POSTHARVEST QUALITY AND PH OF FUSARIUM INOCULATED RED-RIPE TOMATOES STORED UNDER CONTROLLED ATMOSPHERES

Tomato (Lycopersicon esculentum Mill. cv. BHN 91) fruit were hand harv ested at the pink stage of maturity and stored red-ripe at 12.5, 20, a nd 30 degrees C in air, 3% O-2 + 5% CO2, and 0.5% O-2 + 20% CO2 for up to 16 days. Half the fruit were inoculated with Fusarium solani. Cont rol fruit retained the best appearance in 3% O-2 + 5% CO2 at both 20 a nd 30 degrees C. Inoculated fruit at 12.5, 20 and 30 degrees C in air or 3% O-2 + 5% CO2 remained acceptable for approximately 12, 3, and 2 days, respectively, but deteriorated more rapidly than those in 0.5% O -2 + 20% CO2 as temperature and time increased. Off-odours were presen t in all 0.5% O-2 + 5% CO2 treatments by days 12, 9, and 5 at 12.5, 20 , and 30 degrees C, respectively. Subjective evaluations tended to rem ain higher for 0.5% O-2 + 20% CO2 even though internal firmness and ph ysical integrity were inferior, and symptoms of anaerobiosis were pres umed. A significant time- and temperature-dependent increase in pH of locular and pericarp tissue and supernatant pH occurred in inoculated regions of fruit held in air by day 12, 6 and 3 at 12.5, 20, and 30 de grees C, respectively. In contrast, reduced acidity occurred at 9 and 5 days in 3% O-2 + 5% CO2 at 20 and 30 degrees C, respectively. Genera lly, increased pH followed a trend with air > 3% O-2 + 5% CO2 > 0.5% O -2 + 20% CO2. Titratable acidity in control fruit declined regardless of atmosphere when held at 12.5 degrees C. Initial locule and supernat ant pH was sufficiently low to be considered safe, but the pericarp pH of 4.63 approached the food safety threshold, and exceeded 4.7 with s torage. Subsequently, food service establishments should beware of pot ential contamination when holding ripe fruit due to possible decay and metabiosis, anaerobiosis occurring in dressings, and decreased acidit y with ripening.