In the last years, several studies have succeeded to enrich milk fat from dairy cattle, sheep and goats with conjugated linoleic acid (CLA) and omega-3 fatty acids (FA), by using unsaturated vegetable or marine oils. However, the effect of the enrichment on the triglyceride (TG) composition has been poorly studied. Since in human intestine FA in the sn-2 position are preferentially absorbed than FA in the sn-1 and sn-3 positions, it is of interest to study the position of CLA and omega-3 FA in the triglycerides (TG) of enriched milk fat, in order to better evaluate the bio-availability of beneficial FA from dairy products. With this aim, individual milk samples from twenty dairy ewes were analyzed in order to determine the total and sn-2 FA composition. Milk samples were obtained from a previous trial where the diet of dairy sheep was supplemented or not with extruded linseed, in order to achieve an enrichment of milk fat with CLA and C18:3 n-3. Ten individual milk samples for each group were collected after 5 weeks of treatment. Monoglycerides (MG) were obtained by incubation of milk TG with porcine pancreatic lipase and the FA composition of total and sn-2 position was obtained by gas-chromatography. The preferential incorporation of individual FA in the sn-2 position was evaluated by the ratio between percentage composition of MG and TG. Data were analyzed by ANOVA taking into consideration diet as a fixed factor (linseed or control diet). In the milk from the linseed diet, the triglyceride contents of CLA and C18:3 n-3 were enriched by 290% and 250%, respectively, whereas saturated FA content decreased by 30%. The content of these FA in the sn-2 MG reflected the TG composition, but the content of SFA in sn-2 MG from enriched milk decreased more than 40%. In the control milk the FA preferentially incorporated in sn-2 were C14:1, C16:1 C14:0, whereas in the enriched milk the FA were C18:2 n-6, C14:1, C14:0.
Study of the sn-2 fatty acid composition in ovine milk fat enriched with CLA and omega-3
MELE, MARCELLO;SERRA, ANDREA;CONTE, GIUSEPPE;
2012-01-01
Abstract
In the last years, several studies have succeeded to enrich milk fat from dairy cattle, sheep and goats with conjugated linoleic acid (CLA) and omega-3 fatty acids (FA), by using unsaturated vegetable or marine oils. However, the effect of the enrichment on the triglyceride (TG) composition has been poorly studied. Since in human intestine FA in the sn-2 position are preferentially absorbed than FA in the sn-1 and sn-3 positions, it is of interest to study the position of CLA and omega-3 FA in the triglycerides (TG) of enriched milk fat, in order to better evaluate the bio-availability of beneficial FA from dairy products. With this aim, individual milk samples from twenty dairy ewes were analyzed in order to determine the total and sn-2 FA composition. Milk samples were obtained from a previous trial where the diet of dairy sheep was supplemented or not with extruded linseed, in order to achieve an enrichment of milk fat with CLA and C18:3 n-3. Ten individual milk samples for each group were collected after 5 weeks of treatment. Monoglycerides (MG) were obtained by incubation of milk TG with porcine pancreatic lipase and the FA composition of total and sn-2 position was obtained by gas-chromatography. The preferential incorporation of individual FA in the sn-2 position was evaluated by the ratio between percentage composition of MG and TG. Data were analyzed by ANOVA taking into consideration diet as a fixed factor (linseed or control diet). In the milk from the linseed diet, the triglyceride contents of CLA and C18:3 n-3 were enriched by 290% and 250%, respectively, whereas saturated FA content decreased by 30%. The content of these FA in the sn-2 MG reflected the TG composition, but the content of SFA in sn-2 MG from enriched milk decreased more than 40%. In the control milk the FA preferentially incorporated in sn-2 were C14:1, C16:1 C14:0, whereas in the enriched milk the FA were C18:2 n-6, C14:1, C14:0.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
