Fumonisin B₁ Reduction in Lactic Acid Bacteria Fermentation of Maize Porridges

Abstract

Fumonisins are natural contaminants of maize and other cereal crops. They are heat-stable and highly toxigenic metabolites produced by Fusarium spp, of which fumonisin B1 is the most toxic to both humans and animals. The toxin has been linked to oesophagus cancer, neural tube defects, and stunting in children. In Tanzania, maize-based porridge is a popular weaning food for infants. Typically, the porridges are homemade and are never tested for mycotoxin levels. Thus, control measures, such as processing methods that may significantly reduce fumonisin B1 levels in foods is therefore warranted. This study investigated how fermentation can promote fumonisin B1 reduction in maize-based porridges. Four starter culture of lactic acid bacteria (Lactobacillus plantarum, Pediococcus pentosaceus, Lactobacillus casei and Lactobacillus fermentum) were used, porridge samples was spiked with fumonisins B1 and allowed to ferment in an incubator set at 30°C for 24 h. Overall, lower pH (below 3.50, achieved by longer fermentation time) favoured greater fumonisin B1 reduction, indicating that pH and time were intricately involved in fumonisins elimination.  Lactic acid (related to sample pH) produced by the Lactic Acid Bacteria (LAB) used in this study, ranged from 3.30 – 3.95 mg/mL, and was also considered a significant factor in fumonisin B1 reduction. Fumonisin B1 reduction by LAB cultures ranged between 14.0 – 30.0%, after 24 hours was more pronounced using in the back-slopping fermentation method (30% reduction) than in the natural fermentation process (20% reduction), indicating fumonisin elimination by LAB could be strain specific. This suggests that, careful selection of LAB strains is therefore critical. Overall, results from this study suggest that back-sloping technique was the most economical, feasible and effective method to detoxify mycotoxins and reduce fumonisins levels in homemade weaning foods such as maize-based fermented porridges.

Keywords: Mycotoxins, Fumonisins, Lactic acid fermentation, food safety, maize porridge, Tanzania.