A study of the estimated shelf life of fresh rocket using a non-linear model

Abstract

The shelf life (SL) of fresh rocket leaves stored at 0, 5 and 15°C was studied using a non-linear model. In particular, the cumulative form of the Weibull equation and a log-logistic model were, respectively, used to fit the experimental data over time and to study the temperature dependence of the degradation rates for several sensorial, chemical and physical attributes. The Weibullian model fit the experimental data, exhibiting correlation coefficients between 0.950 and 0.996; when using traditional first-order kinetics, this value ranged from 0.902 to 0.985. Additionally, a log-logistic model that could accurately describes the temperature dependence of the Weibull parameters also accounting for the thermal history of the product. Due to the different degradation patterns of the degradation curves, the definition of the shelf life significantly changed based on the quality attributes and the storage temperatures. In particular, when the samples were stored at 5°C, the appearance score limited the shelf life, exhibiting value of 5.8days; when non-isothermal conditions were considered, the ascorbic acid content became the critical factor due to its major sensitivity toward temperature abuse. Results may be useful for planning produce logistics with fully automated distribution steps and better managing stocks, according to thermal history and, possibly, the priorities of potential customers.