Yogurt is a diary product widely used by the present generation in their daily diets. you probably don't give much thought to buying yogurt in the store. You have your favorite brand, or maybe you like trying new varieties each week; either way, you just grab it and go. It is easy to take yogurt for granted, but this delicious dairy product has a long and storied history that started way before the convenience of commercialized yogurt. Read on to discover its surprising origins in ancient civilizations and how it started being mass-produced.

1. Major Seminar
Fermentation Process
in Yogurt Industry
9th November, 2019
Shryli K S
Vth Semester
Molecular Biology
Yuvaraja’s College (Autonomous)
Mysuru
Guided by,
Dr Anu Appaiah K A
Sr. Principal Scientist
Microbiology & Fermentation Technology
Central Food Technological Research Institute
Mysuru

2. Major Seminar
Fermentation Process in Yogurt Industry
CONTENTS
Introduction
Nutritional Value
History
Production
Health benefits
Conclusion
References
Acknowledgement
INTRODUCTION
Yogurt is a diary product widely used by the present generation in their daily diets. you probably
don't give much thought to buying yogurt in the store. You have your favorite brand, or maybe
you like trying new varieties each week; either way, you just grab it and go.
It is easy to take yogurt for granted, but this delicious dairy product has a long and storied
history that started way before the convenience of commercialized yogurt. Read on to discover
its surprising origins in ancient civilizations and how it started being mass-produced.
YOGURT
Yogurts are fermented dairy products obtained from lactic acid fermentation by two species of
lactic acid bacteria, that is, Streptococcus thermophilus and Lactobacillus delbrueckii subsp.
bulgaricus. This fermentation leads to acidification and milk coagulation, without addition of
rennet (as in cheese), and allows an increase of the shelf life as a result of the low pH. world.
They involve probiotic bacteria, which are defined according to the FAO/WHO in 2011 as ‘live
microorganisms that, when administered in adequate amounts, confer a health benefit on the
host.’
Yogurt, Greek, plain (unsweetened), whole
milk (daily value)
Nutritional value per 100 g (3.5 oz)

3. Energy 406 kJ (97 kcal)
Carbohydrates 3.98 g
Sugars 4.0 g
Dietary fiber 0 g
Fat 5.0 g
Protein 9.0 g
Vitamins Quantity%DV†
Vitamin A equiv.
beta-Carotene
lutein zeaxanthin
0%
26 μg
22 μg
Thiamine (B1) 2%
0.023 mg
Riboflavin (B2) 23%
0.278 mg
Niacin (B3) 1%
0.208 mg
Pantothenic acid (B5) 7%
0.331 mg
Vitamin B6 5%
0.063 mg
Folate (B9) 1%
5 μg
Vitamin B12 31%
0.75 μg
Choline 3%
15.1 mg
Vitamin C 0%
0 mg
Minerals Quantity%DV†
Calcium 10%
100 mg
Iron 0%
0 mg
Magnesium 3%
11 mg
Manganese 0%
0.009 mg
Phosphorus 19%
135 mg
Potassium 3%
141 mg

4. Sodium 2%
35 mg
Zinc 5%
0.52 mg
Other constituents Quantity
Selenium 9.7 µg
Water 81.3 g
Link to Full Report from USDA Database
 Units
 μg = micrograms • mg = milligrams
 IU = International units
†Percentages are roughly approximated
using US recommendations for adults.
HISTORY
The word is derived from Turkish: yoğurt,[5] and is usually related to the verb yoğurmak, "to
knead", or "to be curdled or coagulated; to thicken" An ancestral version of yogurt probably
appeared 9000 or 8000 years BC in Mesopotamia and Egypt and subsequently spread in the
northeast of Africa, in the Middle East, in Central Asia, and later in Balkan countries, offering a
large variety of ‘fermented milks.’ The shepherds who stored their extra goat's milk in
containers made out of animal stomachs to preserve it while on the go. Some of the milk stored
in these skins, to their surprise, became thick and tart. More importantly, it was still edible —
even after a surprisingly long period of time in the hot sun.
In ancient Indian records, the combination of yogurt and honey is called "the food of the
gods".[9] Persian traditions hold that "Abraham owed his fecundity and longevity to the regular
ingestion of yogurt”.
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 the Indian subcontinent. 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-producing bacteria.
In 1907, the rod-like bacterium was called Bacillus bulgaricus (now Lactobacillus delbrueckii
subsp. bulgaricus). The Russian Nobel laureate and biologist Elie 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

