Application of a Continuous Flow Radio Frequency Pasteurization System for Quality Preservation of Passion Fruit Thickened Pulp

Passion fruit thickened pulp closely resembles fresh passion fruit in both texture and flavor, and pasteurization is essential for extending its shelf life. This study investigates the feasibility of radio frequency (RF) pasteurization of passion fruit thickened pulp under continuous serpentine flow conditions by comparing the effects of continuous RF pasteurization at different electrode gaps (RF-95, RF-115, and RF-135 mm) with traditional pasteurization (PS) on various characteristics of the pulp. The results showed that, while there was no significant difference (p > 0.05) in the reduction of total bacterial counts (TBC), the heating rate for continuous RF treatment (6.75–7.01 °C/min) was significantly (p < 0.05) higher than that of PS treatment (2.23 °C/min). Continuous RF pasteurization resulted in superior characteristics in terms of color, bioactive components, aroma, and viscosity compared to PS treatment. Additionally, RF treatment significantly increased the total phenol content of passion fruit thickened pulp by 13.1–19.9%, and the ABTS scavenging ability improved by 11.67–13.52% compared to the untreated group. Given the operational safety of the RF equipment and its heating rate, the optimal electrode gap for continuous RF heating of passion fruit thickened pulp was determined to be 115 mm, which resulted in significant enhancements in color, active component content, and retention of volatile compounds. Therefore, continuous RF pasteurization is superior to conventional thermal sterilization methods.