8 March 2002

Silage inoculants boost food safety

By Simon Wragg

SILAGE inoculants could improve food safety by reducing the multiplication of listeria bacteria in conserved forages.

Studies of French forage samples show up to 40% of silage silos, 30% of big bale silage and 10% of hay samples contained listeria bacteria, says Lallemand scientific director Henri Durand. "The study was conducted in France, but it is probably as relevant in other countries."

Statistics suggest listeriosis causes 400 human deaths/year in the US, 50 in France and 10 in the UK. "In the US, the problem is probably due to poor storage of prepared meals and in France the consumption of raw milk," suggests Dr Durand.

"Good management when harvesting and ensiling grass lowers the risk. Where silage is under pH4, the presence of listeria bacteria is reduced six-fold. Inoculants can help achieve the right, stable conditions where growth of the original listeria cells is restricted, but not destroyed."

An anti-listeria project, funded by the French Ministry of Agriculture, veterinary, breeding and dairy company sources, is investigating treating forages with inoculants to prevent raw milk contamination by listeria monocytogenes.

"Use of Pediococcus acidilactici in lab tests has shown that listeria cannot survive around its colonies," says Dr Durand.

Lallemand hopes to complete small-scale trials using the bacteria strain this year, field trials in 2003 and launch a commercial inoculant able to suppress listeria in 2004. &#42