5. of Bulgarianpeasants. 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. Yogurt with added fruit jam was patented in 1933
by the Radlická Mlékárna dairy in Prague.
In 2017, the average American ate 13.7 pounds of yogurt.
PRODUCTION OF YOGURT
The industrial manufacture of yogurts is organized along three main steps:
(1) the preparation of the mix and all corresponding physical treatments such as
homogenization, heat treatment, cooling, and deaeration;
(2) the fermentation process starting after inoculation of the mix; and
(3) the yogurt harvesting, post-treatment, and packaging.
(4) The quality checking
1) Preparation of the mix
A) Milk standardization
In order to obtain the mix to be fermented, milk preparation involves mainly fat and protein
content standardization and optional addition of sweeteners and stabilizers. Fat standardization
consists of fat removal by centrifugation (at about 55 C), followe d by cream reincorporation to
reach the targeted fat content,ranging from nonfat (0.01%), to low- or light-fat (1–2%), to whole-
fat yogurts (>3.2%). Protein standardization aims at increasing the protein content of the mix
(from 3% to 5–15%) in order to improve the yogurt firmness (texture) and reduce its syneresis
(the contraction of a gel accompanied by the separating out of liquid). It is mostly done by
addition of milk powder, which is the easier and traditional way. The use of milk proteins or milk
replacers as caseinates or whey powders is also common. In some countries, the use of
thickeners and stabilizers (gelatin, pectin, xanthan gum, carrageenan, starch, etc.) at
concentrations varying from 5% to 10% is allowed by FAO/WHO to improve the yogurt texture.
B) Physical treatment of the mix
Heat treatment is an essential step of the mix preparation. It allows removing spoilage
microorganisms,inactivating lactoperoxidases and producing stimulatory compounds in milk. In
parallel, heat treatment contributes to improved yogurt texture by allowing whey protein
denaturation and interaction with casein, resulting in a decrease of gel syne resis and an
increase of gel firmness. During industrial yogurt manufacture,the mixesare generally heated at
90 or 95 C for 3–7 min before cooling down to fermentation temperature.Plate heat exchangers,
with a tubular holding zone, are generally used and are designed in order to cool the mix
accurately at the fermentation temperature (between 37 and 43 C).
Two other physical treatmentsof the mix, deaeration and homogenization,are closely associated
with the heat treatment, and the design of the heat exchangers takes into account the
temperature favoring their effect. Homogenization is compulsory for yogurt quality, as it

