How to Second Ferment Kefir: The Ultimate Guide
Kefir, whether the milk or water variety, is delicious, fun to make, and incredibly nutritious. But there are also those of us who might find the sharp and sourness of finished raw kefir a little harsh on the taste buds. People who prefer their kefir on the less sour side are usually advised to stop their ferments earlier so that they do not become so potent.
If you are one of those who are inwardly saying ‘but the whole point of this is to make a potent probiotic for myself – packed with nutrition!’ you might have come to the answer: Second ferments!
Like Kombucha fermentation, you can also do a double ferment on kefir to improve the flavor and texture. It follows that you should already know how to make your basic kefir. If not, them make sure you read that article first!
Second ferments are a great way to reduce sourness but at the same time extend fermentation time – which also results in higher nutritional and probiotic levels.
The Benefits of Second Ferments
Secondary fermentation, while simple to do, might sound like a waste of time when you have just harvested and are ready to bottled and refrigerate your fermented kefir. It did to me when I first heard about it!
But if you like less harsh tasting kefir, and still want a properly matured ferment, second fermenting is the perfect solution. Secondary fermentations in milk kefir also lower the levels of lactose present in kefir, a big plus for the lactose intolerant or sensitive.
How Your Kefir Changes With Secondary Fermentation
More Complex Tastes
When doing a secondary ferment on a batch of kefir, you have the opportunity to alter the taste quite a lot.
- Reduction in Sourness: For some reason which doesn’t quite make sense – as usually the longer a substance is left to ferment the sourer it gets – letting your kefir go through a second fermentation has the result of a drop in sourness. The aggressive tartness that kefir can sometimes take on is smoothed out and the overall flavor becomes a bit more mellow.
- Creamier Kefir: Another thing which happens to milk kefir which has undergone a secondary fermentation is that it becomes creamier. Quite why this happens we are not sure, but it is a lovely side effect.
- Opportunity to Add in Flavorings: If you are going to do a secondary fermentation, this is a great time to add in additional ingredients to enhance or change the flavor, without risking contamination of your kefir grains by a foreign substance. Because fermentation is still taking place, whatever ingredients you add to enhance the flavor will be incorporated into the bacterial mix, and the flavor profile will be more complex than if you merely added it in when serving or consuming the kefir.
Secondary ferments usually have the effect of increasing carbonation levels in your kefir. This is because secondary ferments are done in a jar with a lid screwed on or clamped down, which means that carbonation building up as the fermentation continues is trapped in the kefir and cannot escape through the usual cloth covering.
Usually carbonation is most sought after in water kefir, as a lot of people particularly enjoy the natural fizzyness of water kefir, and try to make sure that their ferments are as fizzy as possible. Although good levels of fizz is generally thought to be more important in water kefir, carbonation in milk kefir is also desirable, as it is part of the reason why kefir has such a fresh, live taste.
Better Nutrition Profile
Secondary ferments have another great benefit, and this is the rise in nutrients and probiotic bacteria which they cause. If you are wanting to have a less sour kefir, then this is the opposite result to what you would get if you were to practice stopping the fermentation early to reduce tartness.
While some people make and consume kefir merely for the taste, many people want to eat it specifically for its super food like health components, probiotic and otherwise. On a nutritional level these are the things which can happen to kefir if it has undergone secondary fermentation:
- B Vitamins: Milk kefir contains the B vitamins 1 and 12, as well as biotin, a vitamin which helps the body to assimilate the B vitamin family. Secondary fermentation significantly increases the levels of these vitamins in kefir.
- Calcium & Magnesium: Milk kefir contains up to 20% of one’s RDA of calcium, and 5% of one’s RDA of magnesium. Secondary ferments increase the bioavailability of both of these vitamins.
- Probiotic Bacteria: Because fermentation is allowed to carry on for extra time when doing a second ferment, the levels of probiotic bacteria present in the kefir also rise.
The other effect which could have some of your jumping for joy is that secondary ferments reduce lactose levels in milk kefir. The longer fermentation is left to take place, the less lactose will be present. This is because it is the food source of the bacteria, and they eat it up!
