Occurrence of aflatoxin M1 in raw milk traded in peri-urban Nairobi, and the effect of boiling and fermentation

Figures & data

Figure 1. Aflatoxin knowledge scores for milk traders with varying education levels, Kasarani sub-county, June 2018.

Table 1. The different forms of milk consumed by the household and children between 6 months and 3 years of age.

Form of milk consumed	Percentage for the household	Percentage for children
Raw milk only	2.1	6.7
Boiled milk only	4.1	26.7
Made in tea/porridge only	42.1	13.3
Boiled milk and made in tea/porridge only	35.8	40.0
Boiled milk, fermented milk products, and made in tea	6.3	10

Table 2. Mean levels of AFM1 in milk (ng/kg) sourced from farms, dairy shops, and distributors and for different business types, Kasarani, June 2018.

Source	Mean ± SE	Type of business	Mean ± SE
Farm (25)	627.5 ± 238.19^a	Milk kiosk (37)	269.5 ± 68.00^a
Dairy shop (1)	28.8 ± 0.00^b	Dairy shop (34)	139.9 ± 31.28^a
Distributors (59)	146.7 ± 19.85^ab	Milk ATM (13)	175.3 ± 46.98^a
Farm and distributors (3)	179.6 ± 136.63^ab	Street vendor (4)	246.9 ± 102.35^a
Aggregation centers (1)	127.8 ± 0.00^ab

Values with different superscript letters show significant difference, while same superscript letters show no significant difference at p < 0.05.

Table 3. Mean AFM1 levels (ng/kg) during fermentation and boiling processes.

	Stage of sampling	Mean aflatoxin levels ±SE	Range
Lala fermentation	Raw	307.4 ± 36.29^b	108.87
	Pasteurized	379.3 ± 13.41^c	48.14
	Cooled to 23°C	334.1 ± 2.43^b	21.58
	After incubation	86.7 ± 2.65^a	7.96
	After day 1 at 4°C	89.3 ± 0.89^a	2.67
	After day 2 at 4°C	83.9 ± 0.78^a	2.50
	After day 7 at 4°C	94.2 ± 4.01^a	12.02
Yogurt fermentation	Raw	307.4 ± 36.29^b	108.87
	Pasteurized	379.3 ± 13.41^c	48.14
	Cooled to 43°C	334.0 ± 2.43^b	7.39
	After incubation	90.8 ± 1.17^a	3.51
	After overnight cooling	96.1 ± 2.23^a	3.88
	After day 1 at 4°C	93.9 ± 0.0^a	1.01
	After day 2 at 4°C	79.4 ± 1.36^a	4.13
	After day 7 at 4°C	81.0 ± 1.21^a	3.64
Boiling	Raw	127.8 ± 29.07^a	89.7
	Immediately after boiling	166.5 ± 13.38^d	45.16
	Cooled to 23ºC	134.6 ± 7.17^d	19.08
	Boiled milk after day 1 at 4ºC	141.1 ± 5.57^d	17.69
	Boiled milk after day 2 at 4ºC	147.3 ± 4.13^d	17.37
	Boiled milk after day 7 at 4ºC	70.96 ± 9.18^a	27.54

Values with different superscript letters show significant difference, while same superscript letters show no significant difference at p < 0.05.