**5. Utilization of Mango Processing Waste**

Mango processing and value addition generate an enormous amount of waste consisting of mainly the peels and the seeds, also known as stones [61–63]. Depending on the variety, 20–60% of the fruit weight comprises the seed while the kernel within the seed accounts for 45–75% of the seed's weight [64]. It has been reported that the mango seed is among the dominant agroindustrial wastes, generating about 123,000 metric tons of wastes annually in the world. Mango peels account for 7–24% of the fruit's weight [65,66]. Hence in general, mango processing generates millions of tons of solid waste approximated at 30−50% of the raw material. Furthermore, the volumes of mango processing waste are on the rise due to growth in the mango fruit production and processing industry [65]. The current standard waste disposal for industrial mango agro wastes and by products comprise of recovery (e.g., co product processing), recycling (e.g., internal upcycling of industrial side-streams into animal feeds or composting into manure), or solid waste disposal (e.g., into land fill or dried and incinerated as a source of energy) [66]. Food processing solid waste disposal has an adverse effect on the environment, such as water pollution, unpleasant odors, asphyxiation, vegetation damage, and greenhouse gas emissions. In addition, waste disposal is costly and adds to the total cost of production [67]. In addressing these challenges, there have been attempts to valorize the waste materials into value-added products.

The nutritional, physiochemical, and bioactive composition of mango seed and peels has been reviewed by Sharma et al., [68] and Mwaurah et al. [64]. There are some potential industrial applications of the value-added products derived from the seed and the peels as illustrated in Figure 2. The mango kernel contains about 15% of edible oil that is comparable to 18−20% oil content in soybeans and cotton seeds [64]. However, the oil from mango kernel comprises low free fatty acid and peroxide value and hence does not require further processing prior to consumption Blending oil from mango kernel and palm oil in the ratio of 80:20 (*w*/*w*) produces an oil with palmitic, oleic, and stearic acids comparable to cocoa butter [64]. Oil from the mango kernel has been considered to be a novel, cheaper, and readily available alternative to cocoa butter due to its phytochemical and physicochemical properties. The seed kernel has also been demonstrated to have antimicrobial activity, probably due to high content in different phenolic compounds, fatty acids, tocopherols, squalene, and sterols [67]. The mango kernel contains anti-nutritional factors and has to be preprocessed by dehulling, washing, soaking, boiling, and drying. The dried kernels can then be ground into flour and used as a functional ingredient in bakery products due to the presence of essential vitamins such as provitamin A and vitamin E and antioxidant activities [69].

Mango peel is a major byproduct of the mango processing industry and it constitutes about 15–20% of the total weight of mango fruit. The peel has been found to be a good source of biologically active substances such as polyphenols, carotenoids, flavonoids, anthocyanins, dietary fiber, vitamin E, vitamin C, and enzymes and hence has a potential use as a functional food [18,70,71].

The peel has been demonstrated to have more polyphenols than the pulp, and has a potential use as a functional food that can be used to supplement various food formulations such as bakery products, ice cream, breakfast cereals, pasta products, beverages, and meat products. It can also be used as a replacement in products such as cream, cheese, and yogurt.

Mango peel has been demonstrated to be a substantive source of odor-active compounds, that could be revalorized and used directly as a flavoring ingredient or even as a natural source out of which volatile compounds could be extracted [72]. Both the extract and the peel byproduct itself would be feasible to be used in food and cosmetic industries to provide or enhance the mango aroma of the product [73–76].

**Figure 2.** Utilization of mango processing waste.
