What types of information can you get from a food nutrition facts label? Explain what the term efficiency of extraction means. As always

Experiment 9 QUANTITATIVE ANALYSIS of FAT IN CHIPS

Data Collection and Results Pages Name: __________________________ Date: ___________________

I. Theoretical Percent Fat

Ingredients listed on the labels: Regular Lay’s Baked Lay’s

Information from Label Sample Regular Lay’s Baked Lay’s Total fat (g) (i.e. fat per serving)

Serving size (g) % DV fat Theoretical % fat

Show Calculations for following:

Calculation for Theoretical % Fat in Regular Lay’s:

Calculation for Theoretical % Fat in Baked Lay’s:

Experiment 9: QUANTITATIVE ANALYSIS OF FAT IN CHIPS

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II. Experimental Percent Fat

Regular Lay’s Baked Lay’s Mass of crushed chips (g)

Mass of empty 50-mL Erlenmeyer flask (g)

Mass of Erlenmeyer flask plus fat residue (g)

Mass of fat residue (g)

Observation for fat residue (color, texture, etc.)

Experimental % fat

Efficiency of Extraction

Show the Calculations for the following:

Calculation for Experimental % Fat in Chips: Regular Lay’s:

Baked Lay’s:

Experiment 9: QUANTITATIVE ANALYSIS OF FAT IN CHIPS

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Calculation for Efficiency of Extraction: Regular Lay’s:

Baked Lay’s:

Experiment 9 QUANTITATIVE ANALYSIS OF FAT IN CHIPS

Purpose: To determine and compare the amount of fat in regular Lay’s and baked Lay’s potato chips. Introduction It is common knowledge that we should not consume an excessive amount of fat as it is linked to a myriad of health problems such as high cholesterol and coronary disease. Yet potato chips, with a high fat content, have been a favorite snack food for many Americans for decades. According to the United States Potato Board however, natural potatoes do not contain fat as such. One serving size of potato, about 148 grams, contains 0 grams of fat. So, where does all the fat come from? It comes from the process of preparing the chips. Today however, there are potato chips on the market with low fat or no fat content. A quick check of the product label will indicate whether the product is regular fat, low fat, or fat-free. In this experiment, a sample of regular Lay’s potato chips and a sample of baked Lay’s potato chips will be analyzed for their fat content. This is done by extracting the fat out of each sample with petroleum ether, a solvent that dissolves only the fat and not the other components in the chips, such as carbohydrates and salt. The petroleum ether is then evaporated off, leaving behind the fat as a residue. By measuring the mass of the chips before the extraction and the mass of the fat extracted, the mass percent of fat can be calculated as follows:

Experimental percent fat = mass of fat extracted mass of sample

x 100

To determine whether the extraction of the fat from the chips (with the petroleum ether), is efficient, the experimental percent of fat will be compared with the amount of fat per serving indicated on the nutrition facts label of chips. We will call the amount of fat indicated on the label to be in the product, the theoretical value. So theoretically, the percent fat per serving of product can be calculated as follows:

Theoretical percent fat = mass of fat per serving

mass of a serving of product x 100

It is important to note that the percent fat (theoretical percent) in a food product is generally not the same as the percent daily value (% DV) on the nutrition facts label. The percent daily value of fat is calculated from the highest recommended intake of 65 g of fat per day for a person on a 2000 Calorie diet. For instance, if a serving size of 28.0 g of potato chips contains 9.0 g of fat, the percent of fat per serving would be 32% while the % DV would be 14%, as shown below. Theoretical % fat = !.! !

!".! ! x 100 = 32%

% daily value = !.! !

!" ! x 100 = 14%

Experiment 9: QUANTITATIVE ANALYSIS OF FAT IN CHIPS

Because the %DV is often different from the actual percentage of fat in foods, it is important to know how to read nutrition facts labels. Before you begin the experiment, you are going to first obtain some information from the Lay’s labels. In this experiment, the analysis will be for the percent fat in the Lay’s chips not the %DV of fat. The efficiency of extraction will also be calculated as follows: Efficiency of extraction = !"#!$%&!'()* % !"#

!"#$%#!&'() % !"# x 100

Equipment/Materials Two 50-mL Erlenmeyer flasks, 150-mL beaker, 10-mL graduated cylinder, two large glass test tubes, two long tipped disposable glass pipets, mortar and pestle, hot plates, two boiling chips, petroleum ether, regular Lays, baked Lay’s. WARNING: Materials provided in the lab are for experiments only. Never consume any of the materials provided for experiments. Procedure (Using a pen or pencil, record by hand all of your data and results on the Data Collection and Results Pages.) I. Theoretical Percent Fat 1. Obtain the nutrition facts for regular and baked Lay’s. Record the ingredients that are

found on each label. (See images.)

