Fermented dairyproducts

1. FERMENTED DAIRY PRODUCTS
Fermented milk produ cts, also known as
cultured dairy foods, cultured dairy products,
or cultured milk products, are food from
bovine milk that has been fermented by
lactic acid bacteria

2. MILK
The lacteal secretion, practically free of
colostrum, obtained by the complete
milking of one or more healthy cows,
containing not less
than 8.25% milk solids
not fat and not less
than 3.25% of milk fat
(US Public Health
Service, 1985)

3. MILK
COMPOSITION
Water 86 to 88%
Milk fat 3-6%
Protein 3-4%
Sugar 5%
Total solids 11-14%
Phosphorus and minerals (ash) 0.7%

4. TWO TYPES OF FERMENTED
DAIRY PRODUCT
• Semisolid cultured dairy products
• Solid cultured dairy products
11/06/14

5. SEMISOLID CULTURED DAIRY
PRODUCTS
Yoghurt Soft white cheese

6. YOGURT
A probiotic fermented dairy product
produced by the growth of lactic acid
bacteria in warm milk and characterized
by a smooth, viscous gel-like texture with
a delicate walnutty flavor
Etymology
From the Turkish word “yoğurt”, related
to the word “yoğurmak” meaning to
cogulate, curdle, or thicken

7. NOTES ON YOGURT
Yogurt in other languages
“Laban” or “Leben” in Morocco
“Dahi” in India
“Zabadi” in Egypt
“Yohourt” in Bulgaria
Yogurt substrates
Fresh milk, concentrated milk, or skim milk
Types of yogurt
Plain, sweetened, set, stirred, drink, flavored

8. Yogurt Bacteria
Yogurt fermentation is carried out by Streptococcus
thermophilus and Lactobacillus delbrueckii subsp.
bulgaricus (in a 1:1 ratio) in an associative or
symbiotic relationship or in a synergistic reaction.
•Both are thermophiles.
•Present in fresh yoghurt at about a billion cells/ml
•Inoculated as a mixed culture or separately as
individual cultures.
[Bifidobacterium adolescentis, L. acidophilus, and L.
casei are Sa. ltsheorm yopohgiluusrt bacteriaL]. delbrueckii subsp. bulgaricus

9. Notes on the Synergistic Effects of
Yoghurt Bacteria
• The coccus grows faster than the rod and is
primarily responsible for the initial acid
production at a higher rate
• More acetaldehyde (the chief volatile flavor
component of yogurt) is produced by
Lactobacillus delbrueckii subsp. bulgaricus
when growing in association with
Streptococcus thermophilus

10. Carbohydrate Metabolism
Streptococcus thermophilus
 Has a lactose permease system including a proton-dependent
membrane-located permease and an intracellular β-
galactosidase
 Some strains have the capability of metabolizing galactose via
the Leloir pathway
Lactobacillus delbrueckii subsp. bulgaricus
 Uses only the glucose moiety of lactose and releases
galactose into the growth medium
NOTE: Sucrose has an inhibitory effect on growth of yogurt
organisms owing to the adverse osmotic effect of solutes in milk
and the low water activity

12. Yogurt Fermentation
Lactose glucose + galactose
Glucose lactate
Lactic acid bacteria have proteases and
peptidases that act on proteins and increase
the peptide and amino acid content of
yoghurt.

13. Roles of Starter
• Milk acidification
• Synthesis of aromatic compounds
• Polysaccharide production for the
development of texture and viscosity

14. Polysaccharides
Exopolysaccharides, which are high-molecular-weight
polymers composed of sugar residues.
Digestible.
•Contribute to the gelatinous texture of fermented
milk product
•Gives a ropy texture
•Some of them cover the cells with a uniform
layer, and the rest bind cells together or bind milk
casein via a dense network of visible filaments

15. STEPS IN YOGURT PRODUCTION
Fresh Milk
Heat, 40 ° C
Add 4% skim milk
Stir to dissolve skim milk
Pasteurize, 80° C, 10 min
Cool to 45° C
Inoculate with starter
Incubate at 40 - 42° C
for 4 h or until pH
reaches 4.5
Refrigerate (4 – 5 °C)

16. Nutritive Value of Yogurt
Do not differ much from that of milk except for
the following:
1.Increased milk-solids-non-fat content as a
result of fortification
2.Contains additives, e.g., stabilizers, flavoring
and coloring agents, fruit pulp, dietary fiber,
sugar, etc.
3.Different carbohydrate component as a
result of fermentation

17. Nutritive Value of Yogurt per 100 g
Energy 257.0 kJ (61 kcal)
Sugar (lactose) 4.7 g
Fat 3.3 g
Protein 3.5 g
Vit. A equiv. 27.0 mg
Riboflavin 0.14 mg
Calcium 121.0 mg

18. Therapeutic Value of Yogurt
1. Maintenance of normal intestinal
microflora
2. Improvement of lactose intolerance
3. Useful remedy for dry skin
4. Has antitumorgenic activity
5. Has immunogenic properties.

19. Factors Affecting Shelf-Life of Yogurt
1. Bacterial growth during incubation
2. Storage temperature
3. Acidity

20. SOFT WHITE CHEESE
Cheese with a bloomy or velvety white
rind characterized by a soft, buttery
golden interior.
Produced using a special culture, Penicillum
candidum, that encourages the growth of a
white bloom on the cheese surface. This
culture is responsible for maturing the cheese,
ripening it from the outside in, softening its
center and developing its flavor.

21. NOTES ON SOFT WHITE CHEESE
• Made from cow’s milk
• Evolved in Brie in Northern France and then popularized
by a farmer in Camembert
• Brie and Camembert handmade in the traditional
method take time to ripen, developing delicious
complex flavors and surprising textures
• The white rind (sometimes tinged with orange) is edible.
• Taste varies from really mild and buttery to rich and
savoury with a light mushroomy aroma
• Considered the most elegant of cheeses and takes the
center stage on a cheese platter. Brie has the nickname
“The Queen of Cheeses”.