Evaluation Of Nutritional Quality Of Distiller's Grains And Study On The Physicochemical Properties Of The Prolamin

Sorghum is the raw material for the white wine making,and distiller's grains has high acidity and is difficult to preserve.Therefore,how to improve the comprehensive utilization of distiller's grains is a huge challenge for major white wine companies.This experiment studied the nutritional changes of substances before and after wine making.The alcohol-alkali method was used to extract and optimize the prolamin.The physical and chemical the prolamin were been discussed,and the antibacterial and antioxidant properties of the protein hydrolysate were been studied.It provides a theoretical basis and research ideas for the application of distiller's grains,aiming to increase the added value of the utilization of the distiller's grains and achieve the purpose of effective recycling of resources.The results of this experiment were as follows:1.Changes in material composition before and after white wine making:sorghum had the highest starch content,the proportion of crude protein in distiller's grains increased while the tannin content decreased,and the content of crude ash and crude fat had little changes;The ratio of the most amino acids had little changes,and the composition of amino acids were relatively balanced.Both of the restrictive amino acids were the same,the first restrictive amino acid was the lysine.In comparison,the nutritional value of the prolamin was better than sorghum.The proportion of various levels of protein in distiller's grains were:gliadin>gluten>albumin>globulin.2.Optimum experimental conditions for the extraction of the prolamin:The experiment selected the dry distiller's grains with a particle size of 200mesh and did not add?-amylase in the process.Then designed single factor and response surface experiment by changing the ratio of material-to-liquid ratio,extraction temperature,and ethanol concentration.The order of influencing factors were:ethanol concentration>material-to-liquid ratio>extraction temperature.The optimal combination of experimental conditions obtained in the experiment:the material-to-liquid ratio was 1:10(g/m L),the ethanol concentration was 69%,and the extraction temperature was 40?.The actual yield of the prolamin was 23.49±0.27%.3.The physicochemical properties of the prolamin:the proportion of amino acids before and after the extraction had changed,which may be related to the method of protein extraction.The nutritional score of amino acids contained in the prolamin were low,and food-based application was not strong;The protein had low water holding capacity and oil holding capacity,and the foaming performance and emulsifying performance of the protein were the lowest when the p H was 4.0.The denaturation temperature of the prolamin was about 123.47?,It had good thermal stability.Compared with commercially available zein,the prolamin contained a similar alpha helix structure.4.Digestive properties and hydrolysate functions of the prolamin:The prolamin hydrolysate had obvious antibacterial effect on Escherichia coli and Staphylococcus aureus,but had no antibacterial effect on Shigella flexneri.The protein hydrolysate had good antioxidant capacity,according to the IC₅₀ value of antioxidant capacity,The superoxide anion free radical scavenging ability>the hydroxyl radical scavenging ability>the DPPH free radical scavenging ability.