Part 3b

Question 1

colour and form of nitrities?

Answer 1

white to pale yellow crystalline; solid and liquid forms

Question 2

nitrites come in these two forms

Answer 2

sodium nitrite, potassium nitrite

Question 3

nitrites water solubility?

Answer 3

100%!

Question 4

nitrites involved in this flavour response

Answer 4

salt

Question 5

how produce nitrites?

Answer 5

industrially by rxn nitrogen oxides with alkaline solution

Question 6

what are nitrites primarily used for?

Answer 6

inhibit growth of clostridium botulinum in processed/cured meats

Question 7

antimicrobial activity increases as ____ increases

Answer 7

alkyl chain length

Question 8

what to watch out for with nitrites?

Answer 8

explosive

Question 9

what are mechs of action for nitrites?

Answer 9

enzyme inhibition, cell mem damage/destruction

Question 10

example of enzyme inhibition?

Answer 10

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)

Question 11

cell membrane damage caused by _____

Answer 11

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

Question 12

do nitrites have GRAS status?

Answer 12

no

Question 13

what is max level of nitrites in most?

Answer 13

200ppm

Question 14

how is nitrites diff form others in terms of toxicity?

Answer 14

more lethal for humans than rats (this is rare)

Question 15

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

Answer 15

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

Question 16

FDA lymphocyte study showed:

Answer 16

possible link to induction of cancer (^ tumour incidence)

Question 17

why industrial resistance to eliminating use of nitrites?

Answer 17

colour and flavour

Question 18

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

Answer 18

myoglobin (purple); MetMb (brown-grey)

Question 19

Mb+NO–>MbNO which contributes to:

Answer 19

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

Question 20

daily intake of nitrates or nitrites higher?

Answer 20

nitrates

Question 21

how convert nitrates to nitrites?

Answer 21

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

Question 22

nitrosamines/nitrosamides can be formed in the ___

Answer 22

stomach

Question 23

___ inhibits nitrosamine formation

Answer 23

ascorbic/erythorbic acid

Question 24

comprises a group of sulfur containing comps that are industrially produced

Answer 24

sulfites

Question 25

sulfites naturally found in:

Answer 25

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

Question 26

sulfites used to stabilize ___

Answer 26

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

Question 27

physical properties of sulfites?

Answer 27

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

Question 28

exception to being colourless/odourless sulfites?

Answer 28

SO2 in winemaking

Question 29

sulfites inhibit ___

Answer 29

yeasts, moulds, bacteria

Question 30

sulfites used to control ____ bacteria in fresh fruits and vegetable

Answer 30

acetic acid/malolactic bacteria

Question 31

only form of sulfite that has antimicrobial activity?

Answer 31

undissociated sulfurous acid (H2SO3)

Question 32

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

Answer 32

sulfurous acid

Question 33

mech of action for sulfites?

Answer 33

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

Question 34

example of chem reaction with cofactors/vitamins?

Answer 34

thiamine destruction-->cofactor for several fermentative enzymes

Question 35

sulfites act as ___ agent

Answer 35

reducing (break sulfide bridges)

Question 36

do sulfites have GRAS status?

Answer 36

yes, was taken off but now back

Question 37

how are sulfites used?

Answer 37

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

Question 38

why treat fruits before dehydrating?

Answer 38

^ storage life, peserve flavour and colour

Question 39

what are sulfites added to in EU, and why?

Answer 39

fresh meat, restore colour

Question 40

sulfites may boost :

Answer 40

asthma symptoms

Question 41

examples of biologically derived antimicrobials?

Answer 41

polypeptide (lantibiotic) produced by lactococcus lactis, nisin

Question 42

what is nisin?

Answer 42

naturally present in dairy, industrially produced via fermentation

Question 43

industry nisin is ___, natural is ___

Answer 43

A; Z

Question 44

phys properties of nisin?

Answer 44

water/food sol. is ph dependent

Question 45

nisin is stable as ____ and at ___ temp

Answer 45

solid; refrigerated

Question 46

nisin unstable when?

Answer 46

high temp, also lose activity when added to food

Question 47

what is activity spectrum of nisin?

Answer 47

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

Question 48

what is bacteriocin?

Answer 48

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

Question 49

example of chelating agent?

Answer 49

EDTA

Question 50

what is mech of action for nisin?

Answer 50

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

Question 51

nisin approved for use in ____ but not in Canada

Answer 51

dairy, canned, baby foods

Question 52

nisin usage in things other than food:

Answer 52

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

Question 53

Are Lactococcus species GRAS?

Answer 53

yes (rapid inactivation in human GI)