Effects of heating methods on the quality of ready-to-drink roselle juice mixed with chinese jujubes

Abstract

This research aims to study the result of heating’s effects on ready-to-drink roselle juice mixed with Chinese jujubes qualities by studying 4 heating methods: Method 1, direct heating at 72 degrees Celsius for 15 seconds; Method 2, heating by steaming at 72 degrees Celsius for 15 seconds; Method 3, heating by using an 800 watts microwave for 1 minute; and Method 4, heating by using an 800 watts microwave for 2 minutes. The research found the 4 heating methods caused ready-to-drink to have color values of L*, a*, and b* differed in a statistically significant way. The pH values were between 2.82 to 3.03 which were not different. Conversely, phenolic compounds, antioxidant activities by DPPH method, and anthocyanins differed in a statistically significant way. Method 3 heating by using 800 watts for 1 minute caused ready-to-drink roselle juice mixed with Chinese jujubes to have the most quantities of phenolic compounds (0.43 mg of gallic acid/100 g), antioxidant activities (85.53 µM T.E/100 g), and anthocyanins (177.50 mg/L of Delphinidin-3-glucoside). In addition, this method had the highest satisfaction scores in the sensory test which consisted of appearance; color; taste; and overall satisfaction when compared to other heating methods. The total viable count, total yeasts and molds count were undetectable in ready-to-drink roselle juice mixed with Chinese jujubes that went through the 4 heating methods.