Its a short study on the microbiological basis on frozen dairy product.

1. Md. Ashfaq Aziz (151-009-031)
Shahrin Akter Aurin (151-038-031)
Department of Microbiology
Primeasia University

2. • Foods produced from or
containing milk are dairy
products.
• Dairy products are frozen to
increase storage life of the
products.
• Freezing the products
improves its availability
during off-seasons.
• Frozen products are
maintained at -200C or
lower.

3. • There are various types
of frozen dairy products.
• Most of them are
desserts. Such as ice-
cream, frozen yogurt,
parfait, frozen custard,
sorbet etc.
• All these products
contain milk fats and
cream.

4. • Consist of a mixture of dairy
ingredients such as milk &
non-fat milk.
• Contain at least 10% milk fat
&1.4% egg yolk.
• Stored at -200C ; no concern
for microbial growth.
• Disease can be caused due to
raw milk, inadequate heat
treatment or contamination
during handling.

5. • Low fat ice cream
• Most popular dessert made
from fermented milk
• Consists of <3.25% milk fat,
8.25% solids & 6.5% lactose
• Contain cultures of
Streptococcus thermophillus &
Lactobacillus bulgaricus

6. • Microbial degradation of
frozen desserts occurs only
in the ingredients used or in
the mixes prior to freezing.
• Staphylococcus aureus,
Salmonella typhi can be
found in ice cream.
• Bacillus cereus, Escherichia
coli, Campylobacter jejuni,
Salmonella spp. are found in
raw milk.

7. • The most dominant organisms that cause the
spoilage are the psychrophiles, such as Pseudomonas.
• Other important psychrotrophic genera are Bacillus,
Micrococcus & Lactococcus & of the family
Enterobacteriaceae.
• Yeasts are a major cause of spoilage of yogurt.
• ]
• The most common spore-forming bacteria found in
dairy products are, Bacillus cereus, B. subtilis & B.
megaterium.

8. • Dairy products are considered the most nutritious
food. So, it is necessary to preserve them in a safe
way.
• Novel technologies and preservatives are needed to
prevent the growth of spoilage microorganisms.
• When frozen desserts are exposed to temperatures
above -12°C, their texture and flavor characteristics
change.
• To maintain the quality of frozen dairy products it
must be covered tightly in a plastic container with a
lid.