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Week 6: Food Colourings - Coggle Diagram
Week 6: Food Colourings
Roles/functions of colours/colourings in foods. :check:
Roles
Gives perception of the quality of food. E.g. Freshness - Redness in meat
Indication of chemical Reaction.
Affect acceptability.
Functions
Intensity colours naturally in foods to meet consumer expectations
Restore the original appearance of the food which has being altered by process and storage conditions.
Make food attractive
Ensure uniformity of colour due to variations in colour intensity.
Classification of colourings.
Exempt from Certification
:check:
Natural Colours :check:
Caramel Color: Dark brown liquid or solid :check:
Results from carefully controlled heat treatment of various sugars
commonly used are sucrose, malt syrup, lactose, dextrose, molasses, dextrose & starch hydrolysates.
Carotenoids: Colours range from yellow to red. :check:
Sensitive to Oxygen (conjugated double bonds)
Fat soluble natural pigments.
Measured in IU = International Units a unit of measurement for the amount of a substance, based on measured biological activity
4 Ways to be used commercially
Liquid suspension in vegetable oil (20-30%)
Semi-solid suspension - 25% in hydrogenated vegetable oil - (It’s least popular, why?)
Beadlet - water dispersible (100%)
Emulsion
Application
STABILITY
Crystalline B-carotene is sensitive to
Light
Air
Vegetable oil solutions and suspensions are quite stable during handling.
Annatto (Bixin): Carotenoid, slightly more to orange in colour. :check:
Bixin (Oil soluble) processed into Annatto (Water soluble)
Plant pigment permitted for coloring cheese (Cheddar), margarine, popcorn oil.
Susceptible to oxidations (in powder form)
Fairly stable to heat and light
Betanins ( a form of betalains) :check:
Dried beet juice has 0.2-1.0% betanin.
Useful at ~ 50 ppm.
Has 2.5x coloring strength of red #2 (amaranth)
Most stable between pH 4.0-5.0.
Unstable against heat, oxygen and light.
Uses
dairy desserts
jellies and jams
beverages
Chlorophyll :check:
Stability
Heat → turns dull to olive brown.
Light & oxygen → bleaching occurs.
In acidic condition → Mg2+ ion is lost and turned to olive green
In alkaline condition → Mg2+ ion produces more stable Chlorophyll
Anthocyanins :check:
pH indicators
Heat labile
Oxygen labile
Enzyme labile
Light stable
Acylation: process of introducing an acyl group into a compound increases the stability.
Use in red fruit drinks, fruit prep for yoghurts, fruit preparation, jams, gums, jellies.
Nature Identical
b-Carotene
Canthaxanthin
Ferrous gluconate – jet black color
colouring of ripe olives
Riboflavin – yellow - orange
Inorganic
Titanium dioxide - whitener
Ferrous lactate - colouring of ripe olives, drinks, beverage bases & alcoholic beverages
Ultramarine blue
for coloring salt intended for animal feed
Synthetic iron oxide & hydroxides
for sausage casings, pet foods
Subject to Certification
Synthetic colours :check:
4 Examples of Synthetic Colouring Chemicals
Sulfonated Indigo
Azo with N2 Linkages
Stability
REDUCING AND OXIDIZING AGENTS
Rapid losses
LIGHT
Reduced stability
METAL IONS
Colour fades or losses due to Al, Zn, Fe
Colour changes with copper
Xanthene
Triphenylmethane
Stability
Acid: More resistant to chemical reaction than Azo dyes.
Oxidation: Poor stability such as by UV light; fades rapidly
Light: Fairly stable than Azo dyes
In 2 forms :check:
Dyes
Solubility
Dissolve in certain polyhydric solvents: Has more than 1 hydroxyl group (OH) in the molecule
such as propylene glycol, glycerine.
Readily soluble in water
Generally good heat and light stability
Regulation: Must consist min. 85% pure dye but generally contain 90-93% pure dye.
Available in:
powder/granule (beverages)
pastes/dispersions (baked goods/ confectionery)
liquid (dairy)
Dosage of use: 0.01 – 0.03%.
Lakes
Dyes are made water insoluble by coating with alumina (Aluminium hydroxide).
Colour by dispersion.
Use in water repelling foods (fats) & packaging.
No bleeding.
Colouring strength not proportional to concentration.
Extremely fine particle size has big effect on colouring power – surface area !
Powders mainly with no min. colour content (10 – 40%).
Better light, chemical & heat stability but more costly
Dosage of use: 0.1 – 0.3%.
Regulations on colourings.
Stability of colourings.
Applications of colourings.
Factors to consider when choosing a colouring for your product :check:
Must be safe, comply with legislation.
Must not impart undesirable properties.
Stable to the processing & storage conditions.
Non reactive with product and packaging.
Easy to apply to product ie. solubility.
Cost - Liquid colourings cost < powder form
Potential scenarios
