Stability of lipids and proteins in leaf protein concentrates

Abstract

AbstractAlthough freeze‐dried leaf protein concentrate (l.p.c.) contains as much as 15–20% of lipids in which linolenic acid (60%) is the predominating component fatty acid, it appears to be unexpectedly stable when stored under ordinary conditions, i.e. at room temperature and exposed to air. Linolenic acid, in the form in which it occurs in l.p.c. is less prone to destruction than in the form of total lipid isolate, or in the form of more conventional linolenic‐containing vegetable oils. Rates of disappearance of linolenic acid and also loss of protein quality as judged by dye‐binding capacity, on heat treatment appear to follow a progressive trend as temperature is increased, without displaying a well‐defined order of reaction. With increasing temperatures, increased moisture levels result in an increase in the rates of both lipid and protein transformations. In heat treatments involving temperatures below 100°C, the presence of the lipid fraction does not affect protein transformation. At higher temperatures, when the lipid itself undergoes substantial oxidation, protein quality as judged by dye‐binding capacity is considerably affected.