I've made a number of cheeses now with rennet (apparently about 20 according to my notes). I was going through my notes the other day trying to get a better understanding of what I was doing. However, I was struck by a couple of things that was hampering my analysis.
First, most recipes give you no clue about the expected yield for the cheese. The recipe calls for 8 litres of milk. You do some stuff. You get cheese. I made a reblochon last weekend to make up for my disaster the last time. One of the things I wanted to do was to reduce the moisture content of the cheese. Due do basic stupidity on my part, I ended up making a cheese with *exactly* the same moisture content of the last cheese: a 14.7% yield in both cases. To calculate this, I measure the weight of the milk before I start and the weight of the cheese after salting (and just before it goes into the cave). The higher the yield, the higher the moisture content. The crescenza I made yesterday had a yield of 17.9% -- very high moisture content. The second Caerffili I made was 10.7% -- quite hard.
The thing is, I would really like to look at a recipe for a reblochon and find out what kind of yield they *expect* to get. That way I can see if I need to cut my curds smaller, or cook longer, or whatever. Without this information, I don't really have any idea what the recipe author was doing other than vague descriptions about how clean their break was, how big they cut their curd, how long they stirred the curd, what the acidity of the cheese was when it was draining... I can't duplicate those things exactly, so it's much better to understand what they expect the end product is going to be like so I can troubleshoot it myself.
Similarly, I was reading about a type of cheese where one of the defining characteristics is that they add a lot of starter culture (I forget what the type of cheese is). So I looked up recipes. What did I see? 1/4 tsp in 2 gallons of milk. But what does that actually tell me? Nothing as it turns out.
I was looking at my remaining supply of MA4001. By guestimate I think I have only about 1/3 of the original volume that I purchased. Bulk DVI cultures are usually sold in DCU units or U units. 1 DCU innoculates 25 gallons while 1 U innoculates 1 gallon. My package held 1 DCU originally, so it can innoculate 100 litres of milk at normal addition rates. But that 1 DCU weighs only 1.6 grams for my package! The strength of the starter culture is highly variable (like close to an order of magnitude difference) and so the 1 DCU might weigh 1 gram or it might weigh 5 grams or whatever. That's why they sell them in DCU or U units and not grams (or volume). I've used 2/3 of my 1 DCU, which should have innoculated 66 litres of milk and yet my notes indicate that I've only used 37 litres of milk! I'm using almost twice as much starter culture as the manufacturer recommends on average!
Getting back to the recipe, when you see 1/4 tsp in 2 gallons of milk, that is a completely *useless* measurement. You might as well say, "put some starter culture in". Jim Wallace has some recipes where he uses yogurt instead of DVI cultures. In those he adds 1.5% of the initial milk volume as yogurt. This works out to about 15 grams per litre of milk (give or take -- I haven't actually measured it). I was thinking about my measurement problem here as well. 1.6 grams of starter culture innoculates 100 litres of milk. I want to innoculate 4 liters of milk. That 0.16 grams of start culture. I can't measure that. Like literally, that is not a thing I can measure, whether volume or weight (maybe if I was a drug dealer, I'd have a scale that could measure that, but alas I am just a lowly computer programmer). I started to think that the *only* way I can have any semblence of repeatability in my recipes is if I make yogurt from the starter culture and add that -- then I have a measurable amount. The variability of viable cells in the yogurt is almost certainly going to be much, much less than the variability of measurement for adding the DVI itself.
But with the recipe, I wish that recipe writers would write (perhaps in parentheses) the percentage of "normal" innoculation amounts that they are using, rather than some stupid meaningless volume. That way I can see, "OK. 80% of the normal amount" or "120% of the normal amount".
And continuing with this theme... Rennet. As far as I can tell rennet comes in a very wide variety of strengths: 60 IMCU, 100 IMCU, 200 IMCU, 400 IMCU, 550 IMCU, 600 IMCU... and that's only ones I've seen in various online shops. "Single strength rennet" is 200 IMCU (why not scale it around 100 IMCU??? I don't know). I am led to believe that with 200 IMCU rennet, 2 ml will coagulate 10 litres of milk. 1 US tsp is 4.9 mls. This means that 1 tsp will coagulate 24.5 liters. Cheesemaking.com sells vegetable rennet tablets where 1 tablet will coagulate 18 liters of milk. Fromase sells 2 kinds of tablets (at least): Ones that will set 25 liters of milk per tablet and ones that will set 50 liters of milk per tablet.
