Mature green cherry tomato fruit were harvested and treated with ultraviolet-C (UV-C) irradiation at a predetermined dose of 4.2 kJ m −2 , and stored at 18 °C for 35 days. The effects of UV-C treatment on color change, pigment contents, and the expression of major genes involved in carotenoid metabolism, including Psy 1, Pds , Lcy - β , and Lcy - ɛ , encoding phytoene synthase, phytoene desaturase, lycopene β-cyclase and lycopene ɛ-cyclase, respectively, were examined. The UV-C treated fruit developed a pink red color in contrast to the normal orange red color of control fruit. Lycopene accumulation during ripening in UV-C treated fruit was significantly inhibited but its final content was not affected. However, both accumulation and final content of β-carotene were significantly suppressed in UV-C treated fruit. The lower content of β-carotene, leading to a higher lycopene to β-carotene ratio, is probably responsible for the altered color phenotype in UV-C treated fruit. Psy 1, a major gene involved in lycopene synthesis was inhibited by UV-C irradiation. Significantly suppressed expression of Lcy-β gene was also observed in UV-C treated fruit. Thus it is possible that the lower transformation from lycopene to carotenes contributed to the relatively stable content of lycopene.
The present study investigated influences of ultraviolet light C (UV-C; 2 kJ m −2 ) irradiation and high-oxygen modified atmosphere packaging (MAP; 80 % O 2 , 10 % CO 2 and 10 % N 2 ) on physiological quality, microbial growth and lignification metabolism of fresh-cut carrots. After 15-d cold storage, comparing with either treatment alone, the combination of UV-C irradiation and high-oxygen MAP (abbr. UV-C + MAP) more obviously inhibited firmness, weight loss, ascorbic acid, total carotenoid and γ-aminobutyric acid declines, reduced respiration and ethylene production rates as well as delayed bacterial growth. UV-C + MAP more strongly restrained whiteness index, total phenolic, lignin and malondialdehyde increases. Furthermore, UV-C + MAP treatment more efficiently retarded lignin synthesis by suppressing phenolic metabolism-related enzyme (phenylalanine ammonialyase, PAL; polyphenoloxidase, PPO; peroxidase, POD) activities and their gene ( DcPAL ; DcPPO ; DcPOD ) expressions. Above results indicated that UV-C + MAP exhibited synergistic effects in retaining physiological quality, delayed senescence process, reducing microbial growth, alleviating lignification degree, and lessened surface whitening. Therefore, UV-C + MAP could maintain overall quality and extend shelf-life during storage of fresh-cut carrots.
危险品化学品经营许可证（带存储）