Effect of microwave heating on content of cyanogenic glycosides in linseed

Abstract

Linseed is a good source of linoleic (LA, 18:2, n-6) and especially α-linolenic acid (ALA, 18:3, n-3), ω6 and ω-3 polyunsaturated fatty acids (PUFA), which are essential because mammals, and therefore humans, cannot endogenously synthesize them and must adopt them exogenously from dietary sources. In spite of its high nutritive value, linseed has not been effectively exploited in animal feeding, due to the fact that it contains antinutritive components, which are cyanogenic glycosides (CG) and antivitamin B6 (linatine). CGs are a major limitation in application of linseed and its meal in animal nutrition. The objective of the study was to investigate effect of microwave heat treatment on the content of hydrogen cyanide, and consequently cyanogenic glycosides in linseed. Operating frequency of microwave oven was 2450 mHz, and working power was 240W, 400W, 560W and 800W. Samples were treated for 0, 3, 6 and 10 minutes for every working power. When microwave power of 560 W and 800 W was used for 6 min and longer, linseed samples were burned and damaged, therefore these treatments should not be used. Minimal time of heating with microwave power of 400W, which would provide reduction of HCN content under allowed limits (250 mg/kg of linseed), was determined graphically using three-dimensional contour plot graph and it was 290 s (4 minutes and 50 s). This regime is recommended for treating linseed before usage as a feed compound.

Keywords

• cyanogenic glycosides
• hydrogen cyanide
• linseed
• microwave heating