The Importance of Microbiological and Shelf Life Testing in the Food Industry

Safety and sanitation are key components of modern food production, which is why microbiological testing is crucial. Human health can be at extreme risk when bacterial pathogens or their toxins are present in food. Under the right conditions, microbes can multiply and possibly introduce toxins into products, spoiling the food and causing disease and other dangerous health problems.

Routine microbiological testing helps quickly identify and treat contaminants before they can cause problems. Bacteria such as E. coli, Campylobacter, Listeria, Staph. aureus, Salmonella, Bacillus cereus, and others are commonly tested for, along with yeasts and molds. Food producers and outlets that don't adhere to food safety standards may suffer harsh financial penalties for failing safety inspections. Being proactive rather than reactive is always better when it comes to food safety procedures.

Any product that can support the growth of pathogenic or spoilage microorganisms must be assigned a 'use by' date, after which the product must not be sold or consumed. The manufacturer is responsible for setting this date and must be aware of all factors affecting microbial growth. This is particularly important when developing new products, where knowledge may be limited. Shelf life is defined as the time after production during which the product remains acceptable for consumption. The product must remain safe and retain its sensory, microbiological, and chemical characteristics.

Factors Affecting Shelf Life:

• Raw material quality
• The heat process
• Product formulation, including pH, salt, water activity, and preservative levels
• Distribution and storage
• Packaging, including gaseous atmosphere
• Consumer handling

Stages in Determining Shelf Life:

• Stages under commercial control: This includes manufacture, in-house storage, distribution, and retail display, typically held at 5-7°C.
• Stages outside of commercial control: This includes consumer purchase (typically at 22°C for about 2 hours) and consumer storage (typically at 5-7°C for the rest of the product’s life).

Shelf life tests usually mimic these temperature and time combinations. Ideally, enough identical retail units of a product should be submitted for shelf life testing to cover the desired test period and number of sampling time points, thus avoiding the need to repeatedly open a single unit for sampling.

Challenge tests on a product are most valuable when the organisms used represent those that might realistically be present in the product, either from manufacturing or post-process contamination. Challenge tests do not estimate shelf life, but they indicate whether the proposed shelf life is inherently safe.

Southern Microbiological Services – A Tentamus Company is UKAS accredited to ISO 17025 (lab No. 1922) for analysing foodstuffs for the microorganisms detailed above. Shelf life and challenge tests are available to help food producers meet their product development and safety requirements. In addition to microbiological tests, chemical, physical, and preservative analyses are also available.

The article is written by Steve Wilde, Senior Microbiologist at Southern Microbiological Services – A Tentamus Company.