FOOD CHEMISTRY Applied to a biology class in the macromolecules section. PURPOSE To illustrate the chemical testing procedures for fats, sugars, starches, and protein. Core 40 application is extensive, many of the questions are based on proteins, lipids, and carbohydrates. PRE-LAB Prior to this lab a model building lab would have taken place. In that lab they construct a glucose and a lipid monomer, then they add it to their neighbors to create the polymer. In this process they also discover dehydration synthesis. Also a protein synthesis lab, where they pick an amino acid to construct and then add it to their neighbors to create the protein. PRIOR KNOWLEDGE GAINED The students will know what a monomer, and monosaccharide are, and what they do. As well as how they contribute to the polymers, and what polymers actually are. They will understand the ratios within the lipids. As well as the effects of saturated, unsautared, and polyunsaturated. WHAT THEY SHOULD LEARN What foods contain the four macromolecules. How they effects us. What the different types are in various forms. Ex. Maltose, lactose, glycerin. Finally what the chemical reaction are and how they tell use what a sugar, protein, lipids, and carbohydrate actually are. SET-UP CAN BE ACCOMPLISHED IN MULTIPLE WAYS. Basic • Four groups of four test tubes. • First group is Sugar • Second is starch • Third is protein • Fourth is oil Each of the four test tubes in the group will be for the reaction of the Benedict's, potassium iodide, Sudan IV, and Buiret reagent. VARIATIONS ON THE SET-UP Have the students set-up the groups That also gives away the mystery. Have the teacher set it up as I have done. Number each group. 1-sugar 2-starch 3-protein 4-lipid Letter each tube within the group, A-D A-Benedict’s B- Potassium-iodide C-Sudan IV D- Buiret Reagent VARIATIONS ON THE SET-UP Each group of students Tests all the macromolecules, Sugar, Carbohydrates, Lipid, and Starch Test one of the above. Test all of the above and an unknown Test one of the above, then present it to the class. The next day give each group one or two unknowns to figure out what food they are. Can include computer lab access to elaborate on their presentation, or to let them search for what their unknown is, if given a more difficult example like peanut butter, or lettace. EXPERIMENT WHAT WE WILL BE DOING TODAY Two groups will use the given chemicals that came with the lab. The third group will be using real food samples. Everyone add 5ml of distilled water to all the tubes. Distilled water is in the smaller faucet, on the left side. Group one and two place 2-3 drops of each macromolecule to the corresponding test tube. 1-sugar - dextrose 2-starch - starch soln. 3-protein - gelatin 4-lipid - veg. oil EXPERIMENT Group three will be using, 1-syrup 2-instant mashed potatoes 3-egg whites 4-veg. oil Again telling the students this is an option. Everyone picks up on procedure 4 in the experiment lab provided. EXPERIMENT PLEASE RECORD YOUR OBSERVATIONS SO WE CAN SEE IF THE EXPERIMENT ACTUALLY WORKED. Benedict’s solution goes into all of the ‘A’ test tubes. Add 10 drops and place in the hot water bath for 10 minutes. If sugar is present a color change will occur form yellow to orange. Potassium iodide solution to all of the ‘B’ test tubes. Add one drop. Starch turns blue in the presence of iodine, and animal starch turns mahogany red in the presence of iodine. EXPERIMENT PLEASE RECORD YOUR OBSERVATIONS SO WE CAN SEE IF THE EXPERIMENT ACTUALLY WORKED. Sudan IV to all of the ‘C’ test tubes. Add one drop. Can act as a color tag. Has been known to not work well. Buiret reagent to all of the ‘D’ test tubes. Add 10 drops and allow 10 minutes for the color change to take hold. The color change will be from blue to violet to pink. It may fade, because it is a reversible reaction. Please pay attention to this reaction because it has been known that more drops may need to be used. IDEAS FOR THE CLASS ROOM Each group gets to test all of them, like we did today. Each group gets one. Each groups gets one, and has to present it. Each group gets to test all of them, but with real food samples. (individual groups get different types of samples) Each group gets one food sample. Each groups one food sample and has to present it. IDEAS FOR THE CLASS ROOM Add on to each group gets one sample and has to present it. The next day they receive some unknowns and have to test it like the day before. Once complete they describe their results, and tell what the actual food item is. Other ideas?? Less diluition for a brighter color change when doing the chemical section of the lab Egg whites turn purple in Benedicts soln Make sure the potassium iodine works Make sure the benedicts is qualitative, for the orange reaction.