Abstract:A compound fruit vinegar drink was developed with ′Guire No.1′ red-fleshed dragon fruits and ′Tainong No.1′ passion fruits in this research content to broaden the product forms of passion fruits and dragon fruits and reduce the risk of being unsalable after expanded production.Single factor tests and response surface methodology were employed to optimize the fermentation time,initial pH value,and initial alcohol content of fermentation,with the flavonoid content,betacyanin content,DPPH free radical scavenging rate,and total acids as the response indexes.The fermentation conditions were optimized as follows：fermentation with the initial pH4.0 and initial alcohol of 5% vol for 73 h,under which the obtained raw vinegar showed the total acids of 43.35 g/L.Furthermore,single factor and response surface tests were carried out to optimize the addition of raw vinegar,white granulated sugar,and red yeast rice powder extract,with the sensory score of compound fruit vinegar as the response index.The optimal formula of the compound fruit vinegar was as follows：raw vinegar of 6%,white granulated sugar of 99 g/L,and red yeast rice powder extract of 64%.The obtained compound fruit vinegar drink was sweet and sour,bright red,with a sensory score of 88.5,total acids of 2.81 g/L,total sugar of 101.78 g/L,and color value of 0.36 U/mL.Twelve organic acids and 31 volatile flavor substances were detected in the compound fruit vinegar drink.