Effects of different direction of temperature jump treatment on cucumbers

Abstract

A novel method of uninterrupted temperature jump treatment was proposed. Effects of different directions of temperature jump were studied. Cucumbers were first put into ice‐water for 40 min (CST) and then immersed into hot water (40 °C) for 20 min uninterruptedly (CHT); and reversely, cucumbers immersed into hot water (HST) for 20 min and then ice‐water for 40 min (HCT). The results showed that the decay incidence of CHT was 24.0 and 49.3% lower than that of CST and HST respectively. And the CAT activity of CHT was also obviously higher than that of CST and HST. However, the HCT displayed negative results except CAT and POD activity. The results demonstrate that temperature jump treatment of appropriate direction (CHT) integrates respective advantages of cold and heat shock to further improve resistance abilities. With the temperature jump treatment of negative direction (HCT), the damage of thermal stress could produce harmful effects on preservation quality. Practical applications To provide the circulating water of constant temperature, the equipment of temperature shock treatment for fruit and vegetable is designed. This equipment can meet the requirement of different direction of temperature jump treatment. The results reveal that the temperature, time and direction of jump treatment have an important influence on the sensory quality and antioxidant enzymes. In terms of storage quality of the cucumber, CHT, temperature jump from low to high, shows better results than single temperature treatment (CST and HST). However, HCT, temperature jump from high to low, causes the damage from thermal stress. The optimal treatment intensity is not determined by simple combination of some treatment parameters. The direction of temperature jump has a significant influence on physicochemical properties. This article provides an experimental basis for acquiring the best control of three factors (T‐T‐D) to improve preservation quality of fruit and vegetable maximally.

Correlations among Quality Characteristics of Green Asparagus Affected by the Application Methods of Elevated CO₂ Combined with MA Packaging

“…This is consistent with the results that high CO 2 delayed chlorophyll degradation and anthocyanin accumulation by inhibiting chlorophyllase activity and downregulating the expression of FaChl b reductase, FaPAO and FaRCCR, which are related to chlorophyll state in postharvest storage of strawberry fruits [26]. Likewise, cold shock delayed the degradation of chlorophyll by suppressing the activity of chlorophyllase in cucumber [27].…”

“…A change in firmness is related to the change of cell structure caused by the transformation of SSC and storage sugars in cell walls [49]. The changes in cell structure affect the transpiration of plants which relates to water content and fresh weight loss [27]. In addition, negative correlations were observed between FWL and h • and Chl.…”