cheese for world food

8/13/2019 Cheese for World Food

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Principles of cheese making

University of Minnesota

Origin of cheese

Good milk gone bad

- Raw milk l eft at room temperature will sour and

form a gel that wil l syneresis (whey separation)

- Can increase syneresis by cutt ing heating andstirring

-

curd in a cloth

Trip across the desert

- Milk was stored in the stomach of a calf for a trip

across the desert

- Enzyme called rennet present in the stomach

coagulated the mil k and at the end or the trip cheese

was produced

Cheese Folk Lore/Trivia

- Captain Bligh and mut iny on t he HMS Bounty

- The art of cheese making has been practice since

several centuries BC in the Mediterranean Basin

- Largest piece 1964 Worlds fair, Wisconsin Cheddar34,591lbs

Cheese evolution

- Cheese has evolved into many varieties with

various compositi ons, tastes, and shapes

During most types of cheese manufacture:

A large port ion of casein and fat in the mi lk i s

concentrated in the cheese

Cheese keeps longer than milk during st orage

(ripening) and its properties (flavor, texture,

appearance, functi onality) change durin g ripening

Objective of modern cheese making:

- Rapidly (manufacture on a time schedule) process

milk and precisely adjust the composition of thecheese to control quality and yield

Composition of milk/cheese

- In its simplest form

cheese making is a

process of

concentrating milk

Cheese Diversity

- All cheese manufactu re invol ves col lect ion of mil k,

cheese making, and ripening

- Can vary from very simple to com plex modern

technology


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Milk transport

Adapted from Ch eese and Ferment ed Milk Fo ods

Cheese making

Adapted from Cheese and Fermen ted Mil k Foods

Industrial scaleIndustrial scale

Composition of fresh cheeses

Adapted from Cheese and Fermen ted Mil k Foods

Composition of natural ripened cheeses

Adapted from Ch eese and Ferment ed Milk Foo ds


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Cheese making steps

- Complicated process involving numerous steps and

chemical as well as physical changes

- Several variable affect yield, composit ion, and qu ality

of the cheese

- Optimization of cheese making is i ntricate and the

process system used influences productio n costs

- Overall a full understanding of the various physical and

chemical transformations, their int erdependence, and

the ways in w hich they can be affected is needed if

cheese making is going to be based on scientific

principles instead of rules of thu mb and art

- Several different discipli nes are required including:

process engineering, physical chemistr y, biochemistry,

and microbiology

Cheese making steps

Processing steps

- Pasteurization, culture addition, clotting of milk,

removal of whey, acid product ion, salting, curd

fusion, and ripening

1. Milk pasteurization:

HTST or LTLT applied to kill pathogen

2. Addition of culture:

m croorgan sms

Also destroys other mi croorg anisms and enzymes

that may be harmful or helpful during cheese

ripening

Usually lactic acid bacteria, specific microorganismsadded are depend on the cheese variety

Processing steps

3. Clotting of the milk:

Enzyme (rennet), acid, or a combination of both

results in the formation o f a gel

Caused by casein aggregation and entrapment of fat

Also plant and mi crobial based enzymes available to

4. Cutting and removal of whey:

coagulate milk

Syneresis of the coagulum formed in st ep 3

Final curd is 10-30% of the weight of the origi nal milk

Drier curd is f irmer, resistant to mechanical treatmentand is easier to transport

Processing steps

Clotting of the milk:

Processing steps

Cutting and removal of whey:


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Processing steps

5. Acid product ion:

Actuall y occurs at all stages of manufacture as a

result of conversion of l actose into lactic acid by

lactic acid bacteria (starter culture)

Changes in the pH of t he curd as a result of acid

roduction influence curd ro erties flavor and

6. Salting :

ripening characteristics

Salt is added to the cheese (typically 1-4%), salt content

is often expressed as the ratio of salt:moisture

Can add salt in various ways but dry salting and brine

salting are primarily used

Salt influences texture, flavor, and rip ening

Processing steps

7. Curd fusion:

8. Ripening:

Can be done by pressing (Cheddar) or melting int o a

mass (Mozzarella)

Microbial, biochemical, chemical, and physical processes

occur and result in changes in flavor, texture, and

appearance

- Fresh cheeses are not ripening and may not have

curd fusion (i.e. cottage cheese)

Cheese varieties

- Cheeses can vary widely i n compositi on and can

be manufactured and cured using a wide variety of

methods

- Results: an enormous variety of cheeses are

available

consequences?

