Apples are fruits containing anthoxanthin pigments, which are responsible for their white edible pulp. Anthoxanthins are polyphenolic compounds and can therefore be acted upon by polyphenol oxidases. Polyphenol oxidases are enzymes requiring the presence of oxygen to function in browning reactions. Minimizing these color changes in apples and other sensitive foods helps maintain food and sensory quality (freshness).

Procedure

Cut 6 slices from an apple.

Label 6 different cups:

Vinegar

Lemon Juice

Baking Soda Solution (1 Tablespoon of baking soda per ¼ Cup water)

Milk of Magnesia Solution (can be found at any common pharmacy)

Water

Control – No solution

Add a slice of apple to each cup.

Pour 50 ml or 1/4 cup of a substance over the apple in its labeled cup. You may want to swirl the liquid around the cup to make sure the apple slice is completely coated.

Allow the apples slices to sit in the cup for roughly 30 seconds.

Once removed, make note of the appearance of the apple slices immediately following treatment.

Set aside the apple slices for a day on your counter-top. Make sure they are labeled.

Record your observations in intervals for ~24 hours.

You must take photos to include in your report.

Two-page report (Doubled spaced, 12 size font / 1 inch margin)

Provide a detailed description on how enzymatic browning occurs. What compounds and enzyme are involved? What compound is responsible for the brown color we see?

Describe your observations; are there any conclusions you can draw?

What can we conclude about the effect of each solution on enzymatic browning?

What is the purpose of a ‘control’ in experiments such as this one?

Include at least 3 academic sources (research article, textbook, culinary school websites)

Make sure to include in text citations and a reference page.

Citation Style: Journal of the Academy of Nutrition and Dietetics. http://jandonline.org/content/authorinfo#ref