6. increases the gel texture and reduces syneresis. It provokes a reduction of the size of the fat
globules (near 2 mm) and a better link between fat and hydrophilic proteins. Homogenization of
the mix is done at high pressure (20 or 25 MPa) and at a temperature close to 70 C. Associated
with the heat treatment of the mix, it takes place just after the holding section of the heat
exchanger. Double-stage high-pressure homogenizers are recommended for high-fat yogurts.
Vacuum deaeration of the mix is performed at large industrial scale to reduce its oxygen content
and consequentlyshorten the fermentation time, as to improve the yogurt texture and to remove
off-flavors. This step is generally performed at 70 C, before homogenization.
2) The Fermentation Process
A) Inoculation of the mix
At industrial scale, yogurts are prepared through inoculation of the mix with concentrated
starter cultures of the two yogurt bacteria (S. thermophilus and L. delbrueckii subsp. bulgaricus).
The commercial starter cultures are composed of specific blends of selected and well-defined
strains, at a concentration higher than 1010 colony-forming units (CFU)g 1, and are preserved
as frozen or freeze-dried formulations.The inoculated mix contains generally 106–107 CFU ml of
bacteria. After mixing, it is transferred to the fermentation tanks (for stirred, drinking, or
concentrated yogurt manufacture) or directly to the packaging machine for fermentation in cups
(for set-type yogurt manufacture).
The two thermophilic lactic acid bacteria, S. thermophilus and L. delbrueckii subsp. bulgaricus,
which trigger yogurt fermentation, are considered as ‘Generally Recognized as Safe’ in the United
States and possess the ‘Qualified Presumption of Safety’ status in Europe, as a consequence of a
long history of safe use in food and an absence of pathogenicity. They are Grampositive,
anaerobic, aerotolerant, and catalase-negative, do not form spores, and have less than 55% GþC
content in their DNA. They are able to grow between 42 and 50 C, but not at 10 C. S.
thermophilus forms linear chainsof rods, whereas L. delbrueckii subsp. bulgaricus grows as ovoid
cells.They convert lactose into galactose that is not metabolized and glucose that is fermented
predominantlyto lactic acid, thus corresponding to homofermentative metabolism. In milk, these
two species demonstrate a positive interaction called protocooperation, which is mutually
favorable. This phenomenon inducesa more rapid growth and acidification, higher production of
aroma compounds and exopolysaccharides,and more pronounced proteolysis. An upregulation
of biosynthesis pathways for nucleotides and sulfur-containing amino acids is also observed.
Growth of S. thermophilus is promoted by free amino acids and small peptides that arise from
milk proteins by the action of the cell wall protease PrtB of L. delbrueckii subsp. bulgaricus. In
return, L. delbrueckii subsp. bulgaricus is stimulated by formic acid, folic acid, and CO2 that are
synthesized by S. thermophilus in milk. As a consequence of this interaction, growth of S.
thermophilus starts first by using the nitrogencompounds and stops early as this species is very
sensitive to lactic acid inhibition. Growth of L. delbrueckii subsp. bulgaricus begins later but is
prolonged even at low pH, due to the better resistance of this species to acidity.
B) Fermentation of the Mix

7. During the lactic acid fermentationof milk, numerous parameters vary as a function of time, as
shown in Figure 4. The growth of S. thermophilus occurs first, followed by that of L. delbrueckii
subsp. bulgaricus, reaching final concentrations close to 109 CFU g1. The consumption of
lactose and nitrogenous compounds permits the growth of both strains and leads to the
accumulation of many relevant metabolites. Lactic acid, galactose, acetaldehyde, and
exopolysaccharides are the most important ones, contributing to flavor and texture of the yogurt.
The synthesis of extracellular lactic acid provokes an acidification of the mix characterized by a
decrease of the pH (Figure 4(a)), the coagulation of proteins, and the subsequent gel formation.
Acetaldehyde confers to yogurt its particular aroma, and exopolysaccharides contribute to its
texture. The acidification process is controlled by the final pH of the yogurt and the acidification
rate, whichare key factors to master quality. The fermentation is stopped (by a fast cooling of
the product) when the final pH of the yogurt is reached.The targeted final pH varies from 4.8 to
4.5, as a function of the type of yogurt.
The coagulation phenomenon that occurs at about pH 5.2. Acidification of milk leads to
coagulation as a result of destabilization of the casein micelles. The mechanism relies on two
concomitant phenomena. During acidification, the net negative charge on casein micelles
decreases, thus reducing electrostaticrepulsion between charged groups. In the same time, the
colloidal calcium–phosphate complex is solubilized, whichresultsin the depletion of calcium in
the micelles. Then, electrostatic and casein–casein attractions increase due to enhanced
hydrophobic interactions.When the isoelectric point of caseins (pH 4.6) is achieved, coagulation
occurs as a result of the formation of a three-dimensional network consisting of clusters and
chain of caseins, which leads to the formation of the yogurt gel.
3) Yogurt Harvesting and Packaging
A) Cooling and harvesting
The first stepin yogurt harvesting corresponds to a fast cooling of the product in order to stop its
acidification. It takes place when the required final pH of yogurt is obtained. Set yogurts are
cooled within 1 or 2 h to 4 or 5 C using cold air in ventilated cabinets, cooling rooms, or tunnels,
as a function of the size of the manufacturing unit. For stirred yogurt, the cooling is performed
in an external heat exchanger reaching an intermediate temperature (between 18 and 25 C) in
less than 1 h (20–60 min for industrial tanks). At this temperature, some additives as aroma
compounds, sweeteners, and fruits (jam, pulp, and pieces) can be added to stirred yogurts. In
modern large plants, these additions are generallyperformed online at the level of the packaging
machine, using metering pumps and mixers. The final texture of yogurts, especially stirred ones,
is a critical factor for consumer acceptance. As the texture is influenced by many factors (mix
composition, strains used, and processing conditions), it is a real challenge to obtain the
targeted texture. The mechanical constraints exerted on stirred yogurt by all the harvesting
devices (pumps, heat exchangers, pipes, mixers,filling machine, etc.) tend to reduce its texture
but can give them some smoothness.
B) Industrial Design of Manufacturing units.
All equipments used for milk storage, mix preparation, fermentation and yogurt cooling, and
harvesting and packaging are especially designed to allow for the cleaning in place (CIP)
procedures commonly used in dairy industry. These procedures assume the existence of a CIP
kitchen in the factory to automatically provide the cleaning mixtures at the right temperature
and for the right duration. Yogurt fermentation is a batch process, but some operations such as
mix preparation and treatment and yogurt cooling and packaging are designed and managed as
continuous or semicontinuous processes. In industrial manufacturing units, automation and
process control systems are more and more popular. They encompass (1) sensorsthat essentially
measure physical parameters such as temperature, pressure, level, and weight; (2)

