15 - chemical preservatives

Question 1

What are the two classes of preservatives

Answer 1

1. traditional

2. naturally occuring

Question 2

What are preservatives ?

Answer 2

chemicals that are added to foods that retard the growth of or kill microorganisms. (most of them do not kill they are bacteriostatic)

Question 3

Traditional preservatives:

Answer 3

1-Have been used for many years
2-Are approved for use in many countries
3-Are produced by synthetic processes

Question 4

What are the traditional antimicrobial we saw in class

Answer 4

1- organic acids 
2- Dimethyl bicarbonate 
3- lactoferrin
4- lysosyme
5- nitrites
6- para-hydroxybenzoic acid esters
7- sulfites

Question 5

___ (weak/strong) organic acids are more effective

Answer 5

weak

Question 6

The best acids for preservatives are ___protic acids

Answer 6

mono

Question 7

What are the monoprotic acids seen in class

Answer 7

1- acetic acid
2- propionic acid 
3- lactic acid
4- sorbic acid
5- benzoic acid

Question 8

what are the multiprotoic acids seen in class

Answer 8

1- citric acid
2- malic acid
3- tartaric acid
4- fumaric acid

Question 9

What are the consideration you need to take when choosing an acid as a preservative

Answer 9

1- pKa value

2- pH of the food

Question 10

What is the maximal pH foods need to be for the organic acids to have a preservative effect

Answer 10

food needs to have a pH under 5.0

Question 11

What is acetic acid more effective on?

Answer 11

more effective on yeasts and bacteria than on molds

Question 12

Why is acetic acid added to breads?

Answer 12

can reduce the ropiness produced by bacillus subtilis

Question 13

T or F : acetic acid is only used for spoilage microorgnisms

Answer 13

false, it is also used for safety in the poultry processing for the reduction of the salmonella

Question 14

Benzoic acid is most effective against what kind of microorganisms

Answer 14

most effective against fungi (molds)

Question 15

What are the common use of benzoic acid

Answer 15

reducing E.Coli

reducing molds in grape juice

Question 16

What is the use of lactic acid

Answer 16

used on carcasses to reduce the microbial load

Question 17

What is sorbic acid effective against ?

Answer 17

fungi, bacteria and most yeasts

Question 18

What are the common use of sorbic acid

Answer 18

inhibtion of fungi in bakery products

salad dressing

Question 19

what is dimethyl dicarbonate effective against?

Answer 19

yeasts but can also be bactericidal

Question 20

What is the mechanisms of dimethyl dicarbonate

Answer 20

leads to enzyme deactivation

Question 21

What is the common use of dimethyl dicarbonate

Answer 21

used in the alcoholic beverages like apple cider or wine

Question 22

What is lactoferrin effective against

Answer 22

bacteria

Question 23

What is the mechanism of lysozyme?

Answer 23

it is a peptidoglycan hydrolase that will hydrlyse the bonds in the cell wall and result in cell lysis.

Question 24

What is the common use of lysosyme

Answer 24

cheese to prevent the fermentation and production of CO2 by anaerobe C. Tyrobutyricum

Question 25

What are the other use of nitrites in meat products other than preservation?

Answer 25

- nitrosomyoglobin production and pink colour | - yummy taste of cured meats

Question 26

The primary application of nitrite is for the inhibition of

Answer 26

C. botulinium

Question 27

what is the mechanism of nitrites?

Answer 27

work by inhibiting the ability of bacterial cells to generate ATP (depletion of the energy stores).

Question 28

What are nitrites effective against?

Answer 28

bacteria

Question 29

What is used in combination of nitrites

Answer 29

sorbic acids

Question 30

What are parabens effective against?

Answer 30

against fungi and gram positive bacteria

Question 31

What is the mechanism of action of parabens

Answer 31

interference with the electrochemical graident

Question 32

What are the common use of parabens?

Answer 32

- beers, fruit juices and soft drink to inhibit the fungal growth - used in baked goods - wine - pie fillings

Question 33

T or F : the use of parabens is really common in the food industry

Answer 33

true

Question 34

Why do you see parabens more often in low Aw products

Answer 34

because they are effective against fungi

Question 35

what are the common use of sulfite ?

Answer 35

frutis and vegetables products

Question 36

Which preservative are we referring to : They also have antioxidant properties that inhibit the enzymatic and non-enzymatic browning of foods

Answer 36

sulfites

Question 37

what is the downside pf the naturally occuring preservatives

Answer 37

- they lead to adverse sensory changes | - a the concentration they are found they don't inhibit the microbial growth

Question 38

What is the downside of the lactoperoxidase system

Answer 38

to use it you need to add extra hydrogen peroxide

Question 39

What is chitosan effective against?

Answer 39

fungi and bacteria (even more if combined with other organic acids and antimicrobial)

Question 40

What is the supposed mechanism of chitosan

Answer 40

chelation of the ions associated on the LPS

Question 41

What is the source of chitosan?

Answer 41

from the chitin of the shrimps

Question 42

The greatest antimicrobial activity of spices comes from

Answer 42

cloves, cinnamon, oregano, thyme and to a lesser extent sage and rosemary

Question 43

Cinnamon and cloves contain __ and ___

Answer 43

eugenol and cinnamic aldehyde

Question 44

What is cinnamon active against?

Answer 44

bacteria, fungus and yeasts

Question 45

Allicin is effective against the growht and production of toxin of ___

Answer 45

clostridium bottulinum

Question 46

Onions also produce ____ which may also contribute to the antimicrobial activity of onion essential oils and extracts

Answer 46

chain phenolic compounds (catechol)

Question 47

What is the mechanism of allicin

Answer 47

oxidation of thiol groups to disulfide, so it inhibits the disulfide contining enzymes

Question 48

What are hops effective against ?

Answer 48

bacteria and fungi

Question 49

What part of the hops is antimicrobial?

Answer 49

the resin formed by it is composed of bitter acids

Question 50

T or F : hopping is noly effective if used in combination with low Aw

Answer 50

true

Question 51

What are isothiocyanate effective against

Answer 51

yeast, fungi and bacteria