Milk Biochemistry Overview

Milk Biochemistry

• Milk is the primary substance for dairy products.
• Milk quality and safety are highly influenced by milk characteristics (fat, protein, salts, lactose, enzymes).
• Milk is a fluid secreted by female mammals to nourish offspring.
• Humans have domesticated mammals (cows, goats, sheep, buffalo) for milk production for millennia.
• Milk is a major global food industry.
• Lactose intolerance is a problem for many, particularly in Asia.
• A genetic mutation allows most Europeans to tolerate milk.
• Milk tolerance in Saudi populations shows a recent adaptation.

Introduction

• Milk composition varies, influenced by factors like diet and lactation.
• Milk is a complex physicochemical system.
• Milk composition is readily unstable.
• Milk's scientific mechanisms of production were not understood initially, before understanding dairy products.
• Understanding the secretion, composition, and influencing factors is crucial for processors and farmers.

Milk Composition and Constituents

• Milk is a complex mixture of various constituents in different phases.
• Main constituents are salts, lactose, and emulsified fat globules in a protein matrix.
• Casein (milk proteins) exists in colloidal aggregates.
• Milk proteins are classified into two groups based on their solubility.

Lactose

• Lactose is the dominant sugar in milk, composed of linked glucose and galactose.
• It's a disaccharide.
• Lactose influences milk yield due to its bacterial fermentation properties.
• Milk's pH drops due to lactose fermentation, leading to coagulation.

Milk Fat

• Milk fat is mainly triglycerides, esterified glycerol and fatty acid molecules.
• Milk fat globules (MFGM) have a protective coating to prevent degradation and maintain stability
• Fat globules vary in size.
• Milk fat quality is related to nutritional values.
• Milk fat quality impacts its technological applications.

Milk Proteins

• Milk contains casein, the main constituent with four caseins (as1-, as2-, β-, and к-caseins).
• Casein forms micelles.
• Whey proteins and their interaction with heat.
• Milk contains different proteins that have differing characteristics.
• Caseins are primarily responsible for the coagulation of milk, forming a matrix for dairy products.

Milk Salts

• Milk contains various minerals, primarily K+, Na+, Ca2+, Mg2+, Cl-.
• Salts are associated with casein micelles and serum phase.
• Milk salts influence the freezing point.
• Milk salts balance maintains osmotic pressure.

Indigenous Enzymes

• Milk from all mammals naturally contains multiple enzymes, essential for milk quality.
• The primary enzymes are alkaline phosphatase, plasmin, and somatic cell enzymes.
• These enzymes' activities can be affected by production treatments.

Factors Affecting Milk Composition and Processing

• Stage of lactation influences milk composition.
• Colostrum has nutrients, different to normal milk.
• Seasonal variations in feed, and calving times substantially affect milk output and composition.
• The diet of milk-producing animals significantly influences milk components.
• Factors such as mastitis, somatic cell count, and genetic make-up impact milk quality.

Mastitis and Somatic Cell Count

• Mastitis is mammary gland inflammation, typically bacterial.
• Mastitis increases somatic cell count (SCC) drastically in milk.
• Increased SCC alters the composition of milk, particularly protein profiles and enzymes.
• Subclinical mastitis poses difficulty in testing milk.

Explore the fascinating world of milk biochemistry, including its composition, quality influences, and health implications. This quiz delves into how milk serves as a vital food source and its role in the global dairy industry. Test your knowledge on the genetic aspects of milk tolerance and the physicochemical properties of milk.