STEM Electrophoresis with Food Dyes

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STEM Electrophoresis with Food Dyes

• Bio-Rad Biotechnology Explorer IDEA and STEM Kits

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Instructors - Bio-Rad Curriculum and Training
Specialists

• Sherri Andrews, Ph.D., Eastern US
• sherri_andrews_at_bio-rad.com
• Damon Tighe, Western US
• damon_tighe_at_bio-rad.com
• Leigh Brown, M.A., Central US
• leigh_brown_at_bio-rad.com

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Why Use Bio-Rad?

• Guaranteed to work
• Easy to prep
• Cost Effective per student group
• Easy, inexpensive first exposure to
  electrophoresis
• Independent inquiry opportunities for what dyes
  are present in food items, what is the charge of
  the dyes, can they be separated based on
  charge/size?
• Engineering inquiry with STEM kit ranging from
  optimizing metal composition and diameter for
  electrodes, gel matrix composition, buffer
  composition, etc.
• Extensions including paper chromatography,
  spectroscopy, and researching food dyes commonly
  used

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Separation technology How do you separate two or
more compounds from each other?
Materials to be Separated Property Used to Separate Components Explanation
Iron filings from other metals Magnetism Iron filings will be attracted to a magnet while other metals will not
Salt from sand Solubility Salt will dissolve in water and can be separated from the sand
Caffeine from coffee beans Solubility A solvent is used that selectively dissolves the caffeine (such as dichloromethane or ethyl acetate) but not most of the remaining coffee oils
Ethanol from fermented grain Boiling point Ethanol will boil off at a lower temperature than the other components of the fermented grain
Wheat from chaff Density Wheat kernels are more dense and will fall to the ground while chaff can be blow away by the wind
Tea from tea leaves Size Filtration can be used to separate the liquid extract from the large tea leaves
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Electricity can be used to separate molecules by
charge
Acetate ions
Tris ions
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Sieves can be used to separate materials by their
size
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Electrophoresis separates molecules by CHARGE and
SIZE

• Electrophoresis means to carry with electricity

Molecular sieve
Electricity
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Food dyes What have you recently eaten?
Did you eat any cheddar cheese? Was it orange?
Starbucks Strawberry Frapuccino?
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Food dyes Color tells our brains about foods.
What flavor is this Skittle?
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Food dyes We have been dying our foods for
hundreds of years

• In the early 1800s some cheese and cayenne pepper
  was colored with LEAD tetroxide
• Pickles with COPPER sulfate
• Green tea with COPPER carbonate

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Food dyes - Regulation
There was NO control or regulations on food dyes
until the early 1900s in the US

• Food and Drug Administration (1902)
• Due to public outcry over adulterated foods
• Upton Sinclair The Jungle (1906)
• Elixir sulfanilamide Poisoning, 100 dead (1937)
• Food Drug and Cosmetics Act (1938)
• Synthetic Dyes Seven approved for use
• Natural Dyes (derived from plants or animals) can
  also be used and are not regulated

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FDC Dyes and Natural dyes

• FDC Synthetic Dyes
• FDC Red 40 or FDC Red 40 Lake
• FDC Yellow 6 or FDC Yellow 6 Lake
• FDC Yellow 5 or FDC Yellow 5 Lake
• FDC Blue 1 or FDC Blue 1 Lake
• FDC Blue 2 or FDC Blue 2 Lake
• FDC Red 3 or FDC Red 3 Lake
• FDC Green 3 or FDC Green 3 Lake
• Natural Dyes
• Beetroot red or betanin (from beets)
• Curcumin (from tumeric)
• Caramel coloring (from sugar)
• Annatto (seeds of achiote trees)
• Carminic acid, carmine, or cochineal (from ground
  up beetle abdomens)
• Lycopene (from tomatoes, watermelons, papayas,
  and red carrots)

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Food dyes in the news
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Food dyes have an intrinsic SIZE and CHARGE and
thus can be separated using Electrophoresis
Food dye Molecular weight Charge
FDC Blue 1 792.86 -2
FDC Yellow 5 534.37 -3
FDC Yellow 6 452.37 -2
FDC Red 40 496.43 -2
Carminic Acid 492.38 0
Beetroot red 551.48 1
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So how do we design an electrophoresis chamber to
separate food dyes?
Dye Electrophoresis Commercial versus built box
comparisons
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Combining Science, Engineering and Math to
Develop a Separation Technology
Engineering Design parameter based no single
correct answer
Science Hypothesis driven try to find specific
cause/effect
Best electrode material
Understanding the chemistry of metals in salt
solutions, physics of conductivity and currents
Conducts well, has low reactivity, inexpensive
Measurements Analysis
Best gel matrix
Conducts electricity, moldable, inexpensive,
non-toxic, correct pore size
Polymer chemistry, melting points, gelling
properties
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What are some of the design factors we want to
think about?
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Dye extraction from candies
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Building and running your electrophoresis system
to separate the dyes
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Building and running your electrophoresis system
to separate the dyes
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Building and running your electrophoresis system
to separate the dyes
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Building and running your electrophoresis system
to separate the dyes
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Building and running your electrophoresis system
to separate the dyes
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Extensions
Copper electrode

• Paper chromatography
• Spectroscopy
• Food diary
• Electrochemistry study
• pH changes at the cathode and anode
• Effect of material choice for electrode
• Optimization of STEM box system
• Electrode material choice and thickness
• Different materials for gel thickness
• Impact of TAE Concentration and Volume
• Gel percentages

Gelatin matrix