Interaction between dynamic controlled atmosphere (DCA-CD), 1-methylcyclopropene and elevated temperatures in the long-term storage of organic ‘Santana’ apples

Abstract

This study investigated the effects of controlled atmosphere (CA - 1.0 kPa O2 and < 0.7 kPa CO2), dynamic controlled atmosphere based on carbon dioxide production (DCA-CD), 1-methylcyclopropene (1-MCP), and raised storage temperatures (1 °C to 3 °C), on fruit metabolism and quality, disorder incidences and the volatile profile of ‘Santana’ apples after 6 months storage and 7 d shelf life at 20 °C. The evaluation is based on a comparison to a control group of cold storage under regular atmosphere (RA). Low oxygen partial pressures (pO2) in CA and DCA-CD in combination with 1-MCP slowed down fruit respiration and ethylene production and thus compensated for the ripening-inducing effect of raised storage temperatures. ‘Santana’ apples stored under CA or DCA-CD with additional 1-MCP, had the highest flesh firmness, titratable acidity, and greener peel coloration after storage and shelf life. CA and DCA-CD reduced core browning and fungal decay in comparison to RA. Low pO2 and 1-MCP application lowered the abundance of straight-chain alcohols and esters in ‘Santana’ apples. DCA-CD storage enabled a safe induction of anaerobic metabolism in ‘Santana’ apples, which increased levels of ethanol and derived ethyl esters. 1-MCP enhanced anaerobic metabolism in DCA-CD. Raised storage temperatures were found to increase alcohol and ester accumulation in DCA-CD. This technology consequently enables the storage of ‘Santana’ apples at higher temperatures, which could contribute to limiting stress experienced by the fruit and enhancing the formation of key aroma compounds, while also reducing energy usage of the refrigeration system.