FOTE 262: Dairy Science & Technology

Vocabulary cards covering key terms and definitions from the lecture notes on milk composition, colloidal systems, processing, microbiology, and quality control.

Milk

Secreted by mammary glands of mammals; primary nutrition for the young; also consumed by humans.

Lactose

Milk sugar; reducing disaccharide consisting of glucose and galactose; the distinctive carbohydrate of milk.

Fat (milk fat)

Triglycerides forming the fat portion of milk; present as fat globules in an oil-in-water emulsion.

Casein

Major milk protein (about 4/5 of milk protein); phosphorylated and forms micelles; binds calcium and magnesium.

Casein micelle

Colloid in milk composed of casein proteins, water, and salts (calcium phosphate); negatively charged and stabilized by κ-casein hairs.

κ-Casein

Component of casein that forms the hairy surface layer on micelles; stabilizes micelles and prevents coagulation.

Fat globule

Small fat droplets in milk; oil-in-water emulsion; size ~0.1–15 μm and surrounded by a membrane.

Fat globule membrane

Phospholipids, cholesterol, and proteins surrounding fat droplets; prevents coalescence.

Milk plasma

Liquid phase of milk after fat globules are removed; contains minerals, lactose, and other soluble components.

Milk serum

Liquid remaining when casein micelles are removed; contains serum proteins in soluble form.

Lipid components in milk

Primarily triglycerides; also small amounts of phospholipids and cholesterol.

Lipase

Milk enzyme that hydrolyzes triglycerides to free fatty acids and glycerol; key in lipolysis.

Lipolysis

Enzymatic hydrolysis of fats in milk producing free fatty acids and glycerol; can cause soapy/rancid flavors.

Lyophobic colloids

Colloids that are solvent-hating (e.g., fat globules, gas bubbles) and tend to destabilize under certain conditions.

Lyophilic colloids

Colloids that are solvent-loving (e.g., casein micelles) and are relatively stable across conditions.

Colloid stability

Stability determined by interparticle forces; aggregation, coalescence, and Ostwald ripening describe instabilities.

Ostwald ripening

Growth of larger droplets at expense of smaller ones due to diffusion of molecules between droplets.

Creaming

Rising of fat globules to the milk surface due to density differences; enhanced by aggregation and temperature.

Partial coalescence

Rupture of the fat–fat interfacial film when droplets are close, forming granules and releasing membrane materials.

Coalescence

Fusion of fat droplets to form larger droplets when intervening films break down.

Calcium phosphate in micelles

Colloidal salt in casein micelles that helps stabilize structure and bind calcium.

Casein micelle dynamics

Micelles exchange mineral components and casein between micelles and serum; submicelles can form.

Milk enzymes (examples)

Catalase, peroxidase, xanthine oxidase, alkaline phosphatase, amylase, lipase, aldehyde oxidase.

Lactalbumin

Whey protein; about 87% of whey protein; simple, highly digestible, rich in cysteine.

Lactoglobulin

Whey protein; about 13% of whey protein; alpha and beta subfractions; easily digested.

Milk proteinsa: casein vs whey

Casein forms micelles; whey proteins (lactalbumin, lactoglobulin) are soluble in serum.

Casein hairs (hairy layer)

C-terminal portion of κ-casein forming a hair-like surface that stabilizes micelles.

Surface phenomena in milk

Study of interfaces, surface tension, adsorption, and surfactants affecting colloidal stability.

Surfactants

Molecules that adsorb at interfaces to reduce surface tension; include amphiphiles like certain fats and proteins.

HACCP

Hazard Analysis and Critical Control Points; system to identify hazards and control points to ensure safety and quality.

QA (Quality Assurance)

System ensuring products meet defined quality criteria; ‘fitness for use’ in food production.

Heat treatment intensity terms

Thermalization, low pasteurization, high pasteurization, sterilization, preheating—levels of heat exposure for safety and quality.

Heat coagulation time (HCT)

Time and conditions at which milk coagulates during heating; influenced by pH and composition.

