Making your own ferments and brews at home may follow many different recipes. Now keep your batch safe, healthy and tasty by following these simple basic procedures.
Kombucha Mushroom Tea
Preserving Your Brew
by Ed Kasper LAc. Acupuncturist, Herbalist, & Homeotoxicologist
Kombucha Tea like other food and drink go through the same "checklist" for freshness and acceptability. Fresh fruits, vegetables, meat and drinks are first visible inspected, then sniffed, and lastly tasted for acceptability.
Taking simple precautions can effectively control molds, viruses, and bacteria like e.coli and botulism that might grow.
Low pH (meaning high in acid) is the precaution that safeguards Kombucha Mushroom Tea and all home ferments. According to research by Cornell University Food Science the typical kombucha mushroom tea ferment (9 day ferment at 79F (26C)) produced a pleasant healthy kombucha tea with an average 33-g/L total acid (7 g/L acetic acid) and a typical pH of 2.5. This coincides with my experience of the common home fermenting recipe for making kombucha.
By comparison the acetic acid concentration typically of table vinegar is 4-8 % and pickling vinegar as high as 18% acetic acid. Braggs Organic Apple Cider Vinegar is 5.14% acetic acid with a pH of 3.07.
The pH meter is an electronic instrument used to measure pH for testing home-processed or home-canned foods ...Paper strips that measure pH are not that accurate and rely on a color change in the paper. Therefore, paper strips would not be applicable for testing acidified or acid foods for sale
reference: Pickle Bill Fact Sheet Fact Sheet for Certain Home-Processed and Home-Canned Foods
The acidity, temperature of fermentation, and the availability of oxygen determine which microorganisms dominate, and determine the flavor and character of the end product. For example in pickles when both salt concentration and temperature are low, Leuconostoc mesenteroides dominates where higher temperatures Lactobacillus plantarum dominates (McGee 2004, p. 291-296). Kombucha, which is primarily an acetic acid ferment has an optimum temperature range is 74F - 84F. For the differences temperature can make in kombucha ferment see our Kombucha Research Library.
The distinguishing feature is pH less than 4.6, which is sufficient to kill most necrobacteria. You should be able to keep your kombucha tea below 4.0 pH and a nice pleasant taste.
Antimicrobial herbs and spices, such as ginger, garlic, cinnamon or cloves, may also be added.
When is your Kombucha Mushroom Tea ready?
On day 1 of the fermenting process the pH may stand at ~ 6.9 pH. The pH should go down slightly each day as the ferment continues. Typically 9 days at 80 F (26C) or 14 days at 74 F (24C) the pH is under 4.0 pH Temperature is a critical factor and may be controlled by heating pads. The longer the ferment the more sour and the less sugar, the lower the pH (the more acidity)
Taste as an indictor. Some people rely upon taste only. Seeking the characteristic semi-sweet cider taste. The acetic acid is associated with the vinegar taste. The sharpness or kick that most people like in their Kombucha Tea. Gluconic acid, a major component of kombucha tea soothes the harshness of the acetic acid. Lactic acid is also smoother than acetic acid and some kombucha tea may be higher , or have no lactic acid. Therefore not every ferment will have the same quality of taste. The ratio of gluconic acid to acetic acid is a balance we strive for in a kombucha ferment. Our fermentation method produces about a 2% (1g/L) gluconic acid. The other major component identifying kombucha tea is fructose. (4.8 g/L). To a first time brewer should use the pH, not their taste buds, to determine when the brew is ready to bottle. However, one may drink a fresh brew at any point. If you are bottling and refrigerating simply to be able to drink your kombucha in a few days than there is no worry. Treat your kombucha as you would any other drink.
Bottling & Preserving Your Brew
We suggest selecting a size bottle that you will finish within one or two days. This is prevent the brew from going flat or sour. Similar to the demise of soda, beer or wine that once has been opened loses their appeal.
Cleaning, sterilizing, and hygiene are important and integral part of the process.‰Û¬One method is to Place bottles and utensils in a container filled half way with warm (120 to 140 F) water. Then, add hot water to a level 1 inch above jars. Heat the water enough to maintain 180 to 185 F water temperature for 30 minutes. Check with a candy or jelly thermometer to be certain that the water temperature is at least 180 F during the entire 30 minutes.
Kombucha home brewers and home wine makers to sanitize equipment and bottles often use iodophor. This feature is important because kombucha and other ferments rely upon the health of specific bacteria and yeasts while still having the necessity to eliminate other either competing bacteria and yeasts and /or pathogens. This is a major advantage over other sanitizers that may leave toxic residues. It is also non-toxic to humans and therefore especially suited to food processing applications.
