cheese

What is the primary ingredient used to make cheese?

Milk.

What are some of the most popular styles of cheese in the United States?

American style cheeses, such as Cheddar and Colby, and Italian style cheeses, such as Mozzarella and pizza cheese.

Which state is the leading producer of cheese in the United States?

Wisconsin, followed by California.

What is syneresis?

The removal of water from cheese curds.

What conditions enhance syneresis?

High or moderate temperatures and low pH.

What happens if the temperature becomes too high during cheese production

It can kill the microorganisms responsible for producing acids.

cheese production?

It can kill the microorganisms responsible for producing acids.

What happens when too much acid is produced during cheese manufacturing?

Minerals, specifically calcium, are lost, potentially making the cheese crumbly.

What is coagulation?

The precipitation of milk proteins to convert liquid milk into a solid curd.

What happens to dissolved solutes during coagulation?

They are removed from the curd along with the whey, lowering the amount of lactose available to the culture.

What percentage of milk protein is casein?

Approximately 80%.

What percentage of milk protein consists of whey proteins?

Approximately 20%.

What happens to whey proteins during most cheese production?

They are removed with the water during whey drainage.

What are the primary components of the casein matrix?

Casein proteins, some water, and a large portion of the milk lipids.

What are the three major methods of milk coagulation?

Acid coagulation, enzymatic coagulation, and acid and heat coagulation.

What causes acid coagulation?

Acid produced by lactic acid bacteria (LAB).

At what pH does casein reach its isoelectric point?

Approximately pH 4.6.

What happens to casein at its isoelectric point?

Its solubility reaches a minimum, causing it to precipitate.

What happens to the coagulum after acid coagulation?

It is cut into smaller pieces called curds.

What are acid coagulated curds primarily composed of?

Casein and water.

What is an alternative to fermentation for producing acid coagulation?

Direct addition of food grade acid to milk.

What type of mixture is milk?

An emulsion.

What is suspended in the water phase of milk?

Fat globules and casein micelles.

What are the two major categories of milk proteins?

Casein and whey proteins.

What is a casein micelle?

A submicroscopic protein particle consisting of alpha , beta , and kappa casein held together by hydrophobic and ionic bonding.

What is the function of kappa casein?

It stabilizes casein micelles through its charge and hydrophobic region.

What is the overall electrical charge of casein micelles before coagulation?

Negative.

Why do casein micelles remain suspended in milk?

They are highly hydrated, small, and negatively charged.

What pH range is used to achieve acid coagulation of casein?

Approximately pH 4.6–4.7.

How does lowering the pH cause casein micelles to coagulate?

It neutralizes their negative charges, allowing the proteins to interact and aggregate.

What are examples of cheeses made through acid coagulation?

Cottage cheese, cream cheese, Quark, and Chèvre.

Why do acid coagulated cheeses generally have high moisture content?

Their curds do not readily expel whey.

Why can acid coagulated cheeses not typically be cured?

Their high moisture content makes them susceptible to spoilage during storage.

Which bacteria can be used to acidify milk during cheese production?

Lactococci and Streptococcus thermophilus.

What is direct acidification?

Adding food grade acid directly to milk instead of relying on fermentation.

What acids are commonly used for direct acidification?

Citric acid, lactic acid, and acetic acid.

What are the physical characteristics of acid curds?

Gelatinous, fragile, and nonelastic.

Do acid curds undergo substantial syneresis?

No. They have a low amount of syneresis.

What enzyme is most commonly used for enzymatic coagulation?

Chymosin, also called rennet when referring to the enzyme preparation.

What does chymosin do during cheese production?

It hydrolyzes specific peptide bonds in kappa casein.

What causes casein to precipitate following chymosin activity?

Calcium ions.

What happens to milk fat during enzymatic coagulation?

Nearly all the fat becomes trapped within the casein network.

Why are LAB cultures added when chymosin is used?

To produce acid and contribute to desirable flavor, texture, and other cheese properties.

What are the two major steps of enzymatic coagulation?

Chymosin converts kappa casein into para kappa casein and a soluble macropeptide

What is the chemical form of cheese curd protein at pH 6.0–6.6?

Dicalcium para casein.

What happens to calcium in the curd as pH decreases during cheese manufacturing?

Calcium is lost from the curd.

What type of macropeptide is released during enzymatic coagulation?

A hydrophilic, acidic macropeptide.

How does enzymatic coagulation change the properties of casein micelles?

They become more hydrophobic and less negatively charged.

What type of bonding allows casein micelles to aggregate following chymosin activity?

Hydrophobic bonding.

What are examples of cheeses made through enzymatic coagulation?

Cheddar, Gouda, and Queso fresco.