Standardization

Adjusting product composition (fat, solids-not-fat) to meet specifications and economic goals.

Milk storage and transport terms

Tank milk vs canned milk; cold storage to slow microbial growth; gravity and pumps used in transport.

Bacteria growth kinetics

Growth described by generation time and exponential doubling; N = N0 · 2^n.

Psychrotrophs, mesophiles, thermophiles

Bacteria with different temperature preferences (psychrotrophs 0–20°C, mesophiles 20–45°C, thermophiles 45–60°C) relevant to milk spoilage.

Milk contamination sources

Cow teats, skin, soil, dung, dust, water, feed, milking equipment; routes of contamination.

Milk processing equipment (examples)

Plate heat exchangers, tubular heat exchangers, autoclaves, UHT systems; used for heat treatment and sterilization.

Milk

Secreted by mammary glands of mammals; primary nutrition for the young; also consumed by humans.

Water Content in Milk

Approximately 87\% of milk's mass, acting as the solvent for soluble components.

Lactose

Milk sugar; reducing disaccharide consisting of glucose and galactose; the distinctive carbohydrate of milk.

Fat (milk fat)

Triglycerides forming the fat portion of milk; present as fat globules in an oil-in-water emulsion.

Casein

Major milk protein (about 4/5 of milk protein); phosphorylated and forms micelles; binds calcium and magnesium.

Alpha- and Beta-Casein

Major fractions of casein; \alpha{s1}- and \alpha{s2}-casein are highly phosphorylated, while \beta-casein is more amphiphilic.

Casein micelle

Colloid in milk composed of casein proteins, water, and salts (calcium phosphate); negatively charged and stabilized by κ-casein hairs.

κ-Casein

Component of casein that forms the hairy surface layer on micelles; stabilizes micelles and prevents coagulation.

Fat globule

Small fat droplets in milk; oil-in-water emulsion; size ~0.1–15 \mum and surrounded by a membrane.

Fat globule membrane

Phospholipids, cholesterol, and proteins surrounding fat droplets; prevents coalescence.

Milk plasma

Liquid phase of milk after fat globules are removed; contains minerals, lactose, and other soluble components.

Milk serum

Liquid remaining when casein micelles are removed; contains serum proteins in soluble form.

Lipid components in milk

Primarily triglycerides; also small amounts of phospholipids and cholesterol.

Vitamins in Milk

Contains fat-soluble vitamins (A, D, E, K) and water-soluble vitamins (B complex, C).

Minerals in Milk

Rich source of calcium, phosphorus, potassium, magnesium, and zinc.

Lipase

Milk enzyme that hydrolyzes triglycerides to free fatty acids and glycerol; key in lipolysis.

Lipolysis

Enzymatic hydrolysis of fats in milk producing free fatty acids and glycerol; can cause soapy/rancid flavors.

Plasmin

Endogenous milk protease that breaks down proteins, particularly casein; contributes to flavor development in cheese.

Lyophobic colloids

Colloids that are solvent-hating (e.g., fat globules, gas bubbles) and tend to destabilize under certain conditions.

Lyophilic colloids

Colloids that are solvent-loving (e.g., casein micelles) and are relatively stable across conditions.

Colloid stability

Stability determined by interparticle forces; aggregation, coalescence, and Ostwald ripening describe instabilities.

Zeta Potential

Measure of the electrical potential at the slipping plane of a colloidal particle, influencing its stability against aggregation.

Ostwald ripening

Growth of larger droplets at expense of smaller ones due to diffusion of molecules between droplets.

Creaming

Rising of fat globules to the milk surface due to density differences; enhanced by aggregation and temperature.

Partial coalescence

Rupture of the fat–fat interfacial film when droplets are close, forming granules and releasing membrane materials.

Coalescence

Fusion of fat droplets to form larger droplets when intervening films break down.

Calcium phosphate in micelles

Colloidal salt in casein micelles that helps stabilize structure and bind calcium.

Casein micelle dynamics

Micelles exchange mineral components and casein between micelles and serum; submicelles can form.

