15 Experiment 9: Measuring Fat in Potato Chips and Snacks

Ron’s project 13

DETERMINATION OF FAT IN FOODS

Objective:  To analyze foods for their fat content

learning points:

1. determine the amount of fats in various foods

2. compare the fat content among various foods

3. calculate percentage of fat in foods by mass

The various kinds of dietary fats that exist in foods includes saturated fats, unsaturated fats, trans fats and cholesterol.   It is known that our bodies requires some fat each day for good health, however consuming too much can cause health problems. Furthermore, studies have shown that even if your overall fat intake is low, eating predominantly unhealthy saturated or trans fats can be detrimental to your health. A poor balance in the types of what are known to be heart-healthy unsaturated fats can be problematic in terms of health.

Health providers have encouraged that a low-fat diet is important for losing weight, managing cholesterol, and preventing various health problems associated with excessive fat consumption. In addition to the amount of fat,

the types of fat consumed are important for health considerations. Certain fats increase cholesterol and your risk of certain diseases, while other fats protect your cardiovascular system and support overall health. Certain fats such as omega-3 fats are essential to physical and emotional health.

There are four major types of fats:

• monounsaturated fats
• polyunsaturated fats
• saturated fats
• trans fats

Monounsaturated fats and polyunsaturated fats are known to be the healthier fats due to some studies that have shown they are good for your heart, help manage cholesterol, and beneficial for your overall health.  The type of fats known as trans fats (or hydrogenated oils), are used in the manufacturing of food to help it stay fresh longer. These fats may increase your risk of disease and elevate cholesterol.  Saturated fats are more difficult to categorize since some can have health benefits as well as potentially undesired effects on levels of cholesterol.

Clean Up

Left-over meat and chips can placed into the trash.  Return everything to its place, wipe your bench clean, lock your drawer, and return the key to the key cabinet. Your drawer key stays in the laboratory.

PROCEDURE

Fat in Potato Chips

1. Use a clean 150 mL beaker, weigh the 125 mL flask on a balance. Mass =  _____

2. Using plastic weighing dishes now obtain and weigh 1 to 5 grams portions of

potato chips provided for you (weigh to accuracy and record the mass).  You may zero the balance with the weigh boat in place and thereby obtain the direct mass of the potato chips.  Mass of chips = _________

3. Place your weighed potato chips into a clean mortar and pestle and grind up

the chips thoroughly.

4. Then you can add about 15 mL of petroleum ether (do not breath the fumes) and grind again in the presence of the petroleum ether. The petroleum ether evaporate quickly so you may need to add more aliquots of 15 mL.

5. Using Whatman #1 filter paper, form a filter funnel with your glass funnel to filter out the chip particles and catch the ether extract into the pre-weighed 125 mL flask.

6. Rinse the filtered chip particles, while they are on the filter, with an additional

10 mL of the ether.  Discard chips and filter paper into trash.

7. Place the flask containing the ether extract onto a hot plate IN THE HOOD.

8. Evaporate the ether but stop the heating when the residue looks like and acts

like popcorn oil.

9. Allow it to cool and then weigh the beaker plus fat. The difference between the empty beaker and the beaker containing the ether extract is the mass of the fat.  See calculations to determine the percent fat in the chips.

Fat in Hot Dogs

1. Weigh out into two plastic weigh boat about 2 to 5 grams of provided chopped up hot dog meat (keep track which meat is which). Place the meat into separate

centrifuge tubes.  Mass of the meat for (1) _________; (2) __________

2. Place about 5 mL of isopropyl alcohol into each tube. Set the tubes containing the meat into beakers containing hot tap water (~70oC) for about 15 minutes.

3. Balance the tubes on an appropriate balance, then spin at ~3000 rpm for 5 minutes. Stop the centrifuge and you should see a layer of fat to the top of the liquid.

4. Carefully remove the fat layer (use eye dropper) into plastic weighing dishes and obtain the mass of the fat for each tube. Record the mass of the fat for calculations. Discard remaining meat into trash.

Report your data and calculations according to directions from Instructor.

CALCULATIONS

For each Run calculate the percent fat (show your math)

Percent Fat =           mass of fat      X 100

mass of food

QUESTIONS

1. Is there a significant amount of fat in foods? (over 7% is significant)

2. Was there a consistent amount of fat in the chips?

3. Was there more fat in the chips than in hot dogs?

4. What process (chips or hot dogs) would be most useful for pizza?

5. What two errors could occur in each of the processes you used?