Lab-5_Victoria Aiello

The Caloric Content of Food- Victoria Aiello Learning Objectives  Understand how caloric content is measured  Determine the energy content of various foods Laboratory Skill  The use of a homemade calorimeter Equipment and Materials  Empty Soda Can  Glass rod  Ring  Ring stand  Funnel  3-prong extension with clamp  50-mL Graduated cylinder  Thermometer or Vernier temperature probe  Large paper clips  Cork stopper  Food Samples: Cheetos®, Reduced Fat Cheetos®, Protein Puffs®, A solid snack food item of your choice  Hot pad  Distilled water  Lighter or Matches Safety and Hazard Information  Before the beginning of the lab ensure that you can locate the lab’s fire extinguisher and pull back your hair if it is long. Clear your benchtop of any unnecessary debris (especially paper). Exercise caution at all times while using the lighter and igniting the food items. If, at any time, something other than the food or matches ignite, immediately inform the instructor. If any clothes or accessories on your body catch fire, stop, drop and roll. Background Information The expected caloric content in food is associated with carbohydrates, fat and protein. The Food and Drug Administration (FDA) has regulated the reporting of such macronutrients (carbohydrates, fats, protein) on food items in the United States. The label is referred to as the Nutrition Facts label on food packaging. This label provides the size of the serving (in grams or ounces [1 ounce (oz) ~ 28.3 grams]). Appropriate scaling of the food serving size has to be taken into consideration for accurate caloric content. Typical energy content values ( kcal/g ) for the macronutrients are: Carbohydrate – 4 kcal/g Fat – 9 kcal/g Protein – 4 kcal/g In order to obtain caloric content in food, food scientists perform an indirect measure of the amount of heat generated from the burning or combusting of a food item. Surprisingly, the combustion of food is very similar to what takes place in your body. After digestion, food is generally converted into glucose and combined with oxygen in a combustion reaction to generate energy for your body. When measuring the energy content of food in the lab, water is the medium that is used to monitor this heat that is generated. A calorimeter is an isolated environment in which the heat absorbed or generated can be accurately measured. The Page 1 of 8

temperature change of the water, combine with its mass and heat capacity, allow for the heat released by a food item to be determined. The equation for heat capacity (q) is: q = m ∗ C ∗ ∆T (Equation 1) where m = mass of system in grams, C = specific heat capacity of the medium (water, for this lab) in cal g ∗ ℃ , and Δ T = temperature change in  C. The specific heat capacity of water is 1.00 calorie per gram per  C ( 1.00 cal g× ℃ ) . The calorie in this compound unit is a scientific calorie. A conversion is required between scientific calories ( calories ) to food calories ( Calories ): 1 C al ( food ) = 1000 cal ( scientific ) = 1 kcal ( scientific ) . You will construct a calorimeter using a soda can. The change in temperature of a system can provide a representation of the amount of heat that the system absorbs. In this experiment, you will expose a soda can of distilled water to the heat generated by the combustion of a solid food item. The food items in this lab include: regular Cheetos®, Reduced Fat Cheetos®, a protein puff (brand will be available in lab) and a solid food item of your choice. The food item will be suspended below the can of water. Once ignited, the observation of initial and final temperatures of the water in the can will provide data on the temperature difference in degrees Celsius. Procedure Measuring the caloric content of food (See table 1 for data) 1. Construct the soda can calorimeter according to Figure 1. Insert the glass rod through the loop of the can opening. Suspend the glass rod above the ring. Clamp the three- prong extension on the ring stand (above the ring) and place the temperature probe (or thermometer) in the three-prong extension and ensure that the probe just above the bottom of the can. 2. Measure the mass of 50 mL of distilled water in a graduated cylinder and report it on Table 1. Fill the soda can with the 50 mL of distilled water. Use a funnel as needed for the liquid transfer. 3. Anchor the Cheeto® about 0.5 inches below the soda can using the large paper clip on a cork as shown in Figure 2. 4. Weigh a regular Cheeto® on the cork/paper clip stand and record the mass (in grams) in Table 1. Be sure to include all digits viewable on the balance; all digits are significant! 5. Record the initial temperature (in Celsius) of the water in Table 1. Page 2 of 8 Figure 1 : Soda can calorimeter - Experimental setup

