Cogent Food & Agriculture (Dec 2022)
Post-harvest quality assessment of freshly harvested and processed kola nuts [Cola nitida (Vent.) Schott & Endl.] from selected growing regions in Ghana
Abstract
AbstractElucidating the post-harvest quality of marketable kola nuts is essential in developing standards for grading the nuts. This was done in the present study by quantifying the phytochemicals and determining the moulds associated with kola nuts using standard laboratory methods. Mould and phytochemical assessments have both health and safety implications to marketers and consumers. Fresh and cured (3 months) kola nuts of three colour types (red, white, pink) were obtained from three different kola growing regions (Eastern, Ashanti, Ahafo) in Ghana for assessment. There were no significant differences in the amount of phytochemicals in fresh and cured nuts except for moisture (fresh = 56.21 − 59.42%; cured = 53.70–57.99%) and total polyphenol (fresh = 42.6–59.30 mg g-1; cured = 45.51–73.01 mg g-1) contents. Phytochemicals in the nuts after curing were as follows: pH 5.81–5.92, fat 0.49–0.60%, crude fibre 4.62–8.44%, total ash content 2.85–3.01%, alkaloids 0.40–0.99%, saponins 0.29–1.27%, terpenoids 0.30–1.09%, flavonoids 0.76–0.82% and tannins 38.67–45.22 mg g-1. These values are comparable to limits reported in kola nuts consumed in other countries. However, moisture, crude fibre, total polyphenols, alkaloids, saponins and terpenoids contents significantly (p < 0.05) differed across the sampled regions in Ghana. A total of 30 moulds belonging to 14 genera were isolated from the kola nuts. These were Absidia, Aspergillus, Colletotrichum, Fusarium, Fusoma, Geothricum, Gliocladium, Mucor, Neurospora, Penicillium, Rhizoctonia, Rhizopus, Syncephalastrum and Trichoderma. Most Aspergillus, Fusarium and Penicillium species detected are known mycotoxin-producing moulds. The information serves as a useful basis to optimize post-harvest processes of kola nuts to maintain high quality and safety nut for consumption.
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