Simple and efficient approach for shelf-life test on frozen spinach and parsley

A simple test for shelf-life assessment of frozen spinach and parsley is presented. A specific shelf-life test that considers three storage temperatures is proposed to accelerate the rate of quality decay in frozen spinach and parsley. The scope was to provide a reliable and rapid way (one month vs years) to predict shelf-life by using a simple experimental approach and mathematical models based on some physical quality product attributes. Physical properties were evaluated at three storage temperatures: –5°C, –10°C and –26°C, to simulate a possible thermal abuse. Mechanical and thermal indexes were defined measuring maximum compression force (N) and latent heat involved in ice melting (J/g). A zeroorder kinetic model was used to properly fit experimental data and thus to obtain related reaction rates. The determination coefficient indicates that there is a strong linear relation between kinetic parameters at –10°C or –5°C and –26°C. This suggests a reliable procedure for shelf-life estimation, carrying out a test at –10°C or –5°C for one month and extending values to data acquired at – 26°C for the same period of time. The relations obtained from this research have led to a simple practical approach: one day at –10°C could be considered roughly equivalent to 30 days at –26°C. Accordingly, it could be possible to obtain a shelf-life estimation in short time, also considering other similar products.