There are several common problems that come up when making cheese. Keep in mind that it is fairly likely that you will experience all of these issues at some point or another. Making cheese is a great opportunity to let go of your perfectionism and just make something yummy. So don't worry if your first few attempts don't come out exactly as expected; drain, salt, and eat them anyway!
Cultured Cheese Won't Set
This is most commonly caused by the temperature being too cool at the fermentation stage. If you have let your cheese ferment for 12 hours and there is no firming up or change in the texture of your milk (normally soft cheeses), move the cheese to the oven and turn on the light. Check every 3 hours, and when the cheese reaches the desired consistency, drain and salt.
Milk Does Not Coagulate
Your milk may be old or perhaps it is pasteurized beyond usefulness. Your rennet may also be unviable or old. Try changing milks and if the problem persists, buy new rennet.
Milk Coagulates Too Fast
The milk you are using may be too acidic. This can be caused by too much culture addition or an overly long ripening period. You can fix this by using less starter next time or try shortening the ripening time.
Curds That Won't Come Together
If you were trying to make mozzarella and you ended up with a bunch of rice-like curds that won't stick to each other, this is an example of curds that didn't come together properly. This is often caused by improper temperatures; either you used UHT (Ultra High Temperature) pasteurized milk, or your curds got too hot when you were preparing for the stretching stage, or they didn't get hot enough. The temperature of the curds before stretching should be 160° to 170°F. It's not fixable, but it is edible. Drain, salt, and use like ricotta or cottage cheese. It's delicious with fresh fruit or sprinkled on salad!
Coagulation Does Not Result in a Clean Break
Your milk may simply need more time to set. Give it a few more minutes. If it is still not right, you can add more rennet in half or a quarter of the amount that you used the first time. This problem may also be due to inactive rennet. Keeping your rennet tightly closed, very cold, and away from light when you are not using it will lengthen the rennet’s lifetime of viability.
Curds Are Too Soft
Giving the milk a bit more time to set might help. If it does not improve, this problem may come from ultra-pasteurization or ultra-homogenization of the milk. You can try adding more rennet, depending on where you are in the cheesemaking process. You should add more rennet only to milk that has not yet been cut into curds. Adding more cultures may help, but again, only in the earlier stages.
This is normally caused by two things: Either the cheese was not drained enough, or the cheese was not salted enough. Add a little extra salt, stir, and try to get some more whey out. If you happen to have a cheese press, give it a shot here. Wrap your cheese (even if it's soft) in a cheesecloth and press at 10 pounds of pressure for 15 minutes. Then taste again.
Cheese can also become too bitter with age. If you made ricotta three weeks ago and it tastes bitter, it's probably better just to discard it.
There are two possible causes for rubbery cheese. First, this can happen when an excess amount of rennet is used. Use a bit less rennet next time. It can also happen if cheese is overworked or overcooked, and all the butterfat runs down the drain. If you've made cheddar and it's rubbery, you may have over-cheddared. Again, while it's not exactly fixable (because you can't add butterfat back into cheese) it is edible. Rubbery cheeses taste delicious when melted. Use it for pizza, grilled cheese, or on top of veggies.
For hard cheese varieties there are several causes. Cheese that is bland or tasteless may have not expelled enough whey during the cooking process, causing the flavor to be diluted. You can try cutting the curds into smaller pieces next time, or stirring them a bit more to help them release more whey. The curds may have been heated too rapidly, and this problem can be fixed by raising the temperature of the curds and whey by only 2°F every 5 minutes during cheesemaking. Or, it may just need to be aged longer. Wrap it back up and re-wax (if it's a waxed cheese) and try again in another two weeks.
If you are finding that your hard cheese is consistently bland, you may want to start adding a little lipase to your recipes. Lipase is an enzyme that works on fat and gives cheese a distinct tang. It will make your curds softer, so be careful and add a few extra drops of rennet if necessary.
If your mozzarella or ricotta is too bland, the cheese may need a little salt. Add a little extra and taste again.
Curds Are Difficult to Press
This is caused by excess stirring or cooking of curds during the curds-and-whey stages The curds have probably expelled too much moisture to be very pliable or pressable. Always follow directions closely and avoid overstressing the curds with excessive stirring or too-high temperatures.
Cracks Form in Pressed Cheese
This may mean the pressure was too light during the pressing process, resulting in curds that have not molded together completely, and causing those undesirable cracks on and within the cheese. You can try increasing pressure and pressing time. If mold begins to form in these cracks, you can try spraying brine into the cracks with an atomizer to flush the mold out, but you must to ensure that you dry the cracks out thoroughly after this process, because excess moisture may encourage more mold growth. For this reason, you should not spray out any really deep cracks.
Cheese Surface Is Oily During the Drying Period
The temperature may be too high in the room in which you are air-drying your cheese, causing the fat in the cheese to rise to the surface. Move your cheese to a cooler location.
Finished Cheese Is Too Hard, Dry, or Crumbly
This is only a problem in hard cheeses, and it's so minor that it isn't really even a problem; more an irritation. First, remember that when making cheese at home, you're making 2-pound cheeses, not 200-pound cheeses. So a homemade cheese is going to dry out and crumble a little more than one made in a factory. Some of the most delicious artisan cheeses are crumbly. But of course if you're trying to cut a slice of cheese for a sandwich, it's nice if that cheese stays together.
You may have used a bit too much rennet, or perhaps the curd-cooking time was too long or at too high a temperature. Write this down in your cheesemaking notebook, and decrease these things, one at a time, to help pinpoint and fix the problem in future batches of cheese.
Another possible remedy is to try adding a few more layers of wax during the aging process. Check your aging cheeses regularly, and if they start to feel like big hard bricks, add some coconut oil or wax to the outside of them. There is no rule that says that you can't wax parmesan, even if it's not traditional. Also, make sure that your aging cooler stays humid. Keeping a glass of water in the refrigerator can help. Some cheesemakers hose down the inside of their caves at least once a day to create moist, flavorful, and delicious cheddars.
Above all, keep trying. If your cheese doesn't turn out and isn't edible, chalk it up to a learning experience and try again. It's hard to waste ingredients (especially if you're on a tight budget) but try not to get frustrated. Just remember that once you hit on the right technique for YOU, you'll save a fortune and be making an amazing artisanal product.