Bacterial sporeformers, such as Clostridium botulinum and Bacillus cereus and their toxins, do not get industry’s attention like Listeria monocytogenes and E. coli O157:H7, but that doesn’t mean these microbial contaminants aren’t on the radar screen for food manufacturers. This may be related to the fact that since the implementation of the low acid canned food regulations, there has been a precipitous decline in the number of incidents of reported botulism outbreaks in the U.S. But, as food companies strive both to develop products with extended shelf life and meet regulatory mandates for improved food safety and defense, these spoilage and potential public health contaminants must be addressed anew.
The National Center for Food Safety and Technology (NCFST), a unique food safety and engineering research consortium composed of scientists from academia, industry and the U.S. Food and Drug Administration (FDA) located at the Illinois Institute of Technology’s Moffet Campus, has been investigating microbial behavior of sporeforming organisms in order to foster scientific and technical exchange to better understand the science and research needs. NCFST experts note that while little spore research has been conducted since the 1970s, due to the advent of new food preservation (sterilization) technologies, there is a need to look at more closely the testing methods for determining resistance, the mechanisms of spore inactivation, and methods of production control. By studying resistance of spore populations to various food preservation technologies, particularly novel technologies, the food industry will have a better opportunity to create ambient shelf-stable, low-acid food products that consumers want, as well to implement new technologies to attain production efficiencies and food safety goals.
This Food Safety Magazine (FSM) panel, comprised of NCFST experts and members, discusses the importance of supporting new research in this field and why it is vital in helping government and industry achieve food safety objectives (FSOs).
FSM: Why at this juncture has NCFST undertaken such a big initiative relative to spore-forming bacteria?
Martin Cole: Twenty years ago, I was most fortunate to have Grahame Gould as my first boss in industry. Grahame and his co-worker Jerry Dring were famous for their pioneering work on spores. In those days, there was still a buzz around spore research and there were many labs around the word carrying out excellent research in the area. In hindsight, this was probably the beginning of the end for large-scale spore research. Cutbacks in basic research in companies and food safety attention turning to Listeria, Salmonella and pathogenic E. coli, not to mention other worthy candidates, led to a steady decline in spore research.
Today, with a few exceptions (notably, Peter Setlow in the U.S. and Mike Peck in the U.K.), there is very little spore research being carried out in the food area. Perhaps one might think that we know all we need to know about spores; certainly the excellent safety record of the canning industry might suggest this. So, why would we think of embarking on a research program on spores now? Well, to paraphrase Hoffer, in times of change the learned find themselves beautifully equipped to deal with a world that no longer exists. The truth is that during the past 20 years the demands on the food business have indeed changed—and changed in ways that now put the need to control spores at the forefront of things again. I can see three major trends driving a renewed interest in spores: consumer desire for products that are both fresh-like and convenient, an increase in international trade in food, and new developments in risk management.
The desire for freshness and convenience has led to the development of minimal processes where spores are the limiting factor. The increase in international food trade is being led by processed foods, which are growing twice as fast as commodities and set to double by 2050. International trade tends to need longer product shelf life and again raises the issue on controlling spores. Finally, although the rules of canning are based largely on data that was derived 90 years ago, new developments in risk management offer the promise of improving our understanding on the basis for currently used sterilization processes. These traditional processes have served us extremely well but may be in danger of slowing innovation in this area. Any innovation in an area involving hazards such as Clostridium botulinum will need to be carried out in a prudent and safe manner by those who have a mechanistic understanding of spore inactivation.
Dan Brown: I agree. Consumers are looking for fresher, natural and refrigerated products with extended shelf life, and today, technologies exist to produce these types of products. We need to ensure the application of these technologies will produce safe products. The Center is unique, enabling both industry and government to work together to arrive at a successful application of technology that meets the objectives of both groups.
Cindy Stewart: Since its inception 19 years ago, the NCFST has actively conducted research and provided expertise in the field of bacterial sporeformers, with particular emphasis on C. botulinum and its toxin. Traditionally, this effort was focused on supporting LACF regulations via the NCFST/FDA scientists and engineers. More recently, the Center has expanded its spore expertise to include pathogenic and spoilage Bacillus spp., to support both its initiatives in the novel preservation technologies, aseptic processing and food defense programs.
As Martin and Dan stated, the food industry’s focus on meeting consumer’s demands for convenient, “minimally processed,” more natural, high quality foods has driven the need for innovation in food processing and preservation systems. The need to be competitive and profitable in the global marketplace has driven industry to explore ways to extend the shelf life of food products, while retaining quality, so that the products can be delivered to markets at greater and greater distances from manufacturing sites.
Additionally, the recent needs to address food defense issues, has had industry and government assessing the vulnerability of the entire food chain, and consideration of handling foods intentionally contaminated with nontraditional agents, including bacterial spores and toxins, has been included in the risk assessments and research to address gaps in our current body of knowledge.
John Larkin: Much of our current operational standards/controls for extended shelf-life and shelf-stable foods that the food industry operates under, with regards to an agreed target level of safety, has come from experimental validation of the adequacy of a given process. Most of the time these experimental evaluations cannot be translated to new and/or modified processes. As an example, peroxide is used to sterilize package material, and there are agreed set treatment levels for its use that are linked to the target level of safety. If a processor were to incorporate high pressure with peroxide as an improvement to package sterilization, it would be potentially unreasonable to assume that the same treatment dose should apply, because both the mechanism(s) and kinetics of destruction would not be the same as for peroxide alone. This results in a different type of link between the target level of safety and the treatment validated by way of a surrogate to the organism of concern. The anticipation is that as we understand the mechanisms by which spores are destroyed, our ability to appropriately develop links between the required treatment dose and the one that is measured by way of validation will be made less costly and less experimentally intensive.
Larry Keener: From my perspective, NCFST, owing to its unique relationships with industry, academia and government, is in a unique position to provide global leadership in validating novel preservation technologies, given that much of this validation effort will rely on bacterial spores. NCFST’s member base is composed of scientist from the food industry’s leading companies. It is precisely these companies that are likely to see the benefits in taking new products derived from new preservation methods to market. Clearly, it is of great value to industry to have NCFST at the forefront of this activity.
FSM: We’ve using canning as a primary food preservation method for 90 years. What are the advances in preservation technology that look promising for producing high quality, safe food?
Larkin: Yes, we have been canning for well over 90 years, but the canning industry has been very progressive in the implementation of new and novel technologies. As long as the mechanism of destruction did not change, the experimental validation of the adequacy of the process was primarily relegated to the collection of process delivery parameters. For example, if a new processing system was developed to treat a new packaging application (i.e., foil-laminated pouch) the experimental validation conducted on the new process focused on the ability of the process to deliver and control the heating rate of the package. It was assumed that the mechanism of destruction of the microbial hazards within the package was similar to other thermally processed food and did not require new agreed target levels of safety (i.e., target sterilization value), but only a measurement of the differing death kinetics of the process were needed.
As I look at “soon to be implemented” technologies that might change our current ability to describe the destruction rate of both the surrogate and the pathogen of concern for canned foods, the three major areas that I see are high pressure, formulated chemical sterilants, and combination treatments involving multiple destruction mechanisms. The apparent targets these new technologies are directed at are either improvement in fresh like quality or improved package/convenience for the consumer.