fdsc - natural food pigments

The flashcards below were created by user K.A on FreezingBlue Flashcards.

  1. what attracts us to food?
    • appearance : texture and color
    • flavour: smell/odor and taste
    • microbial load
    • nutritive value
  2. what are some natural food pigments?
    • chlorophyll
    • myoglobin & hemoglobin
    • carotenoids
    • anthocyanins
    • flavonoids
    • tannins
    • quinones and xanthones
    • melanins and betalains
  3. what are different food sources of natural food pigments?
    • chlorophyll : fruits, vegetables
    • heme : muscle foods
    • carotenoids : eggs, fish, crustaceans, dairy products, fruits and vegetables
  4. what is chlorophyll?
    • green pigment found mainly in plants : fruits, vegetables, algae, seaweed
    • has a blue-green color
    • these organisms = photosynthetic + can use light energy to produce chemical energy (food)
    • 5 membered ring
  5. what are 2 types of chlorophyll?
    • 1. Chlorophyll a
    • bright green
    • CH3methyl group in 1 of pyrole rings in "a"

    • 2. Chlorophyll b
    • dark green
    • is replaced by a formyl group in "b" (CHO)
  6. what do both types of chlorophyll have?
    both chlorophylls have side chain 20-C alcohol (phytol) esterified to one of the pyrole rings
  7. what is the molecular weight of chlorophyll?
  8. what is the molecular weight of phytol?
    300 (1/3 of chlorophyll)
  9. what is phytol?
    • phytol = fat soluble, H2O insoluble
    • it is the portion of the molecule that makes chlorophyll fat soluble 
    • (dissolved in the fat of plastrols** in the plants)
  10. what is the effect of the phytol group?
    • ↑ degree of unsaturation impacts free radical binding capacity to chlorophylls 
    • enable them to behave as antioxidants
    • the hydrophilic nature of the phytol side chain enables chlorophyll to bind tightly (via non-covalent bonds) with other hydrophobic molecules
    • Examples
    • polycyclic aromatic hydrocarbons
    • heterocyclic amines
    • aflatoxins

    the molecules listed above are toxic to humans thus chlorophyll can act as a detoxicant antioxidant
  11. what are some pigments related to chlorophyll?
    chlorophyll = dark green + H2O soluble

    chlorophyllide = bright green and H2O soluble

    pheophytin = H2O insoluble but dull brown in color

    pheophorbide = H2O soluble but brown in color

    •                       Image Upload
  12. what are some uses of chlorphyll?
    • antioxidant
    • detoxicant
    • food colorant
    • added to cosmetics and other personal hygiene products ex. mouth wash
    • heat : cooking + blanking = formation of brown coloured products 
    • dehydration = color loss
  13. whats the effect of processing on chlorophyll?
    • cooking → pheophytins
    • dehydration → blanching by photodegredation (lipoxidases)
    • exposure to O2 + light → bleaching
    • blanching → pheophytins and pheophobides
    • irradiation → degradation by peroxydation
  14. summary - chlorophyll
    • chlorophyll is a plant pigment
    • it is a tetrapyrolle compound
    • it is green in color and fat soluble
    • it is destroyed by heating under acidic conditions 
    • it is degraded by various enzymes such as chlorophyllase and lipoxidase
  15. what is an enzyme treatment?
    its a change in functional properties from fat soluble → H20 soluble
  16. What are heme pigments?
    • ex. myoglobin and hemoglobin
    • responsible for red color of muscle
    • complex molecules with protein part (global) and an essential non protein part (heme)
    • both Mb and Hb are tetrapyrolle compounds
  17. what the main differences between the myobglobin and hemoglobin?
    • Myoglobin
    • found in muscle
    • about 1/4 smaller than hemoglobin

    • Hemoglobin
    • found in blood vessels
    • bigger than myoglobin
  18. what are some similarities between myoglobin and hemoglobin?
    • both hemoglobin and myoglobin are found in animals and are both H2O soluble
    • both tetrapyrole compounds are similar to chlorophyll
  19. what are some major food sources of myoglobin nd hemoglobin?
    • fish
    • meats: beef, pork, chicken
  20. myoglobin structure
    • single polypeptide chain
    • 4 N's in the 4 pyrole molecule, covalently linked to central Fe atoms
    • Fe also covalently linked to N in a  histidine residue global (protein)
    • Fe can bind electron pair donors (ex. O2, CO, CO2, CN)
    •                                            Image Upload
  21. what is oxymyoglobin?
    • bright red color of fresh meats
    • Fe present as ferrous (Fe2+) form
    • Mb + O↔ MbO2
    • Mb (purple color; Fe2+)
    • MbO2 (bright red; Fe2+)
  22. what is metmyoglobin (Met-Mb)?
    • brownish color (Fe3+)
    • MbO2 ↔ Mb → Met-Mb
    • MbO2 (bright red)
    • Mb (purple)
    • Met-Mb (brown)
  23. what are the effects of handling and processing of meats?
    • Storage
    • gradual oxidation, forming dark/brown color

