Effects Of Ultrasonic Ageing On The Quality Of Zhenjiang Vinegar

Zhenjiang vinegar is famous for its unique flavor of “sour is not astringent,fragrant and sweet,rich in color and delicious,more and more fragrant” and is one of the four traditional vinegars in China.The flavor of Zhenjiang vinegar is the result of the sensory interaction of various volatile and non-volatile flavor molecules on humans.Zhenjiang vinegar flavor quality continues to increase to increase with the ageing time,ageing time is an important basis for consumers to buy vinegar.In view of the significant effect of natural ageing on the flavor quality of vinegar,natural ageing has the disadvantages of long production cycle,many influencing factors,high cost,etc.The use of ultrasonic technology for vinegar ageing has achieves certain progress.This topic mainly studies the effect of ultrasonic ageing on the flavor of Zhenjiang vinegar,and discusses the effect of cavitation yield and hydroxyl free radical on the ageing of Zhenjiang vinegar.The main research contents and results of this article are as follows:(1)Under ultrasound conditions,compared with fresh Zhenjiang vinegar,total acid content in Zhenjiang fresh vinegar after ultrasonic treatment decreased by 6.07%;total ester content increased by 33.15%;reducing sugar and aminopeptide nitrogen content decreased by 16.53% and 13.89%.There was no “returning” phenomenon after 1 month and 3 months of ultrasound.The contents of amino acid and organic acid in vinegar also changed significantly.The content of glutamic acid,which was umami,increased.Most of bitter and astringent taste of Zhenjiang vinegar is weakened,acetic acid is reduced,and the increase of lactic acid can effectively improve the flavor quality of Zhenjiang vinegar products.PCA combined with sensory analysis results showed that the changes in the indexes of Zhenjiang vinegar after ultrasonic treatment were consistent with the changes in the natural ageing vinegar.The quality of the vinaigrette reached 18 to 32 months,and the flavor was more delicious,mellow and soft.(2)SPME-GC-MS was used to analyze volatile constituents and contents of 7 kinds of different vinegar aged Zhenjiang vinegar and Zhenjiang vinegar and Zhenjiang vinegar after ultrasonication at 0,6,12,18,32,44 and 56 months.Of the changes,a total of 56 volatile components were detected.With the increase of vinegar age,the content of acids and alcohols in the volatile components of balsamic vinegar decreased,and the content of ester compounds and heterocyclic compounds increased,among which the heterocycles had the most obvious changes.The aroma active value method was used to study the aroma active ingredients of Zhenjiang vinegar before and after ultrasonication and the volatile components of Zhenjiang vinegar with different vinegr ages.17 kinds of aroma active ingredients were indentified,and Zhenjiang vinegar flavor fingerprint was drawn based on the aroma activity value and aroma properties.Combined with PCA analysis,more accurately characterize the intrinsic relationship between the aroma active ingredients of different vinegar age Zhenjiang vinegar,and provide a theoretical basis for the study of ultrasonic ageing on the molecular flavor of Zhenjiang vinegar.(3)Ultraviolet spectrophotometry was used to measure the chemical yield and hydroxyl free radicals of ultrasound.The physicochemical indexes and free radical mechanism were compared to verify the cavitation effect and hydroxyl radicals in the ultrasonic process can accelerate the vinegar ageing process.Part of the chemical reaction,effectively promote the ageing of vinegar.By studying the effect of ultrasound on the fructose-glycine Maillard simulation system,the results show that ultrasound can promote the production of Maillard reaction intermediates and increase the degree of browning.In summary,it can be further demonstrated that the free radicals produced by ultrasinication have a positive effect on the chemical reaction during the ageing process of Zhenjiang vinegar.