Changes in the antioxidant properties of cactus pear juices with and without fruit peeling

Abstract

Food waste is an economic, ecological, social and ethical problem, in consequence, strategies that allow the integral use of food and its by-products are of great interest. In fruits and their processed products as juices or nectars, the peels are usually wasted; however, they may contribute with bioactive compounds and, hence, with beneficial health effects. This work aims to evaluate the difference in antioxidant traits of three different coloured cactus pear juices prepared with and without their peel.Yellow, orange and purple cactus pears were harvested, brushed and washed. Half of the harvested fruits were peeled and afterwards, liquefied, while the other half were liquefied without removing the peel. Yields were measured in each case. The juices were then centrifuged to removed suspended solids, and each juice was evaluated for antioxidant activity by DPPH• and ABTS•+ radical bleaching methods, total phenolic compoundcontents (TPC) by the Folin Ciocalteu method, and betalain content by spectrophotometry. Finally, juice color was determined using a colorimeter. The sensory acceptability by a consumer panel.Juices made with the whole fruits had a 47-52 % higher total phenolic compound content than those made with peeled fruits. Regarding the antioxidant activity of the juices, the preservation of the fruit peel resulted in an increase of up to 89% by the DPPH•method and up to 51% according to ABTS•+. In terms of betalain content, the purple fruits had the highest values, and the juices made with peel had almost double the concentration of those made with peeled fruits. This work allows us to revalue the use of integral fruits and reduce the energy and time costs of a fruit processing step as a strategy for sustainability.