Effect of ultrasound-enhanced fat separation on whey powder phospholipid composition and stability

Abstract

Fat from freshly pasteurized liquid whey was partially separated by gravity for 5, 10, and 30 min, with and without simultaneous application of ultrasound. Ultrasound treatments were carried out at 400 and 1,000 kHz at different specific energy inputs (23-390 kJ/kg). The fat-enriched top layers (L1) and the fat-depleted bottom layers (L2) were separately removed and freeze-dried. Nonsonicated and sonicated L2 powders were stored for 14 d at ambient temperature to assess their oxidative stability. Creaming was enhanced at both frequencies and fat separation increased with higher ultrasonic energy, extended sonication, or both. The oxidative volatile compound content decreased in defatted whey..