The impact of ultrasonic processing on the stability of water-and fat-soluble vitamins in milk

This study investigated the effects of ultrasound and thermal treatment on the water-soluble vitamins B1, B2, B5, and derivatives of B6, as well as the fat-soluble vitamins A and E in cow milk. Raw cow milk was subjected to ultrasound at varying amplitude levels, high-temperature short-time pasteurization (72 degrees C for 15 s), and mild-heating treatment (55 degrees C for 15 min). Losses of vitamins A, B1, B2, B5, B6 derivatives, and E in cow milk were quantified using a chromatographic technique. Additionally, peroxide value and hydrogen peroxide content in milk were evaluated by ultraviolet and fluorescence spectrophotometry, respectively. Results demonstrated that ultrasound treatment and pasteurization did not significantly reduce the levels of vitamins B1, B2, and B5 in raw milk. However, both treatments significantly influenced total vitamin B6 and pyridoxal + pyridoxal-5-phosphate. The concentrations of vitamins A and E remained unchanged in raw, pasteurized, and mild-heated milk samples, whereas ultrasound treatment caused notable reductions in these vitamins, particularly at higher amplitudes. Specifically, milk treated with ultrasound at 50 % amplitude (US4) showed a marked decline in vitamin A content compared to raw milk. Pasteurized and ultrasound-treated samples exhibited similar peroxide values. A reduction in hydrogen peroxide content was observed in pasteurized and heat-treated milk samples. Among ultrasound-treated samples, hydrogen peroxide levels increased with increasing ultrasound amplitude. Overall, the findings suggest that ultrasound application to milk and dairy products is advantageous with respect to preserving water-soluble vitamins such as B1, B2, and B5.