UK Government’s Advisory Committee on the Microbiological Safety of Food (ACMSF), has been reviewing the risk basis of the FSA’s guidance on the control of non-proteolytic Clostridium botulinum (npcb) in vacuum packed and modified atmosphere packed (VP/MAP) chilled foods. In June 2022 CFA Director Karin Goodburn presented evidence to the group (CFA News #58 & #59). ACMSF has now published its report on Botulinum Neurotoxin-Producing Clostridia. The report is available on on the ACMSF website.
CFA welcomes this Report, which not only updates the risk basis of the guidance but also extends the scope of interest to all Botulinum neurotoxin-producing Clostridia.
The Report reviews botulism incidents globally, noting they have only occurred in very rare occasions in chilled foods and only when not sold or stored chilled, and there is no correlation between the major growth in the chilled prepared food market and botulism.
We are pleased to see mention of our Sustainable Shelf Life Extension (SUSSLE) projects as a positive example of how collaborative research should tackle major food safety topics, and that a some of our key recommendations have been endorsed by ACMSF:
- At the first opportunity to make explicit in guidelines that z = 7 and z = 10 centigrade degrees should be used to evaluate equivalent thermal processes for npcb for operating temperatures below and above the 90°C reference temperature, respectively. We would add as a matter of great concern about FSA’s/ACMSF’s internal processes that it should not have taken 11 years since first notifying FSA for this necessary change to be acknowledged, the lethal rate table having been identified by the first SUSSLE project and FSA-funded PhD by Ewelina Wachnicka to be incorrect below 90°C and reported by CFA and its research partners to FSA in 2012. This change needs to be made rapidly as companies are being charged consultancy fees for process evaluation using the incorrect values.
- Toxin testing should be a minimum requirement for challenge testing. This needs amendment needs to be acted on rapidly, and is covered in the CFA/LFR/QIB/MLA/BRC guidance from 2018.
- As part of the ‘7 ways to ensure safety’ “heat and preservative factors” is proposed to be removed from the FSA guidance to open up potential use of non-thermal processes. It is important to note that QMRA data such as that gathered in the first Government-funded SUSSLE project (AFM266) quantified npcb spore presence in raw material, and was published more than 7 years ago (open access): Barker et al, 2016. Where such data exist tailored thermal processes in combination with chilled storage should continue to be recognised. Several hundred SUSSLE-treated foods are on the UK market and have been for nearly a decade.
However:
- We note that current information does not facilitate revision of the current reference process, heating at 90°C for 10 minutes, but that there is strong evidence that this provides a lethality that exceeds the target 6 order of magnitude reduction in population size a product could be demonstrated to contain no lysosome, then it could have a longer shelf life than 42 days when using a process equivalent to at least 90°C for 10 minutes. It should be noted that the 6-log work (Fernandez & Peck, 1995) that is the basis of this figure of 42 days used 106 spores/ml in broth, which is not representative of any known loading or foodstuff. There are numerous foods on the market using 90°C/10 and more than 42 days without any issue. Lysozyme is not a widely relevant component of foods that are given such heat processing. Unless this is made clear in guideline reference to this will most likely result in enforcers and others unnecessarily seeking testing, wasting scarce funds and resources.
- Other controlling factors, including herbs and spices, bacteriocins, phosphates, citrates, sorbates, sulphites, etc., can be highly variable in delivering consistent and reliable control of botulinum, and other botulinum neurotoxin-producing clostridia. FBOs relying on such controls must provide evidence demonstrating efficacy of the factors used for controlling these organisms in their foods as well as ongoing control and measurement. Guidance has been issued by BRCGS in relation to demonstration of safety of fresh meat and npcb, which we would take to be the basis of such an approach.
- The Report recommends that FSA should consider commissioning a review of controls used in other countries for non-proteolytic botulinum in foods, to determine whether a subsequent exposure assessment should be undertaken for VP/MAP chilled foods in the UK. It needs to repeated that nowhere else in the world has such guidance as that issued by FSA as controls are simply based on knowledge of physicochemical growth/toxin production parameters as well as the selection and use of high quality raw materials. The 2019-20 review of the then FSA guidance in relation to fresh meat, which was outside the scope of this review for some reason despite the npcb spore loading being lowest of any food material categories (Barker et al, 2016 QMRA), found that FSA’s approach is reflected nowhere else internationally yet safety was assured through legislated GHP GMP requirements for abattoir operation and subsequent handling. There is similarly no equivalent guidance limiting shelf life in such a way as that from FSA does for other relevant foods, creating a barrier to internal trade in the UK and without enforcement on imported foods, penalising UK businesses, reducing shelf life and impacting on waste.
- We would note that the current FSA VP/MAP guidance does not specifically cover product storage at less than 3°C as this is stated to be out of scope: “Below 3°C, non-proteolytic C. botulinum will not grow and produce toxin, so foods stored at less than 3°C are outside the scope of this guidance.” Unfortunately this is not explicit enough wording, creating an apparent grey area where there can be confusion including on the part of enforcers and FBOs. It needs to be made more explicit in guidance that it is a controlling factor for non-proteolytic botulinum, and it should state that storage where the warmest part of the food material can be assured to be <3°C (e.g. under controlled and monitored refrigeration) this does not encroach on shelf life with respect to the organism. This is reflected in SUSSLE rules which state that such storage time can be added onto the shelf life with the note that other pathogens e.g. L. monocytogenes can grow at temperatures down to as low as -2°C (source: EU Lm RL shelf life guidance, 4th ed, 4/7/21) so their potential growth must be considered when setting shelf life.
We are ready and willing to continue to support the further development of necessary guidance but with the aim of keeping it simple and clear particularly so those FBOs lacking major technical resource, end enforcers, can make appropriate use of it to protect food safety, whilst reflecting scientific developments in the last decade or so.
For more information visit:
https://www.chilledfood.org/sussle-the-10-day-rule-for-shelf-life/
12/9/23