Did a search on the board to see if there was an existing thread. Since the most recent one is 2 years old, I decided a new one would be good.
I use an old practice of holding over whey as a starter culture. A lot of people don't like this practice -they find it prone to error, contamination, etc. What I have found is that this is true for a lot of people trying to use whey in such a way (nice pun there, eh?) because they are skipping some important steps.
Let's get this right out front: Whey culture is prone to contamination if you do it wrong. But when done right, you ensure that favourable cultures will dominate.
Let's get this out front too: Whey using a whey culture, you are NOT going to wind up with the same strain ratios as you might have used as a mother culture to start the batch in the first place. What you will get is a mixture of cultures that is very well adapted to your make recipe after 2 or 3 times. You will also get a much more complicated family of cultures, which if you preserve your culture properly is a very good thing.
The number 1 misconception I have encountered with whey cultures is that you just hold over a bit of whey and use that to culture the next batch. that is not how you make a whey culture. If you do that, you will have problems and your culture can only last a few batches before it becomes so weak and contaminated as to be useless or even dangerous. What you do is use the whey to process the starter culture for the next day's cheese. But even then, the whey by itself is not sufficient. You need to continually reinforce the culture with your desired strains to ensure they dominate.
Here is how to pass on a whey culture. We will get to why you should do this a little later on. We won't deal with specific amounts or acidity ratings, as those vary from cheese to cheese.
First, you start off with your principle starter culture(s), and make a yogurt out of them.
Use this yogurt to culture your first batch of cheese. It is important that this first batch be made of raw milk.
Hold over a bit of your yogurt.
Make your cheese using very sanitary practices. Before removing the curd, take out about 1 liter of whey. It is recommended that you have a container that you use only for this step.
with the aid of a hot water bath, heat the culture to 61 C, and then immediately cool off to 38 C. Add to a preheated, sterilized thermos to incubate.
Take about 1 T of the yogurt culture you made previously, and add to the whey in the thermos. Close the thermos tightly, and shake well to stir. Put in a warm place to incubate overnight.
Using the leftover yogurt you made the first time, continue to make new yogurt every week using sterilized milk.
Each time you make the whey culture, add some of this yogurt to help maintain a strong culture.
After 5 days, you can use the whey culture to make the yogurt as well. This is needful, as the strains in the yogurt will weaken over time.
You can also use any live culture store bought yogurt to periodically reinforce the culture (this is how the do in the Alps, and it works well, so don't be afraid of it)
The most important factor is that the make recipes of a lot of these cheeses are specifically formulated (over a period of centuries of trial and error) to target good bacteria and encourage their growth while killing off or greatly weakening any undesirables or pathogens. Also, the flash heating and cooling of the whey serves to give the desired thermo cultures a boost, and kill of anything else. This will kill of MOST of the wild cultures in the raw milk.
After doing this at least 5 times, you should be able to use this culture in pasteurized milk and still be able to achieve something close to the full raw milk flavor profile.
I also use this whey culture to inoculate yogurt. I always thoroughly cook my milk when making yogurt (this breaks down fats and other proteins which causes the yogurt to set up faster and thicker without becoming overly sour, and without needing any starches or dehydrated milk) But by using my whey, I basically end up with the bacterial profile it would have had with raw milk, but I also ensure that my good cultures will dominate. And by the why, Swiss alpine cheese culture makes some great yogurt.
I also recommend that you periodically take portions of your culture and deep freeze it. It can keep a year or two under these conditions, although you will need to restart it using an intermediate batch of runny yogurt.
If you do this, you place the culture in reserve and have a backup in case of contamination or weakening of your strains. This is also what you do with a whey culture if you do not make cheese every day, and cannot proceed with the daily incubation cycle.
Now here is one important thing to note. If you do not make cheese every day, DO NOT use a straight whey culture. It won't work, you have no way of controlling the strength and the culture will probably continue to grow until it becomes so acidic as to kill itself. Instead, use your whey to make yogurt and use that as your starter culture. This way, you have total control over your culture.
Now here a few reasons why you might choose to do this:
-A whey culture establishes a complex set of bacteria, which since they are drawn directly from the finished cheese are ideally suited to your recipe. (this also makes consistency an important practice)
-You can establish a complex set of safe wild flora which can be used to give pasteurized milk a full flavor profile (you are reintroducing the wild strains)
-You can use anything as a starter, such as yogurt. After 2 or 3 rotations you will have established a set of strains pretty true to your cheese's traditional cultures (with the exception of a few exotic ripening agents). NOTE: This is how the local cultures used for cheeses came about in the first place, they are a direct result of the cheesemaking process. It actually doesn't take hundreds of years to develop a genuine culture for, say, an Alpine or Emmental style cheese. All it takes is a few batches. (Note that the makers of Emmentaler cheese traditionally do not add an PS powder, because it is already in your milk they just cook the milk in such a way as to encourage its growth) The cheesemakers in Switzerland actually make a new batch of culture every year. They are not passing down a collection of strains that has been preserved since the middle ages.
I will repeat this over and over again, so it sticks. In the tradition as I learned it, they start off with a few basic thermo cultures, but the ripeners and flavoring cultures are almost entirely derived from the milk. The cultures that flavor Berner Alkäse, for example, are selected not in a laboratory, but by the process used to make the cheese. Also, the methods used in preparing the whey for incubation help to further isolate desired strains.
Using a whey culture helps you to appreciate how the way you handle a cheese has a significant effect on its flavor. When we use isolated lab cultures, it's easy to get certain results. But then we no longer understand the consequences of our actions as cheesemakers, because we have shielded ourselves from them. The different flavors of our cheeses (with the exception of modern lab made 'Frannkencheeses') developed from wild cultures. Many traditional cheesemakers in Europe actually still to this day isolate their own cultures each year. It sounds kind of mystical and all that, but it's really pretty simple. But the amazing thing about this is that they have done this in some cases for thousands of years without having any idea what it was they were doing. They understood the consequences of their actions, but not the science of it. Today we understand the science of it, but not the consequence of action. Personally, I prefer the former.