How does a decrease in pH affect coagulation time?

It decreases coagulation time.

How does a decrease in pH affect curd strength?

It increases curd strength.

How does increasing calcium ion concentration affect coagulation?

It decreases coagulation time and increases curd strength.

How does increasing temperature affect coagulation time?

It decreases coagulation time.

What are the physical properties of rennet curds?

They are elastic, plastic as pH decreases, and readily undergo syneresis.

What does it mean for a curd to be elastic?

It retains its shape when lightly pressed.

What does it mean for a curd to be plastic?

It can be molded without breaking.

What does chymosin refer to?

A specific milk coagulating enzyme found in the stomachs of suckling mammals.

What does the term rennet refer to?

Any enzyme preparation used to coagulate milk during cheese production.

Where was traditional rennet obtained?

From extracts of suckling animal stomachs containing coagulating enzymes.

What is the natural source of chymosin used in cheese manufacturing?

The stomachs of suckling calves, obtained through a salt extraction process.

What is one disadvantage of naturally sourced chymosin?

It is more expensive.

When was genetically engineered chymosin approved by the FDA?

1990

What are the conditions used for acid and heat coagulation?

Moderate acid addition to approximately pH 6.0 combined with high temperatures above 85°C.

What happens to whey proteins during acid and heat coagulation?

They become denatured and precipitate.

What proteins and other components are present in the resulting acid and heat coagulated precipitate?

Whey proteins, casein, and fats.

What does protein denaturation mean in acid and heat coagulation?

Heat causes proteins to unravel and expose sticky portions of their structure.

How do denatured whey proteins form a coagulated matrix?

Their exposed sticky regions bond with other whey proteins or casein proteins.

What are examples of cheeses made through acid and heat coagulation?

Ricotta, Mascarpone, and Paneer.

What is the primary purpose of cutting curds during cheese production?

To increase surface area and promote whey removal.

Why does increasing curd surface area improve syneresis?

It decreases the distance water must travel to reach the curd surface.

What other treatments help promote syneresis?

Stirring, heating, and acidification.

How does pH 4.6 affect the water holding capacity of casein?

It decreases the water holding capacity.

What microorganisms help achieve acidification during cheese production?

Lactic acid bacteria.

What are the four major factors controlling moisture content in cheese?

Curd particle size, heat application, pH, and salt application.

How does curd particle size influence moisture content?

Smaller curds shrink more and expel more whey than larger curds.

How does heat application affect curd moisture?

Heat promotes hydrophobic bonding within the casein network, causing curds to shrink and expel water.

How does acidic pH affect curd shrinkage?

Acidic pH promotes shrinkage.

How does salt affect moisture content?

Salt has a dehydrating effect and reduces moisture content.

Why is salt application limited during cheese manufacturing?

Excessive salt affects taste and can slow ripening.

What cooking treatment is used for Brie and Camembert?

No cooking treatment

What cooking treatment is used for Cheddar cheese?

Heating to 38–39°C for 45 minutes using 1/4 inch curds, resulting in approximately 37% moisture.

What cooking treatment is used for Parmesan cheese?

Heating to 50°C for one hour using rice sized curds, resulting in approximately 32% moisture.

Why should cooking treatments not be excessively severe?

Excessive heat can injure the lactic acid culture.

Which thermoduric cultures are used in Parmesan and Swiss cheese production?

Streptococcus thermophilus and Lactobacillus bulgaricus.

What are the major purposes of pH control during cheese manufacturing?

Preservation, flavor development, texture, and providing an environment for flavor development.

How are all cured cheeses acidified?

Through the growth of LAB.

Why do cured cheeses require high numbers of LAB?

LAB contribute to the development of nonacid flavors.

What happens to LAB after lactose is consumed?

The LAB lyse and release enzymes that generate flavor precursors.

Why is controlling cheese pH important?

It helps achieve typical flavor and texture while preventing spoilage.

What is the approximate pH of milk?

6.6.

What is the typical pH range of cheese?

4.4–5.4.

What determines the final pH of cheese?

Lactose concentration in the curd and the buffer capacity of the curd.

What happens to lactose remaining in the curd during fermentation?

It is converted into lactic acid.

What primarily determines the buffer capacity of cheese curds?

Calcium phosphate content.

How does lactose concentration influence final cheese pH?

More lactose available for conversion into lactic acid generally results in a lower final pH.

How can cheesemakers control final pH?

By controlling the lactose content remaining in the curd.

What percentage of lactose is present in whey?

Approximately 4.8%.

How does removing more whey affect lactose concentration in the curd?

More lactose is removed, resulting in a higher final pH.

How can higher moisture cheese be produced at a higher pH?

By soaking the curds in water after whey removal.