Objective The effects of different fertilization types and maturity on the aroma substances of Korla fragrant pear in Xinjiang were compared, and the key aroma substances were screened to provide a basis for the evaluation and regulation of flavor quality.
Methods In this study, Korla fragrant pear in the Peacock River Basin were used as experimental materials. Fruits were collected at different ripening stages of 130-150 days after flowering and treated with organic fertilizer, chemical fertilizer and mixed fertilizer. The aroma substances in Korla fragrant pear were determined by solid-phase microextraction-gas chromatography paired with triple quadrupole mass spectrometry (SPME-GC-MS/MS). The differences in aroma components and contents of pear fruits among the three fertilization types were compared. The model was established by orthogonal partial least squares discriminant analysis (OPLS-DA), and the relative odor activity value (ROAV) was used to screen the key aroma substances of Korla fragrant pear in the mature stage, and the change rule was analyzed.
Results A total of 184 aroma substances were detected in Korla fragrant pear, mainly aldehydes, alcohols and esters. The relative content of aldehydes in Korla fragrant pear fruits under three different fertilization types was more than 62%, and the proportion of aldehydes and alcohols was the highest under organic fertilizer treatment. Through OPLS-DA model analysis combined with ROAV method, seven key aroma substances with ROAV ≥ 1 in the ripening stage of Korla fragrant pear fruit were screened out. Among them, decanal contributed the most to the flavor of Korla fragrant pear, with strong aldehyde aroma, followed by 2-hexenal, hexanal and so on. With the maturation of Korla fragrant pear, the relative percentage of hexanal, 2-hexenal and (E, E) -2,4-hexadienal gradually increased from 24.74% to 30.8%, 26.02% to 27.08%, and 1.26% to 4.48%, respectively. The relative percentage of hexyl acetate and 1-octanol decreased from 1.1% to 0.27% and 1.76% to 0.68%, respectively. The change trend of other aroma substances was small.
Conclusion The aroma substances in Korla fragrant pear fruit are mainly aldehydes, alcohols, ketones and esters, and aldehydes are the most abundant aroma substances in Korla fragrant pear. The application of organic fertilizer can increase the types of aroma substances and the relative content of some aroma substances in fruits. The seven key aroma substances gave fragrant pear fruit aroma characteristics such as fresh aroma, fruit aroma and sweet aroma, and the content of some aldehydes increased during ripening.
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