Storage of fresh-cut lettuce at light levels below the light compensation point increases sugar levels and greatly prolongs the shelf-life
The quality of fresh-cut butterhead lettuce held at 12°C was greatly improved when the product was stored under low levels of light, provided by either fluorescent tubes, or red, blue or green LEDs. Although the applied light level (5 µmol m-2 s-1 photosynthetically active radiation) was well below the light compensation point, significant accumulation of carbohydrates (sugars and starch) was observed. The level of carbohydrates positively correlated with the shelf-life. Photosynthetic activity was low and net photosynthesis during storage was negative and cannot account for the observed accumulation of carbohydrates. Treating the leaf pieces with an inhibitor of photosynthetic electron transport, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), diminished the light-induced sugar accumulation and the beneficial effect of light on fresh-cut quality. Currently, it is not clear which processes are responsible for the sugar accumulation in light-stored samples. We hypothesize that, under low light conditions, sugars may be produced through the processing of chloroplast degradation products in the glyoxysome, subsequent production of malate and oxaloacetate and production of glucose through reversal of the glycolysis pathway (gluconeogenesis).
Woltering, E.J., Wang, J.-F. and Seifu, Y.W. (2016). Storage of fresh-cut lettuce at light levels below the light compensation point increases sugar levels and greatly prolongs the shelf-life. Acta Hortic. 1141, 357-364
LED lighting, lettuce quality, carbohydrate status, shelf-life, fresh-cut, photosynthesis