Sapindaceae (Dimocarpus longan and Nephelium lappaceum) seed and peel by-products: Potential sources for phenolic compounds and use as functional ingredients in food and health applications

A large quantity of by-products is annually produced from processing of Sapindaceae fruits including longan and rambutan, accounting for 24.9–40.7 and 52.9–74.7% of the whole fruit on a fresh weight basis, respectively, and these are currently discarded. These by-products are rich in phenolics with over 50 compounds identified. Among these the main components are gallic acid, ellagic acid, corilagin, and geraniin. This review highlights the biological activities, health-promoting effects and safety evaluation of these by-products as well as their potential application in food and pharmaceutical industries. In addition, comparison of the advantages and disadvantages of conventional and modern extraction techniques for the recovery of these phenolics are discussed. This information is intended to inspire further research in areas that are still underexplored and encourage fruit processing manufacturers to find ways to add value to these fruit by-products and to minimize their wastage.