Study On Seasonal Variation Of Leaf Protein Yield And Extraction Technology Of Alfalfa

Medicago sativa L.is a protein rich perennial forage with high yield and feeding value,and is known as the "king of forage".Alfalfa leaf protein is a protein concentrate prepared from alfalfa branches and leaves as raw materials,which is extracted by pressing,protein separation from the juice,and concentration drying.Considered by the Food and Agriculture Organization of the United Nations(FAO)as a protein resource with high development value.The multi leaf trait has the potential to improve the yield and quality of alfalfa,and has a positive effect on increasing the crude protein content of alfalfa.This experiment first studied the hay yield of 20 different leaf types of alfalfa and 8 different varieties(strains)of alfalfa,and analyzed the factors affecting their hay yield and the dynamic changes in hay yield.Secondly,the experiment used hay powder as the material and used ultrasonic assisted alkaline extraction and acid precipitation method to extract alfalfa leaf protein.The optimal extraction process parameters were studied by treating different levels of solid-liquid ratio,alkaline extraction pH,ultrasonic power,and acid precipitation pH.Finally,based on the hay yield of 20 different leaf types of alfalfa and 8 different varieties(strains)of alfalfa,as well as the optimal parameters for leaf protein extraction,the dynamic changes in leaf protein yield and leaf protein yield were studied.The main results of the experiment are as follows:(1)The main factors affecting the yield of 20 alfalfa hay plants with different compound leaf types are individual plant height,number of branches per plant,and type of compound leaf;The factors that affect the hay yield of 8 different varieties(strains)of alfalfa are:variety,cutting time(cutting frequency),and fresh grass yield;The results of the comparative cutting experiment on 8 alfalfa varieties(lines)in the Jianghuai region showed that the population hay yield decreased with the increase of cutting frequency.(2)The optimal extraction conditions for alfalfa leaf protein extraction using ultrasonic assisted alkaline extraction and acid precipitation method are:material liquid ratio of 1:40,alkaline extraction pH of 9.5,ultrasonic power of 200W,and acid precipitation pH of 4.0.And the main and secondary order of factors affecting leaf protein extraction is:acid extraction pH>ultrasonic power>alkali extraction pH>material liquid ratio;The optimized process parameters were used to extract alfalfa leaf protein,and the extraction rate was 53.02%.(3)The single plant leaf protein yield of different compound leaf types of alfalfa is highest in the 5-leaf type(average yield per plant:42.53 g),while the 7-leaf type of alfalfa has the highest yield per unit weight of leaf protein(average 106.71 g kg-1);The yield of alfalfa leaf protein is affected by seasonal changes and decreases with the increase of cutting frequency.