Brine used for the storage of a cheese must be made with care. You could just make a simple brine from water and plain salt and drop the cheese into this liquid, but since the simple brine does not contains the same elements which are inside the cheese, a slow exchange of the elements in the brine and cheese will occur and the cheese will change. This exchange of elements is a natural consequence of the different concentration of elements in the brine and cheese.
If you want to avoid exchange of elements, you must make sure that the elements that you wish to remain inside the cheese is found in equal concentration in the brine so that an exchange will not occur. The following text describes the elements which you must control to obtain a suitable brine for you cheese so that your cheese remains stable while submerged in the brine.
The basic control of the brine is centered around the calcium balance and acid balance in the cheese and brine.
First of all you must prepare a brine with a salt concentration which equals the salt concentration in the cheese. Feta is typically 3-5%, i.e., 30-50g of salt per liter of water. If your cheese is unsalted at the time you will brine it, then you must prepare a stronger brine. If you want a 3% salt content, then you must make a 3% brine and add 3% extra salt (3% of the weight of the cheese) to the brine used for the individual cheese. The cheese will then get salted while submerged in the brine, and with time equilibrate.
One of the main minerals available in the cheese is calcium. Calcium contributes to the bond betweeen the proteins in the cheese. If the brine does not include calcium, then parts of the calcium from the cheese will migrate to the brine, giving a soft or slimy surface of the cheese. Calcium can be added to the brine by means of liquid Calcium chloride to obtain adequate calcium balance. Use 1 ml of calcium cloride per liter of brine.
The last, but also important element is the brine acidity. As with calcium, the cheese structure depend on the acidity of the cheese. The cheese is acidified (pH 4-4.5) and the brine must be prepared to have the same acidity. The brine acidity can be obtained by adding acidified whey (use the last whey which drained of when you produced the cheese).
To achieve an appropriate brine balance you can add the following to the brine (measures per liter brine):
Whey
|
300 ml
|
Vinegar
|
15 ml
|
Lactic acid (15%)
|
5 ml
|
Calcium chloride (33%)
|
1 ml
|
Note: The quantities are proposed maximum quantities and not necessarily simultaneous.
Whey can be added at a ratio of up to 1 part whey per 3 parts of brine. This will make the brine acid with the acid substances are also found in the cheese, which is optimal. This way you will also prepare a brine including other useful elements (including calcium) which then will contribute positively to the element balance. However, you should primarily use (the clear) whey drained from the cheese in the latter phase of the cheese production process.
If you do not use whey, then vinegar can be used to acidify the brine - use up to 1 tablespoon per liter of brine.
Alternatively you may use Lactic acid (15%) to acidify the brine - use up to 5 ml per liter of brine.
Calcium chloride (33%) is added to achieve a concentration of calcium in the brine which reflects the calcium concentration inside the cheese.