Course:FNH200/Projects/2022/Kombucha

Introduction

Kombucha is a fermented and sweetened tea beverage created by making use of microorganisms including yeast and bacteria. Believed to have originated in China more than 2,000 years ago, Kombucha has long been used for its suspected health benefits. The drink is rich in amino acids and vitamins and, due to its black and/or green tea base, contains caffeine. While the ingredients and process of Kombucha creation differs, tea, bacteria, yeast, and a sweetener (often sugar) are common ingredients. Fermentation of a SCOBY - a mat of “symbiotic culture of bacteria and yeast” - placed in sweetened tea is responsible for carbonating Kombucha, as well as adding probiotic bacteria which have been linked to benefit gut health and aid digestion. The cultures' yeast interacting with acetic acid bacteria and lactic acid bacteria also inhibits the growth of spoilage causing bacteria, improving the beverages' shelf life. However, alcohol levels found in most Kombucha drinks is a byproduct of carbohydrate fermentation and has been cause for controversy. New regulations force producers to label their bottles with exact alcohol contents and regularly inspect their batches. If alcohol is found to make up 1.1% or more of the drink in Canada or 0.5% or more of the drink in the U.S., the beverage will need to include alcohol-labeling and be subject to strict regulation.

Despite the challenges in commercial production of Kombucha, sales in North America have consistently increased over the last decades. Consumer demand of this “functional” and healthy beverage has contributed to the rise of large mainstream producers and brands of Kombucha; The industry now produces nearly $2-Billion ($USD 1.84 billion in 2019) in revenue each year globally with key brands such as GT’s living foods founded in 1995 leading the market in sales in North America, the worlds biggest distribution region for Kombucha.

GT's Pure Kombucha (Front label)

Ingredients (GT's Living Foods Raw Kombucha - Pure)

Ingredients	Food Identity	Functional Properties	Other Notes
Water	Base ingedient
Kombucha Culture or (SCOBY)	Symbiotic Culture Of Bacteria and Yeast	-Initiates/contributes to fermentation process -Creates fizziness through carbonation -Inhibits growth of contaminating and spoilage-causing (the bad) bacteria -Enriches beverage with amino acids, vitamins, enzymes, and probiotic bacteria	-Yeast and bacteria consume caffeine naturally found in green tea and black tea, as well as reduce overall sugar content
Kiwi Juice*	Natural flavouring Sweetener	-Less processed sugar source -Gives slightly tangy taste
Black Tea*	Base ingredient Natural flavouring	-Fermentation Process -Stimulant -Gives earthy flavour	-Nutrients found in tea (including nitrogen, caffeine, sugar) react with the SCOBY and contribute to the fermentation process
Grean Tea*	Base ingredient Natural flavouring	-Fermentation process -Stimulant -Gives nutty flavour	-Nutrients found in tea (including nitrogen, caffeine, sugar) react with the SCOBY and contribute to the fermentation process

* = Organic

GT's Pure Kombucha (Nutrition and Ingredients)

Additives in Kombucha:

Despite a recent trend towards organic and natural foods, some Kombucha brands use additives such as artificial sweeteners and food colouring, as well as non-natural added probiotics.

Fermentation Process

Fermentation: Often refers to both aerobic and anaerobic carbohydrates by microorganisms

Chemical Equation: C₆H₁₂O₆ (glucose/sugar)→ 2C₂H₅OH (ethanol) + 2CO₂ (carbon dioxide)

Kombucha Processing Steps:

