Ultrasound stress stimulated volatile biosynthesis of postharvest tomatoes during low-temperature storage: A strategy for improving the aroma quality of postharvest fruits.

Modern tomato cultivars often suffer from flavor loss. This study demonstrates that low-intensity, short-duration ultrasound treatment enhanced volatile organic compounds (VOCs) accumulation in tomatoes, thereby improving the overall flavor, especially in vine and floral notes. The levels of volatile alcohols, aldehydes, ketones, and other compounds, and characteristic volatiles such as E-2-hexenal, E-2-heptenal, 1-penten-3-one, β-damascenone, 2-isobutylthiazole, and 1-nitro-2-phenylethane were all increased after ultrasound pretreatment during low-temperature (10 °C) storage. The short term (1 min) ultrasound-induced VOCs accumulation was attributed to adjustment of the fatty acids and branched-chain amino acids metabolic pathway by upregulating the gene expression level of NCED1, TomloxC, HPL, LeCCD1B, and SlBCAT1. The long term (5 min) ultrasound-induced VOCs accumulation mainly changed the metabolic pathway for phenylalanine-derived volatiles by increasing the expression level of LeAADC1A, LeAADC1B, LePAR1, LePAR2, and SlSAMT1. The present study provides a new insight into ultrasound as a potential abiotic elicitor for modulating VOCs of postharvest fruits.