2. Next, record the mass per serving and the mass of fat per serving from the nutrition facts labels on the regular Lay’s and the baked Lay’s.

3. Using the data obtained in the previous step, calculate and record the theoretical percent

fat in each sample. (These percentages will be the true values for the percent fat in each sample and will be used in the calculations of the extraction efficiency.)

II. Experimental Percent Fat 1. Obtain a mortar and pestle and wipe them clean. Do not wash them or you will have

trouble getting them totally dry.

2. Obtain ¼ of a chip from the carton labeled as “Regular” Lay’s and gently crush it with the mortar and pestle into fine bits. Do not overdo it by grinding all the fat into the mortar.

3. Tare a weighing boat to zero. Remove the boat from the balance and transfer the

crushed chips into it. Place the boat back on the pan and record the mass. (Note: This

Experiment 9: QUANTITATIVE ANALYSIS OF FAT IN CHIPS

mass is the mass of the chip only.) The mass of the crushed chips should be between 0.4 and 0.5 gram. Add more if necessary but be sure to record all the digits displayed on the balance.

4. Transfer the crushed chips into a largest clean and dry test tube. 5. Using a clean and dry 10-mL graduated cylinder and the dropper provided with the

bottle, measure approximately 3 mL of petroleum ether and pour it into the test tube containing the crushed chips. Rock the test tube sideways (not up and down) to thoroughly mix the petroleum ether with the crushed chips. Do this for at least one minute, and then set the test tube aside to let the solid settle to the bottom. Note: If a centrifuge is available, the mixture can be centrifuged to allow the solid to settle to the bottom of the tube.

6. Weigh and record the mass of one of the clean and dry 50-mL Erlenmeyer flasks.

(Remember to zero the balance before you weigh the flask. Do not use the tare.) 7. Use a special disposable glass pipet with a long tip and then carefully transfer the

petroleum ether solution into the pre-weighed 50-mL Erlenmeyer flask, taking extreme care that you are not picking up any of the solids. It is better to leave some liquid behind than to end up picking up any solids! Your results will be grossly inaccurate if you picked up solids with your pipet.

8. Repeat Step 5 with a fresh sample of petroleum ether. Using the long tipped disposable

glass pipet, transfer the petroleum ether solution into the same 50-mL flask as before. 9. Prepare a hot water bath by adding two boiling chips and approximately 25 mL of tap

water in a 150-mL beaker and placing it on a hot plate set to medium. Keep the hot water slightly below boiling. NOTE: If available, set this up in the hood or in front of the hood if your exhaust system is on the benches.

10. Place the 50-mL Erlenmeyer flask containing the petroleum ether and fat extract in the

hot water. Be careful not to let any water get into the flask. If the water is boiling rapidly, some of the water may get into the flask and your results will be in error. So, be sure to watch the boiling and lower the heat if necessary.

11. After all of the petroleum ether has been evaporated (about 10 to 15 minutes), allow the

flask to cool to room temperature. 12. Weigh and record the mass of the flask containing the residue and set it aside. Calculate

the mass of the residue. Be sure to dry off any water on the flask before weighing it. 13. Repeat the entire procedure (Steps 1 through 12) using the baked Lay’s chips. You must

use a clean and dry test tube, 50-mL Erlenmeyer flask, and long tipped disposable glass pipet.

Experiment 9: QUANTITATIVE ANALYSIS OF FAT IN CHIPS

14. Compare the appearance and color of the residues from the regular Lay’s and baked Lay’s chips and record your findings in your lab notebook.

15. Find the experimental percent fat and the efficiency of extraction for both the regular

and baked Lay’s.

Clean-up (Read this carefully!) 1. Do the clean-up under the hood. With the disposable dropper provided, add one

squirt (about 2 mL) of petroleum ether to each flask. 2. With the spatula/scoopula provided in the hood, loosen the oil residue at the bottom

of the flasks and stir for 30 – 60 seconds. 3. Empty the contents of the flasks into the designated waste container. 4. Add a second squirt of petroleum ether, swirl and empty it into the waste container. 5. At the sink, add detergent and scrub the inside of the flasks with a brush. 6. Rinse thoroughly with hot tap water. 7. Rinse once with deionized water. 8. Return both flasks to your instructor or return them to your drawer if they belong in

your drawer. 9. Wipe up your work area.