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> The one remaining problem relates to use of pasteurized, homogenized milk (as one would get from the store). I am less familiar with it than the fresh raw goa
by cheese_goddess 5y ago
> The one remaining problem relates to use of pasteurized, homogenized milk (as
one would get from the store). I am less familiar with it than the fresh raw
goat’s milk I use, but the processing alters the protein structure, and may
cause problems establishing a firm curd. Some recipes call for purchasing a
solution from a cheese making supply house, and adding “1/2 to 1 teaspoons” per
gallon (5-10 mL).
The "solution" here is calcium chloride (CaCl₂) and the standard concentration
is 30% by weight (the article says 0.02%).
CaCl₂ is needed to replenish the calcium lost during pasteurisation, and
also during refrigeration. Basically any change to the temperature of milk will
cause the calcium in the milk to precipitate which means it is less available to
the rennet enzymes. I don't pretend to understand the chemistry any further than
that, but that's why we add CaCl₂ to cheesemaking milk.
On the other hand, CaCl₂ doesn't do anything for homogenisation. Homogenisation
basically pushes milk through a very small funnel with great force so that the
fat globules in the milk cream burst and become more evenly distributed
throughout the milk emulsion (milk is an emulsion!). This is done to consumer
milk to avoid having the cream float to the top that, legend has it, consumers
find icky. More honestly, the reason that milk is homogenised is to standardise
its appearance so that its fat content is not immediately obvious, leaving the
producer free to skim off any "excess" fat and standardise fat content to 3.5%
on the dot, while the rest of the fat is sold as cream. Skimmed milk is the
byproduct of the same marketing incentive.
In any case, pasteurised, homogenised and standardised milk can be used in
cheesemaking just fine and indeed most commercially produced cheese sold today
anywhere is made that way, both for public health reasons and for marketing and
regulatory reasons (for example, regulations for PDO cheeses typically specify
the minimum fat content of cheese, so cream must often be added or removed to
meet them). On the other hand, setting a curd gets progressively more difficult
the more such processing is applied to milk.
Pasteurisation is really the mildest treatment one can apply and it doesn't
really hurt if the milk is fresh and good quality milk to begin with.
Pasteurisation temperatures and durations are expressly tuned to avoid damaging
the milk proteins (contrary to what the article says) while ensuring the total
destruction of all vegetative forms of bacteria known to cause disease (the
standard of 63°C for 30' is calculated to exterminate 100% of individuals of
Coxiella burnetii with 97% accuracy, C. burnettii being the most heat-tolerant
disease-causing bacterium we generally expect to find in raw milk). In my
experience, home-pasteurised ewe's milk doesn't even need CaCl₂ to set the
firmest of curds, rather the opposite, the problem is to keep the curd from
coagulating too quickly (at least that is the case with sheep-derived rennet;
bovine rennet tends to act less immediately on ewe's milk for some reason I
don't understand. It's the same enzyme?). That's because of the highest amount
of protein in ewe's milk that makes for a firmer curd and greater yields. Cow's
and goat's milk are slightly thinner and they need more care to get all the
variables right.
Homogenisation on the other hand, makes it much harder to set a firm curd. In my
experience, making cheese at home with homogenised (cow's) milk from the
supermarket, I always get a thinner curd and have a lower yield than normal, so
I avoid it. There's nothing I know of that can be done to improve homogenised
milk. How the large factories do it, I know not, but for anyone who doesn't have
a factory the best is to stay away from homogenised milk if you're making your
cheese at home.
Also: don't make cheese with raw milk. You'll regret it. Trust me.
- radarsat1 5y agoYou've answered several questions I had recently, amazing thank you.
- margalabargala 5y agoOne note on homogenization, it indirectly helps the milk keep slightly longer. With fat floating to the top, the milk jug is given a hard shake prior to opening, and any microorganisms on the underside of the lid are washed into the milk.
- cheese_goddess 5y agoI hadn't thought of it that way but I'm sure that works!
- ajacksified 5y agoThank you for all the information- your username checks out! Re: "don't make cheese with raw milk. You'll regret it." If the only non-homogenized milk I can find is raw, is it safe to home-pasteurize it (63C for 30 mins,) or am I better off using the homogenized stuff? I've only made ricotta and mozzarella so far, but I've been thinking about diving into hard cheeses soon. I was just talking to my partner about cheesemaking over the weekend, so a random cheesemaking article on Hacker News is rather serendipitous...
- cheese_goddess 5y ago> Re: "don't make cheese with raw milk. You'll regret it." If the only non-homogenized milk I can find is raw, is it safe to home-pasteurize it (63C for 30 mins,) or am I better off using the homogenized stuff? That's something you need to decide for yourself, depending on your risk tolerance and considering who you'll share your cheese with. Me, I make all my cheese with home-pasteurised milk. I buy it raw and I pasteurise it in my cheese vat. I think that this makes it much safer than raw milk, although probably not as safe as milk pasteurised in a dairy plant. The combination of heat and time in home pasteurisation is just as effective as the process most commonly used in dairy plants (72°C for 15 seconds) but there are more opportunities for post-pasteurisation contamination in a home kitchen and anyway I'm an amateur so I can always bungle something without even knowing until it's too late. Btw, the reason we do it this way at home (63°C for 30') is because for pasteurisation to be done right every milk particle must be heated to the target temperature for the indicated time, which is much harder to do when the duration is short. For the same reason I stir gently but constantly while the milk is on the stove and also make sure that the needle of my milk thermometer is one or two degrees above the target temperature, because thermometers always have some error and it's best to err on the side of overheating than not-pasteurising. Also, pasteurisation temperatures are standardised for cow's milk with 3.5% fat so if you have fatter milk, say from Jersey cows or from ewes (as I do) you need to increase the temperature (so I pasteurise ewe's milk at 65°C for 30'). You can find more information about this kind of pasteurisation if you search online for "Long Time Low Temperature pasteurisation" (or "LTLT pasteurisation") or "vat-pasteurisation". Here's a very comprehensive report on pasteurisation in general: https://www.foodstandards.govt.nz/code/proposals/documents/Scientific%20Evaluation.pdf https://www.foodstandards.govt.nz/code/proposals/documents/S... To be honest I used to think that home-pasteurisation is just as safe as industrial pasteurisation but I had a conversation with a professional cheesemaker who told me it basically isn't and recommended that I age my cheeses for two or three months to be sure (as a general rule, the longer cheese has aged for, the safer it is to eat). To be more honest, I mostly do, but I also make some fresh cheeses that I eat within a couple of weeks. I expect though that if I was really messing it up with sanitation, I'd be seeing some signs like early blowing more often (currently I'm at 0 times, that is). So I think I'm doing it right. Anyway for me home pasteurisation is well below my risk threshold so I'm fine with it. On the other hand, the big problem with microbes is that you can't see them, so unless you have access to a bio lab everything you do to get rid of them is basically ritual and your faith in your procedures is er, well, it's just that, faith. So it's up to you to decide what you think is safe. In fact I know plenty of folks who swear by raw milk and have been making cheese with it for many years. But I also know of professional cheesemakers who have killed off a few of their clients with their raw milk cheeses, so I feel my responsibility is to warn people against it.