This is a simple process where you strain your kombucha through a layer of cheesecloth. Coffee filters clog up pretty fast. I usually have one fine mesh strainer first and right below a few layers of cheesecloth. The more filtering the greater the reduction of possibly containments as well as the reduction of beneficial bacteria and yeasts. The taste becomes "lighter" with filtering. Beer and Wine shops have filters in the micron range preventing further fermentation or spoilage of the product.
Filtering will actually weaken the kombucha taste but should produce a more clear, sparkling beverage that looks appealing as well. Another method of clarifying your ferment is Bentonite Clay This amazing healing clay is an effective natural intestinal detoxifying agent as well. Also there is Gelatin, which helps rebuild cartilage and is effective in reducing harsh flavors and aromas. Helps to keep the sediment on the bottom rather than floating around.
Flavors are often added to create taste sensations as well as off-setting an otherwise sour undrinkable brew. There is also the option of adding the advantages of medicinal herbs,
it is had to accurately know how much sugar or fructose remains. Cornell Study indicated 5% (4.8 g/L) glucose after their typical 9 day ferment (pH 2.5). Their initial sugar start was 10 g/L.
Stevia is sweet and does not ferment.
Fructose and other sugars will ferment while sweetening the brew see also Secondary Fermentation.
Calcium Adds FIZZ and decreases the acidity/ (use 1/2 tsp. per gallon or about 1/4 of a calcium pill/capsule per 16 fl. oz. bottle or a pinch or two to a glass of kombucha.) This was done with the German KOMBUCHAL of the 1920's and Dr Robert Barefoot (The Calcium Factor). http://tinyurl.com/2wzbcb
Potassium Bicarbonate, 3-4 grams reduces acidity by 0.1 pH
Gypsum is added to raise acidity, use 1 tsp. per 5 gallons.
Flavoring can be added just before bottling. Herbal additives include ginger, cayenne, elderberries, ginseng, goji berries, or any combination of dried or fresh herbs.
A few pieces, may be added right to the bottle before capping, For example a slice of Ginger, a piece of apple or fruit, some GoJi berries
Another method is to stop your kombucha a day or two earlier, filter (if you prefer) and place in another container. (keep your kombucha mother mushroom and starter tea separate and ready to begin a new batch when you're ready). Place flavoring, or herbs in a small cheesecloth bag and place in the container with the kombucha tea you set aside for bottling. Sit in a warm spot for 2-3 more days. This allows you to better determine the actual taste, though it will change as it goes through bottling. Adjust the amounts to taste, but be careful not to overload the kombucha. Too much vegetable matter can destroy the acid and ruin the preservative quality of the kombucha tea.
Kombucha is now ready for storage in separate, capped bottles. Stored kombucha will stay in excellent condition almost indefinitely.
Options 1: Pasteurization. To pasteurize, heat the kombucha before pouring it into sterilized bottles, or bottle, then place in a hot water bath. In both cases, the temperature of the kombucha must reach at least 140 degrees F and should not exceed 160 degrees F. Use a cooking thermometer to ensure the correct temperature is met. Cool the containers and store at room temperature out of direct sunlight. Pasteurization kills off all life forms in effect killing off the probiotic bacteria and yeasts as well as any potential pathogens. The remaining nutrients, and aids are still extremely beneficial and the brew is still flavorful.
Option 2: Potassium Metabisulphite, Sorbistak-K, or Camden tablet are chemicals added that will kill or prevent present fermentation from taking place. It also prevents pathogenic growth from taking place. Follow the directions with the package. note: often these are used as sanitizers and cleaning agents for fermenting equipment and bottles.
Yes, even vinegar (or kombucha tea) can go bad.What happens to the acetic bacterium when they run out of food (preferring alcohol to food (sugar), the drunkards) they begin eating the acetic acid. The acetic acid becomes carbon dioxide and the vinegar or kombucha mushroom tea turns into water. Nutritious water perhaps but never the less not very well protected. Pasteurization or chemical stabilizers kills the bacterium and saves the acetic acid preventing possible contamination. At some stage when the bacterium have been starved and inactive and the acetic acids are low (high pH >4) other pathogens may take advantage. The danger lies in the opening and closing and reusing the bottle of kombucha (or vinegar). There is the danger of cross pollution and exposure to airborne or wild pathogens that may enter the bottle and then be given the opportunity for growth (here-to-before limited by the acetic acid and acetic bacterium). If choosing option 3, keeping your kombucha mushroom alive and fully probiotic then consider adding a small amount of alcohol or sugar to a opened and unused bottle. note: as long as the probiotics are active then there would be no need to add anything. The taste should be semi-sweet. Again the pH should be below 4.6. If the pH has gone up since you bottled it that is an indication that your bottled ferment is beginning to lose its anti-pathogenic properties.
