Post-harvest quality assessment of freshly harvested and processed kola nuts [Cola nitida (Vent.) Schott & Endl.] from selected growing regions in Ghana

Figures & data

Table 1. Qualitative assessment of phytochemicals in fresh and cured kola nuts

Constituent	Fresh	Cured
Alkaloids	+ +	+
Anthraquinones	-	-
Cardiac glycosides	++	++
Flavonoids	+ +	+ +
Phenols	+ +	±
Phlobatannins	-	-
Saponins	++	+
Steroids	-	-
Reducing sugars	++	++
Tannins	++	++
Terpenoids	+ +	++
Volatile oil	+	+

Strong positive = ++, Positive = +, Trace = ±, Negative = -

Table 2. Phytochemical composition of freshly harvested and 12-week cured kola nuts in Ghana

Phytochemical constituent	Eastern Region				Ashanti Region				Ahafo Region
	Fresh	Cured		Fresh		Cured		Fresh		Cured
Moisture Content (%)	59.42a±0.86	57.99ab±0.62		58.67ab±1.12		54.87bc±0.91		56.21abc±1.46		53.70c±0.81
pH	5.81a±0.07	5.92a±0.03		5.92a±0.04		5.92a±0.01		5.85a±0.04		5.86a±0.01
Fat (%)	0.52ab±0.02	0.60a±0.02		0.51ab±0.02		0.53ab±0.02		0.53ab±0.03		0.49b±0.04
Crude fibre (%)	5.35bc±0.34	5.40bc±10.67		4.26c±0.68		4.62c±1.53		6.89ab±0.97		8.44a±1.09
Total ash (%)	2.74a±0.10	2.85a±0.23		2.88a±0.14		2.92a±0.22		2.80a±0.19		3.01a±0.19
Alkaloids (%)	1.09a±0.26	0.88ab±0.25		0.51abc±0.20		0.40bc±0.14		0.29c±0.05		0.99ab±0.63
Saponins (%)	0.27b±0.04	0.37b±0.20		0.40a±0.11		0.29a±0.05		1.13b±0.30		1.27b±0.25
Terpenoids (%)	0.32ab±0.05	0.30b±0.02		0.68ab±0.43		1.09ab±0.47		1.10a±0.55		0.94ab±0.40
Total polyphenol content (mg g^−1)	42.60c±6.50	45.51bc±1.27		45.67bc±1.68		65.40ab±3.81		59.29abc±8.50		73.01a±6.99
Flavonoids (%)	1.03a±0.21	0.82a±0.25		1.00a±0.27		0.76a±0.19		1.00a±0.20		0.81a±0.24
Tannins (mg g^−1)	54.61b±19.34	39.78a±12.99		41.17a±6.70		45.22a±10.16		34.01a±6.87		38.67a±3.99

Values in each row followed by the same letters are not significantly different at p<0.05. The values after ± are standard error of means.

Figure 1. Samples of the red, white and pink types of kola nuts showing bright colours at harvest (A) and dull colours after 12-week curing (B).

Table 3. Moulds associated with freshly harvested and cured kola nuts from three major production regions in Ghana

Mould species	Eastern region		Ashanti region		Ahafo region
	Fresh	Cured	Fresh	Cured	Fresh	Cured
Absidia ramosa	0.0	0.0	0.0	0.0	0.5	3.3
Aspergillus flavus	9.9	9.0	16.3	25.7	26.7	12.0
Aspergillus fumigatus	9.7	6.5	1.2	1.8	7.5	8.4
Aspergillus Niger	31.2	18.2	37.1	53.4	18.7	25.3
Aspergillus tamarii	7.5	44.2	4.2	4.6	45.8	36.9
Aspergillus terreus	1.2	0.9	0.2	3.0	1.2	0.7
Aspergillus versicolor	0.0	0.0	0.0	0.0	0.7	1.7
Aspergillus wentii	0.0	0.0	0.0	0.0	1.3	0.0
Colletotrichum sp.	13.0	11.5	24.3	15.4	2.5	0.0
Fusarium oxysporum	0.0	0.0	0.0	0.0	15.8	8.6
Fusarium sp.	0.0	0.0	0.8	0.0	0.0	0.0
Fusarium sporotrichioides	0.0	12.4	0.0	0.0	0.3	0.5
Fusoma rubricosa	0.0	0.0	0.0	0.0	0.0	1.2
Geothricum sp.	0.0	0.0	1.1	0.0	0.0	0.0
Gliocladium sp.	0.0	0.0	0.3	0.0	0.0	0.0
Mucor plumbeus	0.0	0.0	3.3	1.1	0.2	0.0
Mucor racemosus	0.2	0.0	2.8	1.4	0.0	0.0
Neurospora crassa	1.4	0.4	1.7	1.0	0.8	0.3
Penicillium citrinum	0.0	0.4	0.0	0.0	0.0	0.0
Penicillium expansum	25.8	25.8	3.8	4.6	17.2	7.3
Penicillium hirsutum	0.0	0.0	0.0	0.2	0.0	0.0
Penicillium viridicatum	0.1	0.0	0.6	0.0	0.0	0.0
Rhizoctonia solani	17.7	13.8	0.0	0.0	18.3	5.1
Rhizoctonia sp.	37.2	35.7	22.9	26.0	0.0	0.0
Rhizopus oryzae	4.0	0.0	0.0	1.0	0.0	0.0
Rhizopus sp.	0.0	0.0	61.8	56.2	0.0	0.0
Rhizopus stolonifer	2.8	0.7	0.0	26.4	47.5	65.8
Syncephalastrum racemosum	0.0	0.0	0.0	0.0	1.3	1.2
Trichoderma harzianum	2.0	2.2	0.0	1.8	0.6	3.7
Trichoderma sp.	0.0	0.0	0.1	0.2	0.0	0.0
Average mould count per region	9.6	10.7	8.7	10.7	10.9	9.6

Values are average count of different moulds isolated from 900 kola nuts (100 each of red, white and pink kola nuts from 3 locations per region).