Dairy: Milk Introduction & Composition

• Milk and dairy products are the focus of this study

Introduction to Milk

• Milk is produced by the mammary glands of female mammals after they give birth
• Legally, milk is the product of continuous milking from a healthy dairy animal, collected cleanly, and free of colostrum
• Milk, a white liquid, nourishes young mammals during lactation
• Milk from cows, sheep, goats, camels, or dromedaries is consumed daily
• "Milk" typically means cow's milk unless otherwise specified

Composition of Milk

• Milk is a nearly complete food source
• Carbohydrates, specifically lactose, provide energy
• Proteins like casein and albumin are present.
• Lipids, rich in saturated fatty acids are a key component
• Contains vitamins A, B, D3, and E
• Includes minerals such as calcium, phosphorus, and magnesium
• Consists of approximately 90% water
• Also contains sugar, soluble proteins, and water-soluble vitamins,
• Proteins, especially caseins, exist in colloidal solution
• Fat is present in an emulsion
• Has a density between 1.030 and 1.034
• Has a near-neutral pH, ranging from 6.6 to 6.8
• Water is the primary component of milk

Milk Components

• Carbohydrates are mainly in the form of lactose and provide energy
• Minerals present include phosphorus, sodium, potassium, magnesium, chlorine, and trace elements that support bodily functions

Calcium Benefits

• Dairy products offer high calcium content (~1.200mg/L) that is easily absorbed
• Not all dairy products have the same calcium levels
• Include calcium in the diet through vegetables, fruits and drinking water
• Dairy alone can meet 60-80% of daily calcium needs

Proteins in Milk

• Dairy products offer high-quality protein.
• Proteins from dairy products are of higher quality than plant-based proteins
• Comparable to proteins from eggs, meat, and fish
• Milk, cheese, and fresh dairy have similar protein content
• Fat content does not affect protein quality
• Modern treatments like Ultra-High Temperature (UHT) do not compromise protein quality

Vitamins in Milk

• Milk and dairy products are a key source of vitamins
• Presence of water-soluble vitamins(B group and vitamin C) and fat-soluble ones (A, D, E, K)
• Dairy is rich in Vitamins B2 and B12
• A quarter liter of milk meets 40% of a child's vitamin B2 needs
• A liter of milk meets 100% of B12
• Non-skimmed dairy is a main contributor to vitamin A intake
• 25g of butter covers 20% of Vitamin A needs
• Vitamins are sensitive to light (B2), heat (B1, B6, B12), and air (C)
• Vitamin loss during food processing is usually minor
• Some "guaranteed vitamin content" milks are fortified to match raw milk vitamin levels

Milk Lipids

• Whole milk provides 9g of lipids, totaling 160 kcal per bowl
• Half-skimmed milk offers 4g of lipids, or 115 kcal
• Skimmed milk consists of less than 1g of lipids, amounting to 85 kcal.
• Milk fat digests easily, especially when raw or melted
• Minimal fat difference exists between low-fat and plain yogurt
• Fat content on labels is calculated using dry matter
• A bowl of whole milk has less fat compared to a tablespoon of oil

Milk Protein System

• Milk is a good protein source, containing 30-34g per liter
• ½ liter of milk has 16g of protein, equivalent to a small steak or two eggs
• Protein Rate or PR measures total nitrogenous matter
• PR affects milk market value
• A high PR will give better the cheese processing yield
• PR depends on race, genetics, photoperiod and food (energy supply)
• Excess protein in the diet will not raise PR
• Milk includes proteins and non-protein nitrogenous compounds like creatinine and uric acid
• Milk proteins have high nutritional value and are rich in essential amino acids
• 80% of milk proteins are casein, 19% are soluble and 1% are other proteins like enzymes

Casein Synthesis

• 90% of milk proteins are synthesized by the udder and are specific to milk
• Caseins come fully synthesized by the udder
• Lactoglobulins are blood proteins that are modified by the udder
• Immunoglobulins at 10% comes directly from the blood

Protein Composition

• Milk proteins include 80% of caseins with 40% being a-casein, 24% being B-casein, 12% being K-casein and 4% being y-casein
• Soluble proteins account for the remaining 20%: 12% Lactalbumin 5% Lactoglobulin 2% Immunoglobulins
• The amount of fat is related to and linked the amount of protein.
• The more fat, the more protein

Milk Proteins

• Unstable phase comprises solid particles in suspension, scattered light along with fatty globules gives milk it's opaque look
• Caseins mainly present.
• Stable soluble phase has soluble or whey (whey) proteins
• Casein consists of tiny solid particles that are suspended in milk in the form of micelles
• Casein micelles and fat globules give milk, taste and flavor
• Caseins consist of acid and amino groups and is sensitive to pH of the medium
• A pH of 4.6 will cause coagulation of the proteins where they are separated from aqueous phase

Casein Types

• Caseins comprise of several molecules:
• αs-casein (50%) – small polymers at pH 7
• β-casein (30%) – monomers at pH 7
• κ-casein (15%) – large polymers at pH 7
• γ-casein (5%)
• αs, β and κ caseins are original molecules
• y-casein results from degradation of the β casein

Casein Stabilization

• к casein stabilizes milk protein with regard to calcium, allows creates micelles
• Molecule contains a labile Phe-Met bond and is a substrate for rennet in milk coagulation Caseins merge with hydrophobic interactions for non-polar groups without presence of Ca
• Molecule charge distribution leads to differences in polymer size, with exception of K-casein
• These qualities are unobserved at high pH and produce dissociation effects

