January 20th Flashcards
Permitted Levels
- based on Acceptable Daily Intake (ADI; mg/kg of body weight)
- ADI values for food additives have been established by JECFA (international organization). Canada (& USA) have established their own ADI values for many of these chemical compoundsscientists and government
- NOEL values (no observable effect level or no observed adverse effect level[s], NOAEL or NOAELs). Defined as “the highest exposure level of the compound resulting in no detectable toxic effect in animals” [determined by subchronic or life-span studies using laboratory animals
- the ADI for humans incorporates a safety factor of 100 into
the NOEL/NOAEL (therefore, the ADI is the NOEL or NOAEL/100)ADI is 100 times less than NOEL- this safety factor is based on two assumptions (usually not true):
1) humans could be up to ten times more sensitive than the laboratory animals to the chemical compound, and
2) human susceptibility may vary by a factor of 10genetics, nutrigenomics (some people respond positively, neutral, negatively with same food)
- this safety factor is based on two assumptions (usually not true):
- estimated intake and ADI are compared to assess the safety of exposure to that additive [important to remember the limitations of food additive intake methods]
- the average intake of a food additive is consided safe only when it is lower than the establishe ADI
- in general, the average intake of any food additive is well below the ADI (normally <10% and rarely exceeds 30 %))
Nomenclature
In North America, food ingredients (including additives) are listed by
In North America, food ingredients (including additives) are listed by name in concentration order (i.e. the ingredient/chemical compound with the highest concentration is listed first).
In the rest of the world, the International Numbering System (INS#) or E-number system (Australia and New Zealand use the A (alphabetical) system) is employed on food packages to identify additives.
Example: INS 102 = E-102: tartrazine/FD&C Yellow #5 (food colourant)= FD&C Yellow #5
in canada they just say artificial flavor or colour- not the number
MSG (E621)/MKG (622)/calcium digutamte (623)/glutamic acids (620) (we dont have these in canada)
- Major Classes/Types of Food Additives
a) Preservatives/antimicrobial agents
b) Antioxidants
c) Flavouring agents
d) Flavour enhancers
e) Sweeteners
f) Emulsifiers
g) Fat Replacers
h) Colouring agents
i) Miscellaneous (phosphates, polysaccharides, bleaching and dough conditioners, glazing and polishing agents)
A) Preservatives/Antimicrobial Agents
-Table XI (Canada Food and Drug Regulations)
Function: preservation of food products/food from the detrimental effects of microorganism
- increased use of chemical preservatives (since the mid 1950’s) has been due to the changes in the way foods are processed and marketed
- consumers expect all foods:
- to be available year-round
- to be free of pathogens (disease producing/iducing organism)
- to have a reasonably long shelf life
- consumers expect all foods:
- To be consistent (e.g. colour, flavor, texture)
Facts and figures (USA; wwwnc.cdc.gov; Painter J.A. et al., 2013. Emerging Infection Diseases. 19:407-415
- Canada: estimate 1 in 8 experience a foodborne illness each year (~12.5%; >80% home!!! situations) - 1998-2008: ~1100 deaths/year due to foodborne illness (food infection/intoxicaton); CDC (2016: 1351) - USA population ~320 million: 0.00034% (risk of dieing from food) - major food commodities: poultry (~300 ppl per year die from poultry products), vegetables (about 100 )and fruit (about 100) - Canada (2013): 1923 motor vehicle fatalities
A) Preservatives/Antimicrobial Agents (cont.)
Factors Which Influence the Selection of an Antimicrobial Agent
1) Knowledge of the microbiological variety (bioburden) of the food/food product [know the microbes which may be present in the food and know the antimicrobial spectrum of the antimicrobial agent]
2) Chemical and physical properties of the antimicrobial compound and the food must be known [water activity (amount of available water), pH, solubility(what processing will break down the products structure) , pKa, etc.]
3) Processing, packaging and storage (freeze, fridge or on the shelf) of the food or food product(in cereal in the bag- there will be some leakage into the food but not considered a food additive, also in margarine containers…)
4) Safety and legality of the antimicrobial agent must be known (allowable, allowable uses (how is it used -can you use it as a spray), allowable levels, etc. )
5) GMP must be followed- not a replacement of making a good product
A) Preservatives/Antimicrobial Agents (cont.)
