One advantage to the high MC of these residues may be their suitability for biogas production without considerable alteration. Although the preparation of biogas feedstock as a liquid slurry is typical, recent research has shown semi-solid and even solid biomass has potential to produce methane [45,46]. Furthermore, the nitrogen content as measured in this study shows further potential for use of these residues as biogas feedstock. The optimum C:N ratio for biogas production has been stated as 25–30:1 [47], while peel and seed residues in this study ranged 36 47:1, but the ratio for mango endocarp was calculated as 130:1. In fact, several studies have already explored the potential of mango peels for biogas production in India with satisfactory results [48–50]. However, no studies have documented the potential of the other residues presented. It is possible that the mango endocarp, which is highly lignified, and the inert seed coats of litchi and longan seeds could pose problems to the digestibility of these residues. Modification in the form of cracking or grinding might be necessary to access the nutritive inner materials. It is therefore the recommendation of the authors that further studies should be conducted to investigate mango seeds as well as litchi and longan residues as biogas feedstock