Abstract:
Milk and dairy products form essential constituents in daily meals of the residents of
Bomet and other parts of Kenya. Dairy products are highly nutritious and may be
susceptible to contamination by bacteria, molds and/or mycotoxins, and in particular
aflatoxin B1 which is the most toxic. Aflatoxin M1 (AFM1) is a hepatic carcinogenic
metabolite of aflatoxin B1 (AFB1) found in the milk or milk products obtained from
livestock that have ingested feeds contaminated with AFB1. The aim of this study was to
determine the mycological quality and aflatoxin M1 contamination of milk and its
products from Bomet County, Kenya. A total of two hundred and twenty seven; (one
hundred and ninety two raw and thirty five processed milk samples) were purchased
from shops, milk vendors, kiosks and milk collection centers respectively. Isolation was
done on Sabouraud Dextrose Agar (SDA) and identification was done using macro and
micromorphological features and confirmed using Analytical profile index (API 20 C
aux). Determination of aflatoxin M1 contamination was by direct competitive ELISA
technique. Three hundred and sixty five fungal isolates of which 27(7.4%) were molds
and 338(92.6%) yeasts were isolated from all the raw milk samples examined. Processed
milk and its products showed no contamination with yeasts and molds. The isolated
fungi belonged to the genera Aspergillus 3% (11/27), Geotrichum 4.1% (15/27) and
Fusarium 0.3% (1/27), Candida 57.8% (211/365), Saccharomyces 6.6% (24/365),
Cryptococcus 1.1% (4/365) and Rhodotorula 27.1% (99/365). Analysis of the data
indicated that the overall occurrence of aflatoxin M1 contamination above the threshold
limit of 0.05 ppb by Food and Agriculture Organization (FAO) and World Health
Organization (WHO) limits was 43.8% (81/185). This was contributed mainly by the
raw milk samples which had 52% (78/150) AFM1 contamination compared to processed
milk with 8.6% (3/35). The difference was statistically significant, p<0.0001. The
overall median was 0.02 (IQR: 0.00, 0.40) g / lwhich is below the threshold limits of
0.05 ppb by FAO/WHO. The levels of AFM1 in milk samples indicate that the feeds
given to dairy cows in the study area could be contaminated with aflatoxin B1 which is
the precursor of aflatoxin M1. This poses a potential risk of chronic exposure to the
residents and therefore there is need for regular monitoring of contamination in milk and control most contaminating causes with special focus on occurrence of AFB1 in the feed of dairy cows. There is also need for awareness creation on aflatoxins in the to sensitize people on health hazards associated with aflatoxin M1 contamination as there may be chronic mycotoxin exposure.