Experimental Report Temperature change: ∆T ( ℃ ) = T f ( ℃ )− T i ( ℃ ) (Equation 2) Calculate the change in temperature (as shown in Equation 2 above) of the water of each combusted food item and report this difference in Table 1 . Cheetos 40.1-20.0=20.1°C Protein Puffs 26.0-20.4=5.6°C Baked Puffs 46.7-20.7=26°C Mass ( food consumed )= Mass ( food samplewith stand )− Mass ¿ ) (Equation 3) Calculate the change in mass (as shown in Equation 3 above) of the food item and report this difference in Table 1 . Cheetos 3.816(mass of food sample with stand) – 3.018(mass of burned sample with stand) = 0.798 g Protein Puffs 3.255(mass of food sample with stand) – 3.083(mass of burned sample with stand) = 0.172 g Baked Puffs 3.863(mass of food sample with stand) – 2.696(mass of burned sample with stand) = 1.167 g Table 1 : Water temperature before and after food combustion Food Mass of Water for each sampl e Mass of Food Sample + Stand (g) T i (  C) T f (  C) Δ T (  C) Mass of Burned Sample + Stand (g) Mass of Food Consume d (g) Page 4 of 8

(g) Cheetos Puffs 72.14 9 3.816 20.0 40.1 20.1° C 3.018 0.798 g Protein Puffs 66.01 4 3.255 20.4 26.0 5.6°C 3.083 0.172 g Baked Puffs 76.64 4 3.863 20.7 46.7 26°C 2.696 1.167 g Heat Calculation: Using the temperature change ( Δ T) and mass of water from Table 1, and the specific heat capacity of water (1.00 cal/g˚C) and Equation 1, determine the quantity of heat (q) released by combusting each food. Note this is the same as heat absorbed by water. Cheetos Puffs 1.00cal/g°C (specific heat of water) * 72.149 g(mass of water) * 20.1°C (temperature change) = 1,450 calories Protein Puffs 1.00cal/g°C (specific heat of water) * 66.014g(mass of water) * 5.6°C (temperature change) = 3,700 calories Baked Puffs 1.00cal/g°C (specific heat of water) * 76.664 g(mass of water) * 26°C (temperature change) = 1,990 calories Divide the energy calculated above for each food sample by the corresponding mass of food consumed (Table 1). This provides the heat released per gram of food. Record this energy value (in calories / g) in Table 2, Column 1 . Cheetos 1,450 calories/0.798 g = 1,800 calories/g Page 5 of 8

Percent Error ( % ) = | ExperimentalValue − Expected Value | Expected Value × 100 (Equation 3) 2. Calculate the percent error (use Equation 3 above) [(Column 3 – Column2)/(Column 3)*100]. Report this percentage in Column 4 of Table 2 . Cheetos (1.8-5.7)/1.8 * 100 = -3/1.8 = -217% Protein Puffs (2.1-4.6)/2.1 * 100 = -2.5/2.1 = -119% Baked Puffs (1.9-4.3)/1.9 * 100 = -/1.9 = -126% Table 2: Caloric content of various foods Food Heat released (in calories / g) Heat released per g (in Food Calories) Expected Food Calories from Macronutrie nts Percent Error (%) Cheetos Puffs 1,800 cal/g 1.8 Cal/g 5.7 Cal/g -217 Protein Puffs 2,150 cal/g 2.1 Cal/g 4.6 Cal/g -119 Baked Puffs 1,700 cal/g 1.9 Cal/g 4.3 Cal/g -126 3. In your calculation, you assumed that all the heat released by the combusted food item was absorbed by the water. Do you think this is true or not? If it is not true, would this tend to make your estimated calories too big or too small? I don't believe that everything the intensity was consumed by the water. I figure it can likewise retain a portion of the intensity which thusly make the water heat up. I feel that this would make the calories be marginally more modest. Page 7 of 8

4. The night shift nurse at Northside hospital administers 255 mL of an IV solution of glucose whose concentration is 5.00 % m/V (5.00 g glucose in 100 mL solution). Calculate the kilocalories of energy that is provided to this patient. Carbohydrate – 4 kcal/g Fat – 9 kcal/g Protein – 4 kcal/g 12.8 grams of glucose Carbohydrates = 4Kcal/1g 12.8g/1=4Kcal/1g=12.8*4 Kcal= 51 Kcal The Kcal of energy provided to this patient ended up being 51 Kcal Page 8 of 8