Specific Reactions for Carbohydrates (Preliminaries)

• Preparation of solid unknown sugar in 5 mL of distilled water

Mucic Acid Test

• Test to identify Galactose and Lactose• The nitric acid oxidizes galactose to an isomer of

tetrahydroxyadipic (tetrahydroxyhexanedioic) acid that crystallizes out from water under the conditions of the test.

• Lactose is a disaccharide, galactosyl(1->4)glucose. The nitric acid first catalyzes hydrolysis of lactose to glucose and galactose. Then the nitric acid oxidizes both of those sugars to the tetrahydroxy acids. Mucic acid crystallizes out, which is a positive test. The acid from glucose remains in solution.

• This test will give positive results if there is a presence of crystal precipitate

Mucic Acid testXYL FRU GLU GAL LAC MAL SUC

1 Clear Solution

Clear Solution

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With White Crystals

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With White Crystals

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2 Clear Solution

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With White Crystals

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With White Crystals

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3 Clear Solution

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With White Crystals

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With White Crystals

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4 Clear Solution

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With White Crystals

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With White Crystals

Clear Solution

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5 Clear Solution

Clear Solution

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With White Crystals

Clear Solution

With White Crystals

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Mucic Acid testXYL FRU GLU GAL LAC MAL SUC

6 Clear Solution

Clear Solution

Clear Solution

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With White Crystals

Clear Solution

With White Crystals

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Clear Solution

7Clear

SolutionClear

SolutionClear

SolutionClear

SolutionWith White

Crystals

Clear Solution

With White Crystals

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8 Clear Solution

Clear Solution

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With White Crystals

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With White Crystals

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9 Clear Solution

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With White Crystals

Clear Solution

With White Crystals

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10 Clear Solution

Clear Solution

Clear Solution

Clear Solution

With White Crystals

Clear Solution

With White Crystals

Clear Solution

Clear Solution