Effect of controlled atmosphere storage on production of volatiles and ethylene from cv. Zaosuli pears

Harvest-mature fruits of the pear cv. Zaosuli (Pyrus bretschneideri Rehd.) were stored at 1.0-1.5°C under two different experimental atmospheres. The controlled atmosphere (CA) had low oxygen (2.0%) and high CO2 (7%), while the regular atmosphere (RA) had 20.9% O2 and 0.1% CO2. Sixty-four volatile compounds were subsequently detected and quantified by solid phase micro-extraction (SPME) including 1 hydrocarbon, 16 alcohols, 15 aldehydes, 4 ketones, 15 esters, 8 terpenes, 2 lactones and 2 fatty acids. The principal component analysis of data was carried out to assess the effects of these post-harvest storage conditions in comparison to fruit stored in air at room temperature for 5 days. Thirteen compounds were found to be sufficient to differentiate the two different pear treatments, which were followed by subsequent warming to 20°C. The observed differences in the production of volatiles between the start of storage and 40 days later (RA), or 40 days later (CA), are principally due to just four compounds, namely n-hexanol, 2-furaldehyde, cis-geraniol and α-damascenone. Ethylene production is also lower in the CA treatment. The higher concentration of CO2 in the CA treatment causes a rise in respiration rates due to anaerobic respiration.