Modification of the low‐molecular weight basic albumin fraction from rapeseed (Brassica napus L.) by acetylation. Part 2. Selected functional properties

AbstractThe influence of acylation on surface functional properties, solubility and heat‐induced aggregation of the low‐molecular weight basic protein fraction (napin) from rapeseed was studied. While the native protein was soluble over the whole pH‐range, the exhaustively acetylated one became precipitable in the weakly acidic range. Acetylation of 70–80% of the protein amino groups caused a stabilizing against heat‐induced aggregation. The native protein had a high foam capacity and stability which were only slightly changed after acylation. Decreasing volume specific work in the order native>acetylated>succinylated protein pointed, however, to an improved foamability of acylated napin. Succinylation increased the interfacial tension on the oil/water interface, while acetylation gave both an increasing and a decreasing effect depending on the degree of modification. The emulsifiying capacity decreased after acylation in the order native>acetylated>succinylated.