Effect of ragi and LXXX-lactate-producing cultures on enteric pathogens in a rice-based weaning food.

The use of the Southeast-Asian starter culture ragi in enhancing the safety of a rice-based model weaning food is described and compared with the use of diastatic malt extract. Ragi was shown to be an effective saccharifying agent convenient for use in weaning-food preparation on a domestic scale. Saccharification and fermentation with ragi alone produced some antimicrobial effect against the three enteric bacterial pathogens tested but this was much improved when ragi was used in conjunction with the LXXX-lactate-producing Lactococcus lactis or Lactobacillus bavaricus. The latter showed the greatest inhibition of pathogens, reducing viable numbers by more than a factor of 10(4) within 4 h. The antibacterial effects observed correlated with the total acid produced (ragi alone giving 0.2%; ragi with Lc. lactis giving 0.3% and ragi with Lb. bavaricus giving 0.4%). The proportion of the physiological LXXX-lactate isomer was highest in Lc. lactis fermentations (>99% compared with 80% with Lb. bavaricus). There was no evidence of any pronounced antimicrobial effect due to the nisin produced during fermentation by Lc. lactis (150 IU/g). Whereas bacteriocin production may play little role in pathogen control, it may be desirable as a way of preventing fermentations conducted non-aseptically from becoming dominated by lactic acid bacteria producing unacceptable amounts of DXXX-lactate.