Abstract

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Watermelon is a commonly consumed fruit. However, only the fleshy pulp is usually consumed leaving the seed and rind to be discarded. The effects of processing (heat treatment and fermentation) on the proximate composition and anti-nutrient components of watermelon (Citrullus lanatus var. lanatus) seeds were investigated. Fermentation was carried out by first boiling seeds for 3h, wrapped in clean plantain (Musa sapientum var. paradisiaca Linn.) leaves and allowed to ferment for 96h. Proximate and phytochemical screenings were carried out on the raw and processed seeds. Microbial analyses were also carried out daily on the fermenting seeds. Results of proximate analysis revealed a significant difference (p<0.05) in contents of protein, crude fat, ash, moisture content and carbohydrate of the raw, cooked and fermented seeds while there was no significant difference in the crude fibre content of the raw and cooked seeds. Protein, crude fat and carbohydrate ranged from 8.55-13.14%, 4.64-9.76% and 49.78-60.29% respectively with the highest values (except for carbohydrate) in fermented seeds while the raw seeds had the least. The anti-nutrient investigation showed that oxalate was present in raw seeds but absent in the cooked and fermented seeds. Anti-nutrients present in the raw seeds showed variable reductions after processing. Nine bacterial genera identified as Pseudomonas, Staphylococcus, Bacillus, Lactobacillus, Micrococcus, Proteus, Pediococcus, Klebsiella and Serratia with one fungal genera identified as Aspergillus were recovered from the fermenting seeds. The pH, titratable acidity and temperature of the seeds at the end of fermentation were 8.02, 0.20 and 28℃ respectively. The study showed that cooking and fermentation of watermelon seeds have direct relationships on its proximate and anti-nutrient compositions. The cooked and fermented watermelon seeds could be used in food and feeds formulation.

Keywords: valorisation, fermentation, feeds, fruit wastes, watermelon