关键词: ξ-聚赖氨酸, 1-甲基环丙烯, 富士苹果, 贮后品质, 挥发性成分

Abstract: Fuji apples were treated with 1-Methylcyclopropene (1-MCP) (1 μL/L) immediately after being harvested, and then stored in a precise temperature-controlled refrigerator (?(0.5 ± 0.3)℃) for 10 months. Thereafter, they were transferred to ambient temperature and sprayed with ξ-polylysine at different concentrations (500, 1 000 and 1 500 mg/L). Our purpose was to investigate the effect of 1-MCP combined with ξ-polylysine on the quality of apples during shelf life. The volatile constituents of different treatments were analyzed by headspace solid phase microextraction gas combined with gas chromatographymass spectrometry (HS-SPME-GC-MS). The results showed that 1-MCP combined with ξ-polylysine treatments effectively maintained fruit firmness and slowed down the decrease in the contents of soluble solids, titratable acid and VC in apples when compared with the untreated control and the best effect was observed at an ξ-polylysine concentration of 1 000 mg/L. The main volatile substances identified included hexanol, hexanal, trans-2-hexenal, 2-methylbutyl acetate. The relative content of aldehydes in the CK group increased first, then decreased, and finally was lower at the end than at the beginning of shelf life. The treatment with ξ-polylysine at 1 000 and 1 500 mg/L showed an upward trend; 1-MCP treatment alone resulted in an initial decrease followed by an increase in the relative content of aldehydes, whereas the opposite was observed for the 500 mg/L ξ-polylysine group. The latter two groups showed a higher relative content of aldehydes at the end than at the beginning of shelf life. The relative contents of esters in the CK, 1 000 and 1 500 mg/L treatment groups showed an upward trend. The 500 mg/L treatment group tended to decrease initially and then increased, while the single 1-MCP treatment group showed the opposite trend. The relative content of alcohols in the 1-MCP and 1 500 mg/L ξ-polylysine groups decreased first and then increased, and the CK and 500 mg/L treatment groups and the 1 000 mg/L treatment group showed an increasing and decreasing trend, respectively. During the shelf life, the relative content of aldehydes in the 1 000 mg/L treatment group was always highest, and this treatment could effectively mitigate the decrease in the relative contents of the main flavoractive compounds 2-methyl butyl acetate and 2-methyl-1-butanol. 1-MCP combined with ξ-polylysine treatment could maintain the quality and flavor of apples and ξ-polylysine was most effective when used at 1 000 mg/L.

Key words: ξ-polylysine, 1-methylcyclopropene, Fuji apples, storage quality, volatile components