Milk Quiz: Types of Milk Products

Study Notes

Milk Secretion and Let-Down

Milk is released by alveoli into ducts, which carry milk to the gland cistern.
40% of milk is stored in the teat and gland cisterns, and the major ducts, while 60% is stored in the alveoli.
Alveoli are grape-like clusters, each composed of a single layer of epithelial cells surrounding a central cavity.
Epithelial cells absorb nutrients from the blood, transform them into milk, and discharge the milk into the cavity of the alveolus.
Myoepithelial cells surround each alveolus, responsible for milk ejection during letdown.

Milk Let-Down Neuro-hormonal Reflex

Suckling stimulus or massaging of the udder stimulates somatic nerves in the teat, sending a signal to the posterior pituitary gland.
The posterior pituitary gland releases the hormone oxytocin, causing myoepithelial cells around the alveoli to contract.
For efficient milking, important factors to remember include:
- Stimulating 1 minute before milk let-down.
- The maximal effect of oxytocin occurs during the first 2 to 3 minutes of milk let-down.
- Stress during cow preparation or during milking will inhibit oxytocin release.

Udder Examination

History includes cow, herd, housing, treatment, and clinical signs.
Detailed examination of the udder includes:
- Inspection of size, symmetry, shape, and lesions.
- Palpation of teat, sinus, tissue, skin, and lymph nodes.
- Evaluation of secretion, including look, smell, CMT, chemistry, and bacteriology.

Mastitis

Mastitis affects profitability by:
- Decreasing milk production (70% of total costs).
- Causing milk to be dumped due to treatment.
- Incurring veterinary and drug costs.
- Increasing labor costs.
- Resulting in culling and death losses.
- Losing quality premiums.
Health concerns of mastitis include:
- Animal health: loss of functional quarter, lowered milk production, and death of cow.
- Human health: poor quality milk and antibiotic residues in milk.

Causes of Mastitis

Mastitis can be caused by various factors.

Milk Products

Fermented and unfermented milk products include:
- Sour cream: cultured and fermented by added lactic acid bacteria (18% fat).
- Crème fraiche: slightly aged, cultured heavy cream (expensive).
- Evaporated milk: milk with 60% of the water removed, having a cooked flavor.
- Buttermilk: fresh liquid milk, usually skim, soured by bacteria.
- Condensed milk: milk with 60% of the water removed, heavily sweetened with sugar (available in cans and bulk).
- Yogurt: milk cultured by special bacteria, having a custard-like consistency (can be dried).
- Dried whole milk: milk that has been dried to a powder.
- Non-fat dry milk: skim milk that has been dried.

Other Products

Whey: the watery part of milk after separation of the curd from the whole milk, containing protein, lactose, minerals, and salts.
Cheese: the clotting casein of milk, made from separated milk or whole milk, and can be made through fermentation.
Butter: solidified milk fat or cream, prepared by churning, and can be made into ghee by heating and clarifying.
Ghee: butter that has been heated and clarified, with the water evaporated and then strained.

Physiochemical Properties of Milk

Milk is a complex colloidal dispersion containing fat globules, casein micelles, and whey proteins in an aqueous solution of lactose, minerals, and other minor compounds.
Major physical properties of milk include:
- Color (white to yellow, depending on the carotene content of the fat).
- Specific gravity and density.
- Freezing point and boiling point.
These properties are influenced by the composition of milk and are important in processing and testing milk for adulteration.
Other properties include:
- Viscosity.
- pH.
- Titratable acidity and acid-base equilibrium.
- Electrical conductivity.

Description

Test your knowledge on different types of milk products including Sour Cream, Crème Fraiche, Evaporated Milk, Buttermilk, and Condensed Milk. Learn about their characteristics and uses in cooking and baking.