8. programmable logic controllerscontrollingvalves, pumps, and motors that permit the regulation
of the main process parameters; and (3) computer supervision that allows traceability.
Nevertheless, as an accurate control of the yogurt acidification rate remains limited,optimization
of yogurt manufacture is not possible.
4) Control and Quality checking
Microbiological controls are carried out on raw materials, in particular fresh milk, powder milk,
fruits, sweeteners, and starters. Somatic cell counts are also verified on fresh milk. In addition,
many physicochemical properties are checked:
(1) temperature, titratable acidity, and fat and protein contents of the fresh milk;
(2) the absence of antibiotics, solubility, moisture, and fat content of the milk powder; and
(3) pH, viscosity, and Brix of the added fruits.
During yogurt manufacture, controlsare accomplished to ensure repeatability of the productions
and maximal levels of quality and food safety of the products. They refer mainly to the control of
temperature (in fermentation tanks, heat exchangers, incubation rooms, and cooling systems),
pH (by sampling either in the fermentation tanks or directly in cups), and duration of the
different steps of manufacture. In addition to these controls, the use of food safety.
Various controls are performed on the final products at the end of their manufacture and during
their shelflife. The frequency of sampling is defined by each dairy factory, as stated by its own
good hygiene practices. Counts of S. thermophilus and L. delbrueckii subsp. Bulgaricus are
controlled to verify that the targeted value of 107 CFU g 1 at shelf life is achieved. The presence
of spoilage and pathogenic microorganisms, includingListeria monocytogenes, Salmonella spp.,
coliforms, yeasts, or molds, is also checked.
USES
1. It's Rich in Important Nutrients
Yogurt contains some of nearly every nutrient that your body needs.
It's known for containing a lot of calcium, a mineral necessary for healthy teeth and bones. Just
one cup provides 49% of your daily calcium needs.
It is also high in B vitamins, particularly vitamin B12 and riboflavin, both of which may protect
against heart disease and certain neural tube birth defects.
One cup also provides 38% of your daily need for phosphorus, 12% for magnesium and 18% for
potassium. These minerals are essential for several biological processes, such as regulating
blood pressure, metabolism and bone health.
One nutrient that yogurt does not contain naturally is vitamin D, but it is commonly fortified
with it. Vitamin D promotes bone and immune system health and may reduce the risk of some
diseases, including heart disease and depression.
2. It's High in Protein
Yogurt provides an impressive amount of protein, with about 12 grams per 7 ounces (200
grams).

