Effects of raw material characteristics and process technology on the valorization of polyphenols and pectin from mango peels

The steadily increasing popularity of fresh mango fruits and derived products induced intensified mango production and processing globally. Industrial mango processing results in the accrual of vast amounts of by-products, i.e. stones and peels, to be disposed at the expense of the processors if valorization techniques are unavailable. While the kernel fat of the stones may be recovered and used as a partial substitute of cocoa butter, economically feasible valorization procedures for mango peels are currently lacking. However, they represent valuable low-cost sources for the recovery of bio- and techno-functional compounds, such as polyphenols and pectin. Although both ripe and unripe fruits of numerous mango cultivars are industrially processed, knowledge about the suitability of the respective by-products for valorization is still scarce. Prior to their valorization, peels need to be stabilized and converted into a storable commodity, since they are highly susceptible to spoilage. Therefore, the present work systematically investigated the suitability of mono- and polyembryonic mango fruits of varying ripeness degrees as well as the influence of peel stabilization by blanching, convective oven drying, lyophilization, and irradiation on the quality of polyphenols and pectin, respectively. Thereby, a rapid ultrasound-assisted extraction procedure for the recovery of polyphenols, and a method for purification of crude extracts using adsorbent technology were provided. Ultimately, the suitability of mango peels, derived products, and different pectins for their utilization as feed supplement was evaluated.

The present thesis provides a comprehensive concept for the technological exploitation of mango peels for the industrial utilization of peels and derived products.