part 3a Flashcards
what are major classes of food additives?
preservatives/antimicrobial agents, antioxidants, flavouring agents, flavour enhancers, sweeteners, emulsifiers, fat replacers, colouring agents, misc.
examples of misc?
phosphates, polysacc, bleaching/dough conditioners, glazing/polishing agents
what are preservatives/antimicrobial agents?
function to preserve food products from detrimental effects of microorg
consumers expect food:
available year round, free of pathogens, long shelf life, consistent
most foodborne illness come from ___ food
unprocessed
examples of natural antimicrobial agents for food preservation:
polypeptides (bacteriocins), proteins/enzymes, polysacc, lipids (dha)
prob of natural antimicrobial?
expensive and lipophilic
what are factors influencing selection of antimicrobial agent?
1) knowledge of microbiological variety (bioburden) 2) chem and phys properties of antimicrobial comp and food must be known 3) processing/packaging/storage 4) safety and legality of antimicrobial must be known 5) follow GMP
antimicrobials incorporated into interior packaging not required on ingredients list in Canada, why?
minimal leakage
benzoic acid/sodium benzoate naturally present in:
berries, fruits/veg, spices
is comp or salt more soluble?
salt
where else is sodium benzoate found?
naturally in rain by pollution, groundwater by animal excretion
how is benzoic acid produced?
oxidation of toluene
benzoate can cause allergy:
orofacial granulomatosis (disfigured lip swelling, gingivae)
benzoate is ___ agent
antimycotic (against yeasts and moulds lvls 0.05-0.1%)
____ form of benzoic acid has antimicrobial activity
undissociated
mech of action for benzoic acid?
not known really, disrupt major energy production system of org
want pka > or < ph?
>
benzoic used in
bev, jam, margarine, baking, condiments, pharmaceuticals, cosmetics
what is ld50?
will kill 50% pop
how does enzymatic conjugation work?
benzoic acid with l-glycine makes comp more acidic so anionic, more H bounding site, more water sol.
what are sorbates/
calcium, potassium, sodium salts of sorbic acid
where sorbates/
rowanberry fruit, other berries in low lvl
how sorbate made/
rxn crotonaldehyde and ketene
sorbic acid is ___ agent, significant activity against _____
antimycotic; clostridium botulinum (gram -)
___ form of sorbic acid is only form has antimicrobial activity
undissociated
sorbic acid mech of action
sulfhydryl enzyme inhibitor (protease), lipophilc comp interfere w/ chem transport across cyto mem
food uses of sorbic acid?
lots, plus packaging and cured meats as nitrite replacement, salads, choc syrup, wine
which is more toxic–sodium benzoate or sorbates?
benzoates
organic acids present naturally almost all fruits and veg
short chain fatty acids
acetic acid found in:
figs, bananas
fumaric acid from :
mushrooms, carrots
SCFA produced via:
fermentation
___ form of SCFA mainly responsible for antimicrobial activity
undissociated
SCFA are ____ so have ability lower pH OF FOOD TO INHIBIT microbe growth
weak acids
acetic acid active against ___, moderate against ___
yeasts/bacteria; moulds
citric acid is __
ANTIMYCOTIC
fumaric acid is __
antimycotic and c. botulinum (for bacon shelf life)
lactic acid has ___ action
antibacterial
mech of action for SCFA?
undissociated, cross cyto mem and dissociate to produce charged anion and H+–>inhibit growth by mem disruption, inhibit metabolic rxns, intracellular pH stress, accumulation toxic anion
other food uses of SCFAs?
flavour, pH control, firming agent, clarifying agent, black spot prevention, improve stability/shelf life of veg oils, radioactive comp removal
alkyl esters of p-hydroxybenozoic acid
parabens
parabens found in:
berry fruits, alcohoic bev, water pollution/usage
how make parabens?
esterification by proper alcohol
phys. properties of parabens/
WATER SOL decrease as alkyl chain length increase, colourless/odourless/tasteless
what bad about parabens/
NOT VERY BIODEGRADABLE
Activity spectrum of parabens?
broad, gram +
mechanisms of action for parabens
solubilize cyto mem–>neg. impact transport across membrane, electron chain disruption
___ parabens used with Gras status
methyl / propyl
parabens used in:
food packaging, alcoholic bev (heptyl)
possible toxicity of parabens/
male repro issues
