Detecting Bacteria in the Food Chain – An ISO Approach

ISO Microbiology of the Food Chain

Standards Assure Safety in What You Eat

With nearly 800 million people worldwide lacking the food needed to live healthy lives and one-third of all viable food going to waste, the planet’s food system is far from adequate. In fact, if you look at the food chain that supports the billions who do have access to food, persistent threats loom with the potential to jeopardize the entire system. Pair these with the rapidly growing globalized population, and bacteria, when emerging at practically any step of the food chain, could raise the hungry count into the billions.

ISO standards have long tackled complex, wide-reaching subjects, in which they have laid the groundwork for success, security, safety, and quality for processes that span numerous industries. The international documents on the microbiology of the food chain outline processes and core guidelines that can assure greater stability throughout the spectrum of processes guiding food from its source to your mouth.

Most eminently, there’s ISO 22000:2018, which helps users confront the many problems present with the food chain by specifying the general guidelines for a food management safety system (FSMS). While this is the most-relied upon international document dedicated to processes within the food chain, there are many standards that can be utilized for detecting bacteria.

Microbiology of the Food Chain – Enumeration by Food Product

The ISO 6887 series provides methods for the microbiological examination of numerous foodstuffs. ISO 6887-1:2017 – Microbiology of the food chain – Preparation of test samples, initial suspension and decimal dilutions for microbiological examination – Part 1: General rules for the preparation of the initial suspension and decimal dilutions defines rules for the aerobic preparation of the initial suspension and of dilutions for microbiological examinations of foods for consumption. These methods are based on the principle that preparation of the initial suspension should obtain as uniform a distribution as possible of the microorganisms contained in the test portion.

However, it is noted in the ISO 6887-1:2017 standard that specific rules that go beyond or against its specifications might be needed in certain instances. Additional standards serve to provide these microbiological examination rules. For example, ISO 6887-2:2017 – Microbiology of the food chain – Preparation of test samples, initial suspension and decimal dilutions for microbiological examination – Part 2: Specific rules for the preparation of meat and meat products details rules specific to the preparation of meat.

ISO 6887-1:2017 Microbiology of Food Chain Meat

It is unsurprising that meat product samples necessitate their own rules, considering that food harvested from animal products can be prone to disease. In fact, a recent study estimated that almost half the meat and poultry sold at US grocery markets and supermarkets contain a type of bacteria potentially harmful to humans. ISO 6887-2:2017 is applicable to numerous type of fresh, raw, and processed meats, poultry, game, and their products, and it covers the rules for their suspension for microbiological examination.

Alternatively, ISO 6887-3:2017: Microbiology of the food chain – Preparation of test samples, initial suspension and decimal dilutions for microbiological examination – Part 3: Specific rules for the preparation of fish and fishery products covers rules specific to raw fishery products, mollusks, tunicates, and echinoderms, as well as frozen fishery products and processed products (such as smoked fish). ISO 6887-4:2017 – Microbiology of the food chain – Preparation of test samples, initial suspension and decimal dilutions for microbiological examination – Part 4: Specific rules for the preparation of miscellaneous products specifies rules for specific food products not covered in other parts of the standard series. It is applicable to acidic products, hard and dry products, animal feed, cereal byproducts, gelatin, fresh fruit and vegetables, alcoholic and non-alcoholic beverages, eggs, and margarines, among others.

These four documents are available as the ISO 6887 – Microbiology of the Food Chain Package.

Please note, however, that ISO 6887 has two other parts.

Microbiology of the Food Chain – Detecting Salmonella

Organizing the methods for detecting bacteria by product is certainly useful in assuring the safety of those food products, but several other ISO standards are dedicated to detecting and enumerating specific known pathogens. ISO 6579-1:2017 – Microbiology of the food chain – Horizontal method for the detection, enumeration and serotyping of Salmonella – Part 1: Detection of Salmonella spp. specifies a horizontal method for detecting Salmonella serovars.

Salmonella ISO Microbiology Detection Enumeration Food
Salmonella Bacteria

The bacteria Salmonella makes people sick, and its common symptoms include diarrhea, fever, abdominal cramps, with these issues sometimes becoming so severe that the patient needs to be hospitalized. In some cases, Salmonella can cause death. Salmonella is known to pop up in the news every once in a while, with its sources in foodstuffs varying from kosher chicken and deli meat to breakfast cereal.

Microbiology of the Food Chain – Detecting Coliforms

A group of bacteria that receives far less media attention are coliforms. Coliforms are not a single species of organism but a group of bacteria, and they naturally live in the environment (e.g. soil, vegetation, and water) and in the gut of animals. While they generally are harmless, their presence can indicate a fecal contamination (E. coli is a coliform). However, this is an extreme correlation of their presence. Instead, the coliform concentration reflects the general hygienic conditions during food production or handling.

Therefore, it is often necessary to enumerate the population of coliforms in food products. ISO standards offer two methods for this. The first, as covered by ISO 4831:2006 – Microbiology of food and animal feeding stuffs – Horizontal method for the detection and enumeration of coliforms – Most probable number technique, carries out enumeration by calculating the most probable number (MPN) after incubation in a liquid medium at 30°C or 37°C. This technique allows for microbiological examination on a larger test portion, ultimately detecting a lower number of coliforms per gram or per millimeter of product.

ISO Vegetables Microbiology of the Food Chain

The alternative method, as detailed in ISO 4832:2006 – Microbiology of food and animal feeding stuffs – Horizontal method for the enumeration of coliforms – Colony-count technique, counts colonies after incubation on a solid medium at 30°C or 37°C. It is more precise than the most probable number technique, but it does not allow for microbiological examination on a large test portion.

ISO/TC 34/SC 9 – Microbiology

The CDC estimates that food is the source of about 1 million illnesses, 19,000 hospitalizations, and 380 deaths in the US. Consumers alone cannot be responsible for the safe handling of the food products they ingest. The many ISO standards dedicated to the microbiology of the food chain and food and animal feeding stuffs lay the shared groundwork for food producing organizations to assure safety in the food that ends up on the public’s plates.

However, the standards detailed in this article are only a mere taste of the total ISO standards dedicated to the food chain. In fact, the Subcommittee responsible for developing standards on microbiology, ISO/TC 34/SC 9, has published 78 documents. You can find these standards by browsing the ANSI Webstore.

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