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FABS 323 > Part 3b > Flashcards

Part 3b Flashcards

1
Q

colour and form of nitrities?

A

white to pale yellow crystalline; solid and liquid forms

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2
Q

nitrites come in these two forms

A

sodium nitrite, potassium nitrite

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3
Q

nitrites water solubility?

A

100%!

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4
Q

nitrites involved in this flavour response

A

salt

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5
Q

how produce nitrites?

A

industrially by rxn nitrogen oxides with alkaline solution

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6
Q

what are nitrites primarily used for?

A

inhibit growth of clostridium botulinum in processed/cured meats

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7
Q

antimicrobial activity increases as ____ increases

A

alkyl chain length

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8
Q

what to watch out for with nitrites?

A

explosive

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9
Q

what are mechs of action for nitrites?

A

enzyme inhibition, cell mem damage/destruction

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10
Q

example of enzyme inhibition?

A

ferridoxin involved in many metabolic rxns as electron carrier, via iron oxidation from Fe2+ to Fe3+ (loss of electron carrier and transfer ability by nitric oxide)

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11
Q

cell membrane damage caused by _____

A

nitrous acid (major active compound of nitrites)–>affects permeability/leakage

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12
Q

do nitrites have GRAS status?

A

no

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13
Q

what is max level of nitrites in most?

A

200ppm

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14
Q

how is nitrites diff form others in terms of toxicity?

A

more lethal for humans than rats (this is rare)

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15
Q

having 2-3% diet as NaNO2 over 10 months caused:

A

decrease motor activity, leg weakness and chronic musc spasms, cardiac/pulmonary damage, ^ incidence infant mortality

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16
Q

FDA lymphocyte study showed:

A

possible link to induction of cancer (^ tumour incidence)

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17
Q

why industrial resistance to eliminating use of nitrites?

A

colour and flavour

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18
Q

___ has iron in the Fe2+ oxidation state, and in the presence of reducing agents (abundant in meat) oxidized to Fe3+, resulting in ____

A

myoglobin (purple); MetMb (brown-grey)

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19
Q

Mb+NO–>MbNO which contributes to:

A

reddish colour of cured meat (colour boost and flavour), NO also inhibit ferridoxine

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20
Q

daily intake of nitrates or nitrites higher?

A

nitrates

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21
Q

how convert nitrates to nitrites?

A

bacteria in mouth and GI tract (about 25% conversion)

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22
Q

nitrosamines/nitrosamides can be formed in the ___

A

stomach

23
Q

___ inhibits nitrosamine formation

A

ascorbic/erythorbic acid

24
Q

comprises a group of sulfur containing comps that are industrially produced

A

sulfites

25
Q

sulfites naturally found in:

A

veg, fermented products, nuts, fruits, eggs, tea, maple syrup

26
Q

sulfites used to stabilize ___

A

wines (since 27 BC), bread, fruits, meats, veg (since 1600s)

27
Q

physical properties of sulfites?

A

water soluble, available in solid and liquid forms, colourless and odourless

28
Q

exception to being colourless/odourless sulfites?

A

SO2 in winemaking

29
Q

sulfites inhibit ___

A

yeasts, moulds, bacteria

30
Q

sulfites used to control ____ bacteria in fresh fruits and vegetable

A

acetic acid/malolactic bacteria

31
Q

only form of sulfite that has antimicrobial activity?

A

undissociated sulfurous acid (H2SO3)

32
Q

in water, regardless of which sulfite you start with, you will get ___

A

sulfurous acid

33
Q

mech of action for sulfites?

A

interaction of sulfurous acid with sulfur bridges of structural proteins, and chem rxns of SO3 with cofactors/vitamins

34
Q

example of chem reaction with cofactors/vitamins?

A

thiamine destruction–>cofactor for several fermentative enzymes

35
Q

sulfites act as ___ agent

A

reducing (break sulfide bridges)

36
Q

do sulfites have GRAS status?

A

yes, was taken off but now back

37
Q

how are sulfites used?

A

sprayed on fresh produce, vapourized solutions used to treat fruits before dehydration, wines, juices, shrimp, processed meats, sanitize equipment

38
Q

why treat fruits before dehydrating?

A

^ storage life, peserve flavour and colour

39
Q

what are sulfites added to in EU, and why?

A

fresh meat, restore colour

40
Q

sulfites may boost :

A

asthma symptoms

41
Q

examples of biologically derived antimicrobials?

A

polypeptide (lantibiotic) produced by lactococcus lactis, nisin

42
Q

what is nisin?

A

naturally present in dairy, industrially produced via fermentation

43
Q

industry nisin is ___, natural is ___

A

A; Z

44
Q

phys properties of nisin?

A

water/food sol. is ph dependent

45
Q

nisin is stable as ____ and at ___ temp

A

solid; refrigerated

46
Q

nisin unstable when?

A

high temp, also lose activity when added to food

47
Q

what is activity spectrum of nisin?

A

range of gram positive and also gram neg. like e. coli, salmonella, shigella when used with chelating agent

48
Q

what is bacteriocin?

A

protein/polypeptide produced by bacteria that kills/inhibits growth of same or related species

49
Q

example of chelating agent?

A

EDTA

50
Q

what is mech of action for nisin?

A

destroy cyto mem by making pores resulting in leak of cell materials coupled with influx of anions/cations, inhibits cell wall synth thru enzyme inactivation, reduce heat resistance of spores

51
Q

nisin approved for use in ____ but not in Canada

A

dairy, canned, baby foods

52
Q

nisin usage in things other than food:

A

diaper wipes, pharmaceuticals (for peptic ulcer disease), med devices, vet. medicine (mastitis)

53
Q

Are Lactococcus species GRAS?

A

yes (rapid inactivation in human GI)

FABS 323 (14 decks)

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