rates of polyphenols and DPPH free radicals in millet.When the microwave time was 30 s and 60 s and the microwave dose was2 W/g,the polyphenol content increased;Microwave treatment under other conditions decreased the polyphenol content and DPPH radical scavenging rate of millet.When the initial moisture content of millet was 35%,it had the greatest impact on the quality of millet.Under this condition,microwave treatment decreased the peak viscosity and breakdown value of millet;Lipase activity decreased by 91.36% to 1.43 mg KOH/g;Polyphenol content and DPPH radical scavenging rate decreased by 47.50% and 52.65% respectively,and were 22.86 mg GAE/100 g and 27.62%,respectively.Except that the microwave time was 30 s and 60 s,the peak viscosity and swelling power of starch were decreased by microwave treatment;After microwave treatment,the transparency of starch in millet decreased,and the short-range order and crystal structure of starch were destroyed;The average particle size of starch increased,the condensability increased,and the contents of RDS(rapidly digested starch)and SDS(slowly digested starch)increased.The setback value of starch increased after different microwave time and microwave dose treatment.When the initial moisture content of millet was 35%,the change of starch in microwave treated millet was the most obvious,and the peak viscosity of starch decreased to 280.67 BU;The content of RDS increased to 51.25%;△H decreased to 4.41 J / g;The average particle size increased to 20.75 μm;The relative crystallinity of starch was the lowest,14.08%.