MediumChemistryHigh School (9–10)GeneralChemical Reactions › Energy Changes and CorrosionConceptualBoard Exam
What is rancidity? Give three ways to prevent it…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
- What is rancidity?
- Give three ways to prevent it.
- A packet of salted peanuts tastes stale after it has stood open for some weeks. Why?
Need a reminder? The key ideaShow
Iron rusts only when both air (oxygen) and water are present; salt speeds it up. Rusting is prevented by painting, oiling, galvanising with zinc, or alloying. Rancidity is the oxidation of fats and oils; antioxidants, airtight packs, cold and nitrogen gas slow it.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Rancidity is the slow oxidation of fats and oils in food, which makes it smell and taste bad.
Step 2. (b) Keep the food cold, keep it airtight, add antioxidants, or fill the packet with nitrogen.
Step 3. (c) Air got into the open packet, and the oil in the peanuts was oxidised.
Answer: as above.
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