Identifying Macromolecules in Common Foods

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Abstract:

We tested five common food items to determine which macromolecules were present. We tested for the macromolecules of simple and complex carbohydrates (sugars and starch), lipids, and proteins. The foods tested were coconut milk, karo syrup, potato chips, peanut butter, and banana baby food. We hypothesized that coconut milk would contain all four types of macromolecules, karo syrup would only contain simple sugars which are monosaccharides and/or disaccharides, potato chips would contain starches and fats, peanut butter would contain sugars, fats, and proteins, and banana baby food would consist of sugars and starch. Each macromolecule test consisted of five test tubes of the food item individually diluted into solutions for reacting each with Benedict's reagent to show the presence of sugar, IK2I for starch presence, and Buiret's reagent for protein presence. A simple paper test was used evaluting lipid existence for each food. Our results confirmed our estimations of the foods' compounds. The testing results verified that coconut milk contained all four types of macromolecules, karo syrup contain only simple sugars, potato chips were starches and fats, peanut butter contained sugars, fats, and proteins, and banana baby food consisted of sugars and starches.

Introduction:

Identifying macromolecules in the foods we eat is essential in comprising a healthy well-rounded diet ensuring our nutritional needs for cellular processes in the human body. The largest biological molecules are known as carbohydrates, lipids, and proteins. Carbohydrates are compounds of monosaccharides, disaccharides, and polysaccharides known as sugars and starches. Lipids, known as fats, are storage molecules in animals and plants. Proteins bind to other molecules performing key roles in DNA and RNA functions.

Five different food items were tested for the presence of specific macromolecules identified as sugars, starch, lipids, and proteins. The food items were coconut milk, karo syrup, potato chips, peanut butter, and banana baby food. We used chemical indicators and brown paper to detect the presence of different macromolecules in various solutions made from each food sample. If sugars were present in a food, then the Benedict's reagent and heat would turn the solution orange and precipitate will form. If starch was present, then the iodine potassium iodide would turn the solution dark purple or brown and form a precipitate. If lipids were present in a food, then the brown paper it was rubbed onto would form a transparent area. If a food contains protein, then the Buiret's reagent would turn the solution violet or purple in color. Our observations of the changes to the solutions in color and consistency indicated the presence of each different macromolecule according to the food item (see Table 1, Chart 1). We predicted that coconut milk would contain sugars, starch, lipids and proteins; karo syrup would only be a simple sugar; potato chips were made of starch and lipids; peanut butter would contain sugars, lipids, and proteins; and banana baby food would only contain sugars and starch.

Materials and Methods:

We tested five food items for sugars, starch, lipids, and protein. The items tested were cocunut milk, karo syrup, potato chips, peanut butter, and banana baby food. All of these food items were thick in consistence. Also, several of the foods had heavy coloring which would make some of the tests difficult to visually measure. Solutions were made of each food item. Our lab professor dilute the foods with water to form solutions for us to test. According to our lab manual, The Pearson Custom Library for the Biological Sciences, chapter Macromolecules, the testing methods are as follows (reference II).

Before any testing chemicals or testing procedures were performed, the intial states and colors of the food solutions were as follows: the negative control water was clear and...
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