Experiment 8. Acid-Base Chemistry of a Sports Drink. Lab Report

CHEM Lab 8 Manual to complete the sports drink post lab 2020

Experiment 8. Acid-Base Chemistry of a Sports Drink
Adapted from J. Chem. Educ. 2013, 90, 8, 1032-1034
Terms:
• Anthocyanins
• Betalains
• Carotenoids
• Chlorophyll
• Vegetables
• Acid
• Base
• pH
• Carbohydrates
• Sugar
• Fructose
• Glucose
• High-fructose corn syrup
Introduction
The Colors of Fruits and Vegetables
Most fruits and vegetables are very colorful – the bright greens of broccoli and kale, thereds of bell peppers, the purples and blues of eggplant and blueberries, the oranges andyellows of carrots and squash and the deep red color of beets. The pigment molecules in fruitsand vegetables fall into four groups: 1) the green chlorophylls; 2) the red, purple and blueanthocyanins; 3) the orange and yellow carotenoids; and 4) the deep red and yellow betalains.Chlorophyls are found basically in anything green (leaves, grasses etc). The challenge for chefsis to keep these vivid colors during food preparation because chefs more than anyone elseknow that we eat with our eyes. Because the chemistry of the four pigment groups aredifferent, they respond differently to heat, changes in pH and the presence salt (NaCl). Yourchallenge today is to find out how the color of pigment anthocyanin changes with pH.
Anthocyanins
Anthocyanins (Figure 1) are a very rich source of color and antioxidants and include thevivid pinks in flowers to the red, blues and purples of fruits and vegetables. Add a few hydroxylgroups (-OH) to the R positions, and the color of the molecule changes dramatically. As a result,anthocyanins are very sensitive to changes in the concentration of hydrogen ions (H+) or pH.
Just like proteins, anthocyanins have a pKa that tells you the pH at which half the moleculeshave a hydrogen ion (H+) bonded to it and half do not. In fact, the collection of anthocyanins inred cabbage juice have pKa values that span the pH scale and colors that change with the pH(Figure 1). In some potatoes species, when a sugar such as glucose is added to an anthocyanin,the color of the anthocyanins in the flower petals goes from a flat color to one with a velvetyappearance. Anthocyanins are a rich source of antioxidants and a nutritious addition to justabout any diet.
Why a Sports Drink?
Sports drinks has been increasing in popularity for the last decade as people are tryingto drink less soda and other soft drinks. Sports drink industry is valued at several billions ofdollars. Other types of beverages are also gaining traction as consumers are looking for newand more interesting drinks. They want drinks that are with less or no sugar and have allnatural ingredients. That’s one challenge of most brightly-colored drinks (and other foods), 
because they use artificial colors, like Red 40, Yellow 5 and so on. Red 40, sometimes calledE129 on food labels, which is used in many consumer products, comes from petroleumindustry. It is approved by the U.S. Food and Drug Administration (FDA) as safe, but its safetyremains a controversial and widely debated topic. Most of the soft drinks also contain highfructose corn syrup (HFCS). HFCS has higher content of fructose rather than glucose. Regularsugar molecule, which is a dimer, has one-part glucose and one-part fructose. HFCS has been amainstay in food industry, because it is a liquid and, therefore, more transportable than regularsugar. Also, HFCS tastes sweeter and hits taste buds faster than regular sugar. High-fructosecorn syrup has been controversial for quite some time due to possible negative health effectsand many consumers prefer not to have it in their diets.Your challenge today is to develop either new sports drink without artificial colors ormaybe a brand-new type of soft drink.Figure 1. Color variations of red cabbage anthocyanin due to pH change
References
• http://www.ocr.org.uk/search/gcs-search/gcsearch.aspx?q=sauces (accessed Nov 1, 2017).
• https://www.ncbi.nlm.nih.gov/pubmed/27235823. (accessed Jan 23, 2017)
• Lopez-Alt, Kenji. The Food Lab: WW Norton: New York, NY, 2016.
• McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen: Scribner: New York,NY, 2004.
• Rohrig, Brian. 2015. Eating with Your Eyes: The Chemistry of Food Colorings.https://www.acs.org/content/acs/en/education/resources/highschool/chemmatters/pastissues/2015-2016/october-2015/food-colorings.html. (accessed Nov 20, 2016). 
Experiment
Part 1. Chemical Characteristics of Plant Pigment Anthocyanin1. Have two 500-600 mL beakers. Add 500 mL of dI water to one beaker and 500 mL of tapwater to the second beaker. Cover both beakers with watch glasses. Increase thetemperature on the hotplate.
2. Retrieve two red cabbage samples, approximately 10 grams each. You don’t have to bevery accurate here. Save a little piece and 10 grams of cabbage to each of the beakerswith hot/boiling water. Boil the samples for 10 minutes, while keeping an eye on itscolor for the first couple of minutes and record any changes that you see on the DataSheet.
3. At the end of 10 minutes, remove the cabbage and allow it to cool 10 minutes.Compare its color to the starting color of an uncooked sample. Did the water changecolor? What does that tell you about the water solubility of your pigment? Is there anydifference in cabbage color between tap water and dI water?4. To test your pigment for its response to changes in pH, place 5 mL of “cabbage water”from dI water beaker to 5 different test tubes.
5. pH Tests:
Ø Control test: Don’t add anything to the first test tube. You will use it tocompare your basic and acid test wells.
Ø Acid test: Add three drops of lemon juice to the second test tube. Hint: Acidsdecrease the pH.
Ø Base test: Add three drops of the baking soda solution to the third test tube.Hint: Baking soda increase the pH.
Ø To the fourth well, add a few drops of club soda. What do you see? Is club sodaacidic or basic?
Ø To the last well, add few drops of household ammonia. What do you see? Isammonia acidic or basic?
Ø You have also boiled red cabbage in tap water. Is tap water acidic or basic?
6. After ten minutes, record any color changes that you see in Table 3 on the Data Sheet.Clean off the spot plate and return it to its original location.
Part 2. Creating Your Own Drink
1. Now it’s time to put your creativity to the test by creating a drink by using red cabbagecolor. Here are some things to consider. Is your drink going to be a sports drink,sparkling/carbonated drink or something else? Is it going to be sweet or sugar-free? Feelfree to use any of the available equipment in the lab and any of the items from thepantry:
Ø Pantry Items: table salt, baking soda, sugar, artificial sweetener, club soda, sprite,citric acid, lemon juice
2. As you make your drink, be sure to keep track of color changes, because you are goingto write the recipe for your drink as part of your post lab assignment. Display your drinkto maximize its appeal and take a photo for to go with your recipe.3. Clean any glassware and cooking equipment that you used today with warm, soap