Silicon, in hydroponics, in postharvest American 'Lucy Brown' lettuce minimally processed

This study aimed to verify the effect of silicon in hydroponics in postharvest of american 'Lucy Brown' lettuce minimally processed. Lettuces were grown hydroponically and silicon source used was potassium silicate at concentrations of 0, 28, 56 and 84mg L^-1. After harvesting, the selected leaves were washed in tap water, and semiprocessed by cutting leaves 20mm wide, immersed in solutions Sumaveg^(r). These leaves were centrifuged manually and packed in polypropylene bags, after, were sealed and stored at 3°C and 85±3% of relative humidity (RH). During 16 days of storage, leaves were evaluated every four days and in triplicate, gas composition, firmness, chlorophyll content and titratable acidity, activities polyphenol oxidase activities and peroxidase enzymes and microbiological analyzes. By the 4^thday storage it was observed reductions in O₂levels for all treatments. However, for levels of CO_2, it was observed an increased percentage of 5% in the treatment with 28mg L^-1of silicon. The highest concentrations of silicon in the leaves mantained higher firmness. Total chlorophyll remained stable during the storage period. Enzyme polyphenoloxidase activity reduced until the 8^thday. Peroxidase activity showed an increase during the study period at a concentration of 84mg L^-1 silicon. Microbial counts of thermotolerant coliforms remained low during storage. A concentration of 84mg L^-1silicon provided greater firmness of minimally processed leaves of lettuce making them more turgid and preserving its useful life for 16 days

Lactuca sativa; silicon fertilization; postharvest conservation