FERMENTED DAIRY PRODUCTS

Fermented milk products, 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

MILK

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

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%

TWO TYPES OF FERMENTED DAIRY PRODUCT

• Semisolid cultured dairy products• Solid cultured dairy products

11/06/14

SEMISOLID CULTURED DAIRY PRODUCTS

Yoghurt Soft white cheese

YOGURTA 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

EtymologyFrom the Turkish word “yoğurt”, related to the word “yoğurmak” meaning to cogulate, curdle, or thicken

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

NOTES ON YOGURT

Yogurt BacteriaYogurt 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 also yogurt bacteria]S. thermophilus L. delbrueckii subsp. bulgaricus

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

Carbohydrate MetabolismStreptococcus 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 yogurtorganisms owing to the adverse osmotic effect of solutes in milk and the low water activity

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.

Roles of Starter

• Milk acidification• Synthesis of aromatic compounds• Polysaccharide production for the

development of texture and viscosity

PolysaccharidesExopolysaccharides, 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

STEPS IN YOGURT PRODUCTIONFresh 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)

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 fortification2.Contains additives, e.g., stabilizers, flavoring and coloring agents, fruit pulp, dietary fiber, sugar, etc.3.Different carbohydrate component as a result of fermentation

Nutritive Value of Yogurt per 100 gEnergy 257.0 kJ (61 kcal)Sugar (lactose) 4.7 gFat 3.3 gProtein 3.5 gVit. A equiv. 27.0 µgRiboflavin 0.14 mgCalcium 121.0 mg

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.

Factors Affecting Shelf-Life of Yogurt

1. Bacterial growth during incubation

2. Storage temperature

3. Acidity

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.

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”.