Why is something coloured?
cone and rods
- light from the sun, light bulbs, fluorescent bulbs) contains all visible wavelengths (why it is white)
- when white light (i.e. visible energy) interacts with an object a portion of this energy is absorbed with the remainder reflected or transmitted (passed through) this is what we see
- an example: a carrot absorbed B and G and reflects
yellow/orange/red
cones: colour
rods: light and dark
Colouring Agents)
Functions:
7
- to restore the original appearance of the product/ingredient (correcting for food color changes during processing, packaging, distribution or storage) -> heat, light, chemical oxidation, enzyme reactions- some can lighten or darken or change colours completely
- to ensure product/ingredient colour uniformity (correct for natural colour variations and intensities)
- To intensify or introduce colour (association of flavor with colour)- purple= grape
- To protect flavors and light-sensitive vitamins (A and E) from photodegradation-> colourant absorbs wavelenght
- to give food an attractive appearance
- to help preserve product identity or
Character ex. Ketchup, coke, mustard - To serve as a visual indication of product quality
Synthetic Food Colours
FD&C:
FD&C: food, drug and cosmetic designation
-> regulated; approved; safety; purity; consistency (2004 vs 2017 colour you buy will be the same- uniformity)
Acidic functional groups, conjugated, comprised of atoms with lone pairs water solubility (12-20 g/100ml and colour [due to conjugation])
Synthetic Food Colours
Two Types
a) dyes : - water soluble (powders (example jello)-and liquids)
- jones pop has high colorant content (99+%) high tinctoral strenghs
b) lakes : - chemically bound/strongly adsorbed on a carrier (e.g. aluminum hydrate: Al[OH]3) chemical compound being carried by an emulsifier
- lake is either oil soluble or via dispersion (chocolate milk)
- low colourant content (10-40%) so need to use more to get same effect (icings are hydrophobic)
examples:
blue number 1
red number40
a) FD&C Blue No. 1 (bright greenish-blue): beverages, bakery goods, condiments, confections and dairy products
b) FD&C Red No. 40 (yellow-red): beverages, cereals, condiments, confections, dairy products, gelatins and puddings
- > rice krispies, cheerios, goldfish/rits crackers, Tylenol, mouth =wash, toothpaste, soaps, etc.
Colourants (Colouring Agents)
FD&C Red No. 40: NOEL/NOAEL, ADI and EDI relationship
points to remeber when determining if the level is safe
- LD50 (mice and rats): 10 g/kg bwt
- NOEL/NOAEL: 631 mg/kg bwt day
- ADI of 7.0 mg/kg bwt day
- 50 kg person: 50 kg x 7 mg/kg bwt day = 350 mg/day
- EDI as a % of ADI: 17.91 (USA)/350 x 100% = ~5% only 5% of ADI
Points to remember: 1) assumption of maximum permitted levels (overestimation); (2) only 5% of ADI; (3) only 3% of noel/ noael; and (4) noel/noael safety factor of 100
H) Colourants (Colouring Agents)
Toxicity
all have undergone extensive safety evaluation testing (>100 published studies) no cmta (+ no reproductive disorders or negative growth implications)
- 1973: linking of behavioural disorders in children (hyperactivity/ learning disorders) with synthetic food colourant intake (“Feingold hypothesis”) 37 studies have shown no scientific linkage - 2007 UK study (Southampton Study) again linked synthetic food colourants (6 tested) and hyperactivity in their study group of 3 and 8/9 year old children - the European Food Safety Authority assessed the results of the study and concluded:” the study provided only limited evidence that the additives had a small effect on the activity and attention of some children - the FDA concluded (based on independent scientific assessment):” that no link was substantiated between the color additives (employed in the study) and behavioral effect” - 2010 (EU): required warning labels on foods that contain any of the 6 colourants used in the UK study (3 of these are not approved for food use in the USA/Canada: quinoline yellow, ponceau 4R, and azorubine)-> Fd&c Red No. 40, Yellow No. 5 and Yellow No.6
canda vs usa colour labeling
Canada
- in 2010 Health Canada requested input from consumers, food manufacturers and industry on possible amendments to the labelling of food colourants - the International Association of Color Manufacturers: supported the adoption of USA regulations (i.e. colourant names listed) - no change in product labelling in Canada to date - ‘colour’ is what is labelled on the packaging
the advantages of synthetic colourants
- extensively tested for safety/lack of toxicity
- highly concentrated and pure (only need to use a little bit of it)
- certified (consistency is maintained) (colour has to be the same)
- wide range of colours can be produced (has the primary colours)
- colours produced are acid, light and processing stable
- application to a wide range of product formulations (can be an issue as they can be hydrophobic)
- uniform final product colour
- reproducible product colour
- cost (cost efficient for the food industry
GHB and GBL (-hydroxybutyric acid and -butyrolactone)
GHB and GBL (-hydroxybutyric acid and -butyrolactone) detection in drinks (date rape drugs)
- nervous system depressants, odourless/colourless, takes effect within 15-30 minutes and the effect can last 3-6 hours - a fluorescent sensor (GHB/GBL-orange) has been developed (March, 2014) that reacts with GHB or GBL to turn the drink orange
