When it comes to fermenting cranberries, to ferment them properly and use them to make cranberry sauce, you will want to split the cranberries. You can do this by chopping them with a knife or smashing them in a jar or a large bowl using a kraut pounder, wooden spoon, or spatula.
When you are splitting the cranberries, you may be tempted to chop them in a blender. DO NOT do this. They will be chopped too finely and will ferment too quickly, creating alcohol. You may use a food processor, but if you do this, you will need to be very careful. You will need no more than a few pulses to sufficiently chop the cranberries.
Once the cranberries are split, add them to the jar, if they are not already in the jar.
Add the salt and the whey to the jar.
Add the water to the jar until the cranberries are completely submerged.
Weigh down the cranberries in the jar with a second small jar or a glass fermentation weight.
Put the cap on to the jar and place the jar in an undisturbed place out of direct sunlight where the temperature is approximately between 68°F and 72°F. (As a safeguard, I HIGHLY recommend placing the jar into a bowl to catch any fermentation brine that might bubble out of the jar, even with the lid on. See my video for an example.)
Each day, release the cap on the jar to remove any buildup of carbon dioxide. If you use special equipment, such as a "pickle pipe" or another fermentation device, you do not need to do this step.
After a few days, you should start to notice a few bubbles accumulating in your jar. The bubbles indicate the fermentation process is moving in the right direction. The secret is to "catch" your fermentation when it is in the bubbling stage before it moves on to turn into alcohol. (This stage of fermentation usually occurs within 3-4 days. See below.)
Within 3-4 days, you should see a lot of bubbles, and this indicates that your fermented cranberries are ready. Now is time to move on to the next step.
Using a mesh strainer, strain your cranberries over a bowl to catch the cranberry brine. DO NOT throw this brine out.
Transfer the cranberries to a bowl and add a whole sweetener to your taste. I recommend between 1/4 cup to 1/3 cup honey. (In my recipe video, I like to use 1/4 cup for myself or 1/3 cup if I'm making the cranberry sauce for my family.)If you would prefer to use a whole sweetener, such as Sucanat, I recommend that you pulverize it first to make it into a powdered form. It will then blend much easier with the fermented cranberries. If you are using a powdered sugar, you may need up to 1/2 cup to reach the desired sweetness. If the cranberries appear dry, you can add back some of the brine. Decant the fermented cranberry sauce into a jar and refrigerate. It will stay fresh, refrigerated, for about 2-3 weeks, after which time it will begin to turn into alcohol and then vinegar.
You will want to save the remaining brine and use it as a jumpstart for other fruit ferments. You can add the brine to the other ferments in addition to whey and salt.As an alternative, you can use this brine to make a refreshing probiotic-rich beverage. Add 1/4 cup of the brine to a tall glass, stir in a bit of honey or honey simple syrup, and then top off your beverage with some sparkling water for a refreshing "Mocktail." (See the recipe notes for information on how to make a honey simple syrup.)