Food Color

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Food Color
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What is color?

• Color is the human response
• to light
• Color is the human judgment of the color
  response.

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What is color?

• Alone, the factors influencing color are made up
  of a complicated series of factors.
• Together they create the human sensation we call
  color.

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Instrumental Measurement of Color

• Goal was to create a computerized device that
  would measure and describe color like humans see
  and judge color
• To simulate a system that creates the human color
  response
• Color instruments need a controlled light source
  that we can define mathematically

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Instrumental Measurements

• The colored materials to be measured must be
  presented to the instrument in a uniform way.
• Devices are created in the instrument that senses
  the light in the human visual range that is
  reflected or transmitted from the materials to be
  measured.

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What is a Color Computer

• Computer programs relate the data from the color
  instrument to the human response to color using
  mathematical simulations of light, human vision,
  and judgment.

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Color begins with light.

• Light travels at the rate 300,000 Km/s in the
  vacuum of space and slows as the material it
  passes through becomes denser.
• Light can pass through clear gasses, liquids,
  solids, and a vacuum. When you change the density
  of the media, you slow the speed and bend the
  light waves in a predictable manner. This is
  called the refractive index of a material.

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Light can be measured in wavelengths in the
spectrum of electromagnetic radiant energy

• Wavelengths of light between 400 nm and 700 nm
  are the range of light energy where 99 of human
  color response occurs and is commonly referred to
  as the visible spectrum.
• Light can be selectively scattered and absorbed
  by some materials in gasses, liquids and solids.
• As a group, these materials are called colorants.

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COLOR
Color is observed as a result of reflection or
transmission of light (400-700 nm)
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HOW ARE COLORS CREATED BY LIGHT?

• Each wavelength area in the visual spectrum
  creates one pure color sensation.
• The individual wavelengths in the visual range
  are called monochromatic light. Objects
  illuminated with monochromatic light can only
  exhibit that single color.

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For example, red, orange, yellow, green, blue,
violet are primary, monochromatic light colors.
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When all wavelengths of light in the visual
spectrum, between 400-700 nm, are mixed at equal
energy, we see the "perfect" white light.
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When all wavelengths in the visual spectrum
between 400-700 nm are not present, we have the
"perfect" black.
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HUMAN VISION

• The eye is the window to the color experience.
• Light from a source can be
• A direct source
• Additive light mixing
• Reflected
• Transmitted
• The brightness and balance of the light energy
  creates the color stimulus

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HOW THE EYE SENSES COLOR

• Light enters the eye, passing through the cornea,
  aqueous humor, the lens, through the vitreous
  humor, and falls on the light-sensitive retina.
• Three types of cone cells in the retina respond
  to the color balance of the light stimulus. There
  are red cone cell responders, green cone cell
  responders and blue cone cell responders.

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HOW THE EYE SENSES COLOR

• Since there are more than 7 million cone cells in
  the retina, we can see many different colors in
  one scene at the same time. Rod cells relate to
  the brightness of light (white to black). There
  are over 17 million rod cells

• Cone cell responses curves cover a broad band of
  color space.
• The responses overlap and have areas where they
  are more sensitive than other areas.

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• Vision sensations sent to the brain create three
  dimensions (tristimulus values) of color judgment
  response
• Often referred to as three-dimensional color
  space.
• The dimensions are
• Light to dark (L)
• Red to Green (a)
• Yellow to Blue (b)

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Color Space
L lightness (white 100)
b () yellow
a (-) green
a () red
b (-) blue
L lightness (black0)
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We express this data in the three dimensions of
human color response. The mathematics is
expressed as L, a, b factors.
L Lightness (black 0 and white 100)
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COLOR WHEEL
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Plant Pigments

• Chlorophyll
• Carotenoids

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CHLOROPHYLLS
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Chlorophyll

• Major light harvesting pigments in green plants,
  algae and photosynthetic bacteria
• Located in the lamellae of intercellular
  organelles of green plants known as chloroplast
• Associated with carotenoids, lipids and
  lipoprotiens

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Chlorophyll Biosynthesis
Tertrapyrrole pigments 4 pyrrole units joined
in porphyrin ring
Mg
Protoporphyrin
Chlorophyll
Porphyrin ring
Phytol chain
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Degradation of Chlorophyll

• Enzymatic chlorophyllase
• Heat and acidity hydrolyze compound reducing
  color
• pH alkaline stable
• Cleavage of phytol chain

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• CHLOROPHYLL effects of pH
• pH 5 chlorophyll has its normal vegetable
  green color
• pH lt 5 Mg2 is lost and the color changes to
  the characteristic pheophytin olive green color
• pH gt7 the methyl and phytyl esters are removed,
  producing chlorophyllin which is a bright green
  color.

