Evaluation of Volatile Compounds Responsible for the Aroma of Fresh Peaches

Volatile active compounds identified in a peach fruit during maturation have been correlated with perceived quality by consumers. Some of these compounds are synthesized as a result of under-ripe and over-ripening of fruit, while others produce as the fruit matures. These compounds interact positively with the perception of a mature fruit flavor. Multiple volatile compounds have been identified and aroma attributes are established. This study surveyed six late season melting peach varieties grown in Fort Valley, GA to compare major volatiles compounds and their aroma attributes. Fruit were harvested 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). Volatiles were separated by solid-phase micro-extraction coupled with gas chromatography-mass spectrometry (SPME GC-MS) technique. Volatiles were extracted from the headspace using a PDMS/DVB coated SPME fiber. Compounds were then identified using the NIST MS library based upon retention times. Linear retention indices were used to determine concentrations of individual compounds with their peak area. Fresh peach samples resulted in the detection of 177 volatile compounds, with major compounds being alcohols, esters, hydrocarbons/alkanes, aldehydes, and lactones. Thirty compounds previously reported in fresh peaches and 28 volatiles with potential impact in peach aroma, based on their sensory characteristics, were identified. Of alcohols detected, major compounds included: hexenols, (3-Hexen-1-ol,2-Hexen-1-ol, 2-Hexenal, and 1-Hexenol) associated with green, fresh aromas; and decanal and nonanol, associated with citrus, floral and citrus, orange, respectively. Ester compounds found for all cultivars included hexenol acetate, associated with sweet, fruit aromas and methyl octanoate. Additionally, hydrocarbons/alkanes included: undecane and heptadecane, and an aldehyde, benzaldehyde, known for its cherry/almond sweet aroma, was found in all varieties. Lactones, the most well known compounds to represent peach aroma, were γ-undecalactone, δ-decalactone, and γ-dodecalactone in all varieties. Of the thirty known volatiles in fresh peaches, Red Sun’ had the highest number of volatile compounds (22), followed by ‘Cresthaven’ (21), ‘August Prince’ and ‘Early August Prince’ (19), ‘Early Big Red’ (18), and ‘Flameprince’ with 13. When reporting all volatiles, fewest volatile compounds were found in ‘Flameprince’, while a highest number were found in ‘Early August Prince’, a peach well known for its aromatic properties and intense flavor. Further analyses of aroma quality combined with sensory evaluation can give insight into the impact of major aromatic compounds and their influence on consumer perception of aroma and flavor quality in peach.