Mycotoxin and metallic element concentrations in peanut products sold in Ugandan markets

Figures & data

Figure 1. Map of Kampala showing markets where peanut samples were purchased.

Note: Reproduced with permission from Kampala Capital City Authority.

Table 1. Categories of the collected peanut samples by market

Sampling site	Number of samples
A: State prior to processing	Unroasted	Roasted	Unknown	Total
Bukoto market	2	1	1	4
Nakawa market	4	1	4	9
Kalerwe market	5	3	2	10
Owino market	2	3	5	10
Home processed samples	3	2	0	5
Total	16	10	12	38
B: Duration of the grinding	<10 min	10–30 min	>30 min	Unknown	Total
Bukoto market	0	1	2	1	4
Nakawa market	3	1	4	1	9
Kalerwe market	3	1	4	2	10
Owino market	4	0	2	4	10
Total	10	3	12	8	33*

^* Total does not include the five samples traditionally-processed in the homes.

Table 2. Percent of samples in which aflatoxins were present

Percent of samples
Concentration of aflatoxin	AF-B1	AF-B2	AF-G1	AF-G2	Total aflatoxin
>0 ppb	63%	45%	61%	68%	82%
≥12 ppb (EU limit)	47%	29%	47%	32%	66%
≥20 ppb (US FDA limit)	34%	16%	32%	8%	55%
ppb
Concentration range	0–540	0–141	0–213	0–36	0–849

Table 3. Mean aflatoxin concentrations in market and home processed samples

Aflatoxin	Mean concentration (ppb) ± SEM		p value
	Market (n = 33)	Home (n = 5)
Aflatoxin B1	103.1 ± 36.6	0.0 ± 0.00	0.0121*
Aflatoxin B2	25.1 ± 8.7	0.0 ± 0.00	0.0539
Aflatoxin G1	41 ± 12.5	0.0 ± 0.00	0.0153*
Aflatoxin G2	11.4 ± 2.39	0.0 ± 0.00	0.0071*
Total aflatoxin	180.7 ± 51	0.0 ± 0.00	0.0019*

* Significantly different at p < 0.05; Wilcoxon Rank Sum test.

Table 4. Effect of roasting on mean aflatoxin concentrations

Aflatoxin	Mean concentration (ppb) ± SEM		p value
	Roasted (n = 10)	Non-roasted (n = 16)
Aflatoxin B1	141.9 ± 72.34	46.7 ± 18.14	0.5768
Aflatoxin B2	34.5 ± 16.72	11.4 ± 4.96	0.3679
Aflatoxin G1	32.4 ± 16.58	33.6 ± 14.09	1.0000
Aflatoxin G2	7.8 ± 3.01	10.1 ± 2.95	0.6690
Total aflatoxin	216.6 ± 99.05	101.8 ± 32.93	0.5132

Table 5. Effect of duration of grinding on mean aflatoxin concentrations

Aflatoxin	Mean concentration (ppb) ± SEM		p value
	<10 min (n = 12)	>30 min (n = 10)
Aflatoxin B1	3.9 ± 2.238	36 ± 17.84	0.0783
Aflatoxin B2	1.5 ± 1.204	9 ± 5.17	0.1225
Aflatoxin G1	9 ± 5.675	22 ± 10.24	0.2136
Aflatoxin G2	5.4 ± 1.778	9.5 ± 2.759	0.2289
Total aflatoxin	19.8 ± 7.864	76.5 ± 29.35	0.1004

Table 6. Mean aflatoxin concentrations in peanuts from different markets

Aflatoxin	Mean concentration (ppb) ± SEM				p value
	Kalerwe (n = 10)	Bukoto (n = 4)	Nakawa (n = 9)	Owino (n = 10)
Aflatoxin B1	60.3 ± 27.99	40.5 ± 12.82	10.3 ± 3.54	143.1 ± 72.16	0.4865
Aflatoxin B2	19.2 ± 7.12	4.5 ± 1.94	1.3 ± 0.88	32.7 ± 17.04	0.1182
Aflatoxin G1	40.5 ± 22.63	48.8 ± 12.39	23.7 ± 12.22	26.4 ± 13.14	0.2320
Aflatoxin G2	15.6 ± 3.89	8.3 ± 1.44	5.3 ± 1.92	6.3 ± 2.88	0.0679
Total aflatoxin	135.6 ± 49.39	102 ± 26.35	40.7 ± 17.26	208.5 ± 99.5	0.5307

Note: Analyzed using Kruskal-Wallis test.

