Further studies on lipid composition of bovine milk in relation to spontaneous oxidised flavour

Abstract

Milk samples from five commercial dairy herds having severe problems with spontaneous oxidised flavour (SOF) and milk samples from five herds without such problems were analysed for parameters connected with SOF in milk. The study was directed towards analysing parameters which primarily are influenced by feeding. The fatty acid compositions of both neutral lipids and phospholipids were determined as well as the concentrations of α‐tocopherol, β‐carotene and copper in the milk. The samples were also analysed by dynamic headspace GC to determine volatile oxidation products. The results showed that the reasons for the occurrence of SOF in a specific herd are still obscure, since the only consistent result found for the five control herds, when compared with the corresponding experimental herd, was a higher proportion of the 18:1 trans fatty acid. However, within the affected herds, the difference between cows giving milk with off‐flavour and cows giving milk without off‐flavour was quite clear. In four out of five herds the ratio between antioxidants and fatty acid unsaturation was lower in milk with off‐flavour, and in the fifth herd an extremely high proportion of 18: 2 in the phospholipids seemed to have been the reason for the off‐flavour that developed. One of the herds also had a higher copper content in milk showing SOF. The data showed differences in importance of α‐tocopherol and β‐carotene, in different herds. Also the unsaturation in fatty acids of both neutral lipids and phospholipids had different importance for the flavour stability in different herds. © 1998 SCI.

Omega-3 supplementation, milk quality and cow immune-competence

“…Cow supplementation with fish oil in order to increase PUFA content of dairy products may cause the production of off-flavours due to the high susceptibility to oxidation of PUFA (Nelson and Martini, 2009), promoted by both transition metals and unsaturated phospholipids present in the milk fat globule (Fox and McSweeney, 1998). However, numerous researches have shown that antioxidants such as tocopherols and carotenoids can be transferred from the feed to the milk and thereby improve the oxidative stability of milk (Granelli et al, 1998). Omega 3 PUFA are considered as important modulators of immune reactions (Calder et al, 2002) as shown in experimental animal models (Pomposelli et al, 1989) and in clinical trials (Stenson et al, 1992).…”

Oxidative stability of bovine milk determined by individual variability in herd irrespective of selenium status

“…We decided to use milk from two cows with distinctly different oxidation patterns to investigate the molecular grounds for this variation, and obtained some remarkable results. These results are not pertinently corroborating with earlier reports on spontaneously oxidized flavour in milk (Barrefors, Granelli, Appelqvist, & Björck, 1995;Granelli, Barrefors, Björck, & Appelqvist, 1998), and possible mechanisms are discussed.…”

Influence of feeding different types of roughage on the oxidative stability of milk

“…Consequently, certain feeding regimes can increase the content of polyunsaturated lipids and make the milk more vulnerable to oxidation (Barrefors, Granelli, Appelqvist, & Bjoerck, 1995;Charmley & Nicholson, 1995;Hermansen, 1995;Focant et al, 1998;Morales, Palmquist, & Weiss, 2000;Bugaud et al, 2001;Timmons, Weiss, Palmquist, & Harper, 2001). Moreover, numerous studies have shown that antioxidants as tocopherols and carotenoids can be transferred from the feed to the milk and thereby improve the oxidative stability of milk (Barrefors, Granelli, Appelqvist, & Bjoerck, 1995;Focant et al, 1998;Granelli, Barrefors, Bjoerck, & Appelqvist, 1998). Other studies have shown no effect of supplementing the diet with vitamin E (Schingoethe, Parsons, Ludens, Schaffer, & Shave, 1979;Charmley & Nicholson, 1995).…”