microbiological aspects of yogurt and condensed milk

1. Microbiology of Yogurt &
condensed milk
Submitted to:
Dr. Amit C Kharkwal
Submitted by:
Himani Bhushan &
Suamreiliu Kamei

2. Yogurt
• Beneficial effects of yogurt on health were first
touted at the beginning of the 20th century.
• Yogurt is a highly nutritious food in its native
form. Yet, the physical nature of this food lends
itself to further enhancement through the addition
of prebiotics & probiotics.
• It is the most widely used fermented product
produced by starter culture consisting of mixed
population of two bacterial species in the ratio of
1:1.

3. • The two bacterial species being Streptococcus
salivarius sub sp thermophilus & Lactobacillus
debruckii sub sp bulgaricus.
• Fermentation of milk produces lactic acid which
acts on milk protein to give yogurt its texture.
• Its nutritionally rich in calcium, protein,
riboflavin, vitamin B6, & vitamin B12.
• Depending upon flavor yogurt is of two types:
1. Simple yogurt
2. Flavored yogurt
• Flavored yogurt is prepared by adding some
additives like skimmed milk powder, sugar,
some flavored compounds, dry fruits etc.

4. Health benefits
• Yogurt has nutritional benefit beyond those of
milk.
• People who are moderately lactose intolerant
can enjoy yogurt without ill effect because the
lactose in the milk is converted to lactic acid
by bacterial culture.
• It has medicinal use as it is used for variety of
gastrointestinal disorders & in preventing
antibiotic associated diarrhea.
• Yogurt is believed to promote good gums
because of lactic acid present in it.

5. Production process

6. Condensed milk
• Industrial production for both sweetened &
unsweetened condensed milk started around the
middle of the 19th century.
• The first sweetened condensed milk in
hermetically sealed cans was manufactured &
sold in 1856 by Gail Borden in the USA.
• Until the early 1880s unsweetened condensed
milk was also produced & was sold open in the
market due to the lack of knowledge & success of
long life preservation at that time.

7. • The basic process for preservation of
unsweetened condensed milk by heat sterilization
was conceived by John B. Meyenberg in 1882.
• The idea of preserving milk without the addition
of sugar was made possible by his invention of a
revolving sterilizer working with steam under
pressure.
• Both sweetened & unsweetened condensed milk
can be made from fresh milk or recombined milk
(Powder, fat & water).
• Unsweetened condensed milk is also called
double concentrated milk & is a sterilized product
which is light in color & creamy in appreance.

8. • It has a large market and is used as a substitute for
fresh milk where its not available.
• Its is also used as a substitute for breast milk after
addition of vitamin D.
• The increased dry weight is reached by either
evaporation of fresh milk or by recombination by
milk powder.
• The sweetened condensed milk is basically
concentrated milk to which sugar has been added.
The product is yellowish in color & highly viscous.
• The high sugar content in condensed milk increases
the osmotic pressure to such a level that most of the
microorganisms are destroyed.

9. Health benefits
• Its high calorie content makes sweetened
condensed milk an excellent ingredient for
people who are trying to gain weight.
• Using sweetened condensed milk to boost
calorie content may be beneficial than using
sugar alone since the product also provides
extra protein, fat and some bone healthy
minerals like calcium and phosphorus.

10. Production processes
Unsweetened condensed milk

11. Production process
Sweetened condensed milk