Evaluation and modeling of changes in color, firmness, and physicochemical shelf life of cut pineapple (Ananas comosus) slices in equilibrium-modified atmosphere packaging.

In this study cut, pineapple slices of 1 cm thick were packaged and stored at different temperatures and equilibrium modified atmosphere packages (EMAPs) to determine changes of color and firmness over time to represent physicochemical shelf life. From the experimental data, a variance analysis was performed to determine the effect of temperature and O2 level on the evolution of color (CIELAB coordinates) and firmness. It was observed that the evolution in L* , a* , and b* coordinates is independent on O2 concentration in the EMAP system. After that, suitable models were adjusted to represent the change of the quality properties as a function of temperature by using first-order models to represent color and a power model for firmness. Likewise, a modified normal distribution function was adjusted to represent the coefficient of firmness loss depending on the O2 level besides the temperature effect. The firmness model was used to obtain a suitable equation to predict shelf life of the pineapple slices for different EMAP systems. Finally, a validation experiment was performed at 8 °C obtaining a high capacity of prediction (R2 adj > 0.90) compared with the experimental data. The adjusted model can be used to configure a satisfactory EMAP system for the best preservation of minimally processed pineapple from the predicted evolution of color, firmness, and shelf life depending on temperature and O2 concentration. PRACTICAL APPLICATION: In this work, we built a mathematical model to simulate the shelf life of pineapple cut into slices based on changes in color and firmness and as a function of temperature and oxygen level. These properties are truly relevant because they are very clear evidence of the fruit deterioration, and for that reason, we chose them for the model. The model we developed can be applied in retail and supermarket systems to determine precisely how long the product on the shelf can last before being disposed of, reducing material losses.

Evaluation and modeling of changes in shelf life, firmness and color of 'Hass' avocado depending on storage temperature.

In this study, 'Hass' avocado samples were stored at different temperatures to determine changes in firmness, color and other physicochemical support properties throughout the storage time and to represent shelf life depending on temperature from the evolution of these quality properties. From the experimental data, a set of models were adjusted to represent the change of each property as a function of time and temperature by using a first-order kinetics to represent the evolution of lightness (L*) and the chromatic coordinate b*, and a logistic equation to represent firmness and a*. The effect of temperature was represented by using Arrhenius equations. From the models of firmness and color, suitable equations were obtained to predict shelf life considering the relationship with the senescence stage (between 20 and 33 days). All the models were adjusted satisfactorily, obtaining regression coefficients higher than 0.95. In order to determine the predictive capacity of the proposed models, a validation experiment was carried out by storing fruits at 12 ℃ until reaching the senescence stage. With the models, it was possible to satisfactorily predict the changes in color and firmness and it was possible to estimate the shelf life time at 12 ℃ (28 ± 3.1 days).

Effect of ethylene and 1-methylcyclopropene on the postharvest behavior of cape gooseberry fruits (Physalis peruviana L.).

Cape gooseberry (Physalis peruviana L.) fruits are highly perishable berries that exhibit a climacteric respiratory behavior. The objective of this study was to evaluate the effect of ethylene and the ethylene action inhibitor 1-methylcyclopropene on the postharvest behavior of cape gooseberry fruits (ecotype Colombia). Fruits were treated with ethylene, in an ethephon application (1000 µL L-1), and pretreated with 1-methylcyclopropene (1 µL L-1), 1-methylcyclopropene+ethylene, and results compared with a control without application. Subsequently, the fruits were maintained at room temperature (20 ℃, 75% RH) for up to 11 days. The pretreatment of the cape gooseberry fruits with 1-methylcyclopropene delayed most of the ripening-associated parameters, with a reduction in the respiration rate and ethylene production, skin color development, total soluble solids, total carotenoid content, loss of firmness, loss of total titratable acidity and emission of volatile compounds such as ethyl octanoate, ethyl butanoate, ethyl decanoate, and hexyl decanoate. Conversely, application of ethephon accelerated most of these physiological changes and also overcame most of the effects prevented by the ethylene action inhibitor. Altogether, the results supported the idea of a climacteric-like behavior for cape gooseberry fruits and pointing out that the pretreatment with 1-methylcyclopropene may be a promising and efficient postharvest treatment to delay maturity and extend the postharvest period.