关键词: 粒度, 紫花苜蓿, 功能特性, 测定与分析

Abstract: The chemical components of stems and leaves from different positions were determined, and the functional characteristics, specific surface area, pore size, chemical groups and surface ultrastructure of alfalfa leaf powders with different particle sizes were measured. The results showed that the contents of soluble dietary fiber, protein, fat and ash in alfalfa leaves were higher than those in stems, with the highest values being found in upper leaves, which were 12.25%, 28.62%, 6.23% and 11.35%, respectively. As the particle size decreased in the range of 0.063–0.250 mm, water-holding capacity and swelling capacity first increase and then decrease, reaching their maximum values of 5.57 g/g and 4.40 mL/g, respectively when the particle size was 0.125–0.160 mm; oil-holding capacity decreased from 2.83 to 1.84 g/g; cation exchange capacity, cholesterol adsorption capacity and sodium nitrite adsorption capacity gradually increased. Specific surface area, cumulative pore volume and the number of some chemical groups increased, while the most probable pore diameter decreased. Alfalfa leaf powder with particle size of 0.125–0.160 mm had better water-holding capacity and expansibility and was therefore suitable for developing functional foods to improve intestinal functions and prevent obesity. In contrast, alfalfa leaf powder with particle size of 0.063–0.080 mm had better adsorption capacity for cholesterol and sodium nitrite and cation exchange capacity, making it suitable for use in functional foods to prevent hypertension, heart disease and cancer.

Key words: particle size, alfalfa, functional properties, determination and analysis