title: The effects of fermentation and/or vacuum flask storage on the presence of coliforms in complementary foods prepared for Ghanaian children.
abstract: Microbial contamination of complementary foods is a major cause of childhood diarrhoea. In a community-based study in Ghana, we evaluated whether fermentation of maize porridge or storage of porridge in vacuum flasks reduces coliform contamination. The complementary food examined, Weanimix, consisted of, on a dry weight basis, toasted maize (75%), peanuts (10%), and soybeans (15%) milled into flour. The fermented food was Weanimix made with drum-dried, previously fermented maize. Fifty women with infants 6-18 months of age participated. A repeated measures cross-over design was used. Each mother participated in all four treatments (1 week per treatment, in random order): (a) non-fermented Weanimix (W), (b) fermented Weanimix (F), (c) non-fermented Weanimix stored in a vacuum flask (WV), and (d) fermented Weanimix stored in a vacuum flask (FV). Each week, mothers were supplied with the appropriate food, and asked to prepare a porridge each morning by boiling the dry mix in water. Samples were collected in the evenings and immediately plated onto 3 M Petrifilm. Contamination was defined as > or = 100 colony-forming units of coliforms per ml. Contamination rates (95% confidence intervals) were W = 48% (38-58%), F = 25% (17-34%), WV = 42% (32-52%), and FV = 13% (6-20%). All pairwise comparisons were significant (P < 0.05) except for W vs WV. Within the WV treatment, contamination rates were 85% when the sample temperature fell below 50 degrees C (N = 41) vs 12% when it remained > 50 degrees C (N = 59) (P < 0.001). These results indicate that contamination is reduced by fermentation, and further reduced by vacuum flask storage of fermented foods. For non-fermented foods, vacuum flask-storage was protective only when the temperature was maintained at > 50 degrees C; at < or = 50 degrees C vacuum flask storage increased the risk of contamination.
authors.affiliation: Department of Nutrition, University of California, Davis 95616-8669, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Kimmons
authors.forename: K H
authors.initials: KH
authors.lastname: Brown
authors.forename: A
authors.initials: A
authors.lastname: Lartey
authors.forename: E
authors.initials: E
authors.lastname: Collison
authors.forename: P P
authors.initials: PP
authors.lastname: Mensah
authors.forename: K G
authors.initials: KG
authors.lastname: Dewey
mesh_terms: D018592:Cross-Over Studies; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D005285:Fermentation; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D005519:Food Preservation; D005869:Ghana; D006801:Humans; D007223:Infant; D007225:Infant Food / Q000382:microbiology*