Milk may be used to make a variety of dairy products, including cheese and yogurt. A variety of lactic acid bacteria are added to milk to create yogurt.
The “yogurt cultures” are a combination of lactic acid bacteria that are added to milk to create yogurt. Streptococcus thermophiles and Lactobacillus bulgaricus are the lactic acid bacteria that are utilized. Other milk acid bacteria may be added to the yogurt cultures in various nations. When the yogurt culture is added, the milk begins to ferment, and some of the lactose that is normally present in the milk is transformed into lactic acid throughout the fermentation process.
The content of the milk, the kind of yogurt culture, the temperature, and the length of the fermentation process all affect the yogurt’s qualities. Because the acid in fermented dairy products prevents the growth of bacteria that might cause decomposition, fermented milk products preserve longer than non-fermented dairy products.
Since roughly 4000 BC, milk products have been fermented. The milk might be stored for a longer time if yogurt and cheese were made from it. When bacteria and a high temperature were present and milk was stored in leather bags or wooden barrels, the milk began to ferment, turning into yogurt.
To make yogurt, milk must first be heated to a temperature that denatures its proteins (scalding), which is necessary, then cooled to a temperature that will not kill the live microorganisms that transform the milk into yogurt, whereupon starter cultures—typically Streptococcus thermophilus and Lactobacillus bulgaricus—are added. The milk is then kept warm for several hours. The milk can either be cooked or kept at 85 °C (185 °F) for a few minutes (giving a somewhat different result). Usually, it is chilled to around 50 °C (122 °F). The incorporation of starting culture and standing is the next phase.
It is possible to use milk that has more solids than regular milk; this milk makes firmer yogurt. Dried milk can be added to yogurt to enhance the solids. The yogurt-making process offers two important barriers to pathogen growth: heat and acidity (low pH). To guarantee a safe product, both are required.
Pasteurization: Milk is pasteurized at 185°F for 30 minutes or 203°F for 10 minutes before the inclusion of the bacterial cultures to prevent the deactivation of those cultures. The whey proteins are also denatured by the high heat, enabling the yogurt to create a more stable gel. Finally, pasteurization successfully eliminates microorganisms that cause illness.
Adjusting Milk Composition and Blending Ingredients: Stabilizers and sweeteners, if less tart yogurt is needed, are now added to the mixture. To stop the milk proteins from coagulating, the nonfat dry milk powder is also added before heating.
Homogenization: Yogurts are not always homogenized. The ingredients are well blended to provide a more stable consistency if this step is followed.
Heating: Depending on the desired yogurt thickness, the milk is next heated to 200°F for 10 to 20 minutes. A thicker yogurt will come from holding it for longer.
Cooling and Inoculation: The mixture is quickly chilled to 112-115°F after that. The live bacterial culture is now introduced into the heated mixture.
Incubation: At 105–115°F, the mixture is incubated for 4–7 hours. The temperature range in which the thermophilic bacteria required to make yogurt thrive is between 98°F and 130°F; below 98°F, they cannot survive and do not grow properly. When a pH of 4.6 is attained, yogurt will become hard. Any additional incubation will enhance the mixture’s acidity and sourness.
Cooling: The yogurt is chilled to around 45°F to stop the fermentation process after the required pH is achieved.
Addition of Fruit and Flavors: When making yogurt in the set style, fruit is put in the bottom of the cup and the yogurt is inoculated before being layered on top of the fruit and allowed to ferment. Fruit is added to Swiss-style yogurt following the fermenting and chilling processes. Following packaging, the yogurt should be kept chilled at 40°F or less.
Yogurt Fun Facts
- One of nature’s superfoods is yogurt.
- The first evidence of the consumption of yogurt dates to Central Asia around 6000 B.C. 8000 years ago, to be exact!
- Like ice cream, frozen yogurt was developed about 50 years ago.
- Turkey is a Middle Eastern nation where the word “yogurt” originated.
- Yogurt can be spelled in at least a dozen different ways, according to Oxford English Dictionary.
Make Yogurt at Home
It is not as tough as you would imagine making strained yogurt at home:
1. Warm-up 1/2 gallon of milk (it can be full, 2%, or skim). Place a 3-quart pot over medium heat and add the milk. When little bubbles start to develop and the milk is almost boiling, stir it occasionally to keep it from burning.
2. Transfer the milk to a glass or ceramic dish after cooling it to a warm temperature of around 110°-115° F. The bacteria can be eliminated by a higher temperature, whereas fermentation may be avoided by a lower temperature.
3. 12 cups of plain yogurt with live cultures or a yogurt starter kit should be whisked into the milk. Put a plate or lid on top of the bowl to cover it. Bowl is covered with a cloth.
4. Turn on the oven light after heating it for 1-2 minutes in a warm setting. Place yogurt in the oven after turning it off but keeping the light on. Allow to sit for at least four hours, or perhaps overnight. Approximately 110°F should be the oven’s temperature.
5. Next, the yogurt is prepared for usage. Place in the refrigerator for a few hours before eating if you prefer this thinner consistency. Strain the yogurt if you like a thicker Greek-style yogurt. Place a big bowl over a fine mesh sieve that is lined with cheesecloth or a coffee filter. The liquid whey and extra water will be strained out of the yogurt after it has been poured into the sieve and chilled for up to several hours. For around 7 days, yogurt may be kept in the refrigerator.
There are several advantages to knowing how the yogurt you eat is made. Luckily, you can also make your own homemade yogurt if you wish to adjust the ingredients based on your preference.