Fundamental aspects of postharvest heat treatments

Heat treatments have been investigated for use in many aspects of postharvest storage. They have been developed for insect control, prevention of fungal development and prevention of postharvest storage disorders including chilling injury. The treatment times and temperature range vary widely, from days at 35 °C to 39 °C in hot air, to up to 63 °C for less than a minute in hot water. Much of the research has been performed to develop solutions to a particular problem, and less investigation has been conducted on the responses of the commodity to the treatment. However, since the turn of the century, a number of groups have been active in examining the molecular responses and changes that occur in commodities during and after the heat treatment. This review examines the changes at the level of transcriptome, proteome and metabolome that occur in response to the different heat treatments. Postharvest physiology: Molecular responses to heat treatments Postharvest heat treatments have similar effects on the levels of specific messenger RNAs, proteins, and metabolites across many fruits and vegetables. Susan Lurie of the Volcani Center, Israel, and Romina Pedreschi of the Pontifica Universidad Católica de Valparaíso, Chile, review high-throughput analyses of the molecular consequences of postharvest heat treatment of citrus, peach, tomato and potato. Heat treatments help to maintain food quality during cold storage and reduce infestations of produce with insects and fungal pathogens. Despite considerable variability in the temperatures and the durations of heat treatments, multiple studies revealed that they change the levels of shared sets of stress-related proteins and small molecules. This knowledge may help to understand the mechanisms of postharvest heat treatments and identify markers that can be used to determine the optimum temperature and duration of treatment.