Investigating Chocolate

Copyright © 2012 Board of Trustees, University of Illinois. All rights reserved.

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Background

Chocolate is a multi-billion dollar a year business.

Very popular worldwide.

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Background

Chocolate contains flavanols

Flavanol--an antioxidant

May also help improve vascular health

Found in other foods

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Background

Chocolate has a shelf life. When it “blooms” it is much less desirable.

Research being done in this area.

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What is bloom?

• Has whitish look

• Crystals become larger

• May not taste as smooth or as good

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Some questions

• Do storage conditions affect rate of bloom?

• Can chocolate be engineered to extend shelf life and storage conditions?

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Focus for Today

Do storage conditions affect rate of bloom?

Three tests:

• Crystal size

• Color

• Taste

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Testing for crystal size

Microscope, but what kind?• Light microscope, can’t see chocolate

crystals

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Testing for crystal size

Microscope, but what kind?• Scanning Electron Microscope (SEM),

but may change crystals

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Testing for crystal size

Microscope, but what kind?• Atomic Force Microscope (AFM), gives

molecular resolution without affecting sample

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How does AFM work?

• Very good probe can see a single atom –

but 3D resolution

still off

• Probe rides along surface of object

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How does a AFM work?

• Measure movement of probe – but how?

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Testing crystal size

• Look at AFM pictures provided

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Testing for color

What does it look like?• What color is it?• Are there any white

patches?

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May not taste as good

Taste!• Consider texture – smooth

taste should have only small crystals

• Consider volatiles – small taste molecules are present and not bound to larger molecules