Quality of guava (Psidium guajava L. cv. Pedro Sato) fruit stored in low-O2 controlled atmospheres is negatively affected by increasing levels of CO2

Abstract

Guava is a climacteric fruit, extremely perishable, that has a short shelf life. Controlled atmosphere (CA) and cold storage can be used to extend guava shelf life. However, few studies have been conducted to evaluate the effects of CA storage on guavas, especially with high levels of carbon dioxide (CO2). Therefore the objective of this study was to evaluate the quality changes of ‘Pedro Sato’ guava fruit during CA storage with atmospheres containing low concentrations of O2 and increasing levels of CO2. For that, ‘Pedro Santo’ guavas were stored at 12.2°C for up to 28 days in atmospheres with low oxygen (O2) concentration (5kPa) and increasing level of CO2 (1, 5, 10, 15 or 20kPa CO2) in order to evaluate the fruit quality changes. It was possible to identify the relationships among quality variables in response to atmosphere composition and storage duration which were related to modifications due to ripening (ratio SS/TA, TSS, RS, TA), ripening and early CO2 injury modifications (pH, SS, chromaticity), and CO2 injury modifications (hue angle, firmness, soluble pectin). A clear CO2 injury occurred in fruit stored in 5kPa O2+15kPa CO2 and 5kPa O2+20kPa CO2 after 28 days at 12.2°C, with increasing pH values and soluble pectin content, which were inversely related to fruit firmness. ‘Pedro Sato’ guavas should be stored in atmospheres with 5kPa O2 and no more than 5kPa CO2 in order to prevent CO2 damage. Further investigation is necessary to identify the metabolites responsible for the onset of responses to high CO2 in guava fruit.