Option 3; No chemicals or pasteurization, keeping your kombucha as raw and live as possible. Relying upon the acid content to be sufficient to ward off pathogenic growth. This is the most common home-kombucha method and outlined above in describing the pH.
If you choose to pasteurize then simply cap and bottle.
Choosing to Leave an airspace
Commercial ferments usually use stabilizers like Potassium Metabisulphite, Sorbistak-K or sulfites to control the ferment. Sulfur is released and collects in the airspace above the liquid. If he airspace is not sufficient than the sulfur will re-dissolve back into the ferment giving off a terrible taste. When the bottle is opened it breathes and the sulfur escape. If you are using these stabilizers to preserve your kombucha then leave an airspace, otherwise kombucha does not need any room.
Choosing to leave your kombucha as raw and vibrant as possible then the bacteria will continue to convert the alcohol to acetic acid (becoming increasingly more sour) and compete with the yeasts for the remaining glucose as long as there is oxygen or airspace in the bottle and temperatures are in the range of 70F-85F.
The yeasts do not require oxygen and will remain active as long as glucose is present. The yeasts will switch to an anaerobic (without oxygen) ferment when there is no available oxygen. The yeasts produce carbon dioxide (carbonation / fizz) when oxygen is present. Carbon dioxide (CO2) suffocates/diminishes the bacteria, but produce the fizz and sparkling brew. Without oxygen the yeast produce more alcohol. One effect may be more alcohol present (still less than 1/2 of 1) but no additional acetic acid created as the bacteria rely upon oxygen. The yeast may be active in temperatures as low as 40F (5C) with or without oxygen.
Leaving your freshly bottled kombucha on the counter at room temperature will allow additional fermentation to take place. This is usually done to increase the carbonation and the fizz. Normally 2-3 days is sufficient.
using Plastic Bottles one can easily tell when the time is right as the bottles will be hard and possibly balloon out of shape. Glass may explode and is dangerous when children are present. If using glass then place the Glass bottles in a large plastic bucket or tub. I prefer to use glass bottles but also have one same size plastic bottle that is the sacrifice goat or canary in the coal mind. The plastic bottle indicates the amount of pressure that has built up and its easier to judge when this stage is finished and should then be refrigerated and taken to the Cold Stabilization phrase.
Now you could bottle right from the tap if you're doing the Continuous Brewing Method or do any of the other options outlined so far. If you refrigerate right away the taste will stay pretty much the same with a slight more mellowness.
Cold Stabilization. Kombucha mellows out with what is referred to as "Cold Stabilization" this soothes out the acids, and other insoluble solids to separate and precipitate out as crystals. This takes the bite out of an otherwise sharp ferment. The harsher acids are reduced while the more tantalizing acids and flavors are allowed to come through.
Since the alcohol content of kombucha mushroom tea is extremely low (less than 1/2 of 1%) the critical low temperatures for wine cold stabilization is not necessary. A few days in the refrigerator is all that is necessary.
Regardless of the options used above your bottled Kombucha Mushroom Tea should be kept in a cool dry dark place until ready to be served. If you prefer your Kombucha Tea cold, chill before serving or pour over ice.
If you're feeling your Kombucha Tea is not quite ready to be bottled, that you need to create some more character, or that its too sweet preferring a dryer taste, or wanting to create a more Kombucha Champagne then consider first doing a Second Stage Fermentation.
see How To safely make Kombucha Tea.
In our opinion the safest, easiest and best way to make great Kombucha Tea is the Continuous Brewing Method
Ed Kasper L.Ac, Acupuncturist & Herbalist
417 Laurent St. Santa Cruz, CA 95060
toll free 1-888-425-8827 local 831-425-8801
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The following links provide information on home processing and home canning
• USDA Complete Guide to Home Canning (PDF: 275 KB / 23 pages)
• Home Food Preservation
• Colorado State Food & Nutrition Fact Sheets
• Home Canning
Adding Flavors and Safe Bottling Tips to Preserve your brew