(256b) Mathematical Study for Prediction of Shelf Life of Curly Hydroponic Lettuce

Refrigerated vegetable preservation is a widely discussed topic in the world in order to define ideal conditions for fresh food storing from the harvest to consumer’s table. Leafy vegetables are very consumed. However their physicochemical characteristics, during storage, undergo changes such as weight loss, moisture loss and degradation of chlorophyll, which reflect changes in sensory aspects such as color and wilting. These characteristics refer to the vegetables quality and the changes have a direct impact on consumer perception. The objective of this study was to evaluate the physicochemical and sensory stability of leaves of hydroponic curly lettuce for 14 days stored at 2 °C, 6 ° C and 10 °C (± 1 °C) in household refrigerator refrigeration, packed in expanded polystyrene (styrofoam) packaging wrapped with polyvinyl chloride film (PVC). Through physicochemical analyzes of mass loss, total chlorophyll, sensorial analyzes of color change, wilted appearance, edge darkening and central vein darkening, the results were evaluated by Tukey test at 5% of significance and for shelf life estimation was used Principal Component Analysis (PCA). These allowed to verify the influence of the cooling parameters of this study, on the quality factors of lettuce leaves. The PCA data were regressed a nonlinear mathematical model, Weibull model, to describe the degradation kinetics. According to Tukey's test, the best refrigerated storage isothermal conditions to maintain the desired physicochemical and sensory characteristics over the storage period were 2 °C and 6 °C. When estimating the shelf life using the Weibullian model was obtained 12.43 shelf life days for refrigerated storage at 2 °C; 8.76 days at 6 °C and 9.87 days at 10 °C. After comparing the results of analysis of the physicochemical, sensorial and shelf life estimation, was observed a good fit of the model to experimental data to predict the hydroponic curly lettuce degradation during the 14 days of refrigerated, resulting in determination coefficients of 0.94 for the storage temperature of 2 °C, 0.98 for 6 °C and 0.99 for 10 °C.