Aflatoxin Contents and Exposure in Young Children, and Sensory Characteristics of a Nixtamalized Supplementary Porridge

Abstract

Aflatoxin contamination of maize, is of major concern in Malawi, and levels are much higher than the tolerance limits for aflatoxin B1 and total aflatoxins. Maize is a staple for Malawians and the forms prepared for consumption are presumed to have carryover toxins.  Likuni phala; a porridge flour formulated from maize and soybean in the ratio of 4:1(w/w), was developed as a supplementary food to alleviate Protein Energy Malnutrition (PEM), which is highly prevalent  in under five year old children. It is assumed that the product is contaminated with carryover aflatoxin. Nixtamalization or alkali cooking has been found to reduce aflatoxin contents among other effects. The aim of this study was to establish the levels of total aflatoxin in the Likuni phala, determine their reduction in porridge preparation by addition of alkali, assess the exposure to aflatoxin in small children and also test for its sensory acceptability. Samples were collected from three factories, two cottage and one large, all located in districts of the Southern Region of Malawi. Three samples were collected from each factory at two week intervals. The samples were analysed for total aflatoxin, then cooked into porridge with addition of lime at levels between 0.1% – 0.8%. The porridges were analysed for aflatoxin and subjected to sensory evaluation. Exposure to aflatoxin on the children was also calculated.  Results showed that aflatoxin was absent in the samples from the cottage industries, but all the three samples from the large factory contained levels above the tolerance levels (10µg kg^-1 for total and 5µg kg^-1 for Aflatoxin B1). Cooking with alkali reduced the levels of aflatoxin to below the tolerance levels even at the lowest level of alkali addition. Sensory evaluation showed that the porridges were acceptable only up to 0.4% lime addition. The potential aflatoxin exposure to children was substantially reduced. The study concluded that acceptable Likuni phala porridge with aflatoxin levels below the tolerance levels, and substantially reduced exposure in children can be prepared by cooking with alkali addition.

Keywords: Aflatoxin, Supplemental maize porridge, Nixtamalization, acceptability, Under 5 children