Rocket (Eruca sativa Mill.) is one of the most appreciated leafy vegetables in Europe. The most important quality attributes are its pungent taste and sharp, spicy and peppery flavour. The leaves may be sold unwashed or as a fresh-cut product, which is washed, dried and packed under a modified atmosphere (MAP) to obtain a shelf-life of 10 days. During storage, the quality of the rocket leaves rapidly decay, particularly through yellowing caused by chlorophyll degradation, wilting, and the production of off-odours.Scientists at University of Foggia (Italy) have used a non-linear model to estimate the shelf-life of fresh-cut rocket. The results of the study were just published in the International Journal of Food Engineering.
The aim of the work was to improve the management of the critical control points and quality maintenance while improving the estimation of the shelf-life of fresh-cut rocket. This is important for planning produce logistics with fully automated distribution steps and better manage stocks, according to the cold chain management and, possibly, to the priorities of potential customers.
More specifically, the work consisted of using the Weibullian-log logistic model to fit the changes of important sensorial, physical and chemical attributes (overall quality, colour, off-odours, texture, vitamin C, package gas composition) of rocket leaves as affected by storage time (up to 10 days) and temperature (0-5-15°C), and the definition of the limiting factor of shelf-life when several quality attributes are taken into account at the same time, and how this may be affected by changes in temperature.
Results show that when fresh-cut rocket leaves were stored at constant temperatures, the appearance score limited the shelf-life, reaching the limit of marketability after 7.3, 5.8 and 3.7 days, respectively, for samples stored at 0.5 and 15°C; nevertheless an increase in the temperature affected the ascorbic acid loss more than the appearance and off-odour scores, allowing this nutritional attribute to limit the shelf-life. During non-isothermal storage, the degradation of quality attributes may show different trends over time, allowing the limiting factor of the shelf-life definition to vary.
Dr Maria Luisa Amodio concludes: "This study demonstrates that a Weibullian-logistic model is useful to predict the shelf-life of fresh-cut rocket under isothermal and non-isothermal conditions; the Weibullian model fits the experimental data exhibiting correlation coefficients greater than 0.9. In particular, any temperature profile detected along the entire cold chain could be used to define the 'best before' date reported on the packages better in the second case".
Source: Amodio M.L., Derossi A., Mastrandrea I., Colelli G., "A study of the estimated shelf life of fresh rocket using a non-linear model", 2015, Journal of Food Engineering, Vol. 150, page. 19-28.
http://www.sciencedirect.com/science/article/pii/S0260877414004506