    • Cooking
    • denature proteins: also oxidation of Fe2+ to Fe3+
    • formation of dark color (as in barbecued meats - pigment formed knowns as hemichrome)

    • Curing of meats
    • with nitrites → red coloured nitrosomyoglobin
    • cooking cured meats denatures the protein
    • Fe2+ → Fe3+ (by oxidation)
    • froms a brown product called nitrosohemichrome
    • reducing agents may be used to reverse oxidation in meats
    • (unacceptable ex. formation of sulfmyoglobin with SH- containing reducing agents)
  24. Curing of meats
    • a form of meat conservation by treatment with nitrites
    • the nitrates have a lone pair of electrons to donate to Fe2+ in Mb to from a complex as nitrosomyoglobin

    Mb (Fe2+) + :NO ⇌ MbNO (Fe2+/ nitrosomyoglobin /reddish color)

    • addition of nitrites/nitrates to meats in primarily to curtail (stop/control) growth of harmful pathogen like clostridium
    • the red color formation  we associate that with cured meat products like salami, sausages, hot dogs, ham etc.
    • when cured meats are cor lead**, there is also denaturation of the protein global and oxidation of Fe2+ → Fe3+ 

    this is also accompanied by color change and the reddish brown to brownide and the product is known as nitrosohemichrome
  25. summary of heme pigments
    • heme pigments are of animal origin
    • there are 2 types - Mb and Hb
    • Mb = single polypeptide linked to 4 pyrole rings through a central Fe atoms
    • Hb = 4 sub units and each subunit is equivalent to 1 Mb
    • both Mb and Hb are tetrapyrolle compounds like chlorophylls
  26. what are carotenoids pigments?
    • present in plants, animals microorganisms
    • responsible for yellow, orange and red orange in plants and animals
  27. what are the major sources of carotenoids
    • plants: fruits, vegetables, vegetable oils
    • ex. tomatoes, carrots, peaches, papaya, canteloupe, water melon . peppers, oranges, palm oil

    animals: milk fat, egg yolk, butter, salmonids (ex. salmon, trout), crustacean species (ex. crab, lobster, shrimp, prawn)

    Microbial sources: fungi (mushrooms), yeasts (ex. Phaffia rhodozyma), algae
  28. what are the structure of carotenoids?
    • 5C compound - isoprene repeating unit
    • may be cyclic of acyclic
    • may be hydrocarbon exclusively (hydrocarbon carotenoids or carotenes) or may contain oxygen (oxy-carotenoids)
    •                                                 Image Upload
  29. what are the different structures of carotenoids?***
    Cyclic vs Acylic

                       Image Upload   Image Upload

    • Hydrocarbon vs Oxygenated
    • β-carotene and lycopene  vs  lutein

                                                   Image Upload
  30. what are different hydrocarbon carotenoids a.k.a carotenes?
    • β-carotene
    • α-carotene
    • lycopene
  31. what is the most common hydrocarbon carotenoid?
    • β-carotene
    • it gives 2 molecules of vitamin A on hydrolysis
    • thus described as pro-vitamin A
    •                                                       Image Upload
  32. what is α carotene?
    • has the same molecular formula as β carotene
    • but the α form is NOT symmetrical
    • by hydrolysis = yields only 1 molecule of vitamin A in the body
    •                                             Image Upload

  33. what is lycopene?
    • a major pigment in tomatoes and apricots
    • lycopene is symmetrical
    • unlike in α and β carotenes, the ring structures in lycopene are open → acyclic
    • lycopene has no vitamin A activity
    •                                             Image Upload
  34. what are oxy-carotenoids?
    • oxygen containing carotenoids
    • common ones : lutein, canthaxanthin, astaxanthin, cryptoxanthin and zeaxanthin
  35. what is lutein?
    • and oxy-carotenoid
    • found in : green leaves and yolk
    • molecule is similar to β-carotene : its asymmetrical but rings are hydroxylated
    • so has no vitamin A activity

