Extremely low oxygen partial pressures for the storage of ‘Royal Gala’ apple

Magno Roberto Pasquetti Berghetti,Auri Brackmann,Lucas Mallmann Wendt,Vagner Ludwig,Fabio Rodrigo Thewes,Flavio Roberto Thewes,Erani Eliseu Schultz,Suele Fernanda Prediger Schmidt

doi:10.1590/1678-4499.20190016

Abstract

The aim of this study was to evaluate the effect of storing ‘Royal Gala’ apple under extremely low oxygen partial pressures on their anaerobic metabolism, ethylene production and fruit quality after 9 months of storage plus 7 days of shelf life at 20 °C. The storage conditions tested were: 1.2 kPa O2 + 2.0 kPa CO2; 0.7 kPa O2 + 1.5 kPa CO2; 0.5 kPa O2 + 1.2 kPa CO2; 0.4 kPa O2 +1.2 kPa CO2 and 0.25 kPa O2 + 0.0 kPa CO2. The fruit storage temperature was 1.0 °C (± 0.1). Fruit stored at 0.4 kPa O2 + 1.2 kPa CO2 maintained higher flesh firmness and a higher percentage of healthy fruit. The fruit stored under the 0.25 kPa O2 + 0.0 kPa CO2 condition had lower flesh firmness as well as a reduced percentage of healthy fruit and a high production of anaerobic metabolism compounds, such as ethanol and ethyl acetate, which may have caused fruit quality loss. The storage of ‘Royal Gala’ apple under 0.4 kPa O2 + 1.2 kPa CO2 is a technique that can be commercially applied to keep a better fruit quality after a 9 months storage period.

Highlights

Brazil has a production of about 1.1 million tons of apples, mainly concentrated in the states of Rio Grande do Sul and Santa Catarina, where Rio Grande do Sul produced 490,000 tons in the 2017 harvest (Agapomi 2018)
This reduction can be explained as a consequence of extremely low partial pressures of oxygen, where molecular oxygen becomes limited to the ACC oxidase activity
This enzyme is responsible for ethylene synthesis and is activated or inhibited depending on the concentration of the anaerobic metabolism products (Yang and Hoffman, 1984; Beaulieu and Saltveit 1997)

Summary

Introduction

Brazil has a production of about 1.1 million tons of apples, mainly concentrated in the states of Rio Grande do Sul and Santa Catarina, where Rio Grande do Sul produced 490,000 tons in the 2017 harvest (Agapomi 2018). Amongst the main cultivars is the ‘Royal Gala’, discovered in New Zealand in 1971, from a mutation of the cultivar Gala (Camilo and Denardi 2006) This cultivar has the potential to meet the requirements of Brazilian consumers because it presents a uniform red coloration of the epidermis and sweet taste, which gives it a good value and commercial acceptance (Brackmann et al 2012). Since the production of apples is concentrated in a short period of the year, the use of appropriate storage techniques is very important, so the fruit can be supplied throughout the entire year (Brackmann et al 2008). The reduction of O2 to partial pressure that is too low (below 0.3 kPa O2), may increase the production of volatile compounds such as alcohol, acetaldehyde and ethyl acetate, which in high concentrations can be harmful to the fruit, reducing the flesh firmness and increasing the occurrence of physiological disorders (Both et al 2017)

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Conclusion