Identification of polyphenol oxidases in potato tuber (Solanum tuberosum) and purification and characterization of the major polyphenol oxidases. (15th December 2021) - Bøjer Rasmussen, Casper
Highlights: Two PPO isoforms constitute 90% of all PPO in potato tuber. A purification protocol for the major PPOs from potato tubers were developed. Potato PPO has an activity optimum at pH 5 and 40 °C. Potato PPO is inactivated at temperatures above 60 °C or pH below 4. Efficiency of industrial relevant inhibitors were determined. Abstract: Potato is widely consumed across the globe. Understanding and inhibiting the oxidation caused by polyphenol oxidase (PPO) could improve shelf life and increase the nutritional and economic value of potato proteins. This study aimed to identify and quantify all expressed PPOs in potato tuber ( Solanum tuberosum ) and to purify and characterize the major PPOs responsible for oxidase activity. Four different PPOs were expressed in potato tuber, with 2 PPOs constituting the majority. These 2 PPOs were copurified and characterized. Both potato juice and the purified PPOs had an optimum pH of 5 and were stable over a broad pH range (6–11). The optimum temperature and stability varied, with potato juice having an optimum at 30 °C and showing a gradual decline in oxidase activity with increasing incubation temperature, while the purified PPOs had an optimum temperature and were stable up to 40 °C. Reducing agents effectively inhibited oxidase activity, while chelators did not.