Publication:

Natural plant extracts as inhibitors of potato polyphenol oxidase: the green tea case study

Natural plant extracts have emerged as a potential alternative to sulphites in minimally processed potatoes. The aim of this study was to evaluate the inhibitory capacity of various plant extracts on potato polyphenol oxidase (pPPO) and to optimize the extraction conditions for preventing browning in fresh-cut potatoes (cv. Monalisa). Fifteen aqueous plant extracts were characterized by their total phenolic content (TPC), antioxidant activity (AA) and their pPPO. Clove extract showed the highest TPC and AA among all plant extracts. Garlic, green tea and wheat bran and, clove and marjoram have a pPPO inhibition >50% at the lowest (1–25 g GAE L−1 extract) and highest (200–350 g GAE L1 extract) range of TPC, respectively. The green tea extract was selected for further evaluation due to its high capacity to inhibit pPPO activity regardless of the solution concentration. The optimum extraction conditions and treatment concentration were 55 °C, 7 min and 50 mL L1 of original extract solution. These conditions guaranteed the conservation of fresh-cut potato colour mainly preventing the reduction of luminosity parameter. Green tea extract controlled browning in fresh-cut potatoes (cv. Monalisa) for 14 days when stored at 4 °C.