Making my first starter

[maykalteyt]

Hello!

I'm a newbie to the world of cheeses and so far I've just made a few simple soft cheeses like penir and queso blanco. Now I want to move on to some cheeses which use cultures and rennet. Fortunately I've managed to get some rennet and one packet of mesophilic culture (hard to get hold of here).

The instructions in the book I have say to use skimmed milk, pasturise it, leave to cool, add the culture, close the lid, leave at a warm room temperature until it coagulates into a yoghurt-like substance, about 15-24 hours.

Can you use shop-bought pasturised skimmed milk or do you have to use raw milk and do it yourself?

Thank you.

[linuxboy]

please see http://cheeseforum.org/forum/index.php/topic,5165

[maykalteyt]

Thanks linuxboy!

What's the purpose of heating the milk if it's shop-bought and already pasturised? Could the  culture be added directly to sterilized milk? I had assumed that this stage was only applicable if using raw milk in order to ensure that only the added culture went to work on the starter (like adding a Campden tablet to apple juice or pasturizing honey before pitching the yeast), but of course, I'm a complete newbie

[linuxboy]

purpose of heating the milk if it's shop-bought and already pasturised?

To bring it up to the proper temp conducive to bacterial growth. I assume you mean heating to normal temps, not sterilization temps?

Could the  culture be added directly to sterilized milk?

Yes, provided that the milk has been cooled down to the right temp.

I had assumed that this stage was only applicable if using raw milk in order to ensure that only the added culture went to work on the starter (like adding a Campden tablet to apple juice or pasturizing honey before pitching the yeast)

Milk from the store is FULL of bacteria. It has all sorts of psychotrophs and putrifying bacteria that survive pasteurization. The store milk is just cheap media for bacterial replication. And you want it to be as sterile as possible. In the lab, we'd autoclave at 121C. At home, have to do the best you can.

[maykalteyt]

Thanks for that; I'm starting to understanding the processes now. It's next to impossible to get info on cheesemaking locally, and harder still to find equipment, additives, cultures, etc., so all the help is appreciated.

My first starter culture has started to set. My book (Home Cheese Making) says to chill it when it reaches the consistancy of 'good yogurt'. Not really sure what the author regards as a good yogurts consistancy, but I would imagine it's that point when it doesn't quite pour without a little help, but sort of 'blobs' out of the pot.

[linuxboy]

says to chill it when it reaches the consistancy of 'good yogurt'.

This is largely irrelevant and anecdotal because the thickness depends on the milk composition and your bacteria strain properties. I can use the same species of two bacteria and one will be done when the milk is very fluid, and the other will be done when the milk is so thick you can stand a spoon in it. What you have to concern yourself with is the pH, as detailed in the thread. If you can't measure pH, then guess based on the sensory attributes. It should thicken and smell buttermilky/sourish.

[maykalteyt]

Well, it thickened and had a sour smell and tasted a little acidic, so I used it. I tried a halloumi recipe from Ricki Carroll's book. Followed the instructions, maintained the suggested temperature (maybe a degree or two higher). Two hours later and not even the first sign of curds forming. After reading a few posts about her rennet amounts being too low, I mixed in a little more, but still nothing. Luckily raw milk here is only about 2US$ a gallon and I can still probably make a fresh cheese with it. Also have a traditional 'telemea de vaca' on the go.

Thanks for your instruction.

[linuxboy]

Did you mix your rennet in cold, filtered/distilled water? And use right away? If it didn't coagulate, your rennet is off. Culture make seems like it went well.

[maykalteyt]

Yes, I mixed it in room temperature bottled still water. I guess I added it about a minute or so after I diluted it in the water, perhaps more. After diluting it, what's the longest you can wait before adding it? After two hours of nothing setting, I added a few more drops directly to the milk (figured there's nothing to lose). Waited another hour, nothing. Still looks just like milk. In the end, supposing the rennet is dud, I heated the milk up to 185F and added some vinegar and lemon, as I've done in the past, to make an easy queso blanco kind of thing. That usually sets it within a few minutes. Again nothing - although obviously I have no idea how dud rennet (if that's what it is) might have affected the ability of milk to curdle.

[linuxboy]

Rennet would have done nothing to prevent acid coagulation.

I think maybe there's something odd about the milk?

[maykalteyt]

It's possible. Is there some simple way of testing the rennet? It's imported so it's hard to know under what conditions it's been kept.

[linuxboy]

Take 1 cup of milk. Take 1 tablespoon ice cold, filtered (no chlorine) water. Add 5 drops (adjust for strength) single strength rennet to water. Mix in water with milk and stir for 20 seconds or so. Milk should flocculate in ~5 minutes and form a thick curd in 15.  Check the flocculation time. If it is drastically off, you will know that the strength is low.

You can also add more drops if you suspect the rennet to be really weak.

There's a more scientific way to do it, it's an ISO standard for determining rennet strength. But I doubt you want that.

[maykalteyt]

Mixed 5 drops of rennet with a little iced bottled water, added it to a cup of whole milk (shop bought, not the same as the stuff I was trying to curdle yesterday). Stirred for a minute. Left it. Nothing after 15 mins. Added five more drops in iced water and stirred it into the same cup. Left it 30 mins. Nothing, not even a hint of a curd. The use-by date of the rennet is Feb 2012, but I suppose adverse conditions during transport to the country could have rendered it inert, no?

But even assuming the rennet was no good, it's still strange that the milk didn't curdle when I added the vinegar/lemon solution, given that inert rennet shouldn't prevent it curdling in any way. Are there any properties of milk that can prevent it curdling?

[linuxboy]

Not really. If you heat and add acid, milk curdles quickly, at a pH of about 5.2 for high quality milk, when the temp approaches 175F or so. It could be that it wasn't enough acid, or not heated enough.

[maykalteyt]

Just a quick update. The supplier I bought the liquid rennet from brought me round a tub of powdered rennet to try instead and it worked just fine. A bit wasteful as I have to knock up a 100ml/1g solution just to use a few ml to curdle the small scale stuff I'm doing (1 gallon batch max at the mo), but he didn't charge me for it so fair's fair.

Thank you once again for your advice, linuxboy.