Milk enzymes (examples)

Catalase, peroxidase, xanthine oxidase, alkaline phosphatase, amylase, lipase, aldehyde oxidase.

Lactalbumin

Whey protein; about 87\% of whey protein; simple, highly digestible, rich in cysteine.

Lactoglobulin

Whey protein; about 13\% of whey protein; alpha and beta subfractions; easily digested.

Whey Protein Denaturation

Irreversible change in the 3D structure of whey proteins, typically caused by heat, affecting functionality.

Immunoglobulins

Antibody proteins found in milk (especially colostrum) that provide passive immunity to neonates.

Milk proteins: casein vs whey

Casein forms micelles; whey proteins (lactalbumin, lactoglobulin) are soluble in serum.

Casein hairs (hairy layer)

C-terminal portion of κ-casein forming a hair-like surface that stabilizes micelles.

Surface phenomena in milk

Study of interfaces, surface tension, adsorption, and surfactants affecting colloidal stability.

Surfactants

Molecules that adsorb at interfaces to reduce surface tension; include amphiphiles like certain fats and proteins.

HACCP

Hazard Analysis and Critical Control Points; system to identify hazards and control points to ensure safety and quality.

QA (Quality Assurance)

System ensuring products meet defined quality criteria; ‘fitness for use’ in food production.

Heat treatment intensity terms

Thermalization, low pasteurization, high pasteurization, sterilization, preheating—levels of heat exposure for safety and quality.

Heat coagulation time (HCT)

Time and conditions at which milk coagulates during heating; influenced by pH and composition.

Standardization

Adjusting product composition (fat, solids-not-fat) to meet specifications and economic goals.

Homogenization

Mechanical process that reduces the size of fat globules in milk, preventing creaming and increasing stability.

HTST Pasteurization

High-Temperature Short-Time pasteurization (e.g., 72°C for 15s); a common method for milk to kill pathogens while preserving quality.

UHT Pasteurization

Ultra-High Temperature pasteurization (e.g., 135-150°C for 1-5s); extends shelf life by achieving commercial sterility.

Milk storage and transport terms

Tank milk vs canned milk; cold storage to slow microbial growth; gravity and pumps used in transport.

Bacteria growth kinetics

Growth described by generation time and exponential doubling; N = N_0 \cdot 2^n.

Psychrotrophs, mesophiles, thermophiles

Bacteria with different temperature preferences (psychrotrophs 0–20°C, mesophiles 20–45°C, thermophiles 45–60°C) relevant to milk spoilage.

Milk contamination sources

Cow teats, skin, soil, dung, dust, water, feed, milking equipment; routes of contamination.

Milk-borne Pathogens

Bacteria (e.g., Listeria monocytogenes, Salmonella spp., E. coli O157:H7) that can cause illness if present in raw or improperly processed milk.

Somatic Cell Count (SCC)

Measure of the number of somatic cells (primarily leukocytes) per mL of milk, indicating mammary gland health and potential mastitis.

Milk processing equipment (examples)

Plate heat exchangers, tubular heat exchangers, autoclaves, UHT systems; used for heat treatment and sterilization.

Milk

Secreted by mammary glands of mammals; primary nutrition for the young; also consumed by humans.

Water Content in Milk

Approximately 87\% of milk's mass, acting as the solvent for soluble components.

Lactose

Milk sugar; reducing disaccharide consisting of glucose and galactose; the distinctive carbohydrate of milk.

Fat (milk fat)

Triglycerides forming the fat portion of milk; present as fat globules in an oil-in-water emulsion.

Casein

Major milk protein (about 4/5 of milk protein); phosphorylated and forms micelles; binds calcium and magnesium.

Alpha- and Beta-Casein

Major fractions of casein; \alpha{s1}- and \alpha{s2}-casein are highly phosphorylated, while \beta-casein is more amphiphilic.

Casein micelle

Colloid in milk composed of casein proteins, water, and salts (calcium phosphate); negatively charged and stabilized by κ-casein hairs.

κ-Casein

Component of casein that forms the hairy surface layer on micelles; stabilizes micelles and prevents coagulation.