Biological control of botrytis cinerea growth on apples stored in modified atmospheres

The combined effect of modified-atmosphere packaging and theapplication of a bacterial antagonist (Erwinia sp.) on Botrytiscinerea growth on apples (cv. 'Golden Delicious') was investigated.Inoculated apples were stored in polyethylene bags at 5 degrees C. Theinitial gas composition in each bag was set according to a centralcomposite experimental design involving five levels of O2 (1 to 15%)and CO2 (0 to 15%). Control samples under ambient conditions were alsoincluded. Without the antagonist, measurements of mold colony diameterover time showed that O2 had no effect on the growth of B. cinerea,while increased CO2 levels delayed its growth by about 4 days.Application of the antagonist resulted in a significant interactionbetween O2 and CO2. At low O2 levels, CO2 had no effect on moldgrowth, but at high O2, CO2 enhanced mold growth. O2 and theantagonist worked synergistically to reduce mold growth by about 6days at low levels of CO2. However, at high CO2 levels, O2 had noeffect. The strongest antagonistic effect was observed under ambientconditions. Overall, results showed that high CO2 atmospheres can slowthe growth of B. cinerea and that Erwinia sp. was an effectiveantagonist against B. cinerea growth on apples, particularly underambient conditions.