Grocery Store Fruit and Vegetable Characteristics
Many grocery stores have informational sheets on fruits and vegetables. Have students go to the grocery store with a parent or other adult and find out information about a particular fruit or vegetable from the manager of the Produce Department. For example: How many kinds of apples are carried by the grocery store? Which apples are best for cooking, eating or storing? Which apple has the shortest growing season, the longest growing season? Which apple sells the best? Which are the most expensive and why? Where do apples grow in your state?
Browning Apples
Students observed browning in different varieties of apples, but what about browning under different conditions? Have your students think of ways they might slow the browning of apples (add lemon juice, wrap apple slices in plastic, put them in the freezer, etc.). Cut slices of apples, and compare the rate of browning under the different conditions suggested by the students. Make observations over two or three days. Don’t forget to provide a control slice (a sliced apple with nothing done to it).
Testing Apple Ripeness
Apple growers try to pick their apples at precisely the right time. They have several ways to test for ripeness that students can try in the classroom. These observations will work best with apples picked in the early fall when you can find varying stages of ripeness—they will not work well with apples from the grocery store.
1: Seed Color Test
Rate the color of the seeds in the apple. A ripe apple has brown seeds. Apple growers use the following scale:
- 1 = clear (no color)
- 2 = trace of color (tips of seeds are brown)
- 3 = 1/4 color
- 4 = 1/2 color
- 5 = 3/4 color
- 6 = fully brown
2: Flesh Color Test
Check the flesh color of the apple by holding a very thin slice—about 1/16th of an inch (1.58 mm)—up to a bright light. A ripe apple has almost no green flesh. Apple growers use the following scale:
- 1 = flesh all green
- 2 = some loss of green from center of fruit
- 3 = heavy green band 1/2 inch (1.27 cm) thick under skin
- 4 = heavy green band 1/4 inch (6.35 mm) thick
- 5 = heavy green band 1/8 inch (3.17 mm) thick
- 6 = green essentially gone from under skin
Have students give their apple a rating from 1 to 6. Remind students that these tests for ripeness involve a skill that scientists must develop—the ability to make careful observations.
3: Starch Test
Divide the class into groups. Give each group an apple, and have them cut the apple in half at a right angle to the core. Apply iodine to the cut surface, drain away any excess, and allow it to stand for a few minutes. (Emphasize that iodine is poison and is not to be taken internally.) The apple will turn a dark purple or blue-black wherever starch is present. Remind students that in a ripe apple the starch has changed to sugar, so a ripe apple will have very little dark stain. Have students give their apple a rating from 1 to 6 based on the amount of dark stain on the apple. A rating of 6 indicates a perfectly ripe apple. Note: This test works well at any time of year with bananas, which are commonly available at varying stages of ripeness.
Apple growers commonly use the following rating system:
- 1 = all blue-black (full starch)
- 2 = all blue-black except in seed cavity and halfway to vascular area (oval area around core)
- 3 = all blue-black except in seed cavity and vascular area
- 4 = half blue-black
- 5 = blue-black just under skin
- 6 = no blue-black (free of starch)
Ag Today Reader
Read Issue 6 of Ag Today titled Plants & Animals...Providing Food, Fiber, and Energy! This reader can be accessed digitally. Explore the facts about the renewable and non-renewable resources that make the products and byproducts we need for survival. Learn how agriculture provides energy through biofuels and hydropower, fiber through cotton and wool, and various food products from plants and animals that have been improved through biotechnology and crossbreeding.