1. A mixture of water, sugar, black tea and green tea is brewed
2. Tea leaves are discarded after brewing is complete
3. The tea is cooled and the SCOBY culture is added in the mixture which will begin the fermentation process
4. The fermentation process takes place over 1-8 weeks at a temperature of around 20-30 degrees celsius, the optimal temperature can vary. During this process, the yeast (SCOBY) acts as a catalyst as it converts/breaks down the sugars into ethanol and carbon dioxide. This would explain why there is little/no sugar, a small trace of alcohol and acidity in the final product.
5. After 2-3 days of fermentation, the mother fungus, which is initially added to start the fermentation process, forms a daughter culture that floats above it. The daughter fungus is a clear gel membrane across the surface of the mixture.
6. After 10-14 days of fermentation, the daughter fungus develops into a 2cm thick, disk-shaped fungus on the surface of the mixture.
7. After fermentation, the cultures are removed. The daughter fungus is preserved in a smaller volume of the fermented tea mixture and is often reused as a new mother culture for future brewing.
8. Additional ingredients like kiwi juice are added to the tea mixture to enhance the flavour.

Flavouring:

The length of fermentation can impact the flavour of the Kombucha. With shorter fermentation, the drink will have a sweeter flavour since less sugar would be consumed by the SCOBY while producing lower alcohol contents and acidity from less ethanol and carbon dioxide formation. With prolonged fermentation, a light vinegar-like flavour in the drink will be produced since the SCOBY would have consumed more sugar while producing higher alcohol contents and acidity as a result of increased ethanol and carbon dioxide formation.

Most bottled Kombucha in stores are sold raw, or unpasteurized, as the pasteurization process would alter the natural flavour and kill off all bacteria through thermal processing. This includes killing off the good, needed bacteria and yeast that contributes to the beverage's carbonation and supposed health benefits. Most commercially bottled Kombucha implement food safety measures that reduce the risk of potential food poisoning, allowing safe consumption of raw Kombucha. Additionally, the low pH and acidity produced from the fermentation process reduces the growth of spoilage-causing (the bad) and pathogenic (the ugly) microorganisms **More Detail in the Next Section**

Preservation Properties and Additives

Preservation for Storage

Following the fermentation process, raw Kombucha is stored at or above 20 degrees Celsius. In that state, the microorganisms are still capable of forming a biofilm, continuing fermentation. While commercialization has progressed in its knowledge of Kombucha tea storage, there are very little preservation possibilities that allow long term storage.

Proper, effective preservation of Kombucha requires killing these microorganisms without fully removing the good bacteria, which would compromise the flavour and features of the drink. Physical, such as heat treatment, and chemical treatments are both common methods of killing these microorganisms.

Heat Treatments:

Although heat is an effective preservation method in term of food safety, it is somewhat unsuitable for Kombucha preservation as it negatively influences the clarity, taste, and flavour of the tea, as well as reduces the beverage's natural stability in storage. Pasteurization is generally unnecessary for Kombucha since the acidity and sugar of the drink also help with preservation. Sugar-free Kombuchas are inherently shelf stable.

However, Kombucha brands with more sugar may offer pasteurized versions, as the added sugar allows more fermentation, changing the flavour and alcohol content of the beverage. These pasteurized teas, while fully shelf stable, also lack the beneficial microorganisms that many consumers look for in Kombucha. The heat treatment reduces the tartness and acidity in the flavour of the drink, and can reduce some nutrients.

Natural and Chemical Treatments:

The nature of Kombucha allows safe consumption from measures taken during the fermentation process. The interaction of the SCOBY with developed acetic acid and lactic acid bacteria naturally inhibits the growth of bacteria related to spoilage. The treatments for processing also have a negative effect on the antioxidant properties.

Acidity as a Natural Treatment:

We have learned in FNH 200 that acidity can determine rates of chemical, enzymatic reactions, survival and growth of microorganisms. Microbes have a hard time withstanding environments of either low or high PH levels. Similar to the effects of temperature every organism has a range of PH levels it can survive in, that limits where they can grow. For example, the common foodborne germ Salmonella spp. can only survive in the pH range of 3.8 to 9.5, with an optimal range of just 7 to 7.5. This is the same reason that foods like citrus juices, and pickled foods commonly with a pH of (0 - 4.6) are categorized as acidic foods. Kombucha would fall into this category as its pH level varies around 2.5 - 3.5. Kombucha's acidity level is dependent on its brand and fermentation duration as shown in figure 1.

