Author Topic: pH Drop Problem - Bacteriophage?  (Read 475 times)

Offline larry8756

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pH Drop Problem - Bacteriophage?
« on: September 08, 2012, 04:09:12 PM »
Hello All, I was wondering if anyone could help me out with a few concerns about phage. There have been aprox. 6-8 affected vats of chevre that have been affected. The target pH is 4.1-4.3 for our chevre but the vat stops dead at 4.8-5.1 and the texture is not consistant with our other vats. This is very rare and I am unsure if it is phage related. We rotate 3 types of Cultures CC02 CC06 (frozens) and R704 (freeze dried) which im assuming is the most phage resistant culture of the 3. The affected vats that have been cultured with frozen ended up with a result of high ph (4.8) gritty texture with no flavor, almost looks separated in the tank (We use 20,000L OST tanks) and %10 yield loss as well as slower acidification, but the pressing time was normal. The affected vats that have been cultured with freeze dried ended up with the same slow acidity progress, looked like milk pumping it, the grading was good creamy texture and taste, almost normal yield and took x3 longer to press (16hrs than our usual 5hrs). I am not sure if these characteristics fit that of phage but I am concerned as I have been here 5 years and this has never happened before and recently happened 6-8 times in the last 6 months after renovations.

Alittle more understanding would be great.


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Offline linuxboy

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Re: pH Drop Problem - Bacteriophage?
« Reply #1 on: September 09, 2012, 09:22:01 PM »
Do you for sure know it's phage? Have you rules out antibiotics, milk quality, sanitizer residue, sanitation schedule issues leading to opportunistic infection, etc?
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Offline FRANCOIS

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Re: pH Drop Problem - Bacteriophage?
« Reply #2 on: September 09, 2012, 10:07:32 PM »
It sounds like you have had issues with vats on the same day cultured with all three cultures.  It is highly unlikely that it's phage.  Phage normally will take out only one strain at a time.  One of our factories has been using CHR FD for donkey's years, continuously made into bulk culture, and it only has one strain inactive.

Are your OST vats fully automated?  Can you check temperature logs?  In three vats on the same day with different cultures I'd be suspecting a pneumatic valve issue or possibly your automation giving faulty temperature readings and not heating the vats properly.

Offline larry8756

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Re: pH Drop Problem - Bacteriophage?
« Reply #3 on: September 16, 2012, 11:04:05 AM »
Sorry the 3 affected vats were not on the same day. I am not sure if it is phage I have ruled out sanitation by numerous inspections and swabs,etc.. I found alot on phage from CHR HANSEN and other websites but nobody explains the affect it has on a closed 14hr innoculation vat. We got our tests back from the whey samples and we are getting high hits for phage. Our production just recently increased %30 and we have now noticed lack of quality and consistancy in the product. The only thing I know about phage is it can slow the acidification down and even come to a complete halt. My major question is can the virus affect the structure of the cheese as well as slow the pH. Could high levels of phage affect quality in different degrees or is it just slowing the acidification. Im trying to rule out phage and look towards milk quality but that could get complicated so im trying to rule out the more controllable problems.