| Abstract
| - Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5.) activity, tanning ability, and polyphenols levels weremeasured in cherimoya (Annona cherimola Mill.) fruit treated with 20% CO2 + 20% O2 + 60% N2 for1, 3, or 6 days during chilling temperature (6 °C) storage. The residual effect of CO2 after transfer toair was also studied. These observations were correlated with texture and cellular characteristics,visualized by cryo-SEM. Tanning ability and the early increase in tannin polyphenols induced bychilling temperature were reduced by CO2 treatment. Conversely, high CO2 atmosphere enhancedthe nontannin polyphenol fraction as compared with fruit stored in air. Lignin accumulation and PALactivation observed in untreated fruit after prolonged storage at chilling temperature were preventedby high CO2. Moreover, the restraining effect on lignification was less effective when the CO2 treatmentwas prolonged for 6 days. In addition, fruits held at these conditions had greater firmness and thehistological characterization of the separation between cells was similar to that in untreated fruits.We conclude that CO2 treatment modulates the phenolic response that seems to regulate the strengthof cell adhesion and so to prevent hardening caused by chilling temperature storage. Keywords: Annona cherimola; carbon dioxide; chemiroya; chilling injury; low temperature; phenylalanine ammonia-lyase; tannins
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