MILK CHEMISTRY - Cheese Science Toolkit › assets › doc › milk_info.pdfMilk Fat Globule...
1
MILK CHEMISTRY Simply, milk is an emulsion with fat particles (globules) and proteins dispersed in an aqueous (watery) environment. x 1 Opaque Liquid x 1000 Fat Emulsion x 10,000 Casein Suspension fat globules fat casein fat As an introduction to cheese science... The components of milk and their basic chemistry Milk is composed of water, sugar, fat, protein, and minerals* Water 87.4% Solids 12.6% Milk Breakdown Milk Solids Breakdown Ash 5.6% Lactose 38.1% Whey 4.8% Casein 22.2% Fat 29.4% MILK BASICS Processing Overview Standardisation Pasteurisation Homogenisation Cold Storage Typical pasteurisation conditions include 72°C for 15 seconds or 63°C for 30 minutes Homogenisation helps form a more stable emulsion by reducing the size of the fat globules MILK SUGAR Lactose is the main sugar found in milk; it’s a disaccharide of galactose and glucose Those who are lactose intolerant lack the lactase enzyme and do not break down lactose. Instead, it is fermented by colonic bacteria Lactose galactose Lactase glucose O OH OH OH CH 2 OH O OH OH OH CH 2 OH O O OH OH OH OH CH 2 OH O OH OH OH OH CH 2 OH MILKFAT Most of the fat in milk is saturated, and is found in globular structures Saturated Monounsaturated 3% Polyunsaturated 65% 32% Range in size: 0.1-22 microns Milk Fat Globule Membrane triglyceride core protein glyco-protein Cytopla s m glyco-lipid cholesterol Milk fat globules are made up of a phospholipid tri-layer, in the form of a bilayer and monolayer. The membranes contain other lipids, sugars, proteins, etc. serum MILK PROTEIN Milk contains two main types of proteins: casein (~80%) and whey (~20%) Casein micelle Casein sub-micelle hydrophobic core kappa casein CMP (caseino-macropeptide) Calcium-phosphate Casein proteins will aggregate under two main conditions: acid addition and enzyme addition Whey proteins are globular proteins that denature when exposed to high heat. Under normal pH, micelles have negative charge and repel each other Kappa casein hairs casues steric hindrance and prevents aggregation Hairs are cleaved Aggregate (curd) formation Once isoelectric point has been reached (pH=4.6), net charge is zero Micelles aggregate H + Acid Rennet Heat (enzyme) Casein Whey Native whey protein Heat denatures protein Aggregation induced Sources: Fox, P.F & McSweeney, P.L.H. Advanced Dairy Chemistry. 2003. Springer Science Kailasapathy, Kasipathy. Chemical Composition, Physical and Functional Properties of Milk and Milk Ingredients in Dairy Processing & Quality Assurance. 2008. John Wiley & Sons, Inc. A.K. Smith and B.E. Campbell. Microstructure of Milk Components in Structure of Dairy Products. 2007. Blackwell Publishing Ltd. Created by Cheese Science Toolkit | cheesescience.org *All numbers and figures are estimates and schematic views
Transcript of MILK CHEMISTRY - Cheese Science Toolkit › assets › doc › milk_info.pdfMilk Fat Globule...
MILK CHEMISTRY
Simply, milk is an emulsion with fat particles (globules)and proteins dispersed in an aqueous (watery) environment.
x1Opaque Liquid
x1000Fat Emulsion
x10,000Casein Suspension
fat globules fat
casein
fat
As an introduction to cheese science...
The components of milk and their basic chemistry
Milk is composed of water, sugar, fat, protein, and minerals*
Water87.4%
Solids12.6%
Milk Breakdown Milk Solids Breakdown
Ash5.6%
Lactose38.1%
Whey4.8%
Casein22.2%
Fat29.4%
MILK BASICS
Processing Overview
Standardisation
Pasteurisation
Homogenisation
Cold Storage
Typical pasteurisationconditions include
72°C for 15 seconds or 63°C for 30 minutes
Homogenisation helps form amore stable emulsion by reducing
the size of the fat globules
MILK SUGAR
Lactose is the main sugar found in milk; it’s a disaccharideof galactose and glucose
Those who are lactose intolerant lack the lactase enzymeand do not break down lactose.
Instead, it is fermented by colonic bacteria
Lactose
galactoseLactase
glucose
OOH
OH
OH
CH2OHO OH
OH
OH
CH2OH
O
OOH OH
OH
OH
CH2OH
O
OH
OH
OH
OH
CH2OH
MILKFATMost of the fat in milk is saturated, and is found in
globular structures
Saturated
Monounsaturated
3% Polyunsaturated
65%
32%
Range in size: 0.1-22 microns
Milk Fat Globule Membrane
triglyceridecore
prote
in
glyco
-pro
tein
Cytoplasm
glyco-lipid
cholesterol
Milk fat globules are madeup of a phospholipid tri-layer,in the form of a bilayer and
monolayer. The membranes contain other lipids, sugars,
proteins, etc.serum
MILK PROTEINMilk contains two main types of proteins:
casein (~80%) and whey (~20%)
Casein micelle Casein sub-micelle
hydrophobic core
kappa casein
CMP (caseino-macropeptide)
Calcium-phosphate
Casein proteins will aggregate under two main conditions:acid addition and enzyme addition
Whey proteins are globular proteins that denature whenexposed to high heat.
Under normal pH, micelleshave negative charge and repel each other
Kappa casein hairscasues steric hindrance and
prevents aggregationHairs are cleaved Aggregate
(curd) formation
Once isoelectric point has been reached (pH=4.6),
net charge is zeroMicelles aggregate
H+
Acid
Rennet
Heat
(enzyme)
Casein
Whey
Native whey protein Heat denatures protein Aggregation induced
Sources:
Fox, P.F & McSweeney, P.L.H. Advanced Dairy Chemistry. 2003. Springer Science
Kailasapathy, Kasipathy. Chemical Composition, Physical and Functional Properties of Milk and Milk Ingredients in Dairy Processing & Quality Assurance. 2008. John Wiley & Sons, Inc.
A.K. Smith and B.E. Campbell. Microstructure of Milk Components in Structure of Dairy Products. 2007. Blackwell Publishing Ltd.
Created by Cheese Science Toolkit | cheesescience.org
*All numbers and figures are estimates and schematic views
![Sheep Milk, Sheep Cheese · Use milk higher in casein and fat Increase casein retention Increase fat retention How to improve cheese yield? [RF (%fat in milk) + RC (% casein in milk)]](https://static.fdocuments.in/doc/165x107/5ec5e9bced3a6867603dc67a/sheep-milk-sheep-cheese-use-milk-higher-in-casein-and-fat-increase-casein-retention.jpg)
