Subject: Fo = 3 (Was Re: bottling garlic

From: [email-masked] (J Ralph Blanchfield)
Date: Sun, 07 Apr 1996 05:35:31 GMT

On Sat, 6 Apr 1996 02:26:39 GMT, [email-masked]
("Tommasso Picardo") wrote:

>A question from an amateur: What does Fo=3 mean? David Auerbach 
>Wow David a little question that's what you think.  
--- snip ---
>To quote from (Phil Cassidy Grimsby.):  NOTE 
>THIS IS A REDUCTION OF TEN PAGES SO ANY COMPLAINS SEND THEM TO ME AND I 
>WILL IGNORE THEM!!!! JOKE:  You asked for it; 

--- gigantic snip --

Hello Tommasso,

You have done a good job in condensing a 10 page account, and given a
useful lesson or reminder of  some of the complex technological
considerations involved in safe canning of low acid foods, but perhaps
a bit "over the top" for an answer to a self-described amateur who
asked "What does Fo = 3 mean?", or for other non-scientist subscribers
A shorter and simpler answer for a non-technologist could be something
like ---
"For every part of the can contents to receive sufficient heat for
commercial sterility  (a reduction of the original population of
microorganisms by a factor of at least 1,000,000,000,000 times) and
practical safety, we must make sure that this is achieved at the
'thermal centre' of the can (i.e. where the heat takes longest to
reach). Fo is an abbreviation for the time in minutes at 121.1 deg C
to achieve commercial sterility in low acid canned foods (pH 4.5 or
more)  in respect of vegetative cells and spores of Clostridium
botulinum, a most dangerous pathogen,  and one of the most heat
resistant. This requires an Fo value of 2.5 and it is normal to aim
for at least  3.. Because external heat takes time to penetrate to the
thermal centre, the processing conditions to achieve Fo = 3 will
depend on the size and shape of the can, the nature of the contents,
and how (static, rolling, or end-over-end) and at what actual heating
temperature the cans are processed. This necessitates specific
evaluation  for each product and manufacturing process, and canning
technologists have well-established methods for doing so. The
resulting processing conditions must be strictly adhered to during
production".

>An example of when the canning industry gets is wrong:  "1978, 
>four elderly people in Birmingham developed botulism after eating a 
>contaminated can of Alaskan salmon.  Two of them died.  In 1989, 27 cases 
>of botulism type B occurred following the consumption of hazelnut yogurt 
>and one person died."  (Sprenger, R. A.  1995.  Hygiene for Management.  
>Seventh edition.  (c)Highfield Publications.)  Credit where it is due 

Outbreaks of, and many deaths over the years,  from botulism, have
occurred most often from home canning, particularly of meat and
vegetables especially in USA,, and also from some home-cured hams and
other "continental meat products in Europe, and  hot smoked fish, .
 
>>they have killed less since 1978 than BSE and BSE has only been going 
>since 1986, sorry forgot the new ten cases of CJD have not been nailed 
>down to BSE yet, only a possibility

Hello, I thought this was about Fo = 3.  How has BSE got in here?
Well, if we're into comparisons, how about the 4000 UK deaths and 2.5
million UK injuries requiring medical treatment, each year from
accidents in the home. Better go out instead, and face traffic
accidents, muggings, etc.

The hazelnut yogurt story is worth further comment. When food
technologists first heard the report of botulism attributed to
hazelnut yogurt, without having details of the background, the initial
reaction was, "But yogurt is too acid to permit Cl. botulinum growth".
The answer was that already-formed botulinum toxin had been  _added_
to the yogurt, which does not undergo any subsequent heat treatment.
What had happened was that a very small company, that had been canning
fruit for use in fruit yogurts and selling it to small yogurt
producers, decided to extend its range by canning hazelnut paste for
use in yogurt. Because of its acidity, fruit canning does not require
a very stringent heat process. But there was nobody there with
sufficient scientific knowledge even to realise that non-acid hazelnut
paste required a far more stringent process than they had been using
for fruit, or, still less to determine and specify what that process
should be . So an appropriately stringent heat process was not used,
the canned hazelnut paste had not been effectively sterilised, the
botulinum toxin had been formed in it, and was in due course added
with it to the yogurt.  It is very fortunate that this came to light
early and was very quickly traced back to its source, otherwise the
toll of death and serious illness could have been much greater.

Object lesson?  Food safety requires

1.  that no food  manufacturing operation should be designed, or
changed, or applied to other products, without those concerned having,
and following, the advice of a competent and appropriately experienced
scientist/technologist (or team in a larger organisation) applying
HACCP.

2. that the manufacturing operation is properly monitored for strict
compliance with specified requirements.

[Notes  for subscribers not familiar with the UK set-up:

There never has been, and there is not now, any _explicit_ mandatory
requirement for a food company  to use the services of such a person.
But we have now got pretty close to it, with Regulation 4(3) of last
year's new Food Safety (General Food Hygiene) Regulations,  which
requires a proprietor of a food business to "identify any step in the
activities of a food business which is critical to ensuring food
safety and ensure that adequate safety procedures are identified,
implemented, maintained and reviewed" on the basis of five stated
principles which, without mentioning HACCP by name, substantially
amount to a version of HACCP. There is no way that a proprietor could
comply with that without having available the relevant
scientific/technical  expertise.

There are no ongoing in-plant regulatory inspectors, only infrequent
inspection visits by local authority officers].

Regards to all

Ralph

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J Ralph Blanchfield
Food Science, Food Technology & Food Law Consultant
Chair, IFST Member Relations & Services Committee
Web Editor, Institute of Food Science & Technology
IFST Web address: http://www.easynet.co.uk/ifst/ 
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