Investigate Enzymatic Browning

Mini-Lab Chemistry Unit Investigate Enzymatic Browning

What factors affect enzymatic browning? When sliced, an apple’s soft tissue is exposed to oxygen, causing a chemical reaction called oxidation. Enzymes in the apple speed this reaction, producing darkened, discolored fruit. In this lab, you will investigate methods used to slow enzymatic browning.

1. Predict the relative amount of discoloration each of these apple wedges will show when exposed to air. Justify your prediction. Sample 1: Untreated apple wedge Sample 2: Apple wedge submerged in boiling water Sample 3: Apple wedge submerged in lemon juice Sample 4: Apple wedge submerged in sugar solution

2. Prepare 75 mL of each of the following: boiling water, lemon juice, and sugar solution in three 250 mL beakers. ( There will only be one lemon juice solution per class, you must share.) 3. Slice an apple into 6 wedges. Immediately use tongs to submerge each wedge in a different liquid. Put one wedge aside. 4. Submerge the wedges for three minutes, then place on a paper towel, skin side down. Observe for 10 min, then record the relative amount of discoloration of each apple wedge. 5. Analyze the following questions: a. How did each treatment affect the chemical reaction that occurred on the fruit’s soft tissue? Why were some of the treatments successful? b. A restaurant owner wants to serve fresh-cut fruit. What factors might be considered in choosing a recipe and preparation method.

Apple Lab Oct 23, 2009 Name: Kimee Harmon

Problem: (What are you looking for?) I am looking for what substances will speed up or slow down the enzymatic process.

Hypothesis: (What do you think will happen?) I think that if we put apple slices into each solution then the lemon juice and sugar solution will slow down the process while the other things will slow it down.

Materials: (What will you use?) Apple slices Beaker Boiling water Lemon juice Sugar solution Graduated cylinder

Procedures: (What will you do?) Prepare 75 mL of each of the following: boiling water, lemon juice, and sugar solution in three 250 mL beakers. ( There will only be one lemon juice solution per class, you must share.) Slice an apple into 6 wedges. Immediately use tongs to submerge each wedge in a different liquid. Put one wedge aside. Submerge the wedges for three minutes, then place on a paper towel, skin side down. Observe for 10 min, then record the relative amount of discoloration of each apple wedge.

Data/Observations: (What happened?) Air Boiling Water Lemon Juice Sugar Solution Prediction I think that it will I think that the I think that the I think that it could take about 5 boiling water will lemon could reduce slow it down by 1o minutes for it to speed up the the process by a minutes. brown. process by one or couple days. two min. Observation at end After three minutes No browning. No browning. No browning. of three minutes in the apple started to solution. brown slighty at the edge. Observation when Browned the most. Browned 3rd most. Did not brown at Browned the 2nd taken out of all. most. solution/Results

Analysis: (Answer the questions?) How did each treatment affect the chemical reaction that occurred on the fruit’s soft tissue? Why were some of the treatments successful? What happened was some solutions served as “blocks” and does not let it react with the apple. When it is browning faster then there is no block and it is reacting directly with the apple.

A restaurant owner wants to serve fresh-cut fruit. What factors might be considered in choosing a recipe and preparation method. The owner may wanted to consider adding lemon juice to each recipe in order to slow down the browning process.

Conclusion: (Refer to your hypothesis: Were you correct? What were sources of experimental error? What happened?) I was incorrect in the prediction that the sugar prediction would slow down the process as well. In fact, the sugar solution browned the second quickest next to air. Lemon juice was the slowest to brown, followed by the boiling water. Some human errors could be not measuring exactly 75 mL exactly and also not following the timing on the air perfectly.