Chlorophyll Pheophytin
Chlorophyllin
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• CHLOROPHYLL effects of heating
• heating ? loss of Mg ? pheophytin
• CHLOROPHYLL effects of enzymes
• chlorophyllase removes the phytol group (even
  under conditions of frozen storage)
• CHLOROPHYLL effects of light and oxygen
• photodegradation ? irreversible bleaching
• If Mg ion is replaced with either zinc or
  copper ? stable
• green complex at low pH

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Chlorophyll ? Carotenoids
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CAROTENOIDS
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Carotenoids

• Function as secondary pigments to harvest light
  energy
• Photoprotection role
• Precursors of Vitamin A
• Prevention of chronic diseases
• ß-carotene
• converted to Vit.A by the body
• reduce risk of lung and stomach cancers
• Protecting LDL oxidation

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Carotenoid Biosynthesis
Mevalonic acid pathway
Carotenoids C40 Make of polymers of isoprene
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Carotenes
Hydroxy- Carotenoids or Xanthophylls
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Nomenclature and Structure
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Nomenclature and Structure
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Nomenclature and Structure
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CAROTENOIDS Effects of processing

• Canning ? 10 loss of provitamin A activity
  because of isomerization of trans configuration
  to the cis conf.
• Storage of dried carrots ? off flavor due to
  carotene oxidation
• O2 and light major factors in carotenoids
  breakdown (good stability to thermal treatments
  if O2 and light are not present)
• Blanching prevents enzymatic oxidation reactions

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Carrot Breeding
Orange
Red
Yellow
White
Purple- Orange
Lycopene
None
Carotene
Carotene Anthocyanin
Xanthophyll
Source USDA-ARS
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Carrot Diversity
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Distribution of Carotenoids

• Approximately 700 Carotenoids have been isolated
  from plants and animals.
• Only 50-60 Carotenoids are present in a typical
  diet (fruits vegetables)

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Food Color
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Beef
Whats for dinner tonight?

• Meat contains both hemoglobin and myoglobin that
  bind oxygen
• The bright red color of fresh cut meat is due to
  oxymyoglobin (oxygenation)
• The red color fades as oxidation occurs,
  converting Fe2 to ferric (Fe3) state

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The Structure of Myoglobin
Myoglobin (MW 17,000) is the pigment in muscle
tissue, whereas hemoglobin (MW 68,000) is the
heme pigment in blood
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Forms of Myoglobin in Meat
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Colors in Fruits and Vegetables

• Natural Colors
• Anthocyanins (grapes, blueberries, etc)
• Betalains (beets)
• Carotenoids (carrots, peach, tomato)
• Chlorophyll (broccoli, spinach)
• Other Colors
• FDC
• Exempt

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Pigments and colorants

• Many natural and artificial colorants
• Some add flavor
• Some are very complex
• Many different compounds
• Often unstable
• Very important food additives
• Not all colorants are legal in foods

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Pigments and Colors

• Pigments can be degraded
• Heat, air, enzymes, etc.
• Brown pigment formation
• Carmelization of sugars
• Maillard reaction reducing sugars and amino
  acids
• Enzymes and oxidation

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Anthocyanins in Fruits and Flowers
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What Are Anthocyanins?

