lecture 4-protien quality

Question 1

what is protien quality?

Answer 1

it is a value assinged to a protien for its ability to meet nutritional requirments so does it supply the necessary amino acids, and are those amino acids digested

Question 2

how many essential amino acids?

Answer 2

9

Question 3

what are semi essential/conditionally essential amino acids?

Answer 3

these are non-essential amino acids that can become essential under certain conditions like stress or illness. An example is tryosine, since it is made from phenylalanine and if your diet is low in that then tyrosine will become conditionally essential. Another example is arginine which becomes essential when under catabolic stress or with dysfunction of the small intestine/kidney

Question 4

what are limiting amino acids?

Answer 4

limiting amino acids are used to describe essential amino acids present in the lowest quanitity in food protien relative to a reference food protien

Question 5

what is a reference food protien?

Answer 5

it is a food protien like egg white, cows milk, meat and fish that has all the essential amino acids in a relatively high []

Question 6

what is the difference between incomplete and complete protiens?

Answer 6

Incomplete protien which is also known as low quality protiens are protiens that contain one or more essential amino acids in inadequate proportions. Wherease a complete protien or high quality protien has all the essential amino acids in adquate proportions

Question 7

what are complimentary protiens?

Answer 7

a combination of incomplete protiens to possibly result in a complete protien

Question 8

what are the three method of testing protien digestability?

Answer 8

1. protien effieciney ratio
2. protien digestability corrected amino acid score
3. digestible indispensable amino acid scores

Question 9

what is the protien efficiency ratio equation

Answer 9

PER= gain in body mass (g)/ protien intake (g)

Question 10

explain PER

Answer 10

it measures the nutritive value of protien sources. It basically is the ratio between weight gain and protien intake over the entire feeding period. So the higher it is the more beneficial the protien is

Question 11

what are the disadvantages of the PER method?

Answer 11

It uses animals and it is tested with growing animals so cannot be used in terms of maintance protien requriments alone. It also assumes that all protien is used for growth. And since its measuring weight gain there is no distinguishing between weight gained as fat and weight gained as lean body mass

Question 12

what is the true fecal protien digestability?

Answer 12

difference between the intake of protien nitrogen and output of fecal nitrogen

Question 13

what are the disadvantages of using PDCAAS

Answer 13

It uses animals. It assumes that x % of protien will be digested and it assumes that the same is true for each amino acid value. It gives an underestimation of high quality protiens and an overestimation of foods with antinutrional factors which would affect digestion as well fecal digestability so the activity in the microflora can lead to overestimation of digestability

Question 14

what is the equation for PDCAA conversion to PER

Answer 14

PER= PDCAAS x 2.5

Protien rating= PER x protien content

Question 15

What is digestible indispensable amino acid scores (DIAAS)

Answer 15

It is the ratio of digestable amino acid content in the food to the same amino acid in the reference protien, this reference protien is age specific.

The lowest DIAA ratio value is multiplied by 100 to get the DIAAS of the food,

Question 16

what are the steps of calculating DIAAS for one ingredient

Answer 16

1. Mulitply mg/g of amino acid by true ileal AA digestability
2. Take that answer and divide it from the reference protien for specific age group (DIAAS)
3. find lowest one and thats ur DIASS and multiply by 100

Question 17

What are the steps of calculating DIAAS for multiple ingredients?

Answer 17

1. Figure out protien content per 1 gram if in g/100g (weight x protien/100)
2. calculate digestable amount (mg/g protien x true illeal aa digestability)
3. calculate true illeal digestable IAA content by multiply results from step 1 and 2
4. Combine all lysine for example basically combine all results from step 3 for each AA
5. Divide result from step 4 by total protien content in grams
6. compare result from step 5 with reference and divide
7. Identify limiting AA and DIAS value

Question 18

what are disadvantages/drawbacks of using DIAAS

Answer 18

• use of animals
• doesnt take into account digestability changes that occur after processing
• focuses on individual isolated foods compared to the food matrix, this could lead to error because in the food matrix there is interaction which can affect the results
• no difference between animal and plant based foods in terms of nitrogen to protien conversion factors

Question 19

what is amino acid scoring?

Answer 19

it is a method to evulate the quality of a protien based on amino acid requirements. It is a ratio of the amount of each essential amino acids in a protien source and the amount of that essential amino acid in an ideal protien

Question 20

explain the limiting protien?

Answer 20

If the AA is less than the complete protien, to fully calculate especially when more than one calculate percentage

Question 21

explain nitrogen content to protien content equation

Answer 21

It uses the conversion factor of N times 6.25

Question 22

Whats the issue with conversion factors?

Answer 22

may lead to a wrong estimation

Question 23

what are the drawbacks of amino acid scoring (ASS)

Answer 23

It assumes 100% digestability but in reality it could be lower. ASS is determined by acid hydrolyses of protiens but some of those protiens could not be bioavabilble

Question 24

how does processing alter digestability?

Answer 24

High pressure/heating leads to protien coagulation which results in a less soluble protien which means it is less digestable

Question 25

What factors influence protien digestability to be higher

Answer 25

animal protiens have a higher digestability than plant protiens

Question 26

what factors influence protien digestability to be lower

Answer 26

Structure= in secondary structures the formation of inter and intramolecular disulfide bonds which are covalent bonds the strongest bonds result in decreased digestability

Protien sources= the presence of antinutritional factors in protien sources will interfere with absorbtion and decrease bioavaibility

Food matrix= if starch is present there will be decreased digestability as they are large particles that absorb a lot of fluid so there where wont be enough fluid/enzymes for the protiens, as well if there are polyphenols present they can inhibit absorbtion

Question 27

anything that increases solubility will do what to digestability?

Answer 27

increase it

Question 28

which thermal processes increase digestability of protien and which decrease it?

Answer 28

Increase→ Microwaving does this by reducing antinutriotonal content, extrusion also does this and unfolds protien structures making it easier for enzymes to access

Decrease→ cooking (extensive heating) can result in coagulation of the protien due to lose of structure, coagulation means enzymes cant acess it and solubility is decreased and so is digestion

Question 29

what are three techinques to improve protien nutritional quality?

Answer 29

1. blending protien sources→ compensates for limiting amino acids present in individual sources
2. conventional plant breeding→ select plants that have desired characteristics and cross breading them to get desired offspring and just keep doing that
3. Genetic modification, genetic engineering, genome editinf and transgenic plants

Question 30

describe hpw non-thermal processing techniques increase digestability

Answer 30

Fermantion improves digestability and so does germination. When food is germinated it reduces antinutrional content, activates enzymes that increase digestability in the seed matrix, and there is partial hydrolysis that occurs during the processes which makes protiens more unfolded and easier to acess.

High pressure treatment can improve digestability similar to how extrusion does but its important to remember its a fine balance, extensive pressure will decrease digestabilty

Question 31

Describe what Genetic modification, genetic engineering, genome editing and transgenic plants are

Answer 31

1. genetic modification= adding a new gene(s) to genome
2. genetic engineering= increase, decrease or remove a gene that is already present
3. genome editing= change codon to increase desired AA
4. transgenic plants= adding or moving a gene that is not normally in this organism