Abstract
In this study, dried rose petals were used as the main raw material, and compound lactic acid bacteria were used for fermentation to optimize the fermentation technology of rose flower enzymes. Taking fermentation time, initial pH, inoculum amount, and fermentation temperature as investigation factors, SOD (superoxide dismutase) enzyme activity and total phenol content as evaluation indicators, response surface optimization combined with Box-Behnken design experiment to obtain the best fermentation process conditions. In addition, the research also used DPPH (1, 1-diphenyl-2-trinitrophenylhydrazine), ABTS (2, 2'-diazo-bis-3-ethylbenzothiazolin-6-sulfonic acid) and FRAP (ferric ion reduction method) method to detect the in vitro antioxidant activity of rose flower enzymes before and after fermentation, and to determine the SOD enzyme activity, total phenol content, flavonoids content, anthocyanin content, pH and titratable acid. The results showed that the optimal process conditions for the fermentation of rose flower enzyme liquid were: Fermentation time 68 h, initial pH5.4, inoculation amount 1 g, and fermentation temperature 32 ℃. Under these conditions, the SOD enzyme activity of the rose flower enzyme solution was 132.07 U/mL, the total phenol content was 6.28 mg/mL, the total flavonoid content was 3.48 mg/mL, the anthocyanin content was 5.64 mg/100 mL, and the titratable acid was 2.82 g/100 g, which was a greater improvement than before fermentation. When the rose enzyme liquid before and after fermentation and 8 mg/mL Vc volume fraction were 0.45%, the DPPH free radical scavenging rates were 73.32%, 83.70%, 35.05%, and the ABTS free radical scavenging rates were 82.18%, 92.74%, 52.82%, respectively. The FRAP values were 0.25, 0.28, and 0.115, respectively. The results of three different antioxidant methods, DPPH, ABTS, and FRAP, all showedthat rose enzyme liquid hadthe strongest antioxidant capacity after fermentation.
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