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Yogurt (also spelled yoghurt, or yoghourt) is a thick or semi-solid food product produced thought fermentation of milk, using bacterial cultures ( Lactobacillus bulgaricus and Streptococcus thermophilus). The milk coagulates when a sufficient quantity of lactic acid is produced. Yogurt is a rich, versatile food capable of enhancing the flavour and texture of many recipes. It is prepared sweetened or unsweetened, and is used in baking to make yogurt-flavoured cream cakes, desserts, and frozen products.


Roots of Yogurt

Yogurt is a very ancient food with no single origin. Yogurt can be found in almost every culture that has kept animals for milk and it is likely that it is discovered in similar ways in each region[1]. However, According to some historical scripts, yogurt is believed to have been eaten as far back as 10,000 to 5,000 BC. It is possible that the earliest yogurt was made by accident in Mesopotamia around 5,000 BC, when milk-producing animals were first domesticated. Additionally, some historians also believe that Yogurt originated in the Tigris-Euphrates Rivers. However, the wide spread popularity and prevalence of yogurt in the world is through Travelers from Mesopotamia that introduced it to other parts of the world. Middle-Eastern immigrants are believed to have first introduced yogurt into the Americas in the 17th century. Moreover, according to historians the word yogurt originates from the Turkish word 'Yogurmak', meaning to thicken or to ferment. However, today it is known as 'Yogurt' as the common American spelling. [2]

A depiction of meal with yogurt from Tacuinum Sanitatis, a medieval handbook on health and well-being

Ancient Culture of Yogurt

Yogurt has been a staple in Arabic, Turkish, Indian, and Russian cuisine for centuries. It is generally agreed among historians that yogurt and other fermented milk products were discovered accidentally because of milk being stored by primitive methods in warm climates[2]. For thousands of years, yogurt has been seen as a sort of super food, with not only physical benefits but also religious and spiritual power. The ancient Indians saw yogurt and honey as the “food of the gods,” and Genghis Khan, founder of the Mongol Empire, fed his army yogurt for bravery. In the Bible, it is said that Abraham’s longevity and health was due to his consumption of yogurt and the promised land of Canaan was also designated the “land of milk and honey.”[3] There is a folklore too linking yogurt consumption to longevity, it is known that the people of Bulgaria had a longer than average lifespan and many scholars and historians believe that this is due to the large quantities of yogurt that they consumed. Furthermore, in one of the folk tales it is told that The French King, Francois I, was cured of a mysterious intestinal ailment by a doctor, who fed him yogurt. After his recovery, the doctor left Constantinople, taking with him the trade secret[2]. Therefore yogurt has a long history with diverse culture all around the world.

Modification and Transition of Yogurt into the Contemporary World

Yogurt has a rich history, but its intriguing that even in most ancient times, the health benefits of yogurt were known and recognized, in spite of its no definite origin. Today, variations of yogurt are known by many names other than yogurt, including 'dahi 'in India, katyk'' in Armenia, leben raib' in Saudi Arabia, skyr' in Iceland, sua cha' in Vietnam and many more. Yogurt is also often used in cooking to make sauces and dips such as 'tzatzikis and curries. The new trend of Yogurt in the contemporary world is the inclination of consumers to opt for low fat or non fat yogurts for their perceived health benefits. Hence, Yogurt is a not only a nutritious food, but a timeless and global one, that has been invented, modified, and devoured throughout the history by different cultures. Yogurt continues to be popular and will evolve further with our changing tastes.[3]

Producing and Processing


Yogurt is usually made with cow's milk.[4] Milk from other animals might also be used, including sheep, goats, and camels. Yogurt is made by adding certain bacteria to milk in a carefully-controlled environment and allowing it to ferment. The fermentation process gives yogurt its consistency and tangy flavor.Stabilizers may also be used in yogurt to improve the body and texture by increasing firmness, preventing separation of the whey (syneresis), and helping to keep the fruit uniformly mixed in the yogurt. Sweeteners are flavors and fruit preparations which used in yogurt to provide variety to the consumer.

Dairy products: concentrated skim milk, non fat dry milk, whey, and/or lactose.

