bacteriophage

[radicalcultures]

Hi,
So I recently attempted to make some yogurt and cultured cream with raw cow milk. For the cream, I just skimmed it off the top and put it in a hot water bath, then added some whey from a cheddar cheese I made a few weeks ago. For the yogurt, I heated up the milk until I could not hold my finger in it and then allowed it to cool until I could, then poured it into two half gallon mason jars that had about 4 tablespoons storebought low fat yogurt in it. In one of the jars I also added some of the whey. The whey had not been handled in a very sterile way, and I'm thinking there might have been some bacteriophage contaminants in it, because the cream and the yogurt which had whey added did not sour at all over the next 6 hours, while the yogurt with only storebought starter did. I also feel like I did not add enough starter whey to the cream. I used about 2 teaspoons for a cup of cream.

If anyone has thoughts I'd love to hear them.

Thanks!

Kevin

[DeejayDebi]

Hi,
For the yogurt, I heated up the milk until I could not hold my finger in it and then allowed it to cool until I could, then poured it into two half gallon mason jars that had about 4 tablespoons storebought low fat yogurt in it.

You really needed to get the milk up to 175 to 180F degrees then cool down to about 85 to 90F degees. You may get a yogurt drink but I seriously doubt you will get yogurt.

[ConnieG]

If you like a thicker yogurt hold your milk just below boiling and allow for evaporation of water (milk has a lot of water in it). If you want a sweetened yogurt add sweetener to the hot milk then allow to cool.

  I find that the yogurt starter must be mixed really well with the milk so after the milk cools to just warm, I put a cup of good quality store bought yogurt into a 2C. measuring cup and add about a cup of the warm milk and whisk that together and then whisk it into the larger amount of milk.  I put the cultured milk into clean, warm jars with and put them into either a yogurt maker or put the cultured milk into canning jars with tight lids and place these in a camping cooler containing hot water. 

[Sailor Con Queso]

Your problem is NOT bacteriophage.

[linuxboy]

yep, right.

added some whey from a cheddar cheese I made a few weeks ago

You can't expect 2-week old whey to be useful as a starter. For meso bacteria, they start to lyse at pH 4.5. The useful life is MAYBE 5 days when the whey is kept at 2-3C.

[radicalcultures]

nevermind, I was just getting impatient. It all started to sour and congeal within a couple hours of my post. The cream didn't get as thick as I'd have like and I ended up just shaking it up into some butter. The yogurt with the whey got really thick and actually formed these little cottage cheese like curds within the coagulum in some places. Thanks for the responses, but I jumped the gun.

[linuxboy]

Great! Sometimes bacteria take a while to get going...

[Tomer1]

If you like a thicker yogurt hold your milk just below boiling and allow for evaporation of water (milk has a lot of water in it). If you want a sweetened yogurt add sweetener to the hot milk then allow to cool.

I would imagine you need to start with rather skim milk to control the fat content of the final yogurt.