Figure 1. The effects of Kombucha fermentation time vs the resulting pH level

This low pH created by the fermentation is one of the main natural preservatives of Kombucha. Paired with refrigeration, raw Kombucha can be kept for up to 8 months. While it does not necessarily pose a large risk after that point, it may lead to toxicity of the liver and inflammation due to the continued fermentation, as well as spoil in flavour and colour.

Packaging and Labelling

Packaging

Due to the formation of organic acids during fermentation, the most suitable containers for Kombucha production are glass or stainless steel to avoid corrosion (toxicity can occur due to the migration of toxic compounds from lead and ceramic containers to the Kombucha during fermentation).

After the Kombucha has fermented, it can take different paths. If the consumer wants a plain and not carbonized drink, then the Kombucha will be bottled and refrigerated. Otherwise, a second fermentation is done to add flavor and carbonate the Kombucha by adding a source of sugar or fruit juice and maintaining room temperature.

Bottling is required to create carbonated Kombucha, so choosing the correct container is crucial: using airtight glass bottles is ideal, since for the carbonation to happen it needs a closed environment and glass containers have less risk of corrosion. When the Kombucha is going through the second fermentation, carbon dioxide is building up inside the container, which can turn into a physical hazard if not controlled.

If the manufacture is trying to carbonate the drink, then opening the bottle to release the pressure is a good practice (method known as “burping”). If the drink has finished the second fermentation process and is ready to be stored, the fermentation of the Kombucha needs to be stopped or slowed. Hence, it is refrigerated.

Labelling

Alcohol Content:

Even though Kombucha is a non-alcoholic beverage, it contains low levels of ethanol (due to the fermentation process). According to the Food and Drugs Act, beverages with alcohol level greater than 1.1%  by volume (ABV), must declare the alcohol content on the label. Therefore, Kombucha companies must include the alcohol content if it exceeds this limit. However, GT's pure Kombucha does not exceed this limit and does not need to label its alcohol content. Alcohol is also often seen in media as a disinfectant, while it may be true for ones of higher concentration, drinking alcohol usually do not have this property due to their nominal alcohol percentage. Therefore, the alcohol content in beverages like Kombucha do not contribute to its preservation factor.

Added Sweeteners:

If the Kombucha has sweeteners, that must be included on the label. GT's pure Kombucha has kiwi juice as a sweetener. Other Kombucha brands or products that offer other flavours may have different added sweeteners.

Health Claims:

Health claims in labelling means that there is a suggestion or assertion that a relationship between the consumption of the food and health exists. These claims are subjected to the General Principles for Labelling and Advertising.

A probiotic claim could be the term “probiotic” and similar terms or the phrase “with beneficial probiotic cultures”. Kombucha companies can make these health claims if following the Health Canada's guidance document, The Use of Probiotic Microorganisms in Food (Health Canada, 2009). These are some summaries of the conditions of use for probiotic claims:

• The use of "probiotic" and other similar terms and representations should be accompanied by specific, validated statements about the benefits or effects of the probiotic.
• When making any probiotic claim, the manufacturer of the product should have documentation supporting the identification, safety, viability, concentration and stability of the probiotic.
• The food should contain, at a minimum, the amount of the probiotic microorganism(s) required to result in the claimed effect or health benefit throughout the shelf life of the product.

Organic:

If the Kombucha is certified organic by the Canadian Organic Standards, then it can be labelled organic.

Exam question

According to the Canadian Food and Drugs Act, which level of alcohol content per volume would require producers to include it in the label?:

1. Equal or greater than 0.5%
2. Equal or greater than 1.1%
3. Equal or greater than 3%
4. Does not need to be included for a non-alcoholic beverage

(Answer: 2)

This could be a good exam question, since it is about the label requirement for beverages that contain alcohol. It is a good remark of the labelling content we studied in class in addition to familiarizing ourselves with the Government resources used to identify Canadian food regulation.