Modelling basil (Ocimum basilicum) visual quality as affected by storage temperature

Visual quality is the main sensory quality factor limiting sweet basil (Ocimum basilicum L.) shelf life. The aim of the present study was the development of a model for the prediction of basil visual quality depending on storage temperature and time. Commercial clamshell recycled polyethylene tetraphyte (RPET) packages containing 20 g of basil were stored at eight different temperatures (2, 4, 7, 10, 12, 15, 22, 30 degrees C). Five packages were stored at each temperature. Basil packages were evaluated daily until the end of shelf-life by a panel composed by trained members. Different visual quality characteristics were evaluated (yellowing, chilling injury, mold growth, firmness) to give an overall visual quality score using a hedonic scale. The experiment was repeated three times. Data on the overall visual quality of basil were used for the development of a model for the prediction of basil visual quality decay at different temperatures. First, the kinetics of visual quality deterioration was characterized. Visual quality as a function of time was modelled by a linear, quadratic, logistic, and exponential equations. Based on the goodness-of-fit statistic (R-2) and model complexity the most suitable primary model was chosen. The parameter (decay rate) of this model was fitted by a secondary model to describe the decay rate as a function of temperature. As the data set was limited, primary and secondary Modelling was performed in one step on the global data set. The model was fitted using nonlinear regression. A linear model was selected to model visual quality as a function of time taking into account the complexity of the models tested. A quadratic function was selected to describe the quality decay rate as a function of storage temperature. The coefficient of determination (R-2) of the obtained model was 0.71. The maximum shelf life of 6 days is predicted at 15 degrees C. The model should be validated under dynamic temperature conditions.