Discussion questions are listed below. Each question is meant to be an independe

Question

Discussion questions are listed below. Each question is meant to be an independent thread. If you are the first to post on a particular question, please use the question number and title in your subject. Once a question has been started, please put your posts on that question within the existing thread.

1. Control Variables

Which control variables did you choose for these experiments? Reply to your classmates and discuss whether some of these are things that would be "coincidentally the same" versus ones that "you take deliberate action to keep the same."

2. Food Storage

Use the knowledge you gained in this lab to begin a discussion about how cooking foods or refrigerating them affects browning of vegetables, growth of bacteria/fungus, and spoiling or decomposing of food. Alternately, speculate on how the apples in a HappyMeal don't turn brown for days on end. What might they have done to them?

3. Other Enzymes

There are many other enzymes common to food and nutrition. Choose one you have heard of and do a little research. Propose an experiment with one of these, complete with all three types of variables named. Critique each other's experiments and suggest improvements. If you're really brave, run the experiment and report on the results. (Suggestions – Bromelain, meat tenderizer, Lactaid, lipase, Beano, etc.)

You must participate in at least one of the discussions. Make sure you post at least once by the first post date (check the schedule), that some of your posts are replies to other classmates, and that you post at least three times.

Explanation / Answer

2. Enzymatic reactions in fresh apples involving the enzyme polyphenol oxidase that oxidizes the phenols into quinones leads to browning of the apples. destroying the chemicals with bleach prevents browning. In apples particularly acids and lemon juices are used to lower the ph and inhibitng enzyme activity.

3. The effect of lipase on milk could be assesed in the experiment. lipase digests lipids into 3 factty acids and glycerol with an increase in hydrogen ion cocentration. the increase in hydrogen ion concentration can be assesed by ph meters or an indicator -phenophthalein (pink at alkaline and colorless at acidic conditiond, therefore as the lipase digests the lipds the hydrogen ions concentration increase, phenophthalein loses color). The three variables of the experiment could be concentration of the enzyme lipase, temperature and effect of pH.

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