Know thy enemy microbiological hazards in RTE foods - Part 3

By Guest Author on 14 February 2017

Ready to Eat (RTE) food can be defined as food products which are in a form that is edible without additional preparation to achieve food safety. The final product may receive additional preparation for palatability or aesthetic, epicurean, gastronomic or culinary purposes but NOT to make it safe to eat.

In part 3 of this series, Rika discusses the unique characteristics of RTE products and what makes them such a risk? Also check out 10 tips starting production of an RTE product and 10 questions to ask your suppliers of RTE products.

Which product characteristics influence pathogen growth and thus shelf life?

Product characteristics such as pH, aw (water activity), salt concentration and/or concentration of chemical preservatives affect pathogen survival and growth within a food, as does the way that these products are packed, and the time and temperature of storage. Because these factors are important to influence the survival and growth of pathogenic microorganisms, the manufacturer must establish the parameters of each of these characteristics for every product produced. The determination of these specifications has to be done under the same conditions that the product is manufactured. If in-house expertise for these trails is not available, it is recommended to contact research organisations and/or laboratories that can help to understand and gather the necessary information.

It is important to understand the formulation of your food. In the case of a multicomponent food such as a quiche the highest pH and aw value within the food must be known throughout its shelf life. Another consideration is whether the food is an emulsion, e.g. mayonnaise, margarine, butter. For these types of foods, aw and pH measurements will be difficult to measure and will vary throughout the food. Where necessary seek specific expert advice. Historical data can also be used.

Data should include information from HACCP and monitoring checks:

  • process validation, verification and monitoring (e.g. temperature, time, pH and aw)
  • Ingredients traceability and microbiological quality testing including for hygiene indicator organisms
  • Sampling for pathogenic species and appropriate hygiene indicator organisms from processing areas and equipment (to demonstrate the efficacy of factory hygiene and cleaning regimes)
  • Final product testing for the presence of pathogenic organisms for example on the day of production and/or at the end of shelf life to verify effective functioning of the HACCP system and durability verification

Top 10 tips for  production of a RTE food

  1. Ensure that requirements for the safe manufacture of RTE foods are in place.
  2. Purchase ingredients from a reputable source, carefully observe usage and storage instructions provided, in particular the Use By date.
  3. Review the ingredients and determine the control for pathogens e.g. L. monocytogenes are in place for each (including shelf life), using the supplier’s information as necessary. Note that data are product-specific and are only valid for the supplier from which they are gathered.
  4.  If there is no further processing of ingredients then shelf life of the finished product must not exceed that of the shortest shelf life ingredient incorporated, e.g. where a product contains ingredients that have a shelf life of between 5 and 10 days the shelf life of the product must be no more than 5 days.
  5. Consider any changes to the ingredients that may occur when they are mixed or assembled, i.e. changes to the individual ingredient characteristics, and determine whether this impacts on the continuing efficacy of controls, which may change the usable shelf life.
  6. Set up a system to monitor the controls on raw materials, focusing on high risk ingredients.
  7. Start an environmental microbiological monitoring programme for the production area swabbing areas that have the greatest risk of contamination, e.g. slicing equipment.
  8. Set up detailed procedures for staff and product handling and supervise these closely
  9. Ensure that any detection of pathogenic organisms in the food or environment is investigated and follow-up remedial action carried out and documented.
  10. Review collated raw material, finished product and environmental data on an ongoing basis to ensure controls are in place.

Buying RTE Foods? 10 tips for your supplier quality assurance programme

When buying RTE ingredients from a reputable supplier it may be assumed that shelf life has been established appropriately. If one is unsure, it is the manufacturer’s responsibility to ensure that the supplier has implemented this guidance and has established the shelf life appropriately.

The following are suggested questions to ask suppliers when buying ingredients from them:

  1. What hygiene-/HACCP-related certifications does the supplier have, e.g. British Retail Consortium Global Food standard, HACCP or ISO22000 certification?
  2. Can the supplier provide a written specification which includes appropriate limits for all relevant pathogens?
  3. Do the results of microbiological testing show that the ingredients comply with the scientifically determines specifications?
  4. Can the supplier provide a Certificate of Compliance or Certificate of Analysis for the ingredient?
  5. What type of process has the ingredient been through, e.g. what heating temperature and for how long?
  6. What type of packaging is the ingredient in, e.g. vacuum packed chilled foods have a limit of 10 days shelf life unless treated as required by ‘FSA guidance on the safety and shelf-life of vacuum and modified atmosphere packed chilled foods with respect to non-proteolytic Clostridium botulinum’2?
  7. Is the business supplying the ingredient part of a larger group and able to use its technical support?
  8. At which temperature and for how long was the ingredient been stored.
  9. Has the ingredient been cooked (a time/temperature combination of 70°C for 2 minutes or equivalent is required).
  10. How much shelf life there is on the ingredient as delivered to the manufacturer?

Don't try this alone

If you do not have the relevant technical expertise to make ready-to-eat foods safely then you are strongly recommended to seek relevant expert advice.


Rika Le Roux Kemp