Often people who are sensitive or intolerant to dairy will find that they can sometimes consume milk kefir without a problem. Consuming a source of probiotics is highly beneficial for most food allergy cases, including lactose intolerance.
If however you find that even kefir sets off a reaction, but still want to enjoy the probiotic benefits of kefir – and perhaps ease your allergy on the way, then have a look at our post How to Make Dairy Free Kefir.
Are you ready to learn how to second ferment your kefir? Let’s go.
How to Second Ferment Your Kefir
Secondary ferments are very easy to do and should only take about 24 hours to mature, depending on the temperature at which they are stored (the warmer the temperature the shorter the time it will take).
The two main differences between primary and secondary ferments are:
1) There are no kefir grains present in the secondary fermentation and fermentation continues by merely the action of the bacteria which have colonized the ferment and are free floating.
2) The secondary ferment is a mostly anaerobic process – in other words you do not cover the fermentation vessel with a cloth covering but use a screw on lid or a vessel with a clamp down lid.
3 Methods of “Second Fermenting Kefir’
Method 1: Refrigerate It
If you don’t want to do a full ‘second’ ferment your kefir, you can also just bottle your kefir after removing the grains as regular and place the finished product in the fridge. The kefir, even in the cool temperature, will still ferment (but more slowly) and refrigerated kefir takes on a creamy and mellow flavor over a few days. I actually love the taste of kefir that’s directly placed in the fridge for 2 days to a week. You get a sweet, creamy kefir. Assuming you naturally will put your kefir into the fridge after finishing with it, this is something you might do anyways.
Method 2: Make Kefir in the Fridge
You can make kefir directly in the fridge. By adding your kefir grains to fresh milk and stashing the container in the fridge, you’ll get a kefir, but it will take longer. If it normally takes 1-2 days to make kefir outside of the fridge, it will usually take 5 days to a week to make kefir in the fridge. However, you do get a more mellow tasting kefir when you brew it in the fridge (or if you don’t have a fridge, then cool weather that’s 50-60 degrees). Usually less yeasty flavors, less tart, and far creamier.
Method 3: Regular Second Ferment Kefir
Finally, if you want to do the regular traditional second ferment, then you ferment the kefir outside of the fridge with the grains removed. We cover these steps below.
Step 1: Harvest your Kefir
Harvest your kefir at the usual time, Depending on the temperature this will probably be between 24 and 48 hours of fermentation. Remove all the grains.
Step 2: Bottling
Select some glass jars in which to do the second ferment. They must have lids. The best are the clamp down bottling jars, but if you do not have any of these, normal canning jars will work just fine. Pour the kefir into the jars. For a list of recommended bottles for better second fermentation, please read our best kefir equipment article and our best containers for making kefir article.
Step 3: Flavoring (optional)
Now is the time to add in flavoring if you want to – fruit, spices, juice, herbs etc. Some people prefer the plain kefir taste, but flavored kefir can also be very nice. Below this section are some general ideas for flavoring. Note that by second fermenting your kefir, you get a creamier, less sour tasting kefir. So even if you don’t add in any fruits or extra flavorings, we do recommend second fermenting it.
Step 4: Seal and Let Stand
Now seal up your jars tightly and leave them to stand and for fermentation to continue. The general time for a second ferment is between 24 and 48 hours. The ideal time is dependant of course on what the temperature is where you live.
The colder it is, the longer fermentation will take, the hotter the quicker. An 8 hour secondary ferment is suitable for very hot temperatures. If the temperatures are very low, you can even extend the secondary ferment to 72 hours. You can check up and taste the kefir along the way to keep tabs on when to stop the second ferment if you want to.
And that is that! Once you decide to stop the second ferment, you can bottle up the kefir in your usual bottles and refrigerate. If you have added in flavorings, you can either remove these out (with a strainer or by hand), or leave them in if the kefir will be consumed in a reasonable time period.
How to Flavor the Second Ferment
As you can see second fermenting kefir is super simple, and you can get some great results. Not only do secondary ferments cause a lessening of sourness, reduced lactose levels and increased nutritional levels, but it also provides an opportunity to add in ingredients and experiment with flavoring.
