Effects of partial substitution of milk fat for canola oil or linseed oil on the oxidative stability and volatile profile of high‐protein dairy beverages

Background, Context or Rationale Due to the increased demand for and use of milk fat, the milk solid nonfat surplus represents a major challenge for the dairy industry. Substituting milk fat for vegetable oils to produce high‐protein dairy beverages with additional nutritional benefits could help to maximise the utilisation of all milk components. Aim(s) This study investigated the effect of total or partial (50%) substitution of milk fat for canola or linseed oil on the physical stability, fatty acid profile, peroxide value and volatiles of dairy beverages (3.25% fat, 6.8% protein) stored at 4°C for 30 days. Methods Two approaches to partial milk fat replacement were studied. The mixed emulsions approach consisted of mixing a milk fat emulsion with a canola or linseed oil emulsion. In the fat blending approach, milk fat and vegetable oil were blended together prior to homogenisation. Experiments were done according to a factorial design, repeated independently three times and analysed statistically using ANOVA. Major Findings When milk fat was substituted for 100% of the linseed or canola oil, lipid oxidation was markedly increased during processing and storage. A major change in the volatile profile was observed, with significant increase in alcohol, aldehyde and ketone contents. Substituting 50% of milk fat for vegetable oils significantly improved the resistance to oxidation when compared with total replacement of the milk fat, and reduced the amount of undesirable volatiles. Compared with the mixed emulsions approach, fat blending approach further reduced oxidation and total volatiles by 18% and 11%, respectively. The presence of milk fat within each lipid droplet contributes to a better protective effect. Scientific or Industrial Implications This study proposes a simple approach to partly replace milk fat and promote the use of milk solid nonfat. Results will support the dairy industry in the development of innovative beverages having a more balanced fatty acids’ profile and enhanced oxidative stability.