Effects of ultrasound combined technology on quality and volatile compound properties of chili sauce

Abstract

In this study, the effect and mechanism of seven kinds of sterilization treatments, including ultrasound (US), pasteurization (PT), high temperature short time (HTST), hot air (HA), microwave (MW), ultraviolet (UV) and steam sterilization, on E. coli, S. aureus and P. aeruginosa were investigated. It was found that PT, HTST, MW, and steam sterilization gave ideal bactericidal effect and were subsequently, combined with ultrasound treatment and applied to chili sauce. The results showed that ultrasound combined with microwave (US + MW) treatment was effective in preserving the maximum nutritional value and flavor of chili sauce while ensuring its sterility. The total number of colonies and coliforms were not detected after US + MW treatment. Furthermore, the contents of total polyphenol, capsaicin and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging ability in the US + MW group were 11.10%, 12.78% and 17.00% higher than those of traditional autoclave sterilization. In addition, polyphenol oxidase (PPO) activity was 2.04 times higher in the US + MW group compared to the autoclave sterilization group. Correlation analysis showed that total polyphenol and capsaicin were positively correlated with 2,2′-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) (correlation coefficients 0.90 and 0.76, respectively) and DPPH free radical scavenging ability (correlation coefficients 0.88 and 0.72, respectively). The results obtained from GC-MS showed that US + MW treatment could reduce the loss of volatile compounds and retained the original flavor of chili sauce. The content of diallyl disulfide was 1.8 times that of autoclave group. This study provides a new theoretical reference for sterilization and flavor preservation of chili sauce.