Effects of intermittent heat treatment on sensory quality and antioxidant enzymes of cucumber

- To obtain the large temperature difference by intermittent heat treatments.
- Intermittent heat treatments have better performance in keeping fresh.
- Intermittent heat treatments can reduce heat stress effectively.
- Explore the relationship between preservation and heat transfer characteristics.

Effects of intermittent heat treatment on sensory quality and antioxidant enzymes were investigated by immersing cucumber in hot water (40 °C) for 30 (H1), 50 min (H2) continuously, or for 30 (I1), 50 (I2) min intermittently, respectively, and the intermittent treatment was realized through the temperature return process by room temperature water after every 10 min continuous treatment. Compared with the control group, the relative lower weight loss, decay index, and higher CAT activity et al., indicated that H1, I1 and I2 helped to delay cucumber ripening, and I1, I2 performed better. At the end of storage, the weight losses of I1, I2 were 79.93, 69.63% of H1, and the POD activity of I1, I2 was 1.31 and 1.23 times of H1. Nevertheless, the severe softening and etiolation implied a slight heat injury occurred in H2 due to heat stress. In addition, results from the analysis of heat transfer characteristics suggested: the superior preservation effect were probably result of the faster temperature change and the higher average temperature gradient of cucumber; the highest temperature that the cucumber achieved and the duration were the important reasons for heat stress.