By Allie Gallant
Yeast helps ferment bread, bacterial cultures help create yogurt and mould in cheeses can provide a unique flavour. These foods all share a reliance on various microorganisms, either in the process or in the final product, for their distinctive flavours. In fact, there are a number of specific types of microorganisms that can affect product quality and/or safety.
Pathogenic bacteria are microorganisms capable of causing disease in humans. Outbreaks are often associated with contamination issues along the farm-to-fork continuum, by bacteria such as Listeria monocytogenes, E. coli O157:H7, or Salmonella. Pathogenic bacteria are acute food safety risks. These bacteria can make people sick and can cause death.
In laboratories, scientists perform a challenge study to determine whether or not a product will support the growth of a given pathogen of concern. Generally, a finished product is inoculated with a number of strategically chosen strains of pathogenic bacteria, to demonstrate a sort of ‘worst case scenario’ situation. The selection is often based upon a historical record of contamination with similar products. Enumeration (counting viable bacterial colonies) is performed at intervals, the number and length of which vary depending on the design of the study. The data is then analysed, and a report given on how the product coped with the food safety breach. Did the pathogens thrive? Were their numbers reduced? Or were they wiped out before reaching critical levels?
Challenge studies are not always necessary. For instance, if measured pH and/or water activity are outside of the ranges friendly to Salmonella, there would be no reason to conduct a challenge study on that particular product, for that particular pathogen — because the product environment precludes its growth.
Spoilage organisms are common in products nearing the end of their shelf life, and include a wide range of organisms, such as yeast and mould. These organisms rely upon friendly, nutrient-rich environments to survive, but have relatively flexible requirements, contributing to their prevalence in many types of foods.
In addition to causing unpleasant side effects in the form of spoilage, certain organisms may also produce toxins and be harmful if consumed, depending on their specific toxicity. Further, they are sometimes correlated with contamination issues, and the presence of pathogenic bacteria.
Shelf life studies examine organoleptic (taste, smell, texture, appearance) indicators, as well as growth of bacteria, as it naturally occurs over the course of a product’s shelf life.
How long does it take before a product is no longer of an acceptable quality or safety? Does your product require refrigeration? If it were to be subjected to temperature abuse along the supply chain, how does that affect its shelf life? Does the addition of an additive extend the marketable shelf life in a substantial way? Shelf life studies can answer these questions, and many others. They allow you to test shelf life-extending strategies, build safety margins into ‘best before’ dates with accuracy, and give your consumers the best possible advice on how to handle and store your product.
Both types of studies are useful for assessing control measures. For instance, examining how well a new formulation stands up against Listeriacontamination, or how well a new packaging technology extends the quality shelf life of the final product.
Challenge studies and shelf life studies evaluate your product in terms of safety and quality. Also, these studies assess the success of new strategies being employed to help you achieve a safe, marketable product.
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