Changes in strawberry volatile sulfur compounds due to genotype, fruit maturity and sample preparation

Abstract

ABSTRACTNineteen volatile sulfur compounds (VSCs), including ten thioesters and eight alkyl sulfides, were quantified using solid phase microextraction–gas chromatography–pulsed flame photometric detection in 12 Florida strawberry cultivars. The major headspace VSCs in all 12 cultivars were methanethiol and methyl thioacetate, together comprising 77–95% of the total VSCs. Concentrations for the 13 major strawberry VSCs were determined at five maturity stages. Puréed fruit produced 10–20 times more headspace volatiles than did intact berries. The relative distribution between total alkyl sulfides and total thioesters was similar from both sample preparation methods but the relative distribution of individual sulfides, especially alkyl sulfides, was appreciably different. VSCs found in the highest concentrations from intact fruit included methanethiol, dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide. In puréed fruit, highest VSCs included hydrogen sulfide, sulfur dioxide and methional. The comparison of concentrations with odour threshold in water suggests that methanethiol was the predominant aroma active VSC at all maturity stages. Total volatile sulfurs (y) increased dramatically during the final two maturity stages (x = 3,4) as described by y = 92.929x2 − 111.41x + 28.457 (R2 = 0.996). ‘Strawberry Festival’ and ‘Florida Radiance’ were distinguished from 10 other cultivars in principal component analysis (PCA) score plots, primarily due to high thioester concentrations. ‘Dover’, ‘Rosa Linda’ and ‘Florida Belle’ were the oldest cultivars and formed a distinct group in the PCA score plot characterized by relatively high sulfide and low thioester concentrations. Relative VSC composition appears to be a genetically controlled trait. Copyright © 2012 John Wiley & Sons, Ltd.