Cheese Flashcards
What is cheese?
Milk concentrate consisting of mainly fat and protein
What three categories does the moisture content generally distinguish between?
Hard
Semi-hard
Soft
Each has distinguishing characteristics
How is the history/evidence of cheese in Europe distinguished?
- milk pottery from 5700 bye
Evidence from lipid residue found in pottery
-sieve fragment used in past and lipid residue from cheese making found in them
-scientific analysis done by scraping top layer off and studying lipids
How can isotopic analysis help us identify cheese in history?
Combination of c18 and c16 tells us whether something is from meat or dairy
What are some of the benefits of cheese?
Hard cheese = next to no lactose as cheese making process means bacteria and fungi in the cheese consume the lactose
Cheese contains lots of vitamins and good bacteria = advantageous to eat
How is cheese produced?
From milk
- need to isolate the milk proteins solids and fats
- water needs to be removed
How is the casein Micelle in milk separated from the liquid?
Casein is hydrophobic due to k-casein tails
Tails removed making it insoluble in water and thus separated from liquid
Why is milk selection important in making cheese?
Composition of cheese is strongly influenced by milk composition
Fat:protein ratio is distinctive in different cheese
Milk could be modified e.g removing fat, adding milk powder/cream
What is done to milk to allow it to form cheese?
Ph adjusted = more acidic - done by adding starter culture
Cacl2 often added to improve coagulation of milk by rennet (chops k-casein tails off)
Can raw milk be used to make cheese?
Yes - comte
Gives more intense flavour due to bacteria
Can be bought in supermarkets
Where does cheese get its colour?
Mainly carotenoids from animals diet
Cattle transfer these but other animals don’t (white vs yellow cheese)
Added pigment to make cheese yellow/red
Annato from pericarp of the seeds of the annatto plant
Annatto contains boxing and norbixin
How is milk converted to cheese curds?
- acidification of milk ucing lactic acid producing bacteria/lactic acid/hcl
- ph for most hard cheese = 5-5.3
-rate and duration of acidification depends on cheese
Coagulation - coagulating casein protein to form a gel entrapping any fat present :
1. Most commonly using rennet
2. Acidification at ph4.6 e.g. cottage cheese - no rennet
3. Evaporating water from a mix of whey and milk- norwegian cheese
How does chymosin work?
Chops at 105/106 -removing casein tail
Very specific target in milk protein
- hydrolysing this protein renders nearly 72% of remaining protein insoluble
What is rennet and where was it originally from?
Originally isolated from cells of stomach in calves -only infant animals produce protease
Stomachs used to be ground up and protease extracted
Now sample cell taking from cow and gene is placed in plasmid to produce rennet
How do cheese curds make cheese?
Coagulation - water remove = syncretism Curds filtered, pressed and moulded Curds coagulate and the are chopped and put in a large sieve to move the whey and water Leaves casein in curd Then pressed and moulded
