Influence of Linolenic Acid Content on the Oxidation of Milk Fat

Abstract

Increasing the content of alpha-linolenic acid in milk fat might be desirable to meet consumer concerns about dietary healthfulness. However, the rich content of polyunsaturated fatty acids (PUFAs) will influence the oxidative stability of milk fat. This experiment was carried out to determine the effects of infusion with different amounts of high-linolenic perilla fatty acid (HLPFA) emulsion into the duodenum of dairy cows on milk fatty acid profile and the susceptibility of milk fat to oxidation. In a crossover design, 4 multiparous Holstein cows were infused duodenally with increasing amounts (0, 40, 80, 120, or 160 g/day) of free fatty acids from HLPFA emulsion or with carrier alone. Continuous infusions (20 to 22 h/day) were for 7 days at each amount. Infusions were homogenates of HLPFA with 15 g/day of xanthan gum, 5 g/day sodium alginate, and 25 g/day Tween 80; controls received carrier only. The concentration of n-3 PUFAs, especially alpha-linolenic acid, in milk fat increased linearly as HLPFA infusion increased, but the saturated fatty acids decreased linearly. The milk production and the activity of superoxide dismutase, glutathione peroxidase, and catalase in milk tended to decrease quadratically. The milk fat percentage, however, tended to increase. The concentration of malondialdehyde increased quadratically in milk fat. Results suggest that infusion with HLPFA emulsion at varying amounts enhanced the content of n-3 PUFAs in milk fat over the length of experiment but decreased the oxidative stability of milk fat.

Fatty acid composition, vitamin A content and oxidative stability of milk in China

“…Timmons et al (2001) found that feeding cows with whole roasted soybeans increased the content of C18:2 and C18:3 in milk fat, which in turn increased the susceptibility to oxidation. Liu et al (2010) found that infusion with high-linolenic perilla fatty acid emulsion enhanced the content of n-3 PUFAs in milk fat but decreased the oxidative stability of milk fat. The position of double bonds in UFA can affect the oxidative stability of milk.…”

Impact of nutrition of food animals on quality of animal products

“…A similar situation was observed in a previous study where greater concentrations of C18:1 in milk did not result in a higher concentration of lipid hydroperoxides, but the elevated concentration of PUFA did (Havemose et al, 2006). And in a second study, Liu et al (2010) observed decreased oxidative stability in milk with increased ω-3 PUFA content. In our study, we did not detect any differences in C18:3 content in milk from the three dietary treatments, potentially because C18:3 and C20:0 co-eluted.…”

“…Higher concentrations of unsaturated fatty acids are also characterized by an "oily" flavor (Kolanowski et al, 2007). Increased CLA increases the susceptibility of milk to oxidation (Liu et al, 2010).…”

Oxidative stability evaluation of milk from cows fed dried distillers grains with solubles, by sensory and chemical analysis

“…(2010) also observed decreased oxidative stability in milk with increased n--3 PUFA content in milk (Liu et al, 2010). In our study, we did not detect any differences in C18:3 content in milk from the 3 DDGS diets (0%, 10%, and 25%), and no apparent oxidation was observed either.…”