Acidulants - lec 4

Question 1

what are uses of bases in foods?

Answer 1

1) pH adjustment (emulsions)
2) leavening
3) colour/flavour
4) protein solubilization

Question 2

What is the role of acids in foods?

Answer 2

1) pH buffering
2) leavening
3) microbial inhibitor
4) chelators
5) gel setting
6) defoaming
7) emulsifier
8) coagulation
9) lowers pH
10) flavour

Question 3

what is this structure?

Answer 3

acetic acid

Question 4

what is this structure?

Answer 4

propionic acid

Question 5

what is this structure?

Answer 5

lactic acid

Question 6

what is this structure?

Answer 6

malic acid

Question 7

what is this structure?

Answer 7

tartaric acid

Question 8

what is this structure? what is its significance?

Answer 8

citric acid
-it has 3 carboxyl groups, giving it a buffering capacity across a wide pH range
-imparts a citrus flavour and is made from fermentation

Question 9

what functions does citric acid have?

Answer 9

1) buffer
2) extend shelf life
3) lower pH
4) flavour enhancer
5) chelate metal ions
6) prevent discolouration
7) control conversion of invert sugars

Question 10

What is chemical leavening in food?

Answer 10

Reacts with base to release CO₂

This process is essential for creating a light and airy texture in baked goods.

Question 11

How do acids inhibit microbial growth?

Answer 11

Low pH suppresses spoilage microbes

This is vital for food preservation.

Question 12

What function do chelating agents serve in food?

Answer 12

Bind metals, prevent oxidation/discoloration

They help maintain the visual appeal and safety of food products.

Question 13

What is the effect of acids on protein coagulation?

Answer 13

Acid-induced curdling (e.g., cheese, tofu)

This process is critical in dairy product manufacturing.

Question 14

What is the primary use of citric acid in beverages?

Answer 14

Provides tart flavor and ‘thirst-quenching’ effect

It is one of the most common acidulants used.

Question 15

what is present in a citrate buffer system? what can be used to calculate the pH? what is the equation?

Answer 15

citric acid + salt [A-]
-the apparent dissociation constant can be used to calculate the pH:
Ka = [H+] x [A-] / HA

Question 16

what is the buffering range for sodium citrate (citric acid) ? what about sodium acetate (acetic acid)?

Answer 16

citric acid = 2.1 - 4.7
acetic acid = 3.6 - 5.6

Question 17

what is responsible for the taste and flavour of apples? what acidulents are present in apples? what flavour does this contribute?

Answer 17

the sugar-acid ration is responsible for the flavour of apples

malic acid is present for much of the tart flavour (0.5-2%), as well as citric acid (0.003-0.05%)

Question 18

what acidulent is common in wine?

Answer 18

tartaric acid
-forms crystals with higher concentration (wine diamonds/weinstein)

Question 19

what is malolactic fermentation? why is it important?

Answer 19

the conversion of malic acid to lactic acid + CO2 by LAB
-softens the acidity + enhances flavour in wine

Question 20

what is the purpose of phosphate food additives?

Answer 20

1) leavening
2) acidulants
3) buffers
4) anti caking
5) chelation
6) emulsifier
7) colour stability
8) moisture binding
9) protection from freeze-thaw damage

Question 21

what is orthophoshoric acid?

Answer 21

a simple phosphate additive
-1 phosphate group (phosphoric acid)

Question 22

what is pyrophosphoric acid?

Answer 22

phosphate additive with 2 phosphate groups
-good for chelation

Question 23

what is a polyphosphate?

Answer 23

phosphate additive with long chain
-higher potential to change pH, bettwe water retention and emulsification properties

Question 24

what is a metaphosphate?

Answer 24

a cyclic phosphate additive with complex behaviour

Question 25

what are 2 common acid preservatives? how are they preservatives?

Answer 25

ascorbic acid + benzoic acid -they target yeast, molds, and some bacteria

Question 26

what range of % is benzoic acid permitted in foods? why?

Answer 26

~0.03-0.1% -there are varying levels permitted due to evidence that too much may be harmful

Question 27

what do you expect of sorbic acid below pH of 4.75? why is this?

Answer 27

below pH of 4.75, sorbic acid is largely undissociated and its antimicrobial activity increases -its pKa is 4.75 -> dissociation with pH below this

Question 28

what are the three most common chemical leavening salts? how do they differ?

Answer 28

1) sodium bicarbonate -requires acid 2) ammonium carbonate 3) ammonium bicarbonate -both decompose at baking T

Question 29

What are the two types of acids used in leavening systems?

Answer 29

* Fast-acting acids * Slow-acting acids ## Footnote Fast-acting acids react at room temperature, while slow-acting acids react during baking.

Question 30

What happens to sodium bicarbonate in water? what about in dough?

Answer 30

Ionizes to form carbonic acid; in dough, with the presence of H+ from the acidulent it further decomposes to release CO₂, water and salt ## Footnote This reaction is critical for leavening but is slow without an acid.

Question 31

what is the neutralising value? why is this important? what happens when it is not correct?

Answer 31

Neutralising value= weight of NaHCO3 that will neutralise the leavening acid -too much NaHCO3 = soapy taste -too much acid = tart/bitter taste or texture issues

Question 32

what is the neutralising value of sodium aluminum sulfate? what is its rxn rate at room T?

Answer 32

100 -slow

Question 33

what is the neutralising value of monocalcium phosphate monohydrate? what is its rxn rate at room T?

Answer 33

80 -fast

Question 34

what is the neutralising value of sodium acid pyrophosphate? what is its rxn rate at room T?

Answer 34

100 -slow

Question 35

what do you expect of the solubility and production of CO2 of monocalcium phosphate, coated monocalcium phosphate, and sodium aluminum phosphate at room T? what kind of leavening acids are they?

Answer 35

1) monocalcium phosphate (fast acting) will have lots of CO2 production at room T 2) coated monocalcium phosphate will have a slow release of CO2 at room T -more consistent CO2 production 3) sodium aluminum phosphate will have a very slow release of CO2 and then plateu; it is triggered by heat -less CO2 production but more consistent

Question 36

how does T impact CO2 production of slow speed acid pyrophosphate?

Answer 36

small changes in T greatly increase the rate of CO2 production

Question 37

what are double acting systems? what do they contain? when are they activated?

Answer 37

leavening systems that contain 2 leavening acids + NaHCO3 1) rapid acting monocalcium phosphate -released during mixing 2) slow acting sodium aluminum sulfate -released during baking