Effect of pressure-assisted thermal sterilization on conjugated linoleic acid (CLA) content in CLA-enriched milk

Conjugated linoleic acid (CLA) has been recently studied for its health-promoting and disease-preventing properties. The objective of this study was to evaluate the effect of pressure (100–600 MPa), temperature (60–120 °C) and treatment time (0–14 min) on CLA content in milk and anhydrous milk fat (AMF) rich in CLA. In milk treated up to 14 min at 100 MPa, CLA was stable (> 80% of retention), regardless of the temperature. In contrast, only 3.4 ± 2% of CLA was retained at 600 MPa and 120 °C. For AMF, CLA retention was considerably higher (40.2 ± 2%) than that obtained for milk. The presence of free metal ions in milk might catalyze CLA degradation. When the antioxidant catechin (1 g/kg) was used, CLA retention increased significantly (> 90%) in milk and AMF, regardless of the experimental conditions.Industrial relevancePrevious research led by Dr. John Kennelly resulted in CLA-enriched milk by manipulating the diet of dairy cattle. CLA in milk suffers significant losses in terms of its biological activity during processing at high temperatures like UHT. High consumption of CLA products has been associated with many health benefits. This study provided new data on CLA retention with and without an antioxidant at pressure-assisted thermal sterilization (PATS) conditions and confirmed the role of catechin in reducing oxidative damage by PATS treatments. Milk rich in CLA can be treated with PATS to deliver shelf-stable milk while CLA activity is preserved.

► Conjugated linoleic acid (CLA) stability in milk and anhydrous milk fat was evaluated under PATS conditions.
► CLA losses at low pressures were minor at all temperatures investigated.
► CLA losses at high pressures were major at all temperatures investigated.
► Catechin addition enhanced CLA retention to over 90% under all PATS conditions investigated.