Kind of mi lk; st andardization; cheese milk heat treatment;

pre-acidification of the cheese milk; starter inocul um;

addition of secondary flora; type of coagulant and

method of coagulation; cutting; cooking; curd washing;

curd size and shape; resting; salting; additi ves; pressing;and ripening temp, time, and conditions

Variations in cheese manufacture

1. Kind of milk:

2. Milk s tandardization:

Cows, goat, sheep, buffalo difference in fatty acid

profile, fat globule size, and milk pro tein fractions

,

regulations are typically based on moisture content and

FDB (fat on a dry basis)

3. Cheese milk heat treatment:

Influences the natural bacterial flora, lipase activity,

rennetability of the milk, syneresis, and retention ofprotein in the curd


4. Pre-acidi fication of the cheese milk:

Pre-culture or ripen the milk prior to renneting can

also add acid to the milk

Results in a change in the calcium and phosphate

content and buffering capacity of the cheese

5. Starter culture inoculum percentage:

Adjust to obtai n the desi red rate of acid producti on

Fast acid product ion is desired in most cheese

Fast acid production shortens the manufacturing time


6. Addition of secondary flora:

Micro flora other than the starter cu lture can be added

Swiss and other cheese with eyes contain proprionic

acid bacteria in addition to l actic acid bacteria

For surface or internal flora development the milk orcheese can be exposed to bacteria (Limburger) or mold

(blue cheese)

General the organisms added are mesophilic or

thermophilic and decompose lactic acid

They influence pH, flavor, and texture of the cheese via

proteolysis, lipolysis and formation of flavor

compounds


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7. Type of coagulant and method of addition:

Rennet or acid (bacteria or direct acidific ation) or a

combination of rennet and acid

Many renneting enzymes are available calf, pepsin

from co ws, pig, chi cken, vegetable (ficin, papain,

bromelin), molds (mucos mie hei), and bacteria

They type of coagulant used wi ll influence the gel

characteristics, syneresis, and ripening characteristics

of the cheese

8. Cutting:

Wire knives of varying size and design or a fixed

horizontal or vertical rot ating knife can be used

Syneresis is inf luenced by curd size and stirri ng


9. Cooking :

Cooking time and temperature i nfluence syneresis, and

rennet activity (proteolysis) duri ng ripening

Swiss has complete r ennet i nactivation whereas as

Mozzarella has partial rennet in activation (chymosin is

more stable at low pH)

The starter culture is also influence by cooking

conditions (activity of mesophilic st arter is decreased

at temps above 30C)

10. Curd washing:

As much as 200% water can be added t o decrease t he

lactose content of the curd influences final cheese

pH


Cooking examples:


11. Curd size and cheese shape:

Final curd size at salting influence salt absorption and

cooling rate

Final cheese size and shape infl uences surface area

and moisture loss during ripening

arge sca e manu ac ure o e ar c eese u zes

290 Kg blocks

12. Resting:

Time between pressing and salting (Gouda) or time

between ditch ing and salting (Cheddar)

Time utilized is variable and depends on the rate ofacid production


13. Salting method and salt content:

Dry salting before pressing (Cheddar and simil ar);

brine salting after pressing (Mozzarella, Gouda); dry

salting by rubbing on the surface of the cheese (Feta)

Salt content varies from .5 to 10% - Feta and Blue are

Salt content has a major inf luence on flavor, texture,

and ripening characteristics

14. Additi ves:

Spices, etc (caraway, peppers, basil, bacon) are mixed

with the curd after whey removal


15. Pressing :

Pressing is not utilized for all cheese surface and

internal mold ri pened cheese is not pressed (mold

growth requires air)

Can vary from light pressing to pressing in conj unction

with a vacuum s stems lar e scale Cheddarproduction)

Curd can also be pressed under the whey prior to whey

removal (Gouda, Swiss, and Parmesan)


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Pressing:


16. Ripening temperature and time:Typically the ripening temp is between 5 and 20C (1

day to several years)

A higher t emperature wi ll s peed up the r ipen ingprocess (temperature has a larger effect on lipolysis

than it does on proteolysis); at high t emperatures

cheese can sag, oil off, evaporate water, and show

microbial defects; generally a higher temperature will

usually leads to cheese defects

Swiss is the exception it is kept at 23C for 5 wks to

speed gas production by propionic acid bacteria

Surface or internal mold ripened (Camembert 85%

RH; Blue hole pierced in t he cheese; red smear 90-

95% RH

How do we look at all these variables?

- A few main variables are the most cri tical and are

influenced in combination

- Concept: Controlled approach to cheese technology

Objective is the removal of moisture from a coagulum

Key to cheese manufacture: acid producti on in t he vat

because the other variable can be control led

How does acid productio n in the vat influence cheese

characteristics?

Moisture expulsion

Acid production in the vat

Basic cheese structure is d etermined w hen curd and

whey is separated (curd mi neral content is crit ical)

The lowest possible pH is d etermined by the

residual lactose present and the final salt to

moisture ratio of the cheese

Each type of cheese has a characteristic mineral

content and pH this is the best way to classify

cheese

Basic cheese structure and flavor


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Cheese classification

cheese for world food

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