Impact of retort thermal pasteurization on the quality and stability of red dragon fruit (Hylocereus polyrhizus) juice

Abstract

Red dragon fruit (Hylocereus polyrhizus) is an exotic fruit with high consumer demand due to its rich content of bioactivecompounds and significant antioxidant potential. Retort pasteurization is a novel thermal processing technology with highcommercial importance. The retort pasteurization of red dragon fruit juice presents an opportunity for the development ofvarious value-added products, including squash, jelly, syrup, and powder. This diversification not only enhances theeconomic returns for farmers but also contributes to the growth of the fruit processing industry. Despite its potential, theapplication of retort pasteurization technology for dragon fruit juice preservation remains largely unexplored. Investigationand optimization of process parameters for thermal pasteurization of red dragon fruit juice can open new avenues forimproving product stability, shelf life, and marketability. Hence this study was undertaken to evaluate how different retortpasteurization parameters (temperature and time) affect key bioactive compounds and spoilage enzymes in red dragonfruit juice and optimized the process parameters. A central composite design was applied, with product temperaturesranges between 70°C to 90°C and processing times from 5 to 15 minutes. The analysis focused on betacyanin content,totalflavonoid content (TFC), total phenolic content (TPC), and the residual activity of peroxidase (POD) and polyphenoloxidase (PPO). The numerical optimization was carried out to maximize TPC while minimizing PPO and POD activity.The optimal processing conditions were determined to be a temperature of 90°C and a processing time of 5 minutes. Onvalidation, the juice exhibited a betacyanin content of 22.24 ± 0.15 mg/100 ml, a TPC of 64.56 ± 0.35 mg/100 ml, a TFCof 20.26 ± 0.16 mg/100 ml, a PPO activity of 5 ± 0.02 % and no peroxidase activity was detected. The microbial studyconfirmed that retort pasteurization maintains the juice’s safety with no observed bacterial, yeast and mould growth. Thefindings indicated that retort pasteurization at 90°C for 5 minutes is an effective technique for the preservation of qualityand safety of red dragon fruit juice.