Table 7. Mean metallic element concentrations in market and home processed samples

Element	Mean concentration (ppb) ± SEM		p value
	Market (n = 33)	Home (n = 5)
Chromium	0.3 ± 0.01	0.5 ± 0.02	0.0009*
Zinc	17.1 ± 0.67	21.2 ± 0.62	0.0253*
Boron	9.5 ± 0.23	9.0 ± 0.51	0.2343
Nickel	2.8 ± 0.22	3.9 ± 0.32	0.0374*
Barium	5.3 ± 0.25	3.4 ± 0.12	0.0051*
Magnesium	1,060 ± 27.46	1,222 ± 42.62	0.0340*
Mercury	0.05 ± 0.01	0.02 ± 0.00	0.1108
Copper	5.0 ± 0.17	6.1 ± 0.21	0.0151*
Arsenic	0.5 ± 0.06	0.6 ± 0.20	0.7285

* Significantly different at p < 0.05; Wilcoxon Rank Sum test.

Table 8. Effect of roasting on mean metallic element concentrations in peanuts

Element	Mean concentration (ppb) ± SEM		p value
	Roasted (n = 10)	Non-roasted (n = 16)
Chromium	0.4 ± 0.04	0.3 ± 0.02	0.3427
Zinc	18.1 ± 1.14	16.9 ± 0.82	0.3928
Boron	9.4 ± 0.47	9.5 ± 0.31	0.7348
Nickel	3.3 ± 0.52	2.9 ± 0.28	0.3928
Barium	4.4 ± 0.45	5.1 ± 0.37	0.5849
Magnesium	1,090 ± 54.5	1,070 ± 37.32	0.5849
Mercury	0.06 ± 0.02	0.04 ± 0.01	0.9525
Copper	5.0 ± 0.40	5.05 ± 0.21	0.6960
Arsenic	0.5 ± 0.10	0.4 ± 0.05	0.6159

Table 9. Effect of grinding duration on mean metallic element concentrations in peanuts

Element	Mean concentration (ppb) ± SEM		p value
	<10 min (n = 10)	>30 min (n = 12)
Chromium	0.3 ± 0.02	0.26 ± 0.01	0.1609
Zinc	17.1 ± 1.00	15.6 ± 0.76	0.1710
Boron	9.6 ± 0.27	9.3 ± 0.39	0.6261
Nickel	2.3 ± 0.26	2.5 ± 0.34	1.000
Barium	5.8 ± 0.50	5.5 ± 0.25	0.8197
Magnesium	1,094 ± 45.97	1,012 ± 45.24	0.3184
Mercury	0.04 ± 0.01	0.05 ± 0.01	0.5471
Copper	5.2 ± 0.24	4.7 ± 0.23	0.1710
Arsenic	0.6 ± 0.09	0.4 ± 0.07	0.1156

Table 10. Mean metallic element concentrations in peanuts from different markets

Element	Mean concentration (ppb) ± SEM				p value
	Kalerwe (n = 10)	Bukoto (n = 4)	Nakawa (n = 9)	Owino (n = 10)
Chromium	0.24 ± 0.00	0.24 ± 0.00	0.3 ± 0.02	0.36 ± 0.03	<0.0001*
Zinc	15.3 ± 0.55	15.4 ± 1.46	19.1 ± 1.18	17.7 ± 1.61	0.1991
Boron	9.8 ± 0.33	9.4 ± 1.03	9.4 ± 0.46	9.4 ± 0.41	0.0851
Nickel	2.2 ± 0.36	3.1 ± 0.27	3.1 ± 0.41	3.0 ± 0.51	0.4874
Barium	5.8 ± 0.48	5.0 ± 0.45	4.9 ± 0.29	5.4 ± 0.63	0.5433
Magnesium	1,032 ± 34.31	997 ± 93.71	1,138 ± 59.58	1,041 ± 52.53	0.3879
Mercury	0.1 ± 0.01	0.04 ± 0.007	0.02 ± 0.00	0.02 ± 0.00	<0.0001*
Copper	4.6 ± 0.15	4.5 ± 0.50	5.4 ± 0.38	5.2 ± 0.35	0.2365
Arsenic	0.5 ± 0.04	0.9 ± 0.29	0.9 ± 0.10	0.4 ± 0.09	0.3380

* Significantly different, Kruskal-Wallis test.