i

Oleh:

Ahmad Fikri Zulfi ( 02 )

Indah Mustikasari W ( 15 )

Nevila Nur Faiz ( 22 )

Rizqy Prastyo ( 31 )

Salihati Hanifah ( 33 )

PRACTICUM REPORT OF

APPLICATIVE CHEMISTRY

MAKING YOGHURT

Oleh:

Ahmad Fikri Zulfi ( 02 )

Indah Mustikasari W ( 15 )

Nevila Nur Faiz ( 22 )

Rizqy Prastyo ( 31 )

Salihati Hanifah ( 33 )

SMA NEGERI 1 JEMBER

Jalan Let.Jend. Panjaitan 55 Jember 68121

Telp. / Fax. ( 0331 ) 338586

website: www.sman1jember.sch.id

Content

Cover.................................................................................................................. i

Content List........................................................................................................ ii

Chapter I

Pendahuluan

Basic Theory

Chapter II

Method

Equipment

Materials

Steps

Observation Result

Chapter III

Conclusion

Suggestion

Daftar Pustaka

ii

Chapter I

Basic Theory

Yogurt or yoghurt is a dairy product produced by bacterial fermentation of

milk. The bacteria used to make yogurt are known as "yogurt cultures". Fermentation

of lactose by these bacteria produces lactic acid, which acts on milk protein to give

yogurt its texture and its characteristic tang.

Worldwide, cow's milk is most commonly used to make yogurt, but milk from

water buffalo, goats, ewes, mares, camels, and yaks is also used in various parts of

the world.

Dairy yogurt is produced using a culture of Lactobacillus delbrueckii subsp.

bulgaricus and Streptococcus salivarius subsp. thermophilus bacteria. In addition,

other lactobacilli and bifidobacteria are also sometimes added during or after

culturing yogurt.

By food law, some countries require a certain amount of colony forming units

of microorganisms to allow sour milk be named as "yogurt", e.g., Swiss Food Law:

Article 56 yogurt 2 The final product must contain a total of at least 10 million colony

forming units of microorganisms under paragraph 1 or 1.2 per gram.

The milk is first heated to about 80 °C (176 °F) to kill any undesirable

bacteria and to denature the milk proteins so that they set together rather than form

curds. The milk is then cooled to about 45 °C (112 °F). The bacteria culture is added,

and the temperature is maintained for 4 to 7 hours to allow fermentation.

How milk was first cultured into yogurt remains a mystery. Analysis of the L.

delbrueckii subsp. bulgaricus genome indicates that the bacteria may have originated

on the surface of a plant. Milk may have become spontaneously and unintentionally

infected through contact with plants, or bacteria may have been transferred via the

udder of domestic milk-producing animals.

There is evidence of cultured milk products in cultures as far back as 2000

BCE[citation needed]. In the records of the ancient culture of India and Iran, yogurt is

mentioned by 500 BCE. In ancient Indian records the combination of yogurt and

honey is called "the food of the gods". Persian traditions hold that "Abraham owed

his fecundity and longevity to the regular ingestion of yogurt".

The oldest writings mentioning yogurt are attributed to Pliny the Elder, who

remarked that certain "barbarous nations" knew how "to thicken the milk into a

substance with an agreeable acidity". The use of yogurt by medieval Turks is

recorded in the books Diwan Lughat al-Turk by Mahmud Kashgari and Kutadgu

Bilig by Yusuf Has Hajib written in the 11th century. Both texts mention the word

"yogurt" in different sections and describe its use by nomadic Turks. The earliest

yogurts were probably spontaneously fermented by wild bacteria in goat skin bags.

Another early account of a European encounter with yogurt occurs in French

clinical history: Francis I suffered from a severe diarrhea which no French doctor

1

could cure. His ally Suleiman the Magnificent sent a doctor, who allegedly cured the

patient with yogurt. Being grateful, the French king spread around the information

about the food which had cured him. Raita is a condiment made with yogurt and

popular in India, Pakistan and Bangladesh.

Until the 1900s, yogurt was a staple in diets of people in the Russian Empire

(and especially Central Asia and the Caucasus), Western Asia, South Eastern

Europe/Balkans, Central Europe, and India. Stamen Grigorov (1878–1945), a

Bulgarian student of medicine in Geneva, first examined the microflora of the

Bulgarian yogurt. In 1905, he described it as consisting of a spherical and a rod-like

lactic acid bacteria. In 1907, the rod-like bacterium was called Bacillus bulgaricus

(now Lactobacillus delbrueckii subsp. bulgaricus). The Russian Nobel laureate

biologist Ilya Ilyich Mechnikov (also seen as Élie Metchnikoff), from the Institut

Pasteur in Paris, was influenced by Grigorov's work and hypothesized that regular

consumption of yogurt was responsible for the unusually long lifespans of Bulgarian

peasants. Believing Lactobacillus to be essential for good health, Mechnikov worked

to popularize yogurt as a foodstuff throughout Europe.

Isaac Carasso industrialized the production of yogurt. In 1919, Carasso, who

was from Ottoman Salonika, started a small yogurt business in Barcelona, Spain, and

named the business Danone ("little Daniel") after his son. The brand later expanded

to the United States under an Americanized version of the name: Dannon.

Tarator is a cold soup made of yogurt, cucumber, dill, garlic and sunflower oil

(walnuts are sometimes added) and is popular in Bulgaria.

Yogurt with added fruit jam was patented in 1933 by the Radlická Mlékárna

dairy in Prague.

