Study On Affecting Factors And Exacting Technology Of Leaf Protein Concentration From Alfalfa

In this study, firstly, the different extraction methods for leaf protein concentration (LPC) were probed on alfalfa (Medicago sativa). The results show that heating by acidification produced better effect, with higher distillation efficiency of crude protein than heating directly. The optimum conditions of extraction for LPC were pH 4.0, temperature 80t~, heating time 2 mm, NaCI concentration 0.4%. Secondly, the seasonal dynamics of the yields and nutrients of alfalfa in the field of Jingtai were analyzed. The results show the increment of the aboveground DM yield of the alfalfa population was a fractal growth process, with self-similarity during growing perid (from 17th, April to 28th, July). The relation between the height and the aboveground DM yield of the population can be expressed as y 14.52 1 x09823.As the plant approached maturity, the DM yield and the crude fiber(CF) content in DM increased, but the crude protein(CP) content in DM decreased. There was significantly negative correlation between CF and CP contents(R~0.9910). The CP yield in per unit area at the first cut was highest(190.5g/m2) when the materials were harvested at the initial blooming stage(around 29th, May). Thirdly, the effect of cutting time and cutting frequency on the yield, quality of alfalfa, yield of LPC and extraction efficiency of CP was discussed, and the prospect of the fiber in the residues of LPC-extracted alfalfa applied in health-care food and functional food were analyzed. The results show frequent cutting at the vegetation stage were devastating that severely damaged the structure of the tussock, the following was at the budding stage, and the cutting at other stages produced insignificant effect on the growth of the alfalfa in the following year. The ideal cutting time should be late blooming stage in order to maintain good re-greening and growth in the following year. Compared with the early blooming stage, the cutting at the fully blooming increased 25.25% of DM yield and 26.54% of CP yield, but resulted in lower CP content and higher CF content in DM. The neutral detergent fiber(NDF) and lignin contents in the residues of LPC-extracted alfalfa ranged from 40.72%-62.09% and 32.10%- 47.94%, and they showed significantly positive correlation(R=0.9663). There was also positive correlation between ADL and lignin(R0.7007). The ranges of the NDF and cellulose contents of alfalfa at the same growing stage were broad, but that of the lignin was narrow.