Recent investigations have highlighted the health benefits of bioactive lipids naturally found in milk fat. Among these bioactive lipids, conjugated linoleic acid (CLA, C18:2) and trans-vaccenic acid (TVA, C18:1 t11) have shown relevant health benefits for cancer prevention, atherosclerosis, weight control, and bone formation. However, there is no data in the literature on the retention of these two bioactive lipids in milk treated by ultra-high temperature (UHT). Combinations of high temperatures and short holding times warrant achieving commercially sterilized milk, which extends the shelf life up to 120 days at room temperature. In this study, milk rich in CLA and TVA was treated at UHT conditions (125-145�C/2-20 s) and stored at 4 and 25�C up to 120 days. In addition, the oxidative stability was evaluated in terms of changes on the fatty acid profile, dissolved oxygen, formation of hydroperoxides and TBARS. Changes in CLA and TVA were minor to moderate with at least 80% of retention, regardless the UHT conditions used. After 15 days of storage at 25�C, the CLA and TVA were relatively stable with values in the range of 67-75 and 63-73 %, respectively. As the storage time was prolonged to 120 days, the CLA and TVA losses become evident (40-48 and 50-56 %, respectively). During storage, CLA oxidized faster than TVA and most of the other fatty acids, independently of the UHT treatment and storage conditions. In addition, the changes in the dissolved oxygen revealed that 1.9-2.6 units of oxygen were needed to oxidize one unit of CLA.

Effect of UHT processing on the retention of bioactive lipids in milk

246th National Meeting (2013)

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