Proteins And Enzymes

Question 1

The formation of disulphide bonds from two sulfhydryl groups of the same molecule or of different molecules result in the __________ or __________ of rigidity in the protein texture

Answer 1

Decrease; increase (decrease or increase)

Question 2

TRUE or FALSE?
The procedure for finding total protein in a food is determined by analyzing for protein nitrogen and then multiplying the results by 6.25 to determine the actual amount of protein in the food analyzed

Answer 2

TRUE

Question 3

TRUE or FALSE?

Some proteins such as ovalbumin in egg white, lactalbumin in milk and gluten in flour are soluble in pure water

Answer 3

FALSE

Question 4

TRUE or FALSE?
Proteins such as those in the muscle tissue of meats are able to bind to water molecules through forces such as hydrogen bonding

Answer 4

TRUE

Question 5

The change in molecular structure without breaking covalent bonds or altering amino acid sequence is referred to as __________

Answer 5

Denaturation

Question 6

The most common method for protein determination in food materials in the __________ procedure

Answer 6

Kjeldahl

Question 7

Proteins are important constituents in hair, skin, muscles, and biological fluids, such as __________ and __________

Answer 7

Milk; blood

Question 8

In foods, proteins serve a variety of functions, such as coagulation, thickening, __________ and __________

Answer 8

Emulsification; gelation

Question 9

In many foods, protein fragments, known as __________, contribute to flavour

Answer 9

Peptides

Question 10

Proteins may exist as homoproteins, which contain only __________

Answer 10

Amino acids

Question 11

Proteins may exists as heterproteins, which include amino acids and other chemical groups, such as lipids, __________, __________, or other organic materials as part of the primary structure

Answer 11

Carbohydrates; metal ions

Question 12

Hemoglobin in meat is an example of a _____ - protein. Casein in milk is an example of a _____ - protein

Answer 12

Hetero; hetero

Question 13

The non-amino acid portion of heteroproteins is called the __________ group

Answer 13

Prosthetic

Question 14

Define protein functionality

Answer 14

Are those properties that enable proteins to contribute to the desirable characteristics of foods

Question 15

Two water-related properties of proteins are __________ and __________

Answer 15

Solubility; hydration

Question 16

Define water-binding capacity

Answer 16

It describes the ability or proteins to hold water molecules

Question 17

In general, denatured proteins become __________ soluble and have __________ water-holding capacity

Answer 17

Less; increased

Question 18

Proteins function as emulsifiers because of their __________ nature

Answer 18

Amphiphilic

Question 19

A foam is a special type of emulsion, where the two immiscible substances are __________ and __________

Answer 19

Air; water

Question 20

Coagulation of protein chains can lead to protein __________ or __________ depending on the concentration of protein

Answer 20

Precipitation; gelation

High protein concentration - GELATION
Low protein concentration - PRECIPITATION

Question 21

How do we get around the problem of proteins that are limiting one or more essential amino acids?

Answer 21

• Complementation (combining beans and rice)
• Supplementation (addition of essential amino acids to food during processing)
• Breeding and biotechnology (selection and producing specific cultivars high in limiting amino acids or transferring genes from one plant to another