5 replies to this topic

[lisacara]

We are having an issue with TVC's on a ready to eat vegetable mix cooked with spices. I know spices contain high TVC count but we cook the product to 80°C and they are heat treated also the TVC's are very erratic from one batch to the next. Has anyone any guidance or can shed any light - i have walked the process and there is nothing wrong

[Strider]

As you can find no obvious source of contamination during your processing I would look into your ingredients to see if they are contaminated with bacteria that survive your cooking process. To check this I would suggest you apply a heat treatment, similar to your process heat treatment, to samples of ingredients and then test the treated samples for TVC. You may find some ingredients (particularly spices) have process resistant bacteria/spores.
If you do find this to be the case a program of positive release or supplier assurance for those ingredients will be required to reduce the risk of future TVC contamination.

[Bawdy]

Hi Lisacara,


My first thoughts/questions re this are as follows, apologies if you have already considered them.

What TVC are you after, i.e what is the specification, and what sort of counts are you getting?

Do you know what type of bugs you are getting, i.e have you asked the lab to test for anything else other than just doing a TVC? Have you asked if the bugs are of the same colony type, basic gram stains etc and or are they sporeformers and or thermophillic? A lot of sporeforming bacteria can easily survive the 80 degree cooking, then multiply to large numbers post cooking/cooling. Knowing the beast you are dealing with may provide clues to the solution. If you are using an outside lab to test, they should be able to do some basic identification for you without much extra costs.

When you say "they are heat treated" are you referring to the spices themselves, i.e. are you purchasing heat treated spices? If so, do you get a COFA from your supplier of them giving you the TVC counts? If so are you able to correlate the TVCs on the incoming goods to the TVC counts on your finished product? Again if the spices are heat treated, the bugs that survive this process are obviously bugs capable of surving a heat treatment - which your cooking step is a type of, so you may not be killing them during your process, then if the conditions in your finished product are favourable for their growth, then they will multiply.


just a few thing you may also want to consider.

Wishing you and everyone else on this forum a safe and happy christmas.

Bawdy.

PS i wrote my reply before i read Striders reply above, so i apologise for the parts of my post that restate what Strider had already written.

Edited by Bawdy, 24 December 2011 - 12:10 AM.

[GMO]

What's your specification? Spices are notorious for having high levels of contamination even when heat treated. Also the way you cook them can have a big impact on how the levels are reduced. I used to work with spices but I can't honestly remember which way round it was but I think if you were boiling them in a sauce they reduced in count pretty well and if roasting them to a high temperature on chicken for example but on vegetables it's likely they're not cooked for long.

Typically 'acceptable' cfu g-1 was considered to be 10,000 TVC at start of life for food containing a lot of spices. Don't let that stop you trying to improve the process though.

Have you tried some trials just to make sure it is the spices? Test the starting materials, roast the veg without spices and test etc, etc? Have you also tested throughout the oven batch? I'm assuming it's a rack oven like a DD? So are samples from the top as contaminated as the middle and bottom? Have you datalogged your oven? (If you don't have a logger, you can sometimes borrow one from a supplier, e.g. your oven supplier.) Your oven might need balancing. Is there steam in the programme? Have the pipes got scaled up?

Hope those are some helpful starting points.

[Charles.C]

Dear lisacara,

Perhaps you might supply some actual data, eg what is "high" ?.

Speculation is valuable and instructive but needs input.

Personally i suspect yr raw material was simply not heat-treated. Some spices typically run into the millions for APC.

Rgds / Charles.C

[Tracey Botes]

Hi

Bacillus spores can survive 80 degrees cooking or working temperatures and in actual fact once cooled with germinate and perhaps may be your bacterial problem.
What population fo microorganism is making up your TVC?