Effects of abusive temperatures on the postharvest quality of lettuce leaves: ascorbic acid loss and microbial growth
UniversidadNacional de Mar del Plata, Argentina; Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONI-CET), Argentina. .Corresponding author: Moreira Maria del Rosario, Grupo de Investigacion en Ingenieria en Alimentos, Facultad de Ingenieria,
DOI: https://doi.org/10.37855/jah.2006.v08i02.25
Key words: Abusive temperature storage, nutritional quality, microbiological quality, shelf life, growth models, lettuce, Lactuca sativa, ascorbic acid retention
Abstract: Changes in lettuce leaf quality (ascorbic acid contents and microbial populations) at two abusive temperatures (8 and 15?C), simulating the commercial storage conditions for fresh vegetables were analyzed. A storage temperature of 8?C was chosen to simulate abusive refrigerated storage and a storage temperature of 15?C was chosen to simulate room temperature. Quality indicators evaluation in samples, stored at abusive temperatures were compared with sample from optimal storage temperature (0?C). First order kinetics is assumed for ascorbic acid degradation. Ascorbic acid degradation rate in lettuce leaves stored at abusive temperatures was from 2.7 to 2.9 times faster than at 0?C. The growth curve of total microbial counts was fitted with the Gompertz and Logistic models. These models allowed us to predict the vegetable microbiological shelf life. Temperature is the controlling factor for lettuce shelf life and quality; microbial quality was retained 1.6 and 4 times longer at 0?C with respect to 8 and 15?C, respectively.
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