TPC reading is Zero in Oil Paste Product.

Hi,

I am still new in this forum and just realise how useful it is.

Recently we are facing "big surprise "  where we get our TPC reading is zero in our oil paste product.

We are using a few type of spices, mixed with oil and then heat until >150 C.

When conducting analysis we found our TPC reading is < 10 cfu/g which can be considered not detected. the problem is our water activity is high 0.8 - 0.9.   :shades:

Is there anybody experienced it before?

Please advise.

Many thanks.

Hello Mr aishah,

   All vegetative microorganisms cannot survive beyond temperature of 85 C.Only spores can survive beyond this temperature.Hence APC/TPC counts may be zero ,but there will be spore count of organisms whose spores are resistant to these time and temperatures combination of Thermal processing .which also depends upon the initial contamination and no of log reduction of spores at that processing temperatures and time and other parameters like Ph of the product etc.

Hi 

the TPC count is less then 10 cfu/g is alright as it is possible due to the temperature you use to heat. As in the earlier comment it has been said that that there is a  possibility of spores to survive and may give a count later over a time. 

As you say your aW is between 08. and 0.9 I will say check out the result for the product with end of shelf life and determine the final micro load limits  accordingly. As you know 0.8- 0.9 aW is still very low water activity to induce  a growth of certain micro . careful about Staphylococcus and Bacillus who can grow at 0.8 to 0.9 aW  

Hi Aishah,

I believe AW > 0.95 would be regarded as high and < 0.86 as low.

Given the temperature you are processing at your results are not entirely a surprise. In long life products waiting to test at end of life is not practical, more common is incubation of product prior to testing (2 sets for 7 - 10 days 30C & 55C).  Do you incubate the product before testing?

Regards,

Tony