Inorganic polyphosphates are generally recognised as safe (GRAS) and are used as food additives in the meat and dairy industry to protect flavour, to maintain the "juiciness" of meat by binding water to it, and to inhibit rancidity and colour deterioration.
Oregon State University researchers claim this is the first time a study has been conducted on the antimicrobial properties of polyphosphates against C. perfringens.
C. perfringens are found in low numbers in many foods, particularly in meat and poultry products. It is also present in soil, the intestines of humans and animals, sewage and animal manures.
Food poisoning linked to C. perfringens is the third most commonly reported foodborne illness in the US. Infection with the bacteria normally causes diarrhoea and severe abdominal pain. While it may occasionally cause nausea, it rarely causes vomiting or fever.
Unlike many other types of bacteria that cause food borne disease, C. perfringens are not completely destroyed by ordinary cooking as it has been found to produce heat-resistant spores.
Although the bacteria are killed at cooking temperatures, the heat-resistant spores they produce are able to survive and may actually be stimulated by the heat to germinate.
The researchers, according to findings published in the journal Food Microbiology, found a significant reduction of survival in C. perfringens was observed when meat samples contaminated with a cocktail of the bacteria's spores were treated with one per cent of the polyphosphate, sodium tripolyphosphate (STPP).
As STPP increases water retention capacity in meat products, the researchers used the polyP to determine its antimicrobial effectiveness against C. perfringens in meat, according to the study.
The researchers said that the sub-lethal concentrations of polyP significantly inhibited sporulation of C. perfringens by reducing heat-resistant cells. While the spores were able to germinate in the presence of one per cent STPP, their outgrowth was significantly inhibited, the study stated.
"The inhibitory effect of polyP on C. perfringens shown in this work constitutes a major contribution that can help the development of safer meat products," claim the researchers.
However, they caution that the use of polyP with other antimicrobial salts such as calcium lactate and calcium sorbate during meat product formulation could decrease the effectiveness of the polyP antimicrobial activity.
Source: Journal of Food Microbiology Vol 25, Issue 6, September 2008 Published online ahead of print doi:10.1016/j.fm.2008.04.006"Inhibitory effects of polyphosphates on Clostridium perfringens growth, sporulation and spore outgrowth"Authors: S. Akhtar, D. Paredes-Sabja, M. R. Sarker