Food testing – how and what to test

As food business owners and managers, you may be asked to carry out food or shelf-life testing for your products, with little guidance from the person who is asking for this.  It is a technically complex subject and it is not always easy to know where to start. Who do you speak to? How do you decide what to test for?  Which laboratory will you use? It can also be expensive, so familiarizing yourself with the basics will prevent wasted money.

The key to effective food testing is to understand why you are being asked to carry out the testing, as this will influence the test type that you select. Is it for routine testing? Is it to justify extending a shelf-life? Is it to validate that your current shelf-life is acceptable? Or something else entirely? Ask for as much detail as possible.

There are different types of food tests available. These include:

• microbiological tests for bacteria and viruses  – often used for shelf-life tests or to check whether food preparation areas are clear of harmful bacteria.

• physical tests for moisture, pH (acidity), and water activity – useful when there is a characteristic of the food that stops microbes from growing. For example, some charcuterie items are acidic and have a low pH, which prevents bacteria from growing.  Dried meat products have low moisture levels or available water which can prevent bacteria from growing.

• chemical tests for salt percentage, pesticides, and acrylamide. For example knowing the salt percentage can help determine if this level can control microbial growth in products like ham.

• water potability tests – establish if a source of water is safe to drink, or use as an ingredient. This testing is important if you are not on mains water, or your cold water is supplied via a holding tank.

• nutrition testing  – may be requested to provide information for packaging.  Laboratory testing is not needed where established nutritional data exists. There are several websites that you can input your ingredients into, and they will provide the information needed.

• allergen testing for ‘free-from’ claims – can be used to validate any claims that you are making. For example, gluten-free claims require a business to be able to prove that there is no more than 20 ppm in a product.

As these tests may be used to prove compliance with legal requirements, or to validate shelf-life or a HACCP plan, it is important to use a suitable laboratory. When choosing, make sure that the laboratory as well as the test method is UKAS-accredited. UKAS (United Kingdom Accreditation Service) ensures that tests are carried out properly, and that the test results can be relied upon. 

You should check if the laboratory will interpret the test results for you. Several do not offer this service, so you could be left with test certificates but with no idea of what they mean or what to do next.  This service may come at an additional cost, so check if it is included when comparing laboratory prices.

Consider how you will collect the food samples, or swab food contact surfaces if it is environmental sampling. It is essential that this process or the containers that you use do not introduce contamination which could skew the results. Wash your hands thoroughly, and use sterile utensils and storage containers.

Perishable foods should be kept at refrigerated temperatures after sampling and throughout the journey to the laboratory. You could deliver them yourself or arrange a refrigerated courier.

Please contact National Craft Butchers head office on 01892 541412 if you have any questions on this advice.