Why Secondary Ferments are a Good Time to Add Flavoring
Usually it is not recommended that one add in any sort of flavoring to the fermentation process. This is because foreign substances can contaminate your kefir grains and have a harmful effect on them. Additional ingredients in the primary fermentation can also sometimes mess with the fermentation process itself.
But because the kefir grains are not present during a secondary fermentation, this means that you can add in anything you like without it affecting your kefir culture in any way.
What happens when you add flavorings to the kefir when it is still fermenting:
With milk and water kefir, people often flavor their finished kefir before they consume it by doing things like blending it with fruit, mixing in fruit juice, adding spices or things like vanilla essence, adding honey etc. While one can come up with some yummy combos like this, flavoring the second ferment can introduce a whole new level of flavoring experimentation!
When fermentation takes place, there is always a change in taste that happens. Kefir and yoghurt taste very different to the milk from which they are made, the same is true for most fermented products like beer, wine, vinegar and sauerkraut. When you add an ingredients into the kefir which is still fermenting, that ingredient will be fermented too, and the flavor profile of the finished kefir will be more unusual and complex than if you merely mixed in the ingredient before consumption.
Flavoring Ideas for The Second Ferment
What all you can add into the second ferment, and what flavors you can aim for are almost endless! Here are some ideas to get you inspired:
Sweet Kefir Flavors
Flavoring kefir with fruit, sweeteners such as honey and/or spices is very popular. You can do this with milk or water kefir. The additional sucrose from any fruit of sweetening added will encourage the secondary fermentation as the bacteria will have some new food to process.
- Citrus (you can used pieces of fruit, or thin slices of peel)
- Black berries
- Cinnamon (sticks can be fished out, powder can be left in when bottled for refrigeration)
- Cloves (used very small quantities as it can be overpowering. Goes very nicely with apple)
- Molasses (use sparingly, taste can be very strong)
- Dates or date paste (paste goes further)
- Maple syrup
- Agave syrup (if unprocessed can have lovely caramel flavors)
You can use any combination of fruits, sweeteners and spices to create your own unique flavors. Depending on what you have on hand, what is cheap, what is in season, and your personal preferences, you can come up with some killer combos!
Savory Kefir Flavors
Savory flavored kefirs can make for some yummy probiotic dips and dressings!
Veg & Herbs
……. The list goes on and on!
Tea Flavored Kefirs
Some people also add in different teas to the second ferment. This is usually done with water kefir not milk kefir, as the thin water kefir is more conducive to the tea infusing into it than the thicker milk kefir. The fermentation draws out the flavor of the tea, and the end result can very pleasant. Herbal teas are most often used because of their lovely flavors. Here are some examples of tea which can be successfully used to flavor the second ferment:
- Apple mint
- Lemon balm
- Honey bush (gives a very slight sweet taste)
- Green tea (used more for its antioxidant content than for flavor)
- Lemon grass
- Jasmine tea
When flavoring the secondary ferment with tea, use tea bags, or if the tea is loose, put it the center of a piece of cloth and tie with a cotton string. Do not use a conventional metal tea infuser.
After You Flavor the Kefir
Once your secondary fermentation is finished, you can bottle up your kefir and store it in the fridge. You can either remove the flavoring ingredients or leave them in. If the kefir is going to be stored for over a week, then it might be a good idea to remove the flavoring ingredients – in the case of fruit they can become soft and unappetizing. It can also often be more practical to remove any flavoring ingredients in water kefir before storing, so that there are no bits and pieces floating around when one wants to drink a bottle. But the choice is yours. A small amount of flavor will continue to infuse out, but very slowly as the low temperature in your fridge will almost halt fermentation.
While there is not a lot of info out there with regards to secondary fermenting of kefir, there are a good number of kefir makes who use this as standard practice. Considering all of the benefits a secondary ferment can bring, it is not surprising!
If you have any questions or thoughts, or have dreamed up a yummy second ferment recipe you want to brag about, feel free to use the comment facility.
Happy fermenting everybody!