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Assignment directions for a project measuring the amount of hexane soluble fats in foods

A consumer education group, The Union for Healthier Foods, would like to know how if the differences shown on the packaging of baked potato chips and regular potato chips accurately reflects the amount of fat in the chips.

The Union believes some packaging misrepresents the amount of fat. The Union has a budget of $80,000 to answer their question.

Before you begin your work, I will need the following information from you so that I can approve your work. The planning space for these items is found in your project packet.

After you complete the analysis, prepare a report for the Union for Healthier Foods. Remember that this report will be seen by a variety of people, so be certain it projects the image we want to present. The items that should be included in the report are found in your project packet.

Good luck with the project. Please keep in close contact me as you proceed with the project. You will need a data verification signature, by having me observe one of the trials in the experiment.

        has the most hexane soluble fat (oil - grease) content ?
        ( percent hexane soluble fat content )
        or
        ( mg of hexane soluble fat content/gram of sample )

              Although water dissolves an enormous variety of substances, both ionic and covalent, it does not dissolve
              everything. The phrase that scientists often use when predicting solubility is "like dissolves like." The
              expression means that dissolving occurs when similarities exist between the solvent and the soute. Generally
              speaking, polar solvents dissolve polar solutes, and nonpolar solvents disolve nonpolar solutes.

                Forces of attraction exist between the particles of a substance. These forces give liquid and solids cohesion
                - that is, they hold the substance together. In order for a solvent to dissolve a solute, the particles of the
                solvent must be able to separate the particles of the solute and occupy the intervening spaces.

              Consider the two examples of salt and sugar being dissolved in water. In the case of the ionic salt, water
              is "like" a charged ionic compound in the sense that it is polar, meaning that it has partially charged ends.
              Water can separate salt ions when the positive end of a solvent (water) molecule approaches the negative end
              of a solute molecule (salt ion). A force of attraction then exists between the two molecules. The solute molecule
              is pulled out of its crystal lattice into solution when the force overcomes the attractive force between the
              solute molecule and its neighboring solute molecules.   Thus, "like dissolves like." Water is polar and it
              tends to dissolve ionic substances.

              In the case of sugar, water is like sucrose in that both compounds contain O-H bonds. More importantly,
              both substances are made up of polar molecules, with partially positive and negative ends. The molecular
              interactions between water molecules. Again, like dissolves like. Water is polar and has hydrogen
              bonding, and it tends to dissolve substances that are polar or that form hydrogen bonds.

              Oil (also other types of fats) and water are a classic example of two substances that do not mix or dissolve in
              each other; they do not form a solution. Oil has many nonpolar covalent compounds made up primarily of
              carbon and hydrogen. The nonpolar oil molecules have no attraction for polar molecules and exert no force that
              can separate the polar molecules of water. On the other hand, a nonpolar substance, such as fat, will dissolve
              easily in hexane. The molecules of both the fat and hexane are held together by forces that are too weak to
              prevent the molecules from intermingling freely. Given the composition of oil, you should not be suprised that
             oil does not dissolve in water. They are simply too "unlike". Even after vigorous shaking, oil and water will
              rapidly seperate into layers.

               Why do some clothes need to be dry-cleaned, while other do not? Washing with water and deteregents cleans
               most clothes. But there are three situations in which dry cleaning may be necessary - if your clothes have a
               stubborn stain such as ink or rust; if you have spilled something greasy on your clothes; or if the label on the
               clothing recommends dry cleaning.

               Dry cleaning uses a nonpolar liquid solvent tetrachloroethylene, C₂Cl₄. As you know, nonpolar solvents will
               dissolve nonpolar materials. Fats, Greases, and oils fall into that categroy and are notoriously difficult to
               remove from fabrics by water-based washing.

             This project involves the dissolving of substances into either water or hexane. The hexane soluble fats
             are collected and measured. The buret set up illustrated below allows a place for the water and
             hexane phases to separate from each other.

WARNING: DO NOT PUT HEXANE A PLASTIC BURET, USE A GLASS BURET WITH AN EYEDROPPER TIP ONLY!!!

            1.    Construct a data table to collect the following information: Mass of empty petri dish,
                   Mass of sample, Mass of petri dish and hexane extract, Mass of hexane soluble
                   extract, Percent of hexane soluble fats.

	_________ sample trial #____
1. Mass of labeled empty petri dish
2. Mass of the sample
3. Mass of labeled petri dish and hexane extract
4. Mass of hexane soluble extract (#3 mass subtract #1 mass)
5. Percent of hexane soluble fats (#4 divided by #2) then multiply by 100

2. Using masking tape, label one petri dish with sample type and trial number to collectthe hexane
soluble extract in. Accurately mass the petri dish and record the mass.

3. Place a film canister on a balance and rezero it. Add approximately 0.25 g to 1 g of the sample
to be tested to the canister. Accurately mass the sample and record the mass in the data table.

            4.    Add 10 mL of water to the canister. Add 10 mL of hexane to the canister. Cap the canister tightly
                   and shake mildly for one minute. Let the sample sit for another two minutes. Shake the sample
                   again for one minute and let stand three minutes.

            5.    Using the funnel, carefully pour the contents of the film canister into the buret. The water and
                   hexane will seperate in the buret. Hexane is less dense than water. The hexane layer is on top of
                   the water. DO NOT HURRY THIS PROCESS - GIVE IT TIME TO SEPERATE!!

6. Using the stopclock, carefully drain the water layer, collecting it an unlabeled beaker. Dispose of
the water extract in the sink.

            7.    Collect the hexane layer in the labeled petri dish. By gently tilting the petri dish, use a cotton swab
                   to absorb any water droplets that may have been trapped in the hexane. Be careful not to
                 absorb any of the hexane extract!!!

10. Accurately mass the petri dish with the hexane soluble extract in it. Record this mass.

            1. Calculate the mass of the sample and the percent of the sample that is hexane soluble,
                            or
                    calculate the mg of hexane soluble fat per gram of sample.

mg of hexane soluble fat per gram of sample = Mass of hexane soluble extract / 1000 Mass of the sample used (g)

All the solutions and apparatus required for Hexane Soluble Molecule studies and analysis will be provided, except that you must provide the basic samples if you are going to analyze cookies, fries, and the like. Here are some general suggestions for the types of projects that you might consider.

o Which brand of non chocolate chip or non cream filled cookie will have the highest hexane soluble fat content?

o Which brand of fries (McDondald's Burger King, Arby's or Wendy"s) has the gihest hexane soluble grease content?

o How does the hexane soluble fat content of any baked food compare to a fried food of the same type?