                                               Image Upload
  36. what is canthaxanthin?
    • an oxy-carotenoid
    • present in microorganisms, plants and animals
    • ex. mushroom, red pepper, brine shrimp and the flamingo
    • commercially produced by chemical synthesis
    • used as feed supplement for cultured salmonids and imitation seafood products
    • has no Vitamin A activity

                                                Image Upload
  37. what are astaxanthin?
    • an oxy-carotenoid
    • major carotenoid pigment in salmonides and crustaceans, redfish, ocean perch/red snapper
    • produced on a  commercial scale by chemical synthesis
    • more stable than canthaxanthin for use as colorant for fish flesh
    • has no vitamin A activity
    •                                             Image Upload
  38. what is cryptoxanthin?
    • an oxy-carotenoid
    • major carotenoid pigment in peaches, yellow corn and egg yolk
    • structure similar to β-carotene, except for presence of -OH group on 1 ring 
    • HAS vitamin A activity

                                               Image Upload
  39. what is zeaxanthin?
    • an oxy-carotenoid
    • widely distributed in nature
    • major carotenoid in yellow corn and egg yolk
    • similar structure to β-carotene, but has 2-OH groups in addition
    • has no vitamin A activity 

                                               Image Upload
  40. what are the effects of handling and processing?
    • O2 and light = major cause of destruction
    • not lost to cooking water
    • destroyed by dehydration
  41. summary - carotenoids
    • yellow, orange, red-orange in color
    • fat soluble and water insoluble
    • present in plants, animals and microorganisms
    • good food sources include crustacea, egg yolk, milk fat, fruits, vegetables and vegetable oils
    • some have antioxidant and vitamin activity
    • destroyed by exposure to light and dehydration and by lipoxygenases
  42. what are anthocyanins?
    • water soluble plant pigments
    • impart red, blue and violet colors to various fruits and vegetables
    • the basic structure is the flavilium ion (a.k.a anthocyanidin or aglycone)
    • are glycosides (or sugar esters) of anthocyanidin
    • can be monoxides (1 sugar), biosides (2 sugars) and triosides (3 sugars)
  43. what are different sugars of anthocyanin?
    • Monosaccharides
    • D-glucose
    • D-galactose
    • L-arabinose
    • D-xylose
    • L-rhamnose

    • Disaccharides**
    • gentiobiose
    • rutinose
    • sophorose
    • neohesperidose

    • Trisaccharides
    • gentriotriose*
    • xylosylrutinose
    • glucosylrutinose
  44. what are common athocyanins and their distribution in fruits and vegetables
    • Cyanidin
    • Cy: orange-red color
    • found in: apples, cherries, oranges, plus, raspberries and cabbage

    • Delphinidin
    • Dp: blue-red color
    • found in: grapes and oranges

    • Malvinidin
    • Mv: blue red color
    • found in: blue grapes

    • Pelargonidin
    • Pg: orange color
    • found in : strawberries

    • Peonidin
    • Pn: orange-red color
    • found in: cherries and plums

    • Petunidin
    • Pt: blue red color
    • found in: blueberries
  45. what is the effect of substituent groups of color on anthocyanin?
    • ↑ hydroxyl (-OH) content = ↑ in blue color
    • ↑ methoxy (-OCH3) content = ↑ in redness
  46. what are the effects of handling and processing of anthocyanins?
    • pH
    • acidic conditions change pigments to red color
    • alkaline conditions change pigments to shades of blue or colorless

    • Effect of cooking
    • loss to cooking water

    • Decolonized by additives
    • sulphites, SO2, ascorbic acid, H2O2 
    • form purple or gray colors with metals

    • High temperatures
    • cause destruction of anthocyanin pigments
    • ex. spray drying

    • High sugar content + presence of O2
    • enhance destruction of anthocyanins

    • Colorless forms of anthocyanins may undergo oxidation in the presence of O2 to form coloured products
    • ex. "pinking" of canned pears
  47. what are the effects of enzymes on anthocyanins?
    • Glucosidases or anthocyanases
    • remove sugars from the anthocyanin
    • thus destabilizing the molecule 
    • causing loss of color

    deleterious effects of these enzymes curtailed by microwave blanching***
  48. what are flavanoids?
    • H2O soluble pigments found in plants and microorganisms
    • most absurd polyphenols in the diet
    • a.k.a antioxidants - they are glycosides with a benzopyrone nucleus
    • most common sugar - rutinose
    • they give certain fruits, vegetables and herbs their dark red, blue and purple colors
    • many are antioxidants
  49. how are flavonoids classified?
    • Flavones
    • double bond at 2:3 positions

