In February & March 2024, to keep my promise to hundreds of Crowdfunder supporters, I produced several hundred cans with a fill weight of 110g (to reduce spillage during seaming), this led to some 'deformation' of the can surfaces, due to the extra 'headspace' (oxygen) in the top of the can which expanded during the sterilisation process.
My HACCP at the time required incubation and sterility testing for new recipes, and sterility testing for every batch. Every recipe was tested and every batch was tested and results were "satisfactory" or 'commercially sterile'. So I sent them out... then had a customer worried they had "blown up in the post"...
I carried out a voluntary recall and had a very small number of cans returned. All but one, which is held in my archive, were sent for incubation (30c for 14 days, one was also held at 30c for 6 months) before being sterility tested, ALL were reported as 'satisfactory' or 'commercially sterile'.
Following some 'root cause investigations' and a trip to the retort manufacturer, we changed the fill weight back to 125g and changed some pressure settings, the results were much better, although still some slight 'distortion'.
Unfortunately my inspector was not happy with 'any distortion', as an old 1988 paper stated "peaking or buckling is unacceptable, as this could compromise seam integrity, and allow for contamination", which could pose a serious risk to food safety, in July 2024 I was served a 'Remedial Action Notice' prohibiting the sale/consumption of all previous cans...
Following many months investigating various 'corrective measures' (fill weight/hot fill/steam flush/nitrogen flush etc.) and spent many many thousands on microbiological end product testing (EPT) and pressure testing of cans etc. plus another trip to the manufacturer, I concluded the 'distortion', commonly referred to as a 'flipper or springer' were NOT "peaking or buckling" and therefore NOT a risk to seam integrity, and therefore NOT a risk to food safety, but just a cosmetic appearance...
The Bluefin Tuna produced in November 2024 (and the Sardines produced in January 2025) used a new fill weight of 130g and further pressure changes, a test with oysters and the first batch of tuna were the necessary evidence in 'Remedial Action' to lift the 'notice' in November 2024. The appeal hearing was later confirmed for January 2025, but was thrown out by the authorities solicitor, as the could see my evidence and used the excuse that the "notice had been lifted already"...
I still continued investigations, and complained to the authority regarding the "unreasonable" notice, and the fact that the inspector would not accept my evidence. Part of my further investigations led to three documents from Canadian canning industry.
The descriptions for all can defects provided evidence that although a 'flipper/springer' could be a serious defect, and cans should be 'Held for Investigation', and that "further testing was acceptable, and if the results proved no compromise to seam integrity, the severity could be moved from 'serious' to 'minor' and the cans could be released for sale/consumption"
On 2nd July 2025, the inspector admitted that he "had not witnessed any of my cans showing signs of 'peaking/buckling", and accepted my investigations/further testing "validated the severity of the 'flippers/springers' was 'minor' IF there was no weight loss to the cans"
While ANY 'distortion' is something I truly hope to eliminate, and believe I have, food safety is obviously paramount in any food manufacturing, despite any costs of investigations and further testing, but this has obviously had a huge impact on my business, it almost bankrupted me before I got started, 150 cans held, then 700 cans, produced after initial investigations, also held, days before a big festival launch of the Tinned Fish Cafe, probably £10,000 stock, prohibited to sell any cans for 4 months, then a year later "admitted it was wrong"... I am truly grateful for all the technical support, and the amazing reviews from Marcus @TinnedFishReviews for unintentionally saving my business when reviewing the first cans I could sell, and I'm sad I lost some friends by not giving up, but pleased I persisted, and WON, as it was looking like the only option was to concede and close down.
The inspectors report is below:
Hello Cornish Canning Company Limited,
Thank you for your time during your recent food hygiene inspection on 2025-07-02. The purpose of the inspection was to assess your compliance with food hygiene legislation.
This is the report that details the outcome of the visit and the works required (if any).
Action Required:
Any issues identified below must now receive your immediate attention to ensure legal compliance:
1. The purpose of the visit was to agree the quality and safety checks that should be carried out and recorded for each batch of cans processed and the relevant associated corrective action/end product rejection criteria. This review included validation against 3 documents: -
• Manual on Fish Canning (FAO Fisheries Technical Paper 1988).
• Metal Can Defects: Identification and Classification (Government of Canada, Canadian Food Inspection Agency, Controls for Food - Current Guidelines, Date Modified 2020-07-29).
• A Guide to Can Defects and Basic Components of Double Seam Containers (Association of Food and Drug Officials (AFDO), November 2011).
The Canadian document was useful in defining severity using the following terms: -
• “Serious” – Evidence of microbial growth in the container; or the hermetic seal of the container has been either lost or seriously compromised and “Minor”
• “Minor” - A minor condition is one which is clearly an abnormal container characteristic, but one which does not result in loss or potential loss of container integrity (hermeticity) and consequently does not represent a potential public health risk.
In some cases, product will need to be “Held for Investigation/Quarantined for Further Checks/Testing”. An example of this would be where permanent deformation has taken place, and cans would be defined as “Flippers or Springers”. In such a case the root cause would need to be assessed; this could be microbial spoilage, however, immediately post processing it would be more likely related to a lack of counter pressure in the retort.
Product with microbial spoilage would be rejected as a “Serious” defect, whereas “Springers” and “Flippers” caused by insufficient counter pressure would require weight checks to confirm hermetic seal integrity and could be downgraded to a “Minor” defect.
Although "Minor", "Flippers" and "Springers", caused by a lack of counter pressure, should continue to undergo root cause remediation to improve process settings and produce an end product with minimal permanent distortions.
We have agreed the following definitions based on the AFDO document in conjunction with the Canadian document were categorised as “Serious”
and should be re-canned (if before sterilisation):-
• Cutover
• False seam
• First Operation
• Knocked down flange
• Vee or Spur
(note: in practice the above cans/product would be re-packed into a new can as they are spotted post-seaming and pre-sterilisation, corrective measures would be a seaming machine adjustment so that these ‘failures’ do not occur)
or rejected: -
• Buckle and/or buckling
• Soft swell
• Hard Swell
• Hydrogen swell
• Leakers
• Panelling (note: Permanent distortion (collapsing inwards) of the can body caused by internal vacuum and excessive external pressure developed during the processing or cooling. Panelling results from internal compression in the can, SERIOUS is when seam integrity or internal coating is damaged, MINOR is when a small indentation is not in the vicinity of the seam, or the coating is unlikely to be damaged)
The Following were categorised as “Serious” and to be
“Held for Investigaion/Quarantined for Further Checks/Testing”: -
• Springer (Based on root cause, weight checks or microbiological testing)
• Flipper (Based on root cause, weight checks or microbiological testing)
• Droop (Seam assessment; note: there is always the chance of ‘droop’ on irregular shaped cans with small corner radii, due to the extra metal/sealant at the corners, BUT the can manufacturers CRITICAL tolerance of max 30% droop and min 0.90mm overlap MUST BE ACHIEVED in the pre canning seam assessments, see attached example)
The following were categorised as “Minor” and need not be rejected: -
• Sharp Seam (not cutover)
Please update your documentation based on the above and include corrective action for each defined quality and safety check/defect.
2. Your HACCP documentation will need to be revised to reflect any new quality control parameters and SOP's. Please review all HACCP documentation to ensure it is current.