- recent advances in food processing & packaging have reduced the use/levels of some antimictobial agents
- introduction of “natural” antimicrobial agents for food preservation: polypeptides (bacteriocins), proteins/enzymes (e.g. lysozyme), polysaccharides (e.g. chitinchemical conversion to chitosan), lipids (e.g. docosahexaenoic acid [DHA])
- antimicrobials continue to play an important and significant role in protecting our food supply
- Benzoic Acid/Sodium Benzoate
benzoic acid sodium benzoate (this is the added one- more soluble than the acid)
- naturally present in most berries (e.g. blueberry, cranberry, raspberry, strawberry [0.05-0.06%]), many fruit species, a number of vegetables (e.g. asparagus [0.5 ppm]) and spices (e.g. cinnamon [0.03%])
- Naturally present in rain (pollution) (0.1 to 10 ppb) and groundwater (up to 860 ppb)
- industrially produced by the oxidation of toluene(don’t need to know) (i.e. chemical synthesis)
Physical Properties
- available in both solid (white crystalline) and liquid forms
- water solubilities (@ 20 oC):
about 0.3g/100 ml for benzoic acid
66.0 g/100ml for sodium benzoate
Short Chain Fatty Acids
- organic acids are present naturally (trace to 2.0%) in almost all foods (fruits and vegetables), as examples:
- acetic acid : figs, bananas
- citric acid : oranges, grapefruit
- fumaric acid : carrots, mushrooms
- lactic acid : fermented dairy products
Short Chain Fatty Acids
Activity Spectrum
Activity Spectrum
- the undissociated forms of these compounds are mainly responsible for their antimicrobial activity
- as weak acids they also have the ability to lower the ph of the food (via dissociation), which can also inhibit/slow down microbial groth
- antimicrobial activity range:
- acetic acid: active against yeasts and bacteria; moderate activity against moulds
- citric acid: antimycotic
- fumaric acid: antimycotic and C. botulinum (esters of fumaric acid; extension of the shelf-life of bacon by up to 56 days; replacement of nitrite)
- lactic acid: antibacterial action (little antimycotic activity)
Short Chain Fatty Acids
Mechanism(s) of Action
- in their undissociated state, these weak acids cross the cytoplasmic membrane of the cell and dissociate to produce a charged anion and H+
- this accumulation of charged species inhibits microbial growth by:
- membrane disruption
- inhibition of metabolic reactions (e.g. enzyme mediated reactions)
- intracellular ph stress
- accumulation of toxic anions
Short Chain Fatty Acids
Food Uses and Concentrations (legal)
- These compounds all have GRAS status
- examples of products/levels:
- acetic acid: baked goods (0.25%), cheese (0.8%) condiments (up to 9.0%) (cant be in drinks)
- citric acid (used for >125 years): baked goods, dairy products, carbonated beverages
- fumaric acid: wines (0.15%), beverage powders, baking and dessert mixes, jams/jellies, bacon (0.05-0.2%)
- lactic acid: dairy products, processed meats
Short Chain Fatty Acids
Other Food Uses
flavor (cheese, snack foods, candy, beverages)
- Ph control (delays/prevents colour formation in dried foods)
- Firming agent for sliced fruits (interactions with pectin)(ex. Canned peaches don’t go to mush)
- Clarifying agent (protein precipitation in juices)
- inhibition of carbohydrate crystallization (e.g. honey- can cut your tongue)
- ‘black spot’ prevention enzyme inhibition (shrimp, fruits and vegetables- enzyme reaction)
- improves the stability/shelf life of vegetable oils- less oxidation
- Radioactive compound removal (e.g. strontium from milk)- chernobyl
Short Chain Fatty Acids
Toxicity
considered to be non-toxic (because comes from Kreb’s/Citric Acid cycle)
parabens
alkyl esters of p-hydroxybenozoic acid (methyl, ethyl, propyl, butyl and heptyl)- in the water so everywhere
- naturally occurring in many berry fruits (e.g. blueberry), other fruits (e.g. passion), and alcoholic beverages (e.g. white wine and bourbon)
- antimicrobial activity of these compounds was first shown in 1924 - used in foods, pharmaceuticals and cosmetics since the 1950’s
took 30 years to become allowed
- industrially produced by the esterification of 4-hydroxybenzoic acid with the appropriate alcohol (i.e. chemical synthesis- pure )
Physical Properties
- water solubility: 0.25 g/100 mL(not very soluble) (methyl paraben; water solubility decreases as alkyl chain length increases) - colourless , odourless and tasteless - biodegradable (pH 7)-
Activity Spectrum
- Broad spectrum antimicrobial activity yeasts, moulds and bacteria (gram positive; e.g. Listeria monocytogenes, Staphylococcus aureus)
- antimicrobial activity increases as alkyl chain lenghth increases
Mechanism(s) of Action
- solubilizes cytoplasmic membranes (e.g. lipophilic) negatively impacts transport across the cell membrane (e.g. cellular leakage); electron transport chain disruption
Parabens
Food Uses and Concentrations (legal)
- methyl and propyl parabens have GRAS status (total addition limit of 0.1%); found in many food products in Canada/USA/EU/Japan (e.g. bakery, dairy, meat and tomato products, jams/jellies, pickles, salad dressings)-used in food packaging materials-helptyl (7) parabens are permitted (USA) for use in alcoholic beverages (12 ppm)
