Project aims to extend chilled shelf-life beyond 10 days
Chilled food manufacturers and their retail customers could receive a significant boost if a new £750,000 project designed to extend the shelf-life of products beyond the current 10 day norm proves successful.
Currently, if products are intended to be kept for longer than 10 days, the temperature and time of thermal treatment have to be raised significantly, which has major energy and food quality disadvantages. The new research aims to extend live to up to four weeks without affecting its quality.
Sussle - sustainable shelf-life extension - is a three-year Department of Environment, Food and Rural Affairs (DEFRA) Link project (jointly 50: 50 funded by industry and government), which kicked off last December. It is the brainchild of the Chilled Food Association (CFA), which wants to see more science injected into shelf-life controls.
Initially the study, being co-ordinated by professor Mike Peck of the Norwich-based Institute of Food Research and involving blue chip firm Unilever as well as the Faraday Knowledge Transfer Network, will involve literature studies and the collation of data on cold-growing (psychrotrophic) non-preteolytic Clostridium botulinum spores from 229 different raw materials (three samples for each) supplied by CFA member firms.
"All these different foodstuffs that we make finished product out of are going to be analysed to see how many spores there are and we can then determine how much heat you need to put into these raw materials to be sure that you are knocking out the spores," says CFA secretary general Kaarin Goodburn. "At the moment it is just a process that is recommended, which assumes there are 1M spores per gram, which you never see. That means you are going to be vastly overheating food if you want a longer shelf-life."
The project aims to discover how many spores are really there so that it is possible to work out how much heat is needed to ensure food safety. "The whole thing is about extending the shelf-life without excess heat or nobbling the quality of the product," says Goodburn. "We want to use the minimum of heat process so that the quality is maintained."
The heat treatment required to kill off spores is related to the number of spores thought to be present. But currently these figures are "plucked out of the air", argues Goodburn. "The reduction should be related to the number there are in raw material."
The research aims to identify the reductions of non-proteolyic Clostridium botulinum necessary using spore probability distributions based on published and experimental data. It will establish example shelf-lives of current chilled foods that are given low intensity heat treatment and then determine the medium intensity heat treatments required to justify shelf lives of two, three and four weeks under defined storage conditions.
The models generated might even prove useful for use by other food manufacturing sectors such as canning, says Goodburn. "So if we can do this right and the science is reputable and solid, it is entirely possible that the principle of looking at this risk-based approach could be transferred across to, say, the canning sector."
