Influence of Postharvest Temperature on Brown Stain of Lettuce1,2

Abstract

Abstract The incidence of brown stain on crisphead type lettuce (Lactuca sativa L. cv. Calmar) was highly dependent on postharvest temperature. Following exposure to 2% O2 + 5% CO2 for 5 days at constant temperatures from 0° to 20°C, brown stain decreased as simulated transit temperature increased and was negligible at 10°C and above. Simulated market temperatures following exposure to 2% O2 + 5% CO2 at 0°C markedly influenced brown stain expression with near maximum expression present after a 3-day period in air at 10°C. Low O2 (2%) was more effective in reducing respiration (CO2 production) of lettuce at temperatures above 5°C than at 5°C, or lower.