Because of the known link between heart disease and high salt diets, food manufacturers have come under increasing pressure from health protection agencies to reduce the salt levels in their products. But reducing salt could also be expected to increase the risk of food spoiling, since salt is an ancient and widely used preservative.
Scientists from the University of Limerick in Ireland checked safety levels of low salt foods by studying the behaviour of different strains of food spoilage bacteria inoculated into model systems.
"In general we discovered that the growth of different sorts of typical food spoilage bacteria was unaffected by the various salt levels we tested, which means that low salt foods are just as safe as conventionally processed ones" says Edel Durack.
All the bacteria studied were capable of growing in the highest concentration of salt used by the scientists at 3%. Even at this level of salt none of the bacteria experienced any difficulty in surviving for 24 hours. The researchers did find differences between the salt tolerances of all the bacteria tested, with some strains actually exhibiting greater resistance to the high salt environment.
Scientists already knew that salt has a stimulating effect on some types of bacteria and the Limerick team confirmed this finding with their work, which was independently funded by the Irish Department of Agriculture and Food. Their research implies that some high salt foods may be more at risk of bacterial spoilage than they need to be.
"At the moment our results are helping processors reduce salt levels in frozen ready to eat meals. Generally these meals carry a large percentage of the recommended daily allowance of salt. This type of food is becoming increasingly popular and is in high demand due to its convenience and time restrictions placed on consumers due to modern day lifestyles", says Edel Durack.
"Hopefully our study will lead to the development of a new range of low salt foods that will help people to reduce salt levels in their diet, reducing their risk of cardiovascular diseases linked to excess sodium, without compromising product safety".