    • Isoflavones
    • benzene ring at 3 position

    • Flavonols
    • -OH group at 3 position

    • Flavonones
    • no 2x bond at 2:3 position

    • Flavanonols
    • -OH group at 3 position; no 2x bond at 2:3
  50. what are some common properties of flavonoids?
    • polyphenolic structure
    • substrates browning reactions
    • may be involved in other discoloration reactions in foods
    • ex. may bind Fe in foodstuffs to form blue/green colors
    • chelating agent
    • antioxidant/free radical scavenger
    • pro-vitamin C activity
  51. what are betalaines?
    • H2O soluble plant pigments
    • synthesized by the aa tyrosine + dihydroxyphenylalanine (DOPA) as intermediate
    • glycosides (glucose commonly present)
  52. how are betalaines classified?
    into 2 groups based on color differences:

    • betacyanins (ex. betanin) → reddish violet
    • betaxanthins (ex. vulgaxanthin) → yellow + orange
  53. where are betalaines mostly found?
    found mostly in beet plants
  54. what are betalaines used for?
    • extensively used as a food colorant because of its intense color
    • also used in beverage and powdered mixes
  55. what are the effects of handling and processing of betalaines?
    • degraded by thermal processing (affected by light and heat/temeprature)
    • some color lost to cooking water due to ↑ solubility in H2O
  56. what are tannins?***
    • complex plant pigments
    • with varying degrees of solubility in H2O based on size differences
    • small ones = more H2O soluble
    • wide range of colors - from colourless to yellow or brown
    • common ones: gallic acid and ellargic acid
  57. what are 2 types of tannins?*****
    • 1. Hydrolysable tannins
    • undergo hydrolysis when heated in H2O to form sugars and phenolic compounds

    • 2. Condensed or non-hydrolysable tannins
    • imp. in teas
    • cause proteins in cheeks to precipitate
    • not hydrolyzed
    • remain to cause astringency to products such as tea
  58. what are tannins used for?
    • tannins contribute to astringency in foods
    • participate in enzymatic browning reactions
  59. what are quinones?
    • H2O soluble pigments
    • present in plants and microorganisms
    • range in color = from yellow → black
    • common ones : emodin and spinulosin
  60. what are quinones used for?
    • extensively used as natural dyes for textile because of their intense dark colors
    • can also cause irritation in the gut to make us "run" if consumed in ↑ quantities and thus is used as a purgative
  61. what are xanthones?
    • plant pigments with structural resemblance to flavonoids and quinones
    • ex. glycosides
    • H2O soluble and yellow in color
    • common one: mangiferin
    • because of their phenolic nature, the can serve as substances for enzymatic browning
  62. what are phytocyanins?
    • blue coloured pigments
    • found mainly in microorganisms 
    • have ↑ antioxidant potency because of their free radical scavenging capacity
    • ex. in blue green algae and cyanobacteria
  63. what are phytoerythrins?
    • red coloured pigments
    • found in microorganisms
    • ex. in red algae
  64. what are melanins or melanoidins?
    • brown coloured pigments
    • found in fruits and vegetables, fungi (mushrooms) and crustacea
    • formed from oxidation of phenolic compounds (tyrosine) by PPO
    • O2 is a co-reactant in the reaction
    • Cu++ is required as a cofactor for PPO
    • formation of melanins desirable in certain foods, but undesirable in others
    • protect against oxidation**
    • they absorb free radicals**

    •                 Tyrosine
    •                       ↓                    (PPO)
    •                    DOPA
    •                       ↓                    (PPO)
    •                 quinones
    •                       ↓                    (polymerisation)
    •                 melanins
  65. what are 2 types of non-enzymatic browning?
    Caramelization and Maillard reaction
  66. what is caramelization?
    • oxidation of sugars @ ↑ temperature
    • reaction leads to brown coloured products + volatile compounds (ex. diacetyl)
    • responsible for nutty falcons in caramelized products
  67. what is the maillard reaction?
    • series of chemical events 
    • take place when amino groups from aa, proteins, peptides and amines are reacted with carbohydrates (sugars) @ ↑ temperature
    • reaction leads to brown coloured products + formation of flavor compounds
    • some Maillard reactions have antioxidant properties while others are suspected to be potential toxicants
Card Set:
fdsc - natural food pigments
2016-10-29 19:11:37
Show Answers: