All Fat Is Not Created Equal!
The properties of fats present in common foods can be examined through science!Copyright Indiana Insider Blog http://www.in.gov/visitindiana/blog/index.php/2012/09/18/national-cheeseburger-day-try-indianas-best-burgers/ (left); NIDA for Teens http://teens.drugabuse.gov/blog/post/addicted-french-fries-food-drug (right)
Students learn that fats found in the foods we eat are not all the same; they discover that physical properties of materials are related to their chemical structures. Provided with several samples of commonly used fats with different chemical properties (olive oil, vegetable oil, shortening, animal fat and butter), student groups build and use simple LEGO® MINDSTORMS® NXT robots with temperature and light sensors to determine the melting points of the fat samples. Because of their different chemical structures, these fats exhibit different physical properties, such as melting point and color. This activity uses the fact that fats are opaque when solid and translucent when liquid to determine the melting point of each sample upon being heated. Students heat the samples, and use the robot to determine when samples are melted. They analyze plots of their collected data to compare melting points of the oil samples to look for trends. Discrepancies are correlated to differences in the chemical structure and composition of the fats.
Understanding the chemistry of fats, as well as compounds that contain fat, is important to chemical and biomedical engineers. Fat molecules are incorporated into cosmetics, medications and food, as well as found in human blood. When designing certain products, engineers take into consideration various fat types and their physical properties. For example, chemical engineers who design skin creams or makeup must know what type of fats to put in products to give them the desired solid or liquid consistency. In the food processing industry, chemical engineers must understand the various properties of different fats so they know their potential effects on food products and human digestion. Some biomedical engineers design devices that interact with blood, such as stents and pacemakers, which are implanted into arteries or valves and must be resistant to the deposition of fats on their surfaces. Engineers who design new medications and drugs also need to know how they will react with fats, which are present in human cells and blood. For all these applications, engineers need to have a clear understanding of the chemical and physical properties of fats.
After this activity, students should be able to:
- Construct a LEGO NXT robot to perform a specific type of measurement.
- Explain the functions of light and temperature sensors.
- Define the term "melting point" and explain its relationship to the chemical composition of fats.
- Explain and infer how certain properties, such as melting point, can be determined through the measurement of other properties, such as translucency, of a material.