An efficient method using ultrasound to accelerate aging in crabapple (Malus asiatica) vinegar produced from fresh fruit and its influencing mechanism investigation

In this study, a kind of crabapple vinegar was developed by the method of mixed bacteria fermentation. It showed that the total acids and total esters in the vinegar increased by 30.51% and 22.67%, respectively. Simultaneously, ultrasound was used to treat the vinegar to shorten the time of aging. In addition, the HS-SPME-GC-MS results show that some volatile components had increased significantly, such as total esters, aldehydes and heterocycles. Combining OAV with radar chart of aroma active ingredients, the order of contribution to the characteristic aroma of crabapple vinegar was esters > alcohols > others > acids. Finally, ultrasonic cavitation and hydroxyl radicals were measured to further prove it could accelerate chemical reaction of crabapple vinegar. The results of FTIR showed that the hydrogen-bonded molecules had increased, while free molecules with irritating taste (such as ethanol and acetic acid) had decreased, which made the taste of crabapple vinegar softer. Results have showed that ultrasound is a promising technique for shortening aging time and it also provides the possibility to improve the taste of fruit vinegar.