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FDSC442 > 15 - chemical preservatives > Flashcards

15 - chemical preservatives Flashcards

1
Q

What are the two classes of preservatives

A
  1. traditional

2. naturally occuring

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2
Q

What are preservatives ?

A

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

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3
Q

Traditional preservatives:

A

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

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4
Q

What are the traditional antimicrobial we saw in class

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

___ (weak/strong) organic acids are more effective

A

weak

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6
Q

The best acids for preservatives are ___protic acids

A

mono

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7
Q

What are the monoprotic acids seen in class

A 
1- acetic acid
2- propionic acid 
3- lactic acid
4- sorbic acid
5- benzoic acid
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8
Q

what are the multiprotoic acids seen in class

A

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

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9
Q

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

A

1- pKa value

2- pH of the food

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10
Q

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

A

food needs to have a pH under 5.0

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11
Q

What is acetic acid more effective on?

A

more effective on yeasts and bacteria than on molds

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12
Q

Why is acetic acid added to breads?

A

can reduce the ropiness produced by bacillus subtilis

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13
Q

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

A

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

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14
Q

Benzoic acid is most effective against what kind of microorganisms

A

most effective against fungi (molds)

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15
Q

What are the common use of benzoic acid

A

reducing E.Coli

reducing molds in grape juice

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16
Q

What is the use of lactic acid

A

used on carcasses to reduce the microbial load

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17
Q

What is sorbic acid effective against ?

A

fungi, bacteria and most yeasts

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18
Q

What are the common use of sorbic acid

A

inhibtion of fungi in bakery products

salad dressing

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19
Q

what is dimethyl dicarbonate effective against?

A

yeasts but can also be bactericidal

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20
Q

What is the mechanisms of dimethyl dicarbonate

A

leads to enzyme deactivation

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21
Q

What is the common use of dimethyl dicarbonate

A

used in the alcoholic beverages like apple cider or wine

22
Q

What is lactoferrin effective against

A

bacteria

23
Q

What is the mechanism of lysozyme?

A

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

24
Q

What is the common use of lysosyme

A

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

25
Q

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

A
  • nitrosomyoglobin production and pink colour

- yummy taste of cured meats

26
Q

The primary application of nitrite is for the inhibition of

A

C. botulinium

27
Q

what is the mechanism of nitrites?

A

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

28
Q

What are nitrites effective against?

A

bacteria

29
Q

What is used in combination of nitrites

A

sorbic acids

30
Q

What are parabens effective against?

A

against fungi and gram positive bacteria

31
Q

What is the mechanism of action of parabens

A

interference with the electrochemical graident

32
Q

What are the common use of parabens?

A
  • beers, fruit juices and soft drink to inhibit the fungal growth
  • used in baked goods
  • wine
  • pie fillings
33
Q

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

A

true

34
Q

Why do you see parabens more often in low Aw products

A

because they are effective against fungi

35
Q

what are the common use of sulfite ?

A

frutis and vegetables products

36
Q

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

A

sulfites

37
Q

what is the downside pf the naturally occuring preservatives

A
  • they lead to adverse sensory changes

- a the concentration they are found they don’t inhibit the microbial growth

38
Q

What is the downside of the lactoperoxidase system

A

to use it you need to add extra hydrogen peroxide

39
Q

What is chitosan effective against?

A

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

40
Q

What is the supposed mechanism of chitosan

A

chelation of the ions associated on the LPS

41
Q

What is the source of chitosan?

A

from the chitin of the shrimps

42
Q

The greatest antimicrobial activity of spices comes from

A

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

43
Q

Cinnamon and cloves contain __ and ___

A

eugenol and cinnamic aldehyde

44
Q

What is cinnamon active against?

A

bacteria, fungus and yeasts

45
Q

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

A

clostridium bottulinum

46
Q

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

A

chain phenolic compounds (catechol)

47
Q

What is the mechanism of allicin

A

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

48
Q

What are hops effective against ?

A

bacteria and fungi

49
Q

What part of the hops is antimicrobial?

A

the resin formed by it is composed of bitter acids

50
Q

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

A

true

51
Q

What are isothiocyanate effective against

A

yeast, fungi and bacteria

FDSC442 (19 decks)

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