Low-light Can be an Effective Postharvest Treatment for Fresh-cut Lettuce During Cold Storage

Storage of fresh-cut lettuce under low levels (5-20 micromol) of light was found to prolong the shelf life. The effect was independent of light color (blue, red, green, white) and storage temperature. The light application was associated with increased levels of sugars in the leaf pieces and decreased electrolyte leakage. In darkness, carbohydrates decrease whereas during storage under light carbohydrates accumulate. Measurements of light dose-response relationship showed that photosynthesis (under low light) is little affected by temperature whereas respiration was greatly affected by temperature. Therefore, at low storage temperature net photosynthesis was apparent under low light resulting in the accumulation of carbohydrates (glucoe, fructose, sucrose) in the leaf pieces. The accumulation of carbohydrates could be fully explained by photosynthetic sugar production. The sugars apparently have an anti-senescence effect leading to prolonged shelf-life.