Yogurt was first introduced to the United States in the first decade of the

twentieth century, influenced by Élie Metchnikoff's The Prolongation of Life;

Optimistic Studies (1908); it was available in tablet form for those with digestive

intolerance and for home culturing. It was popularized by John Harvey Kellogg at the

Battle Creek Sanitarium, where it was used both orally and in enemas, and later by

Armenian immigrants Sarkis and Rose Colombosian, who started "Colombo and

Sons Creamery" in Andover, Massachusetts in 1929. Colombo Yogurt was originally

delivered around New England in a horse-drawn wagon inscribed with the Armenian

word "madzoon" which was later changed to "yogurt", the Turkish name of the

product, as Turkish was the lingua franca between immigrants of the various Near

Eastern ethnicities who were the main consumers at that time. Yogurt's popularity in

the United States was enhanced in the 1950s and 1960s, when it was presented as a

health food. By the late 20th century, yogurt had become a common American food

item and Colombo Yogurt was sold in 1993 to General Mills, which discontinued the

brand in 2010.

Yogurt is nutritionally rich in protein, calcium, riboflavin, vitamin B6 and

vitamin B12.[30] It has nutritional benefits beyond those of milk. Lactose-intolerant

individuals can sometimes tolerate yogurt better than other dairy products, because

the lactose in the milk is converted to glucose and galactose, and partially fermented

to lactic acid, by the bacterial culture.

Yogurt containing live cultures has been found effective in a randomized trial

at preventing antibiotic-associated diarrhea. Yogurt contains varying amounts of fat.

There is non-fat (0% fat), low-fat (usually 2% fat) and plain or whole milk yogurt

(4% fat). A study published in the International Journal of Obesity (11 January 2005)

also found that the consumption of low-fat yogurt can promote weight loss, especially

due to the calcium in the yogurt.

Chapter II

Method

Equipment :

Pot

Ladle

Plastic

Tupperware

Materials :

1 litre milk

100 ml yogurt

1 sachet (27 gr) milk powder

Blueberry jam

Steps

1. Sterilize equipment to be used by washing with hot water.

2. Pour the liquid UHT milk into a pot that has been sterilized.

3. Heat the milk over low heat, stirring frequently continues the same direction

until the temperature reaches 80oC (do not boil). Heating is carried out in

order to evaporate the water so that it will form lumps or solid yoghurt.

4. Remove from the heat and let stand until the temperature drops to 40oC.

5. Prepare a warm water for soaking while waiting.

6. Add seeds yoghurt and milk powder, and stir until the mixture becomes

homogeneous.

7. Pack yogurt in plastic containers and seal tightly, then put in a Tupperware

container.

8. Then do the soaking with warm water and cover tightly so that the

temperature can be maintained so that we will get a sour taste and a

condensed form. This is done by forming bacteria yogurt can work well in

temperatures that are not too hot or too cold. This process takes time for

approximately 8 hours.

9. During the above period, updated hot water used for soaking periodically.

10. Having obtained the yogurt texture is thick, then the yogurt is ready to be

enjoyed.

Observation Result and Documentation

In practice this yogurt creation, our group successfully created yoghurt with the right

level of acidity but slightly less viscous. And to add flavor, we added the blueberry

jam when yogurt has finished.

The Discussion

Yogurt is made with the help of two types of beneficial bacteria, one of the

family of rod-shaped lactobacillus (Lactobacillus bulgaricus) and others of the family

were rounded streptococcus (Streptococcus thermophilus). The bacteria act as acid

forming, forming Yoghurt with a distinctive aroma. The acid formed causes

coagulation of milk protein and help preserve yogurt. Lactic acid bacteria also can

suppress the growth of spoilage bacteria milk, making yogurt more durable during

storage than milk.

Lactobacillus bigger role in the formation of aroma, while the streptococcus

greater role in the formation of flavor. Milk component most instrumental in making

yogurt is lactose and casein. Carbohydre milk lactose is used as an energy source for

the growth of bacterial culture and will produce lactic acid. The formation of lactic

acid from the fermentation of lactose causes increased acidity or pH decreases milk,

casein is the largest component in milk are very sensitive to acid. Under conditions of

low acidity it becomes unstable casein. Casein coagulation will form solids called

yogurt. In general, a good yogurt has a total of 0.85% lactic acid up to 0.95% or the

degree of acidity (pH) 4 - 4.5.

Here's a yogurt-making process:

Warming

Heating process aims to turn microbes in milk that can inhibit the growth

of bacteria and reduce stater water content in milk for yogurt is pretty

solid. Warming liquid milk just until the milk temperature 800C, not to

boiling and stirring constantly in one direction so that the protein does not

undergo coagulation.

Cooling

Milk that has been heated to 800C is cooled to a temperature of 400C to

provide the optimum temperature for bacteria to breed. Once the

temperature 400C new starter bacteria added.

Incubation

During incubation, milk mixed with bacterial starter stored in the

temperature 400C. In practice this is done by soaking the milk that has

been given the starter bacteria and put in a plastic bag in the water

temperature is still maintained 400C for up to 8 hours. After 8 hours and

yogurt was thick and sour, to do additional flavors to taste.

Chapter III

Conclusion

Yogurt is a dairy products fermented with the addition of good bacteria.

Yogurt has many benefits for the human body especially the digestive

Suggestion

Use a pot and ladle made of stainless because stainless metal elements are not

easily soluble in milk.

Sterilize the tools that will be used so that no microbes that can inhibit the

manufacture of yogurt.

Always do check the water temperature in the incubation process to keep

warm and optimum breeding bacteria.

Store the finished yogurt in the fridge but it also should not be placed in the

freezer for basic materials such as milk yogurt that can be broken and that it

would damage the yogurt.

Daftar Pustaka