Ethanol gas was detected in all package headspace only after the 15th day of storage (Fig. 2b). Significant differences (p < 0.05) were found among packaging conditions; fresh-cut pineapple stored under PP-LO or PP-ALG had the higher ethanol concentrations, reaching values of 46 L L−1 after 20 d storage. Wszelaki and Mitcham (2000) indicated that low O2 atmospheres seem to promote the production of anaerobic metabolites due to anaerobic metabolism. On the contrary, pineapple pieces stored under PPHO show the least ethanol concentration (13 L L−1) up the 20th storage day at 5 ◦C. The application of high O2 levels in packages of fresh-cut fruit could be particularly effective in preventing anaerobic fermentative reactions promoted by low O2 atmospheres (Allende et al., 2004). This is in agreement with the hypothesis of Day (1996) which declares that under high O2 atmospheres there would be less fermentative metabolites than under high CO2. Since ethanol can be associated with undesirable fermentation reactions, these studies showed that such reactions did not occur in any of the