Stabilizers: alginates (carageenan), gelatins, gums (locust bean, guar), pectins, and starch[5]

Sweeteners: glucose, sucrose, and/ or high-intensity sweeteners (eg. aspartame, sucralose)

Other flavours: assorted fruits, natural and artificial flavouring[6]

General Yogurt Processing Steps

yogurt processing

Adjusting Milk Composition and Blending Ingredients

Milk composition may be adjusted to achieve the desired fat and solids content. Often dry milk is added to increase the amount of whey protein to provide a desirable texture. Ingredients such as stabilizers are added at this time.[5]


In order to prevent deactivation of the bacterial cultures needed in yogurt production, milk is pasteurized at 185°F for 30 minutes or 203°F for 10 minutes prior to the addition of the cultures. The high heat also denatures the whey proteins, which allows the yogurt to form a more stable gel. Lastly, pasteurization effectively kills disease-causing bacteria.[7]


Not all yogurts are homogenized. If this step is taken, the ingredients are mixed well to ensure a more stable consistency.[7]


The milk is then heated to 200°F for 10–20 minutes, depending on the desired thickness of the yogurt. Holding it longer will result in a thicker yogurt.[7]

Cooling and Inoculation

The mixture is then cooled rapidly to 112–115°F. At this point, the warm mixture is inoculated with the live bacterial culture.[7]


The mixture is incubated for 4–7 hours at 105–115°F. The bacteria used in making yogurt are thermophilic and this is their optimal temperature range; they are killed above 130°F and do not grow well below 98°F. Yogurt will become firm when a pH of 4.6 is reached. Incubating the mixture any longer will result in an increased acidity and more sour taste.[7]


When the desired pH is reached, the yogurt is cooled to around 45°F to end the fermentation process.[7]

Addition of Fruit and Flavors

For set style yogurt, fruit is added to the bottom of the cup and the inoculated yogurt is placed on top of the fruit prior to fermentation. For Swiss style yogurt, fruit is mixed with the yogurt after the fermentation and cooling steps. The yogurt is then packaged; at which point, it should be refrigerated at 40°F or lower.[7]


The yogurt is pumped from the fermentation vat and packaged as desired.[5]


As researched there are totally four ways for us to preserve our yogurt longer.

  1. Prevent cross-contamination : People should not eat straight from the pot, they should take them into their bowl individually and then enjoy the yogurt. Also, when they eating the yogurt, they should also make sure about that their spoon is clean.[8]
  2. Seal it tightly: Using airtight container to maintain the odours of your yogurt, you can also preserve it in the original pot but don’t forget use lid to cover it.[8]
  3. Don’t store it in the door of your refrigerator : The most efficient way to preserve your yogurt in your fridge is keep it in the back fridge because it can keep yogurt in a cool and consistent condition. Sometimes small chanegs can possible have huge influcnce.[8] It should be cooled and stored at refrigeration temperatures (40°F or 5° C) to slow down the physical, chemical and microbiological degradation.[9]
  4. Freeze your yogurt: Although freezing yogurt may change the texture of yogurt like its taste and how smooth it feels like, you can still use it. You can use it as important ingredient of delicious cake. Yogurt can be frozen up to one moth so that people can still enjoy it.[8]

Sensory Properties

When people talk about the types of yogurt there are thousands of yogurt people can find; however, they all have the common predominant taste which is sour. As different procesing method and preservation time, yogurt will have different consistency, smooth and sour level taste. If people who preferred sticky yogurt, they should choose whole milk because as increased level of fat in milk the yogurt will become more sticky. Also, there are some people who preferred sour yogurt, people can preserve yogurt in room temperature for longer time but not too long to go bad. For preserving longer time can make yogurt process fermentation so yogurt will become sour than before.[10] Also, there are some fruit yogurt with different kinds of fruit in it which helps people can not only enjoy yogurt but also their favourite fruit.


For the purposes of understanding nutrition in yogurt we will examine flavored yogurt in contrast with regular/light yogurt. The following will be covered in the these sub-topics: sugar, calories and protein, and additional ingredients.

Sugar: The majority of yogurts contain around 26 grams of sugar. Some brands have up to 34 grams of sugar per serving-- more than some energy drinks and slightly less than a can of coca-cola. Conversely, light yogurts, typically, add low-calorie sweeteners to reduce the amount of sugar and calories. Examples of low-calorie sweeteners that are added include: stevia, aspartame, and erythritol.[11]

Calories and Protein: There are roughly 170 calories in most flavored yogurts. Light and non-fat yogurt contain a significantly decreased calorie count, however, many contain artificial thickeners and sweeteners.[11]

Additional Ingredients: Thickeners that are added include: corn starch, pectin, locust bean gum, gelatin, and citric acid as a flavor enhancer and preservative.

