Understanding the variation in volatile compounds among commercial peach cultivars

Volatile organic compounds or VOCs in mature fresh peaches constitute the aroma and flavor perceived by consumers. This study compared four fresh late-season commercial peach cultivars (‘Augustprince’, ‘Early Augustprince’, ‘Early Big Red’, and ‘Flameprince’) grown in Fort Valley, GA, USA in 2015 and 2016 for the presence and abundance of individual volatile compounds. Fruit were harvested at commercial maturity and stored in a refrigerated room for 5-7 days at 5±2°C, followed by 2-3 days at room temperature (21±1°C) for ripening. Ripen fruit (<1 kg f for puncture and <1 kg f g^‑1 for compression and Kramer firmness tests) were used. Volatiles were extracted by headspace solid-phase micro-extraction (HS-SPME) and separated on a gas chromatograph-mass spectrometer (GC-MS). Compounds were then identified using the NIST MS library based on their mass spectra. Concentrations of individual compounds were calculated using the peak area and concentration of the internal standard (1,3-dichloro benzene). The primary compounds associated with these peaches included: alcohols, esters, hydrocarbons/alkanes, aldehydes, and lactones. Thirty-four compounds were identified in ‘Early August Prince’ (EAP) in both seasons. These compounds were previously reported to be in fruit and/or plants. Thirty-three and 30 compounds were found in ‘Augustprince’ (AP) fruit during 2015 and 2016, respectively. Thirty-two compounds were observed in ‘Early Big Red’ (EBR) in 2015 and 20 in 2016. Twenty-five compounds were identified for ‘Flameprince’ (FP) in both seasons. In 2015, hexenol, hexyl ethanoate, benzaldehyde, and γ-decalactone were the prominent hexane, ester, aldehyde, and lactone compounds, respectively. In 2015, alcohols showed no trend for compounds being predominantly higher in concentration. Similar results were found in 2016, with the exception of (E)-2-hexen-1-ol as the prominent hexane. Esters were the most abundant compounds in 2016 while lactones were the most abundant compounds in 2015. EBR cultivar in both seasons had the highest concentration for lactone compounds (272 ng g^‑1 in 2015 and 238.9 ng g^‑1 in 2016) and esters in 2016 (810.8 ng g^‑1). Esters and lactones give peaches their fruity and floral aromas. Understanding the chemical make-up of individual cultivars and their seasonal variation can provide insight into the different cultivars and their capabilities in regard to fresh peach aroma and flavor.