June Monthly Action Idea
Fruits & Veggies - Every Day the Tasty Way!

Eat at least 5 servings (and up to 9) of fruits and veggies each day.
Help kids learn "More Matters"!

Fruit of the Month Bulletin Board
A.V. Norrell Elementary Fruit of the Month Bulletin Board

Activity Idea: Effects of pH on the Browning of Cut Apples
   
Source: Healthy Kids Challenge, Explore MyPlate with School Nutrition booklet
Description: Kids learn about food science by doing a fruit experiment
Grade: 6-8
Supplies:
  • 1 fresh whole apple
  • Approximately 1/4 cup each of apple juice, white grape juice, pineapple juice, orange juice, lemon juice, lime juice, and water
  • 8 cups

Directions:

  1. Cut the apple into a minimum of 8 slices.
  2. In each cup, pour one of the 6 juices or water at a depth sufficient to cover the apple slice.
  3. Place 1 apple slice in each cup (including the 1 empty cup to observe the effect of air) for 5 minutes.
  4. Remove the apple slices from their respective juices and observe at 15 minute intervals to see what anti-browning effects the juices and water had on the cut surfaces of apple slices.

Questions:

  1. Which juices consistently performed the best, to inhibit the browning of cut apples?
  2. Why did those juices perform better? ( A: The lime and lemon juice have a higher ascorbic acid level, therefore lower pH, and should perform the best.)

What is going on:

  1. Enzymes in light colored fruits such as apples, pears and peaches can cause oxidative browning as soon as the fruit is peeled or cut. Browning can cause loss of vitamin C. Fruits served raw experience discoloration. Chemical compounds are used to control enzymes in these fruits.
  2. The most common treatment is ascorbic acid (vitamin C). Ascorbic acid may be used in its pure form or in commercial mixtures of ascorbic acid and other compounds. Browning can also be halted temporarily by placing fruit in citric acid or lemon juice solutions or in sugar syrup. However, these measures are not as effective as treatment with ascorbic acid in its pure form.
  3. The juice with the greatest amount of ascorbic acid will be the most effective. Note: Ascorbic acid content of fruit juices varies by product and length of storage.

This activity is found on page 106 of the Explore MyPlate with School Nutrition booklet. For more activity ideas like the one above, check out HKC resource materials. See the Online Store for descriptors and to view the Table of Content and booklet sample pages.