Caseins and Calcium

• α and β caseins precipitate while k casein forms a solution in presence of Ca.
• Resultant micelles have a a loose structure, comprising of 70% + water.
• Schmidt models demonstrates that micelle contains of a submicellae from hydrophobic nucleus

Whey Proteins

• Present in smaller quantities than caseins, are often isolated
• Better nutrition value, linked with sulfur amino acid content and lysine
• β-lactoglobulin is the most abundant at 2-3 g/L
• 5 -SH groups
• Involvement in technological treatments and reduces milk coagulation
• α-lactalbumin, a 123 amino acid residue metalloprotein
• Acts as cofactor in the lactose enzymatic system
• most dominant protein in human milk

Immunoglobulins

• Represent 1/10 of soluble proteins.
• Found in higher concentrations in colostrum due to the passageway of blood Ig
• Facilitate the transmission of immunity from mother to young.

Milk Coagulation

• Milk undergoes lactic acidification at pH 4.6, precipitates demineralized casein and gives crumbly curd
• Coagulation by rennet comes from Phe-Met cleavage of K casein and separates large acidic peptide.
• Insoluble K paracasein protein is hydrophobic.
• Enzymatic reaction happens between 0-50°C and requries the presence of Ca2+

Milk Lipids

• Neutral fats or lipids consists of glycerides or acylglycerols, makes up 98% of composition
• Solid at room temp and found in fine dispersion
• Polar compose roughly 1%
• Unsnaponifiable compose the reminder, containing vitamins, carotenes and sterols
• The main component of cow’s milk is lipid at ~35g/L
• Lipids of consists Triglycerides 97-99%, Phospholipids and sterols at 1-3%

Fat Globules

• Fat globules vary among species, sizes range from 1.5 to 10 µm
• In cow’s milk average diameter is 4 to 5 µm
• Has high levels of dispersion
• Fat globules consist of protective membrane or film for a lipid droplet from the heart forming a cream(80°C). Lecithins keeps globules in suspension

Membranes

• Globules consist of the same composition as the plasma cells
• Complex membrane make of the inner and outer layer The inner layer includes glycoproteins, little enzymatic activity, quite resistance The outer layer consist enzymatic activities, various absorbed substances undergoes heating variation where thickness is reduced Triacylglycerols or triglycerides forms more than 98% of neutral alongside diacylglycerols at 1.5% and monoacylglycerols 0.3%

Acids

• Triglycerides contains 60 to 70% of saturaed fatty acids. Some have very high meltingpoints
• Palmitic and oleic are the main acids present in cow’s milk
• Small amounts of non-acids and double-bonded chains present
• 2/3 of total has unsaturated and 1/3 has unsaturation
• Ruminant milk contains C4 to C10 short chain fatty acids and has special odor
• Unsaturated in the cis formation are high for low melting points, biological activity
• Influences the linolenic acid(feeding) which will favor better proportions
• Iodine measures unsaturation

Linoleic Acid

• Linoleic is high for children which is an element omega-3 that bonds from double bond
• Varies between cow and woman, ranging cow at 1.2 to 2.0% and woman at 8 to 9%
• milks is supplemnted for human milk

Milk Fats

• Subject to variety of damage Lipolysis is the decomposition of fats Oxidation is the chemical process that occurs after exposure to elements

Milk Damage

• Milk contains lipolysis and oxidation shows and inverse reaction
• Lipases are found in milk are are present in bacteria
• Intensity changes per feed from cow to cow and is reliant on the season two types spontaneous and induced

Types of Lipolysis

• Linked to enzymes that are fatty the cooling membranes It only affects milks of some animals upon cooling
• "Spoiled" milk appears okay with healthy milk in high quantites
• Speed happens if its is 10C
• Activated upon forming
• Foam
• Agitation
• Homogenization
• Active lipids dissolve but enzymes are still largely inactive

Fatty Acids

• Released by hydrolysis, inhibit activity and lower pH
• Results during chemical defect
• Oxidation is when fat is created
• Is caused Oxidation fat has unfavorable taste or cardboard, created in butter

Fatty Auto Mechanism

• Oxidation has fat that creates bonds forming hydroperode. created from both odors flavor resulting forms the number chain

Milk Processing

• Copper and iron catalyze Sunlight pH of the milk
• Invert cream
• High protein content yields high fat which makes the high water milk and is stable to make air bubble divide to globate and increases agitates the proteins.

Sugar

• Carbohydrates are are glucose the milk
• Can contain 40 grams per milk
• Contains in form of protiens and the 3L and increases content
• Contains a growth of

Milk Lactose

• glucose and synthesis mammary, is soluble
• It is of used sugars for the young

Milk Problems

• Nutritional of it problems many has can

Milk Assimilation

• Sugar hydrolysis
• 20% loss of and has bacteria dry be of water, 100C of and long cases of the proteins.
• And HMF

Milk Acids

• Increase

Sterilization

• Reduces Flora and the

Pasteurization

• Can stop

Milk Quality

• Loss 0 to be the sterilizing and energy.

Quality Control

• Inhibit has it can be tested with of sterilant

Processing of Milk

• Processed 140degrees celsius, retain taste, reduces original properties in original properties
• Reduces to it of the residues. increases
• And a can and and in milk

Cheese

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• Butter
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Cheese Steps

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Final Steps

There also several cheese variations that can be made with these milk types:

• Hard
• Soft
• Stinky

Explore milk's origins, legal definitions, and sources from mammals such as cows, sheep and goats. Understand its rich composition of carbohydrates, proteins, and lipids, along with essential vitamins and minerals for a nearly complete food source.