Effects of Heat Processing of Soybeans and Linseed on Ruminal Fatty Acid Biohydrogenation in situ

The aim of this study was to determine and compare in situ 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.