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Thermal Processing - Fo Value calculation

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Posted 28 December 2010 - 08:26 PM

Also after completing this process. Do not throuw the pouches filled with water. save them you will need in future. Infact i would recommend you to repeat this investigation quarterly.


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Posted 25 April 2011 - 06:13 PM

I've been searching some old reports and the reply below by Nguyen Dinh was sent to me instead of posting, so here it is...


Dear Sir/ Madam!

Base on my experience, For thermal process following 3 level

1. Product


- Setting sterilizing by Fo value
- z =10 (nearly)
- Temperature start calculate: 100oC
- 121,1oC in 1min = Fo=1


PH<4.7 and non-CO2
- Setting sterilizing by Fb value
- z =8 (nearly)
- Temperature start calculate: 50oC
85oC in 1min = Fb=1

3. Product

PH<4.7 and CO2
- Setting sterilizing by Fa value
- z = 5 (nearly)
- Temperature start calculate: 40oC
65oC in 1min = Fa=1

Z value was testing by senior Lab


- One test: the temperature distribute inside the retort. This test we put thermocouples connect direct with computer to follow up
- One test: heat transfer of product.this test we put data tracer inside product and outside product (all Tracer inside the retort)

And finally item: for commercial run, to apply Fo? if you test raw material is high thermophilic (>100cfu/g) the best we will test D value the first, after that use the logarithm to fine Fo for safety
But D value test, we should test base on unit product for commercial run. How many % (unit,can, bottle) unit have spore after sterilizing. Normally, D=5-6 if high thermophilic, and Fo setting increase to 40.

Nguyen Dinh

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sandy soni

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Posted 11 June 2012 - 12:56 PM

we are processing mango pulp and mango slices in mango juice. This product is new for us and we are finding that lot of bulging in these cans. We are packing in 450 gm ca. Drain weight is above 55% and juice strength is 20% TSS.

Please suggest the thermal process for the same.



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Posted 09 July 2012 - 08:11 AM

Hello Sandeep

I can only strongly advise that someone in your company gets educated in this subject, because designing a thermal process is not that easy and a lot of parameters need to be looked at.

Here are some general parameters

- Product related : type of product, pH, texture, is the product liquid or solid or mixed ? what is the packaging (metal or pp or glass) ? ....coldest spot in the packaging

Product related parameters influencing the thermal process are determinated by "heat penetration tests". The data obtained from these tests will give you the thermal parameters specific to your product, and these parameters are used into the calculations

- Retort : type of retort (stative, rotation, immersion , etc) ...., coldest spot in the retort.

Retort related parameters are determined by 'heat distribution tests)

- Here is your product going to ? depending on the climate, the F0 (t=121°C, z=10°c) will be different.

- Also: which mirco-organism are you targeting (this is determing the z value)

- Also pressure is a factor : what pressure do you need to have to avoid lids popping open during the processing

- Building up time / holding time / cooling time need to be established

As you can see it is not possible to give you a general process lay-out .

Kind regards,


Quality is not an act, it is a habit.(Aristoteles 384 BC-322 BC)

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