Minimizing the saponin content of alfalfa sprouts and leaf protein concentrates

Biologically active saponins were found to be concentrated in the white and green alfalfa leaf protein fractions at levels higher than in the original alfalfa. Coagulation and washing of the leaf protein at pH 8.5 resulted in a fourfold decrease in saponin compared to the protein coagulated at pH 6.0 and washed at pH 4.5. The press cakes from high and low saponin alfalfa retained 65 and 87% of the saponin. Protein fractions prepared from a low saponin alfalfa contained saponin levels less than 0.07%, compared to a saponin level of 1.33% in leaf protein prepared form a high saponin alfalfa. The saponin contents of three varieties of alfalfa sprouts ranged from 1.55 to 7.27% depending upon the maturity of the sprouts. The saponin content rapidly increased after sprouting and reached a maximum after eight days' growth. Both starch and total sugar decreased with the age of the sprouts while fiber increased from 8 to 18.7%.