QUALITY AND SAFETY OF FROZEN DAIRY PRODUCTS

QUALITY AND SAFETY OF FROZEN DAIRY PRODUCTS

1. QUALITY AND SAFETY OF
FROZEN DAIRY
PRODUCTS

2. INTRODUCTION
Frozen dairy is categorized into two categories
1.Products frozen for increasing their shelf-life and thawed before
consumption or further processing.
2.Products in which the freezing process is responsible for the development
of the desired structure and texture and which are consumed in the frozen
state
Majority of frozen dairy products fall into this category ice-cream ,aerated
dairy desserts ,frozen yoghurt.

3. INFLUENCE OF FREEZING ON MILK COMPONENTS
1.FAT FRACTION
➢Fat fraction exist in the form of an emulsion with droplet sizes ranging from 0.5
to 5 micrometer.
➢Homogenization increases the number and surface area of the fat globules
present, and milk protein quickly absorbs homogenized fat globule to reduce
their interfacial tension.
➢During Freezing, the greatest concern is related to the fat phase is the loss of
the emulsified state and the separation of fat phase.
➢Homogenization before freezing greatly overcomes the de emulsification of the
fat globules in milk
➢Addition of sugar helps to stabilize frozen milkfat emulsions

4. 01Introduction
02
03
04
05
2.MILK SNF FRACTION
Freezing and frozen storage have a large effect on the proteins of milk, causing the casein
micelles to lose their ability and precipitate on thawing.
Commercial separation of casein from concentrated milk serum may be accomplished by
freezing, storage at -10cand thawing to produce a product referred as cryo-casein
The flocculation of casein from frozen milk is initially reversible with heat and agitation, but
becomes irreversible with continued storage.
Slow freezing has been reported to result in greater protein stability than fast freezing.
The stability in frozen milk depends heavily on the state of the lactose.
06
Ultrafiltration of milk has also been demonstrated to increase the storage stability by three
times.

5. FREEZING POINT DEPRESSION
➢Freezing point is a colligative property that is determined by the molarity of solutes
rather than by the percentage by weight or volume.
➢Freezing point can therefore be used to estimate the molecular weight of pure
solutes or average molecular weight of mixed solutes.
➢Lactose accounts for about 55% of freezing point depression of whole milk ,
chloride accounts for about 25% and the remaining 20% is due to other soluble
components including calcium, potassium, magnesium, lactates phosphates and
citrates.
➢Freezing point of milk is usually in the range of -0.512 to -0.550c.
➢Freezing point of other dairy products depend on their water content and dissolved
lactose and other solids in the water phase.

6. Initial Freezing Point of Various Dairy
Products

7. ICE CREAM
Consists of mixture of dairy ingredients such as milk and non fat milk.
Contains at least 10%milk fat and 1.4%egg yolk.
Stored at -20c; no concern for microbial growth
Disease can be caused due to raw milk, inadequate heat treatment or
contamination during handling

8. FROZEN YOGHURT
Low fat ice cream
Most popular dessert made from fermented milk.
Consist of <3.25% milk fat, 8.25% solids and 6.5% lactose.
Contains cultures of Streptococcus thermophillus & lactobacillus bulgaricus.

9. SHERBETS
Frozen Dessert usually flavored with fruit
Usually made from-
1.Water
2.Sugar
3.Flavorings
4.Milk or cream
Sugar content ranges between 25 –35 % sherbets have a relatively low overrun
at between 30-40 % and the SNF content ranges between 2-5 %.
The product is frozen at -23c and aged between 12-24hrs.

10. ICE CREAM AND FROZEN DAIRY DESSERTS
Typical Compositional Range for the Components used in various
Ice cream Mix formulations

11. INGREDIENTS
1.FAT
The Fat component of the mix increases the richness of flavor of ice cream which
produces a characteristic smooth texture by lubricating the palate, helps to give body and
aids in producing desirable melting properties
Whey Cream , is the principle fat source for dairy ice cream formulations.
Palm kernel oil, Coconut oil, Palm oil, Sunflower oil, Peanut Oil are also used to some extent .
During Freezing of ice cream, the fat emulsions that exists in the mix will partially
destabilize as a result of the presence of crystals of fat, air incorporation, ice crystallization
and high shear in the freezer.

