Gail Betts from Campden BRI’s microbiology department, told FoodManufacture.co.uk: “Many smaller companies are not really aware of the implications of reducing salt in particular on the shelf-life of their products, and several of them are referred to us by the enforcement authorities for this reason.”
While the safety of each reformulated food should be evaluated on a case-by-case basis, said Betts, manufacturers could reduce costs by using predictive microbiology in the early stages of a reformulation programme.
“Modelling will not replace product testing, but it can help you speed things up so that you already know roughly what you’re looking for.”
Reducing salt by less than a third in a mayonnaise or pickle might halve its shelf-life, she said. And for products such as bacon and ham, reducing salt without making other changes to compensate might mean manufacturers needed to reduce the shelf-life from eight days to just three, she said.
“But it’s not just salt. A relatively small reduction in fat in cheese could lead to a big difference in water activity that could significantly affect mould growth.
"At 21.7% fat, water activity in a cheese might be 0.81%, whereas at 16.8% fat, you’ve got 0.94% water activity, which is risky in terms of the growth of things like Staphylococcus aureus.”
The Advisory Committee on the Microbiological Safety of Food (ACMSF) has also tried to raise awareness of this issue by urging the Food Standards Agency (FSA) to work more closely with manufacturers to ensure that reformulation programmes are accompanied by rigorous shelf-life testing.
Although the FSA and the British Meat Processors’ Association had produced a guidance document for small and medium sized businesses on the microbiological risks associated with salt reduction, many firms were still not very clued up in this area, claimed Betts. “Many of them are not really aware of the risks that they are taking.”
FSA salt targets
Industry responses to the FSA consultation on salt targets for 2012 reflect significant anxiety over the growth of spoilage organisms in meat in particular, while manufacturers are also concerned about listeria in fat spreads with very low salt levels.
Modelling techniques enabling firms to predict how a reduced salt product would behave over its shelf-life after factoring in a range of variables (storage temperatures, pH, water activity, preservatives, temperature) were increasingly being used to predict the impact of reformulation on shelf-life and food safety, said Betts.
Predictive microbiology uses mathematics to predict the response of micro-organisms to a given environment.