Regulations in Canada

The use of probiotics in yogurt raises questions as to the safety and regulation of this product. Yogurt, a popular food item often used in diets as a snack various other food recipes contains probiotics and, consequently, issues such as probiotics in the Canadian marketplace, regulations, safety, health claims, misleading claims, the application and impact of guidance documents are all points of concern. The intake of probiotics is safe. This will be shown by looking at what probiotics are, and health Canada regulations on the use of probotics.

Probiotics are microorganisms that are believed to have a positive impact on one’s health. Live bacterial cultures are also represented as probiotics. Example food items are yogurts, cheeses, and milk-based beverages. Along with this, probiotics are also contained in pharmaceutical dosage forms. This includes tablets and capsules as natural health products. As such, probiotics may be consumed as a natural product or as a food product. Among the many benefits of consuming probiotics are a reduction in gastrointestinal disorders, intestinal discomfort, and possible prevention of diarrhea, irritable bowel syndrome, colitis, and the development of colon cancer. Fundamentally, it is for these reasons that the consumption of probiotics is popular amongst many and serves as a beneficial addition to food items such as yogurt.

It is the addition of probiotics to yogurt that raise the issue of regulations. According to the Food and Drug Regulations "live bacterial cultures, including those represented as "probiotics", are food ingredients and can be added to food products.[12] As mentioned above, the role and use of probiotics are two: first, the use of probiotic in food products and, the second, probiotic in pharmaceutical dosage forms. Regarding probiotic in food products, although no specific regulations regarding probiotic bacteria in foods exist, the general requirements are stipulated regarding microorganisms which include microorganisms represented as probiotics.[12] Regarding the natural health products, manufacturing, packaging, labelling, and importation is regulated under the Natural Health Products Regulations. Furthermore, bacterial cultures in food products are ingredients acceptable for use under the Food and Drug Regulations. Finally, concerning health claims, “all claims and representations on food products be truthful and not misleading, deceptive or likely to create an erroneous impression about the product.”[12] Health Canada has posted a document entitled, “The Use of Probiotic Microorganisms in Food” which elucidates acceptable health claims for probiotics in food. This document is then investigated by the Canadian Food Inspection Agency (CFIA) to examine whether food products containing microorganisms represented as probiotics are consistent with the Food and Drugs Act and Regulations.[12] To summarize, probiotics are a healthy and beneficial food choice and could also be classified as safe for consumption.

Lactose Intolerance

Lactose is a natural sugar that can be found in dairy products as well as in breast milk. Lactose is the main nutrient for babies and children, but its consumption is also very common in adulthood. Once it reaches the intestine, lactose is normally split into two other sugars, glucose, and galactose, by lactase a digestive enzyme in small intestine. [13]

As an individual gets older, the lactase activity may decrease after childhood [13]. When the lactase activity becomes too weak the lactase does not get digested, leading to lactose maldigestion. Usually lactose maldigestion is not very harmful whereas, it is somewhat beneficial as it feeds the gut microbes. However, when lactose maldigestion leads to digestive symptoms such as bloating, diarrhea, flatulence, it is called lactose intolerance. To limit lactose intolerance one must reduce his/her dairy intake to only 24gm of dairy a day. [13]

Lactose Intolerance is a difficulty in digesting Lactose

Yogurt is a fermented food with live bacteria, made from fermented milk. It contains simple forms of sugars, proteins and fats.The live bacteria of the yogurt, Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus, produce their own lactase. Some of the lactose contained in the yogurt is broken down by this extra lactase . Hence, lactose of yogurt is digested more easily than any other dairy product by lactose maldigesters and lactose intolerants, [13] Therefore, it is more advisable to eat yogurt instead of other dairy products if you are lactose intolerant.

Exam Question

Carotenoids produce red, orange and orange-yellow colours in which food?

A. apples

B. cherries

C. shirmp

D. red cabbage

Answer: shirmp

Explanation as to why it should be on the exam

All those foods have red colours but the colour pigments are different. Although it seems not that important, we need to pay attention to details.