Old Raw Milk. Bubbles in Curds.

[JsTx]

Ok so, Im not one for practicing poor cheese making methods. I work clean and safe. I recently acquired some 6 day old raw milk that had never left refrideration.  From my understanding raw milk doesn't really go bad (unless it is contaminated), it just sours. The milk had a ph of 5.8. I have read people leaving raw milk in the fridge for weeks and still consuming it without any problems. The milk was a little on the tangy side but it was not unpleasant at all. Out of curiosity I want ahead and made cheese with it. Once it came time to cut the curds several bubbles floated to the top and popped. Is this contamination? Is this a result of fermentation or the age of the milk. It taste fine and has a nice aroma. Im going to go ahead and follow through to the end but whats the reason for this and is it safe?

[Brentsbox]

I have often used 5 day old raw milk with no problems but I have never saw it bubbling.  I have even left a quart of raw milk on my porch for the past 2 days in 95F degree weather to let it clabber and even that is not bubbling.   

[JsTx]

Also the curd adhered to itself much like mozzarella. It was also floating. Im thinking its because of the acidity of the milk. After all that the curd taste fine.

[OudeKaas]

Bought some raw cow's milk Monday AM kept under refrigeration at the farm and continously by me since then. Won't be able to use until Friday eve, so it will be 4.5 days old. Looks from this thread that it should not be a concern, but just wanted to check with the 'cheeseoscenti' here that this would be OK?

Sorry if this is a n00bish question, probably will make more tomme-like stuff with meso and a splash or two of pureed-rind 'morge' in the milk . . . .

[MrsKK]

The only cheese I've had trouble making with older milk (4-5 days old) is mozzarella.  It just turned into a grainy mess.  I've used cheese that old to make cheddar and colby with no trouble at all.

I just cut into a Havarti that appears to have some contamination, as it is holey throughout.  The flavor is good, though it had a really odd odor when I first cut into it.  I let it breathe for an hour before tasting, though.