Quality changes kinetics of apple tissue during frozen storage in fluctuating temperature conditions

Apple quality after freezing is affected by temperature fluctuations during the cold chain storage. Ice recrystallization and sublimation processes occur slowly at constant temperature over long periods of storage, but more rapidly during temperature fluctuations that are often encountered in the food cold chain. These processes lead to quality changes and reducing their storage life. In this paper, samples of apple cortex tissue were frozen and subsequently stored in three different freezers set at -12 ± 3 °C, -18 ± 3 °C and -23 ± 3 °C. In each freezer, three different compartments were created corresponding to achieve ± 0.1, ± 0.75 and ± 2 °C amplitudes of temperature fluctuation. Relevant quality indices such as frost formation, drip loss, color change and vitamin C content were measured during a 5 months storage period in the different conditions. The results showed that a long period of frozen storage under temperature fluctuation conditions significantly affect the apple quality changes. Quality changes were found to be more pronounced at higher mean storage temperature and larger amplitude of the temperature fluctuation. The experimental data for quality parameters were adequately modeled by first order kinetics for each storage condition. The temperature dependency was successfully modeled by an Arrhenius expression which integrates the temperature fluctuations.status: publishe