12. 2.MILK SNF
SNF contains
Lactose
Caseins
Whey proteins
Minerals
Acids
Enzymes
Gases of milk or
milk products
Proteins are
essential for their
functional
contributions of
emulsification
Aeration
Water holding
Capacity
Excess of lactose
may lead to
problems due to
excessive freezing
point depression
Traditionally, the
best sources of
milk SNF are fresh
concentrated
skimmed milk or
spray dried low
heat skim milk
powder

13. 3.SWEETENERS
➢They improve the texture and palatability of ice cream and enhance flavours.
➢They have the ability to lower the freezing point of a solution.
➢Sucrose alone or in combination with other sugars are the most common
sweetening agent.
➢In some Ice cream formulations, sweeteners derived from corn syrup are substituted
for all or a portion of the sucrose.
➢The use of corn syrups in ice cream is generally perceived to provide greater
smoothness by contributing to a firmer and more chewy body to provide better
meltdown characteristics which improves the shelf life of the finished product

14. 4.STABILIZERS
◦They are a group of hydrocolloid ingredients(usually polysaccharides) used in ice
cream formulations to produce smoothness in body and texture and retard the growth
of ice and lactose crystals during storage
◦They also increase the viscosity of the mix and produce a stable foam with easy cut off
and stiffness at the barrel freezer for packaging
◦They also slows down moisture migration from the product to the package or the air in
frozen product.
◦Commonly used stabilizers are –
◦Guar gum
◦Carboxymethyl cellulose
◦Xanthan
◦gelatin

15. 5.EMULSIFIERS
•They are usually integrated with the stabilizers in proprietary
blends but their function and action is different from that of
stabilizers.
•They are used to improve the aeration properties of the mix.
MECHANISM OF ACTION
01
They lower the
fat or water
interfacial
tension in the
mix, resulting in
protein
displacement
from the fat
globule surface
02
Which in turn
reduces the
stability of the fat
globule to partial
coalescence, which
occurs during the
whipping and
freezing process
03
leading to the
formation of an
aggregated fat
structure in the
frozen product
which contributes
greatly to texture
and melt-down
properties

16. PRE-FREEZING TECHNIQUES
◦Pre-freezing techniques are crucial to achieve optimal texture, consistency, and quality
◦Homogenization: This process breaks down fat globules in the milk or cream to ensure a
smoother texture and prevent fat separation during freezing.
◦Pasteurization: Heating the dairy mixture to a specific temperature to kill harmful bacteria
and enzymes. This not only ensures food safety but also helps in stabilizing the product.
◦Aging: Allowing the dairy mixture to rest for a certain period before freezing can improve
its texture and flavour. During this time, the mixture undergoes some structural changes,
resulting in a smoother and creamier end product.
◦Mixing and Blending: Proper mixing and blending of ingredients ensure uniform distribution
of fat, solids, and air in the mixture, leading to a consistent product texture.
◦Emulsification: Emulsifiers like lecithin or mono and di glycerides are added to stabilize the
mixture by preventing fat and water from separating. This helps in achieving a smoother
texture and prevents ice crystal formation.

17. CONTD…
6. Freezing Rate Control: Controlling the rate at which the dairy mixture freezes can influence
the formation of ice crystals. Slower freezing rates generally result in smaller ice crystals, leading
to a smoother texture.
7. Incorporation of Stabilizers and Thickeners: Stabilizers like guar gum, carrageenan, or
xanthan gum are often added to improve texture, prevent ice crystal growth, and enhance shelf
stability.
8. Temperature Control: Maintaining precise temperature conditions during prefreezingand
freezing stages is critical to achieving the desired texture and preventing crystallization.

18. FREEZERS EMPLOYED FOR FROZEN DAIRY PRODUCTS
➢Barrel Freezers-
➢Barrel freezers, also known as batch freezers or ice cream freezers, are a specific type of
freezer commonly used in the production of ice cream and other frozen desserts.
➢It uses refrigerants like ammonia or Freon, to maintain the freezing temperature inside the
barrel. The temperature is carefully controlled to ensure proper freezing of the ice cream
mixture.
➢Barrel freezers are often used in smaller-scale ice cream production settings.
➢Cryogenic Freezers –
Cryogenic freezing involves the use of extremely low temperatures, typically using liquid
nitrogen or carbon dioxide, to rapidly freeze food products.
This rapid freezing helps to preserve the texture, flavour, and quality of the dairy products by
minimizing ice crystal formation and maintaining the integrity of the product's structure.

19. CONTD…
◦Continuous Freezing (e.g.Tunnel Freezers):
◦Continuous freezers allow for a constant flow of dairy products through a freezing
chamber, ensuring uniform freezing and consistent product quality. They are suitable for
high-volume production and offer efficient freezing with minimal labour requirements.
◦Blast Freezing:
◦Blast freezers are known for their ability to rapidly reduce the temperature of dairy
products, minimizing the formation of large ice crystals and preserving product quality.
They are suitable for high-volume production and are often used in industrial settings
where speed and efficiency are critical.

