Changes in quality indices of butter head lettuce during postharvest storage under saturated and low relative humidity conditions.

AGÜERO MARÍA VICTORIA; PONCE ALEJANDRA G; MOREIRA MARÍA R; BARG MÓNICA V; ROURA SARA INES

Foz de Iguazú

Congreso; CIGR International conference of Agricultural Engineering; 2008

Vegetables shelf life is a dynamic process in which the microbial population, temperature, relative humidity and the package atmosphere changes present high levels of interaction. It is interest to understand the evolution of physical and chemical indices of lettuce under adverse storage condition, because these products are subject to non-optimal conditions during postharvest. The aim was to evaluate lettuce quality indices during the storage at 0-2 ºC and under two Relative Humidity (RH) conditions: optimum (98%) and low (72%). Under low RH, lettuces presented considerable weight losses since first day of storage, fasten during the first 3 days and the water content losses were significant in each zone of lettuce at the end of storage (5 d). For both RH, the middle and internal zones showed no chlorophyll content changes during storage while the external zone exhibited degradation throughout all the storage following a first order kinetic. RH had not significantly impact on microbiological index. Ascorbic Acid (AA) degradation followed a first order kinetic, for all situations (zones and storage conditions). At low RH the degradation rate was significantly different between lettuce zones. At optimal RH the three zones presented high Overall Visual Quality (OVQ) at 5 d, while at low RH, only the internal zone were over the acceptability limit.