I frequently see recipes for 1/4 tablet of rennet or 1/8 of a tsp of liquid rennet. Some recipes *should* call for more or less rennet, but it's absolutely impossible to tell how much rennet the author is *actually* using because you have no idea what kind of rennet they are using. Again, I'd love to see recipes that say "80% of the normal amount of rennet", etc. In homebrewing it is now (thankfully) common to see recipes use "alpha acid units" for hops rather than weight or volume of hops. We could do the same thing here. If you need 2 ml of 200 IMCU rennet, then why not say "400 rennet units" (2 x 200 IMCU)?
And I'm not finished yet :-) Because I don't have access to a pH meter, I'm a bit hampered with really dialing in my cheese. Even still, I'd be super grateful for people putting pH targets in their recipes (luckily that's happening more and more). But even if you can't do that, at least give an indication for the flocc time and multiplier, or the equivalent (coagulation time and description of desired break sloppiness??). Even something subjective is better than *nothing at all*. "Wait 40 minutes and if the break isn't clean enough for you wait another 10 minutes" is literally useless information.
Let me explain a bit. The speed at which the milk coagulates will be governed largely by 1) the amount of rennet 2) the temperature of the milk 3) the amount of dissolved calcium in the milk 4) the acidity of the milk. Hopefully we can figure out #1 by specifying it better in the recipe. #2 is always present in recipes that I've seen. #3 is also usually badly specified, but I've never actually heard of recipes that intentionally limit calcium, or intentionally increase it. I think in virtually all situations you can expect your recipe to have 100% of the dissolved calcium, whatever that might be -- so we can assume it is a constant. The *only* thing that is unknown (if you don't have a pH meter, or a way to titrate the acid) is the acidity of the milk.
If you give flocc time and multiplier targets you are giving a lot of information -- even if the flocc time is kind of fuzzy because we don't have a really standard way to measure it. The multiple is telling you how sloppy you are expecting the break to be. 1.6x is practically liquid (take a look at some professional Parmesan producers in videos on Youtube... it's amazing how sloppy the "break" is). 3.5x is really quite hard. 2.0x is leaking a bit of fat into the whey. That kind of thing. It doesn't really matter how you describe it to yourself, it's only important that you have consistency between *your* measure of flocc time and *your* perception of break. Then if the expectation of break type and multiplier is at least close between you and the original author, you have some idea of what they were intending.
Now, the thing is that this give you a pretty good idea of the acidity of the milk compared to the author's expectations. If you are aiming for an 18 minute flocc time and a 2.5x multiplier (45 minute total coagulation), if you find that you have a 13 minute flocc time and hit what you expect to be your target texture at 33 minutes, then you know that your milk is considerably more acidic than the author's and you will probably want to adjust the cooking temperature to compensate. If it's the other way around, then maybe you will need to up the temp a bit to get a little more acid development (or alternatively, maybe next time think about ripening the milk longer).
But seriously the advice of "Wait x minutes and if the break isn't good, then wait some more" is essentially saying, "We're going to be making cheese today. What kind of cheese? We'll find out when we're done!" OK, perhaps that's a bit harsh :-) But definitely I feel like this when I read some recipes or what some videos.
One last comment about pH. Earlier I ranted about yield. One of the reasons why I think it is a vital part of any recipe is that if you can get yourself to a point where you know the kind of yield you are likely to get by looking at the curds in the vat, you can estimate the pH of the curds simply by how they are developing as you cook them. Assuming that you stir similarly to the recipe author, then the rate at which whey is expelled depends on curd cut size, temperature and acidity. With experience, you should be able to get to a point where you can guestimate how to cut the curds and stir them to achieve the yield that you want. If you find that the curds are developing faster or slower, it's because the pH is moving faster or slower. But without knowing what your target is, then you're pretty much lost. You just have to hope that the curds are developing the way the author intended. What's worse is that even when you are done, you have no idea if the result is the same as the author's!
OK... Enough ranting :-) If you manage to get through that book, I'd appreciate feedback and insight.
