Estimation of extractable protein in botanical fractions of legume and grass species

Abstract

AbstractWith a globally strong interest in bio‐based products such as fuels and chemicals, a feasible source of protein for the industry with positive economic impacts could be from leaves. However, more knowledge is needed on how to improve the content of extractable protein. Grasses and legumes have a high content of protein with a favourable amino acid composition. The extractable true protein was estimated at two harvest dates in leaf and stem of the legume species white clover (Trifolium repens L.), red clover (Trifolium pratense L.) and lucerne (Medicago sativa L.) and the grass species perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea L.) using the Cornell Net Carbohydrate and Protein System. Extractable true protein was more concentrated in the leaf than in the stem of all the species. Easily extractable true protein in the leaf constituted 63%–68% and 54% of crude protein in legumes and grasses respectively. If the cell wall‐bound true protein in the leaf can be extracted, concentration of extractable true protein may increase by 7%–14% and 21%–26% of crude protein in legume and grass respectively. Legume leaf could be superior to grass leaf for protein production in a biorefinery due to higher extractable true protein both on a mass basis and per hectare. In white clover leaf, a significant decline in concentration of extractable true protein with maturity was simultaneous with a substantial increase in extractable true protein per hectare.