Lactic acid fermentation as a strategy to diversify fruit products in sub-Saharan Africa

Mangoes (Mangifera indica L.), watermelons (Citrullus lanatus (Thunb.)) and pineapples (Ananas comosus (L.) are among the most important fruits produced worldwide. However, in sub-Saharan Africa, over 40% of fruits produced are lost after harvest, reducing the profit margins of smallholder farmers. Hence the goal of this PhD was to add value to fruit processing through fermentation as a low-cost and sustainable strategy to reduce post-harvest fruit loss, diversify fruit products, and enhance the nutritional value of fruits. The generated fruit byproducts were further transformed into valuable products. Results showed that the fruit juices varied in their nutrient composition which in turn affected the type of lactic acid bacteria (LAB) species that grew and/or survived in them. Lactiplantibacillus (Lp.) plantarum subsp. plantarum, Lacticaseibacillus (Lc.) rhamnosus, Lc. casei, Levilactobacillus (Le.) brevis, and Pediococcus (P.) pentosaceus had the highest growth after fermentation (30 / 37 C, 24 h). Mango and watermelon juices fermented by Lc. casei, Le. brevis, and P. pentosaceus were most liked by consumers, least penalized, and had a higher purchasing power. In watermelon juice, lactic acid fermentation introduced new volatile compounds not previously present in the control and some aldehydes disappeared. In mango juices, sesquiterpenes, aldehydes, alcohols, and esters decreased while ketones and furans increased after fermentation. LAB viability remained > 8 log CFU/mL in fermented watermelon juice and > 7 log CFU/mL in fermented mango juice by the end of storage. Watermelon and mango juices provided a protective effect to P. pentosaceus during in vitro simulated gastrointestinal digestion with a 3- 4-fold higher survival in fermented juice, than as a pure culture. Mango seed and kernel increased the protein, fat, ash, mineral, total phenolic content, and antioxidant capacity of maize porridges but significantly decreased the bioaccessibility of minerals, especially manganese, copper, and iron. In conclusion, this PhD introduces new fruit juice products that are not normally consumed in sub-Saharan Africa