Effects of Particle Size on Nutrients and Functional Properties of Stems and Leaves in Different Parts of Alfalfa

Taking alfalfa as the research object,the basic components,active components and functional properties of the upper(more than 60 cm),middle(30~60 cm)and lower(0~30 cm)stems and leaves of alfalfa were compared,and the nutrient release and functional properties of alfalfa stems and leaves with different grinding granularity were analyzed. The contents of protein,ash,fat,vitamin C,soluble dietary fiber,polysaccharide,polyphenols,total flavonoids,swelling capacity,adsorption capacity of sodium nitrite and cholesterol in alfalfa leaves were higher than those in stems,and the contents of insoluble dietary fiber,water-holding capacity and oil-holding capacity in alfalfa stems were higher than those in leaves. With the reduction of grinding particle size from 0.20~0.25 mm to 0.063~0.08 mm,the dissolution of protein,polyphenols,total flavonoids and crude polysaccharides increased from 27.98%,12.31,6.42,20.72 mg/g to 32.87%,13.86,7.71 and 22.97 mg/g,respectively,and the swelling power increased first and then decreased,reaching the maximum when grinding particle size was 0.125~0.16 mm,which was 4.40 mL/g. Adsorption capacity of sodium nitrite increased from 2.45 mg/g(pH=2)and 7.65 mg/g(pH=7)to 6.01 and 9.66 mg/g respectively. Adsorption capacity of sodium nitrite increased from 437.91 μg/g(pH=2)and 106.43 μg/g(pH=7)to 501.51 and 108.02 μg/g,respectively. With the reduction of grinding size from 0.20~0.25 mm to 0.063~0.08 mm,oil holding capacity decreased from 4.86 g/g to 3.44 g/g,and water holding capacity increased first and then decreased,and reached the maximum when crushing particle size was 0.125~0.16 mm,which was 6.56 g/g. The leaves and stems of alfalfa would be used to develop different functional foods. Reducing the crushing particle size could increase the nutrient dissolution. Properly crushing could improve the functional properties of alfalfa.