Hydrocooling on postharvest conservation of butter lettuce

Abstract

Lettuce is a vegetable highly susceptible to water loss, which reduces its shelf life and increases the final cost to the consumer. The aim of this study was to evaluate the effects of hydrocooling on the postharvest shelf life of butter lettuce 'Vitória de Santo Antão'. The lettuce heads, after selection, were subjected to the following treatments: T1= hydrocooling followed by storage at 5°C in the cold chamber; T2= storage in the cold chamber at 5°C without hydrocooling; T3= hydrocooling followed by storage at 22°C and T4= storage at 22°C without hydrocooling. We determined the shelf life, leaves mass loss, chlorophyll content, relative water content, total soluble sugars content, reducing sugars, non-reducing sugars and starch. The data were analyzed in split plot in a randomized block design with four replications. The hydrocooling was effective in slowing down the visual wilting of the leaves at 5 and 22°C, extending the shelf life. The hydrocooling combined with storage at 5°C maintained the leaves water balance, keeping them hydrated during storage, causing an increase of 20% in the marketing of the product, from 5 days in lettuces without hydrocooling, to 6 days when these were subjected to hydrocooling. No effect of hydrocooling in the chlorophyll content, total soluble sugars, reducing sugars, non-reducing sugars and starch of leaves was observed in any of the storage temperatures. The hydrocooling at 4°C during 5 minutes, followed by storage at 5°C is an effective technique to maintain the leaves water balance, promoting longer shelf life.