• Natural, water-soluble plant pigments
• Display a variety of pH dependent colors
• Polyphenolic compounds (flavonoid)
• Used as food colorants
• Numerous functional components

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What Are Functional Properties

• General Definition
• Any food or food components that impart a
  physiological benefit that can enhance overall
  health, including the prevention and/or treatment
  of diseases.
• Anthocyanins
• Chemical and physical features that enhance color
  and oxidative stability
• Antioxidant capacity and enzyme/microbial
  inhibition

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Anthocyanins in the Foods We Eat

• Common anthocyanin aglycones
• Delphinidin
• Cyanidin
• Petunidin
• Pelargonidin
• Peonidin
• Malvidin

• Common sugar substitutions
• Glucose
• Rhamnose
• Galactose
• Xylose
• Arabinose

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Altering Functional Properties

• Natural pigments have low stability compared to
  synthetic colorants (Red 40).
• Application range in food is limited due by pH,
  temperature, and complexing factors.
• High raw product costs

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Anthocyanin Color at Varying pH
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1
2
2
3
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Modifications to Anthocyanins

• There are two primary means to augment the color
  of anthocyanins.
• Intramolecular and intermolecular copigmentation
• Both rely on complexation with other compounds
  (usually a phenolic compound)
• Greater color and stability is attained

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Intramolecular copigmentation(Acylated
Anthocyanins)

• Aromatic or aliphatic organic acids bound to the
  sugar moiety of the pigment by an acyl linkage.
• p-coumaric, ferulic, caffeic, vanillic, malonic,
  and acetic acids are most common
• Enzyme induced (acyltransferase)
• More red color in pH 4-5 range
• Increased stability to light, heat, and oxygen
• Red cabbage, black carrot, red radish

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Intermolecular Copigmentation
Cyanidin-3-ß-D-glucoside
Cyanidin-3-(6-O-p-coumaroyl- ß-D-glucoside
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Intermolecular copigmentation

• Add polyphenolics to solutions of anthocyanins
• The compounds stack on top of each other.
• Increases the red color and overall stability
• Slows degradation into qunioidal bases
• Results
• More red color at higher pH levels
• Greater application range in foods

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Copigment Stacking
Co-Factor

Pigment
Co-Factor
Hyperchromic shift Bathochromic shift
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Anthocyanin Color with Copigment
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Anthocyanin Color

• The poor stability of anthocyanins creates the
  need to modify stability or find new sources
• Increase color and oxidative stability
• Result
• More red color at higher pH levels
• Greater application range in foods
• Enhanced antioxidant capacity health benefits

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Traditional Anthocyanins Sources and
Applications

• Grape skin
• Red cabbage
• Elderberry
• Purple carrots
• Purple potatoes
• Red radish
• Strawberry, blueberry, blackberry, bilberry,
  chokeberry, cranberries, black current, hibiscus,
  roselle

• Soft drinks
• Instant drinks
• Fruit drinks
• Liquors
• Confectionery
• Fruit jellies
• Jams

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Natural, Non-Certified or Exempt Colors

• Consist of 26 colorants made up of dyes,
  pigments or other substances capable of coloring
  a food that are obtained from various plant,
  animal or mineral sources
• Must be proven safe and meet FDA approval
• Caramel (brown)
• Annatto extract (red/orange/yellow achiote)
• ß-carotene (yellow/orange paprika)
• Beet powder (red)
• Cochineal extract (red carmine)
• Grape skins (red/purple)
• Ferrous gluconate (black)

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Synthetic or Certified

• Widely used, some controversy with consumers
• Each batch certified by FDA
• Less than 10 synthetic colors are actually
  certified
• The FDA has approved certain dyes for use in
  foods FDC Colorants
• Blue 1 (Brilliant blue)
• Blue 2 (Indigotine)
• Green 3 (Fast green)
• Yellow 5 (Tartrazine)
• Yellow 6 (Sunset yellow)
• Red 3 (Erythrosine)
• Red 40 (Allura red)
• Orange B
• Citrus Red 2
• Another class of certified colors FDC lakes.
• Lakes are aluminum or calcium salts of each
  certified color
• Lakes of all of the FDC dyes except Red 3 are
  legal

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FYI

• Cochineal extract (red carmine)

• Carminic acid is derived from the shells of an
  insect and produces a magenta red color
  (cochineal extract).
• The Carmine Cochineal feeds on certain cactus
  species in central and south America.

Yummy