Effect of Glucose Levels in Onions: Does the Amount of Sugar in an Onion Affect How Much You Cry when Chopping Onions?

Overview

Objectives/Goals Sometimes when I chop onions, my eyes get really irritated. I would like to know why onions irritate your eyes and why some onions cause more irritation than others. Methods/Materials Materials: 2 Sweet Maui Onions; 2 Yellow Onions; 2 Red Onions; 2 White Onions; 6 Shallots; 1 Clean, Sharp Knife (9# MAC Mighty brand used by professional cooks) at Room Temperature; 1 Plastic Cutting Board; Glucose Test Strips Methods: 1. Peel test onions and place in zip lock baggies; 2. Brush a glucose test strip against each of the onions (use a separate, clean test strip for each onion.); 3. Record the glucose level of the onion; 4. Call test subject into room; 5. Explain irritation rating scale to test subject; 6. Have test subject commence with the experiment on each onion using the following procedure: Remove onion from bag #1; Cut a chunk of onion from the larger onion piece; Replace larger onion piece into bag; Commence dicing of test chunk using a clean sharp knife and clean cutting board; Dice onion for a period of 60 seconds (a stop watch was used for timing); Report level of irritation based on irritation scale of; Record results on record sheet and compare the results; Repeat above steps for each kind of onion. (Note: After all five onions were evaluated by each test subject, they were allowed to make adjustments to their irritation level ratings based on irritation experienced relative to the other onions.) Results The Yellow Onion (Onion #3) had the least amount of sugar with a level of 100/5 and the lightest green test strip color. The average irritation level for this onion was 3.2, the highest of all of the onions. The Red Onion (Onion #1) was in the 100/5 range of glucose. The average level of irritation for this onion was 2.8. The Shallot (Onion #4) was in the 100/5 range of glucose. The average level of irritation for this onion was 1.8. The White Onion (Onion #2) was in the 250/15 range of glucose and the average irritation level was 1.6. The Sweet Maui Onion (Onion #5) had the highest amount of sugar indicated by the test strip with a level of 500(++)/30 and a color change to brown. The average irritation level for this onion was 1.0, the least of all of the onions. Conclusions/Discussion My hypothesis was proved to be correct. The Yellow Onion had the highest level of irritation and the Sweet Maui Onion made the test subjects cry the least.

Competition history

• CSEF 2007 Pharmacology/ Toxicology · Entry J1523

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