Impact of liquid nitrogen ultra-freezing on the antioxidant profile of yellow passion fruit ( <i>Passiflora edulis</i> ) pulp

This study evaluated the impact of cryogenic ultra-freezing on the antioxidant profile of yellow passion fruit (Passiflora edulis) pulp. Fresh pulp samples (control) were compared against treatment groups subjected to ultra-freezing via liquid nitrogen immersion until reaching a core temperature of −40°C. The research followed a completely randomized design, and all analyses were performed in technical triplicate (n = 3) to ensure statistical reliability. Parameters assessed included total phenolic content (TPC), total flavonoid content (TFC), ascorbic acid concentration, and overall antioxidant capacity measured by the DPPH radical scavenging assay. The results demonstrated that cryogenic treatment induced significant biochemical alterations (p < .05); the antioxidant capacity was reduced by 23.6%, while TPC and TFC decreased by 40.3% and 35.7%, respectively (reaching 123.67 mg GAE/100 g and 1.08 mg RE/L), compared to the fresh control. In contrast, ascorbic acid content exhibited high stability, with measured values ranging from 38.08 to 38.43 mg/100 g. Statistical analysis directly measured parameters confirmed that while ultra-freezing is highly effective for the retention of vitamin C, it leads to a substantial degradation of the phenolic and flavonoid fractions. These findings provide critical quantitative data on the selective preservation of bioactive compounds in tropical fruit matrices under extreme thermal conditions.