dairy products Flashcards
what is milk
The biological fluid secreted as the primary nutrient source for offspring
Why is milk important
It is produced and consumed at a large scale world-wide, Important for NZ economy as NZ produce 2% of the worlds milk. Offer optimal balanced nutrition from the protein, fat, lipid, vitamin and mineral contents.
What is milk structure and the 3 compositions
A complex multiphase emulsion (mixture of two liquids that are chemically incompatible) and suspension (mixture of a liquid and a solid that are chemically incompatible)
1. Aqueous phase – water, dissolved salts, soluble proteins, carbohydrates
2. Milk fat globules – emulsified w/. aqueous phase – contains lipids, proteins
3. Casein micelles – suspended in the aqueous phase, contains protein, calcium phosphate. Role is to solubilise (dissolve) calcium phosphate – is what surrounds the milk fat globule balls
Milk composition prior to processing
Massive variation from – feeding regime, geography, lactation period, and breed
Most commercially significant milk and dairy products
Whole milk powder, cream after standardising, skim milk powder, butter/casein/whey products, cheese/whey products
What is an important part of the milk structure when making cheese
Casein micelles on the outer layer of the milk fat globules
What is casein
Are a group of proteins found in the casein micelles
What is whey
The bi-product of cheese making, it is the liquid in the multiphase emulsion of milk
What is the process of raw milk handling
After milking needs to be cooled from body temp to below 4 degrees to prevent bacteria growth and minimise enzymatic reactions
During storage gentle agitation is needed to prevent cream separation. Process must minimise aeration and fat globule damage
What is the standardisation process
Separation process on the basis of density, size, and shape. the adjustment (raising or lowering) of the milk fat and solids not fat content of milk to prepare different varieties of milk. Involves adding or removing cream
How is the standardisation process conducted - machine
Using a Disc type of centrifuge
What are key food safety processes during pasteurisation
Inactivation of pathogenic and spoilage bacteria by heat
Inactivation of enzymes by heat
What is the pasteurization process
heating milk to specific temp. (round 65 degrees) and holding it there for a set period (30mins) to eliminate harmful bacteria and extend its shelf life and reduce risk of microbial contamination
Mechanisms of homogenization
Reducing the size and altering the composition of milk fat globules
prevent from separating to give more homogenous (same) texture
What is homogenisation
Prevention of ‘creaming effect’. Breaks down fat globules to more uniform sizes. Prevents that cream from separating and floating to the top, giving more consistent texture. Helps improve stability and enhances its mouthfeel
