Continuous flow high-pressure homogenization enhances nutrient retention, antioxidant activity, and probiotic growth...

This study evaluated the impact of High-Temperature Short-Time (HTST) and Continuous Flow High-Pressure Homogenization (CFHPH) on the quality attributes of grapefruit juice by measuring ascorbic acid, phenolic acids, overall antioxidant activity, polyphenol oxidase (PPO) activity, and the growth of probiotic bacteria Lactobacillus plantarum. The results indicate that HTST treatments (75-95 °C) led to a significant (p ≤ 0.05) decline in ascorbic acid content, with losses reaching 80.7 %, and a reduction in antioxidant activity, primarily due to thermal degradation. In contrast, CFHPH, particularly at 300 MPa and 4 °C, was found to be effective in preserving ascorbic acid and phenolic acid levels in the juice, exhibiting significantly lower degradation (≤38.0 % loss) and maintaining higher antioxidant activity throughout the 45-day storage period. CFHPH also inactivated PPO, reducing browning potential and enhancing the bioavailability of phenolic compounds. The growth of Lactobacillus plantarum was favored in CFHPH-treated juices, indicating that the conditions and nutrient availability supported its proliferation. In contrast, HTST juices displayed lower abundance of phenolics, reduced antioxidant activity, and moderate probiotic growth, potentially due to thermal degradation of carbon substrates, resulting in limited nutrient availability to support bacterial growth. These findings suggest that CFHPH, particularly at lower temperatures and higher pressures, is more effective in preserving the nutritional quality and probiotic potential of grapefruit juice than traditional thermal treatments. Despite its higher energy costs, CFHPH offers a promising alternative for retaining bioactive compounds, enhancing the functional quality of processed juices, and ensuring the delivery of high-quality products with health-promoting attributes to consumers.