20. FACTORS AFFECTING QUALITY
Categorized Into Two Categories-
Compositional Factors
➢Flavour, Body and Texture
➢Color and Appearance.
➢Dairy ingredients contribute to
rancid or oxidized flavours
associated with fat content
➢Textural defect associated with
excessive lactose crystallization.
Processing Factors
Pasteurization
Homogenization
Emulsification
Mixing and Churning
Freezing Rate
Overrun
Packaging and Storage
Prevention of Recrystallization

21. FACTORS AFFECTING SAFETY
HACCP should be followed and we should ensure that the mix has been properly pasteurized
and no post pasteurization contamination has occurred
Examples of Post pasteurization contamination include contamination of raw mix with pasteurized
mix, improperly cleaned and sanitized equipment or utensils, contamination from the processing
environment and contamination by personnel handling the process
Effective cleaning is required on a regular basis to ensure low standard plate count and coliform
counts.
E.gin a major outbreak of Salmonella enteritidisassociated with ice cream infecting 224,000
individuals in the United States, the cause was found to be transportation of pasteurized mix that
was not subsequently re-pasteurized in tanker vehicles which had formerly been used to transport
non-pasteurized liquid egg products and improperly cleaned

22. IMPLEME
NTING
HACCP
•Incoming raw materials, such as milk, cream, and other dairy
ingredients, should be monitored for quality and safety. This
may include testing for pathogens, antibiotics, and other
contaminants.
Raw Material Control:
•Pasteurization is a critical step to eliminate harmful bacteria
and pathogens in dairy products. Monitoring and controlling the
pasteurization process, including time and temperature
parameters, is essential to ensure microbial safety.
Pasteurization:
•Homogenization helps ensure uniform distribution of fat
globules in dairy products Proper homogenization parameters
should be maintained to achieve the desired product
characteristics.
Homogenization:
•The addition of ingredients such as stabilizers, emulsifiers,
flavours, and colours should be controlled to ensure accurate
dosing and prevent contamination.
Addition of Ingredients:

23. CONTD…
➢Mixing and Blending:
Proper mixing and blending of ingredients are critical to achieving uniform
distribution of solids, fats, and air in the dairy mixture. Monitoring mixing
parameters and equipment performance helps ensure consistency and quality.
➢Freezing Process:
Freezing is a critical control point in frozen dairy production, as it determines the
texture, structure, and shelf life of the final product. Parameters such as
freezing temperature, rate of freezing, and ice crystal formation should be
controlled to achieve the desired product characteristics.
➢Packaging:
Packaging materials and processes should be controlled to prevent
contamination and maintain product integrity. Proper sealing and labeling
procedures should be followed to ensure product safety and compliance with
regulations.

24. CONTD….
•Proper storage conditions, including temperature and
humidity control, are essential to maintain the quality
and safety of frozen dairy products during storage and
distribution. Monitoring storage facilities and
transportation conditions helps prevent product
deterioration and microbial growth.
Storage and Distribution:
•Control measures should be implemented to prevent
cross-contact with allergens, such as nuts, soy, and
gluten, during production, handling, and packaging of
frozen dairy products..
Allergen Control:
•Effective sanitation and hygiene practices are critical
throughout the production process to prevent
contamination and ensure food safety.
Sanitation and Hygiene:

25. 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.
PATHOGENS OF FROZEN DAIRY PRODUCTS
Bacillus cereus,
Escherichia Coli,
Campylobacter
jejuni, salmonella
spp. Are found in
raw milk

26. The most dominant organisms that
cause the spoilage are the
psycrophilessuch as Pseudomonas
Yeasts are a major cause of
spoilage of yoghurt
Other important psychrotropic
genera are Bacillus, Micrococcus &
Lactococcus& of the family
Enterobacteriaceae
The most common spore forming
bacteria found in dairy products
are Bacillus Cereus , B. subtilis &
B.megaterium
Spoilage Microflora of Dairy Products

27. CONCLUSION
01
Novel Techniques and preservatives
are needed to prevent the growth
of spoilage microorganisms
02
When Frozen desserts are
exposed to temperatures above -
12c their texture and flavor
characteristics change
03
To maintain the quality of
frozen dairy products it must
be covered tightly in a plastic
container with a lid
04
Dairy products are considered
the most nutritious food, so it is
necessary to preserve them in a
safe way

28. THANK YOU