Milk processing

unit operation

1. Milk Processing and Packaging Majed Alghamdi

2. Nutrients in Milk Minerals Calcium Builds strong bones and teeth strengthens body cells; aids in blood clotting; regulates muscles, including the heart; maintains normal nerve functions Phosphorus Strengthens body cells; combines with calcium to make bones and teeth; helps in the oxidation of foods

3. Vitamins Vitamin A Aids vision and growth; helps maintain health of mucous membranes Vitamin B2 (riboflavin) Aids growth; helps maintain health of skin, eyes, and tongue; helps nerve tissues function; helps digestive tract

4. Vitamins Continued Vitamin B1 (thiamin) Assists in maintaining normal appetite, a healthy digestive system Niacin Nerve function; helps release food energy for the body ’ s use Vitamin D Helps body to use calcium and phosphorus to build strong bones and teeth.

5. Macronutrients Carbohydrate Lactose (milk sugar ) Provides energy Fat Protein Aids growth; builds muscles; repairs worn or broken tissues. Water Contributes to body fluids; regulates body temperature

6. Macronutrients

7. Sources of milk food 1- Cows 2- Others: buffalo, goat, sheep, camel

8. How Milk Gets from the Cows to the Stores Those eight steps are (in order) : 1 . Rearing, 2 . harvesting , 3 . storing, 4 . transportation , 5 . lab testing, 6 . processing , 7 .  packaging ,  and 8 . selling.

9. Processing of milk To make milk: safer more appealing or healthier Pasteurization, homogenization, Fortifying.

10. Pasteurization It is named for the French scientist Louis Pasteur, who in the 1860s It requires temperatures of about 63° C (145° F) maintained for 30 minutes or, alternatively, heating to a higher temperature , 72° C (162° F), and holding for 15 seconds (and yet higher temperatures for shorter periods of time).

11. Ultra-high-temperature processing Ultra-high temperature processing (UHT), or ultra-heat treatment, sterilizes  food by heating it above 135°C (275°F) - the temperature required to kill spores in milk - for 1 to 2 seconds .  UHT is most commonly used in milk production, but the process is also used for fruit juices, cream, soy milk, yogurt, wine, soups, honey, and stews Shelf life is extended to 60–90 days Disadvantage: The heat used during the UHT process can cause Maillard browning and change the taste and smell of dairy products

12. High -temperature short- time (HTST) processing An alternative process is HTST pasteurization (high temperature/short time ), in which the milk is heated to 72°C (161.6°F) for at least 15 seconds . It avoid the disadvantage of last method ( Maillard browning) .

13. Homogenization Milk homogenization is accomplished by mixing massive amounts of harvested milk to create a constant, then forcing the milk at high pressure through small holes. Yet another method of homogenization uses extruders,  hammermills , or colloid mills to mill (grind) solids . Milk homogenization is an essential tool of the milk food industry to prevent creating various levels of flavor and fat concentration.

14. Homogenization Homogenizing valve, a method to homogenize at high pressure.

15. milk fortification T he addition of one or more vitamins, minerals, or proteins not naturally present in a food. The term, fortified, also applies when added nutrients include one or more naturally present in the food. In the United States, the Food and Nutrition Council of the American Medical Association pronounced in 1939 the addition of no more than 400 IU of vitamin D per quart of milk, in the interest of public health. The marked decline in the prevalence of rickets, a vitamin D deficiency disorder, in the USA has been partially attributed to vitamin D fortification of milk.

16. Milk separation The fat fraction separates from the skim milk when milk is allowed to stand for 30 to 40 minutes. This is known a `creaming'. The creaming process can be used to remove fat from milk in a more concentrated form. A number of methods are employed to separate cream from milk. An understanding of the creaming process is necessary to maximize the efficiency of the separation process.

17. 1- Gravity separation Fat globules in milk are lighter than the plasma phase, and hence rise to form a cream layer. The rate of rise (V) of the individual fat globule can be estimated using Stokes' Law which defines the rate of settling of spherical particles in a liquid: V = (r 2  (d 1  –    d 2 )g)/9η where r = radius of fat globules d   1  = density of the liquid phase d 2  = density of the sphere g = acceleration due to gravity, and η  = specific viscosity

18. 1- Gravity separation Figure 1.  Batch separation of milk by gravity: (a) Shallow pan method, (b) deep-setting method

19. Centrifugal Separation Gravity separation is slow and inefficient. Centrifugal separation is quicker and more efficient Involves spinning milk through a centrifuge to separate the cream from the milk. After separation, the cream and remaining milk are remixed to provide the desired fat content for the different types of milk being produced. For "whole milk," the cream is reintroduced until the fat content reaches 3.25%. For "low fat milk," the fat content is 1%. For "skim milk" (sometimes called nonfat milk) the fat content is .05%.

20. Transition of Milk Packaging 21 Traditional Steel Containers Glass Bottles Tetra Packs High Density Polyethylene (HDPC) Pouch

21. Glass Disadvantages include its fragility, its weight and the cost of the one-way bottles . Milk exposed to fluorescent light at the grocery store for just four hours can lose nutritional value & develop an oxidized, burnt flavor

22. Tetra Pack 23 Combines attributes of paper plastic and aluminum Paperboard makes the package stable and light weight Polyethylene are added to seal in the liquid and protect external moisture A thin layer of aluminum foil protects product from oxygen and light

23. Advantages of Tetra pak ® Excellent shelf impact and billboard effect Frees up to 40% shelf space Efficient handling and transportation thanks to square shape and light weight. 18% more packages can fit on a pallet, compared to cans. Convenient – easy to open, store and recycle  

24. Milk - HDPE (High Density Polyethylene) Bottles 25 Used for all three milk types : pasteurized , UHT and sterilized A three layer protection against UV rays ( White-Black-White) Preserves natural taste and smell, flexible, durable, low cost, eco friendly and resistance to many chemicals Heat sealing of bottles

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