Abstract: In this study, a composite preservative consisting of protocatechuic acid and Tween-20 was used to evaluate the effect of soaking time, storage temperature, protocatechuic acid concentration and Tween-20 concentration on its efficacy in preserving the postharvest quality of Xiangyan No. 5 green hot peppers. The investigation was carried out using an L9 (34) orthogonal array design. The results showed that compared with the control (CK1) and positive control groups (CK2, using NW20 as preservative), 2.5 min soaking with 125 mg/L protocatechuic acid and 0.02% Tween-20 (V/V) significantly reduced water loss in green hot peppers by 41.98% and 15.74% (P < 0.05) and significantly decreased the incidence of decay by 70.39% and 20.09% after 21 days storage at 10 ℃, respectively. Meanwhile, this treatment could reduce respiration intensity, delay the decline in vitamin C and chlorophyll content, effectively restrain the accumulation of malondialdehyde and polyphenol oxidase, and improve peroxidase and catalase activity. The quality of this treatment was superior to that of CK1 (P < 0.05) with respect to all the above parameters. These data suggest that protocatechuic acid coating treatment (ZJZ) can delay the senescence of post-harvest peppers and extend the shelf life of pepper, so that it has a good efficacy in the postharvest preservation of green hot peppers.

Key words: Xiangyan No. 5 green hot peppers, protocatechuic acid, Tween-20, preservation, composite coating