Dynamic Change in Respiration Rate of Conference Pear in DCA Storage: Experimental Evidence and Modeling

Controlling respiration is a main target in (dynamic) controlled atmosphere storage, (D)CA, for climacteric fruit. Lowering respiration during (D)CA condition results in the slowing down of physiological metabolism, which retains fruit quality better after a long-term storage period. The Michaelis-Menten enzymatic model is commonly used to describe fruit respiration. However, even in (dynamic) controlled atmosphere storage, ripening still happens, so fruit respiration changes over time. Unfortunately, the Michaelis-Menten-based respiration model cannot capture this dynamic change in respiration. In this study, an experiment was conducted to measure the respiration rates of `Conference’ pears (Pyrus communis) during shelf life (18{$^\circ$}C in regular air) at harvest and after storage months under various (D)CA conditions at -1{$^\circ$}C. Respiration rates were compared across three conditions: pears at harvest, pears after 4 months in DCA storage (in a pilot-scale setting), and pears after 5 months in a mixed storage condition (2 months in CA followed by 3 months in DCA, in an industrial setting). The results showed that once pears were taken out from the storage conditions, pears in the mixed storage condition exhibited the highest respiration rate, while those at harvest had the lowest. Furthermore, during the shelf life period, the respiration rate increased over time. Then, it levelled off and slightly decreased between 8 and 12 days, depending on different storage conditions. Based on the experimental data, a dynamic respiration model was introduced to capture the change in respiration rate during (D)CA storage conditions. The proposed model was modified from the Michaelis-Menten approach by adding a dynamic variable to represent the synthesis of respiration enzymes. The proposed model demonstrated a good match with experimental data in both CA and DCA conditions, which offers a good prediction of pear respiration rate to improve storage strategies.

Acta Horticulturae(1456)