Anthocyanins in Wines and Juices Fall 2003 Brienne Olney

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Anthocyanins in Wines and JuicesFall
2003Brienne Olney
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Timeline of inquiry (in terms of my question)
What affect does temperature Have on seasonal
color changes For different elevations?
How are anthocyanin Concentrations affected By
temp. in decid. Trees?
How do growing conditions for the Different
kinds of Grapes used in wine- Making affect
antho- Cyanin concentration?
Season ended too Quickly, no Leaves on trees
Too expensive
What are the different Concentrations of
cyanidin-3- Glucoside in wines and juice and
Does that reflect its color?
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Where are anthocyanins found?
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Background- Anthocyanins

• Water-soluble pigments
• Responsible for pink to blue coloration in plants
• Not found in the plastids like other pigments but
  in the vacuoles
• There are over 300 structurally different
  anthocyanins that have been identified in nature
• Have antioxidant properties
• Are used as a food-colorant
• Anthocyanin concentrations are affected by
  processing

                                
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More about anthocyanins

• The most abundant form of anthocyanin found in
  nature is cyanidin-3-glucoside
• Has a molar absorptivity of 26,900 L/(molcm)
• Has a molecular weight of 445 g/mol
• Has maximum absorption at wavelength of 510 nm
• Red wines and grape juices are believed to have
  the highest concentration of anthocyanins and
  that they therefore have higher antioxidant
  properties (French paradox)
• Cranberries also have a relatively high
  concentration of anthocyanins

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Initial Model
Concentration of cyanidin-3-glucoside
Color density of liquid (wine/juice)
affects
Hypothesis

• The darker liquids will have higher
  concentrations of cyanidin-3-glucoside the
  darkest liquid will have the highest
  concentration while the lightest liquid will have
  the least.

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Assumptions

• Cyanidin-3-glucoside is the most abundant form of
  anthocyanin in each of the 8 samples
• Beer-Lambert law is an adequate equation to use
  to calculate the concentration of this form of
  anthocyanin
• There are no other components/pigments
  interfering with the absorbance at the wavelength
  of 510 nm

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Methods

• Choose 8 samples of liquid to test, none of which
  have any artificial coloring added
• Red wine (Cabernet sauvignon)
• White wine (Riesling)
• Canned grape juice (Concord)
• Frozen grape juice (Concord)
• Bottled apple juice
• Frozen apple juice
• Cranberry juice
• White Cranberry juice (white cranberry and white
  grape mix)
• Rank liquids according to density of color

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To the lab (measuring absorbance)

• Set the spectrophotometers wavelength to 510 nm
• Dilute the red wine, cranberry juice and grape
  juices so that the absorbance reading would be
  between 0 and 1 (for more accurate measurement)
• Take readings for each sample
• Use the following equation to determine the
  concentration of each sample
• C(mg/L) A____ MW(g/mol) DF 10³mg
• ?(L/molcm) L(cm)
• A absorbance MWmolecular weight
• ? molar absorptivity L pathlength

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Data Tables and Graphs
Table 1
Color Scale
Grape juices
Red wine
Cranberry juice
Apple juices
White wine
White cranberry
amber
Dark red
purple
Red
golden
white
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All samples
Red wine has the greatest concentration of
cyanidin-3-glucoside.
Frozen apple juice has the smallest concentration
of C-3-G.
White wine and white cranberry juice have no
C-3-G.
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Just the wines
Red wine (cabernet sauvignon) has much more
cyanidin-3-glucoside than white wine (riesling).
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Grape juices
Frozen grape juice has a greater concentration of
cyanidin-3-glucoside than canned grape juice.
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Cranberry juices
White cranberry juice does not have any
cyanidin-3-glucoside while regular cranberry
juice has 9.5 mg/L.
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Apple juices
Bottled apple juice has a higher concentration of
cyanidin-3-glucoside than frozen apple juice.
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Evidence and Final Claim

• The color of the liquid doesnt necessarily
  represent the amount of cyanidin-3-glucoside
  present
• The grape juice had less anthocyanin than the red
  wine even though its color was darker
• Neither the white wine nor the white cranberry
  juice had any cyanidin-3-glucoside
• Even though the grape juices appeared to be the
  same color, their concentrations differed
• The apple juices also appeared to be the same
  color but their concentrations also differed
  slightly

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Revised Theory/Model
Antioxidant properties
?
?
Concen- Tration of Other antho- cyanins
Not a direct relation
Color density Of liquid
Concentration of cyanidin-3-glucoside

?
?
Growing conditions temp., UV exposure, etc.
Methods used for processing
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References

• Clifford, M.N. Anthocyanins-nature, occurrence
  and dietary burden. Journal of the Science of
  Food and Agriculture. 80 1063-1072 (2000)
• Bancroft, W.D. The biochemistry of anthocyanins.
  Science. 98(2535) 98-100 (1943)
• Roberts, H.F. The causes of autumn coloration.
  The Scientific Monthly. 45(5) 427-435 (1937)
• Burns, J., Mullen, W., Landrault, N., Teissedre,
  P., Lean, M.E.J., Crozier, A. Variations in the
  profile and content of anthocyanins in wines made
  from cabernet sauvignon and hybrid grapes.
  Journal of Agricultural and Food Chemistry. 50
  4096-4102 (2002)
• And many more

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Happy Winter Break!!!