9. Protein has been shown to support metabolism by increasing your energy expenditure, or the
number of calories that you burn throughout the day.
Getting enoughprotein is also important for appetite regulation, as it increasesthe production of
hormones that signal fullness. It may automatically reduce the number of calories you consume
overall, which is beneficial for weight control.
In one study, subjects who snacked on yogurt were less hungry and consumed 100 fewer
calories at dinner, compared to those who ate lower-protein snacks with the same amount of
calories.
Yogurt's fullness-promoting effects are even more prominent if you eat Greek yogurt, which is a
very thick variety that has been strained. It is higher in protein than regular yogurt, providing 22
grams per 7 ounces (200 grams).
Greek yogurt has been shown to influence appetite control and delay feelings of hunger more
than regular yogurt with less protein.
3. Some Varieties May Benefit Digestive Health
Some types of yogurt contain live bacteria, or probiotics, that were either a part of the starter
culture or added after pasteurization.
These may benefit digestive health when consumed.
Unfortunately, many yogurts have been pasteurized, which is a heat treatment that kills the
beneficial bacteria they contain.
To ensure your yogurt contains effective probiotics, look for one that contains live, active
cultures, which should be listed on the label.
Some types of probiotics found in yogurt, such as Bifidobacteria and Lactobacillus, have been
shown to lessen the uncomfortable symptoms of irritable bowel syndrome (IBS), which is a
common disorder that affects the colon.
One study had IBS patients regularly consume fermented milk or yogurt that
contained Bifidobacteria. After only three weeks, they reported improvements in bloating and
stool frequency — effects seen after six weeks, as well.
Another study found that yogurt with Bifidobacteria improved digestive symptoms and health-
related quality of life among women who did not have a diagnosed digestive condition.
Furthermore, several studies have found that probiotics may protect against antibiotic-
associated diarrhea, as well as constipation.
4. It May Strengthen Your Immune System
Consuming yogurt — especially if it contains probiotics — on a regular basis may strengthen
your immune system and reduce your likelihood of contracting an illness.
Probiotics have been shown to reduce inflammation, which is linked to several health conditions
ranging from viral infections to gut disorders.
Research shows that in some instances, probiotics may also help reduce the incidence, duration
and severity of the common cold.

10. Moreover, the immune-enhancing properties of yogurt are partly due to its magnesium, selenium
and zinc, which are trace minerals known for the role they play in immune system health.
Vitamin D-fortified yogurts may boost immune health evenfurther. Vitamin D has been studied
for its potential to prevent illnesses such as the common cold and flu..
5. It May Protect Against Osteoporosis
Yogurt contains some key nutrients for maintaining bone health, including calcium, protein,
potassium, phosphorus and, sometimes, vitamin D.
All of these vitamins and minerals are especially helpful for preventing osteoporosis, a condition
characterized by weakening of the bones. It is common in the elderly.
Individuals with osteoporosis have low bone density and are at a higher risk of bone fractures.
However,research shows that consuming at least three servings of dairy foods, such as yogurt,
on a daily basis may help preserve bone mass and strength.
6. It May Benefit Heart Health
Yogurt's fat content is one of the reasonswhy its healthiness is often controversial. It contai ns
mostly saturated fat, with a small amount of monounsaturated fatty acids.
Saturated fat was previously believed to cause heart disease, but current research shows that
this isn't the case. Nevertheless, fat-free and low-fat varieties of yogurt are still popular in the
US. There is no clear evidence that the fat in yogurt is harmful to your health. In fact, it may
benefit heart health.
Some research shows that the intake of saturated fat from whole-milk products increases "good"
HDL cholesterol, which may protect heart health. Other studies have found yogurt intake to
reduce the overall incidence of heart disease. Furthermore, dairy products like yogurt have been
shown to helpreduce high blood pressure, which is a major risk factor for heart disease. The
effects seem to be most prominent in those already diagnosed with high blood pressure.
7. It May Promote Weight Management
Yogurt has several properties that may help with weight management.
For starters, it is high in protein, which works along with calcium to increase levels of appetite -
reducing hormones like peptide YY and GLP-1. Furthermore, several studies have found that
yogurt consumption is associated with lower body weight, body fat percentage and waist
circumference. One review found that the intake of full-fat dairy products, including yogurt, may
reduce the incidence of obesity. This is contrary to what was previously believed about fat intake
and weight gain.
Other studies have found that those who eat yogurt tend to eat better overall, compared to those
who do not eat it. This is partly due to its higher nutrient content, compared to its fairly low
calorie content.
In addition to its widespread use as a food, yogurt has been studied in clinical trials in amounts
of 100 to 200 g/day.
Probiotic yoghurt is aimed at reducing medical conditions by restoring the beneficial microbial
population in the colon, medical conditionssuch as constipation and diarrhea.It is beneficial to
our digestive system, especially stomach and colon. Cow‟s milk is preferred for preparing
yoghurt as having low fat. It provides immunity, protect us from cold, cough and strengthen

11. body‟s defense mechanism.It strengthens the collagen in the skin and is good for our skin. It
lowers the blood pressure, bad cholesterol and risk of heart attacks. Yoghurt is a source of
natural proteins;it is safer for those having problem in tolerance of lactose. Yoghurt is rich in
calcium so; it protects the bones against osteoporosis and arthritis. It discourages vaginal
infections.It helps in cutting down calorie and thus helps in burning fat. By daily consumption
of yoghurt, disease causing bacteria are flushed out from the colon and thus help in protecting
against colon cancer. Consumption of yoghurt can shut down Helicobaterpylori; the bacterium
responsible for most ulcers. Typical yogurt manufacturing entails the following:
CONCLUSION
Summarise
Typical yogurt manufacturing entails the following:
1. The process begins with milk with a fat level from 2.0-3.5%.
2. The serum solids content of the milk is increased to 10.5-11.5% through a standardization
process by adding condensed skim milk or non-fat dry milk.
3. Milk is homogenized and heated to 185o to 195oF (85-90.5oC) for 30 to 60 minutes for
pasteurization. The high heat treatment improves the body of the yogurt and limits whey
expulsion.
4. The milk is cooled to 104 to 106oF (40 to 41oC) and is inoculated with a lactic acid producing
culture.
5. Acid production is monitored and data (time/temperature/pH) is recorded.
6. The inoculated milk is incubated in a vat (stirred) or placed in consumer-sized sterile
packages (set) to incubate in a temperature controlled environment. To attain yogurt with a pH
of 4.0 the cooling process should begin when the fermenting milk reaches a pH of 4.3-4.4.
7. To extend the shelf life of the product, yogurt can be heat treated after culturing is complete,
destroying viable microorganisms.
Further, there is still scope to improve the technology to get better yield of yogurts which has
higher nutritional values and longer shelf life.
REFERENCES
• Benjamin Caballero, Paul M Finglas, Fidel Toldra, Yogurt: The Product and its
Manufacture; The Encyclopedia of Food and Health; Academic Press, Oxford; 2016, 617-
624pp
• ITDG, Practical answers to poverty, Yoghurt Production; Technical Brief, 2012, 2pp
• Yogurt Production; The Northeast Center for Food Entrepreneurship at the New York
State Food Venture Center, Cornell University; 2007, 3pp
• I. H. Ko, M. K. Wang, B. J. Jeon and H. S. Kwak; Fermentation for Liquid-type Yogurt with
Lactobacillus casei 911LC, 2014; 5pp
• Priyanka Aswal, Anubha Shukla and *Siddharth Priyadarshi; Yoghurt : Preparation,
Characteristics and Recent Advancements; CibtechJournal of Bio-Protocols; Vol-1, 2012,
32pp
• http://www.milkfacts.info/Milk%20Processing/Yogurt%20Production.htm
• http://www.madehow.com/Volume-4/Yogurt.html
• https://dairyconsultant.co.uk/yoghurt-yogurt-production.php
ACKNOWLEDGEMENT
I thank the department of Molecular Biology for providing me an opportunity to present this
seminar. I also thank my guide Dr Anu Appaiah K A, Sr. Principal Scientist, CFTRI for his
valuable guidance and support throughout the preparation of my seminar.