Effects of Heat Processing of Soybeans and Linseed on Ruminal Fatty Acid Biohydrogenation <i>in situ</i>

Abstract

The aim of this study was to determine and compare <em>in situ</em> biohydrogenation (BH) fatty acids in three forms of soybeans and linseed (raw, extruded and roasted). Nylon bags (5×10 cm) containing 4 g of raw, extruded or roasted soybeans or raw, extruded or roasted linseed were incubated in the rumen of fistulated ewes for 4, 8, 12 and 24 hours. Results for linoleic acid (C18:2) showed that the extent of BH only in 4h of incubation was significantly higher than other times of incubation in raw linseed (P<0.05). Proportions of linoleic acid (C18:2) were significantly higher for raw compared to extruded and roasted soybeans for 8 and 12 hours of incubation (P<0.05). Amounts of trans-C18:1 (octadecadienoic acid) in all 4 times of ruminal incubation were similar between each three forms of linseed (P>0.05). But proportions of this fatty acid in roasted soybeans were significantly lower than raw and extruded soybeans in 12 h of incubation (P<0.05). No significant difference was observed for extent of linolenic acid (C18:3) BH between three different forms of linseed and soybeans (P>0.05). Differences were not significant between produced cis-9, trans-11 conjugated linoleic acid (CLA) in three forms of linseeds in all times of incubation (P>0.05), but amounts of CLA in 12 and 24 hours of incubation were significantly higher for extruded soybeans (P<0.05). Proportions of stearic acid (C18:0) for the three forms of linseed (raw, extruded and roasted) in all hours of incubation showed no significant difference (P>0.05). The amount of C18:0 after 24 h of incubation was significantly higher for raw soybeans (P<0.05). According to the results, heat processing had better effects on the preservation of linoleic acid compared to linolenic acid in soybeans and linseeds against rumen BH.