content of food
eLearning
2009
Publication No. 91259
The Great Peanut Problem
Calorimetry
Introduction
All human activity requires “burning” food for energy. How much energy is released when food burns in the body? How is the calorie content of food determined? Let’s investigate the calorie content of different snack foods, such as popcorn, peanuts, marshmallows, and cheese puffs.
Concepts
• Combustion reaction
• Calorimetry
• Nutritional Calorie
• Calorie content of foods
Background
What does it mean to say that we burn food in our bodies? The digestion and metabolism of food converts the chemical constituents of food to carbon dioxide and water. This is the same overall reaction that occurs when organic molecules—such as carbohydrates, proteins, and fats—are burned in the presence of oxygen. The reaction of an organic compound with oxygen to produce carbon dioxide, water, and heat is called a combustion reaction. The chemical equation for the most important reaction in our metabolism, the combustion of glucose, is shown in Equation 1.
C6H12O6 + 6O2 → 6CO2 + 6H2O + heat
Equation 1
Within our bodies, the energy released by the combustion of food molecules is converted to heat energy (to maintain our constant body temperature), mechanical energy (to move our muscles), and electrical energy (for nerve transmission). The total amount of energy released by the digestion and metabolism of a particular food is referred to as its calorie content and is expressed in units of nutritional Calories (note the uppercase C). A nutritional Calorie, abbreviated Cal, is equivalent to a unit of energy called a kilocalorie, or 1000 calories (note the lower case c). One calorie is defined as the amount of heat required to raise the temperature of 1 gram of water by 1 °C. (This is also the definition of the specific heat of water.) The calorie content of most prepared foods is listed on their nutritional information labels.
Nutritionists and food
2009
Publication No. 91259
The Great Peanut Problem
Calorimetry
Introduction
All human activity requires “burning” food for energy. How much energy is released when food burns in the body? How is the calorie content of food determined? Let’s investigate the calorie content of different snack foods, such as popcorn, peanuts, marshmallows, and cheese puffs.
Concepts
• Combustion reaction
• Calorimetry
• Nutritional Calorie
• Calorie content of foods
Background
What does it mean to say that we burn food in our bodies? The digestion and metabolism of food converts the chemical constituents of food to carbon dioxide and water. This is the same overall reaction that occurs when organic molecules—such as carbohydrates, proteins, and fats—are burned in the presence of oxygen. The reaction of an organic compound with oxygen to produce carbon dioxide, water, and heat is called a combustion reaction. The chemical equation for the most important reaction in our metabolism, the combustion of glucose, is shown in Equation 1.
C6H12O6 + 6O2 → 6CO2 + 6H2O + heat
Equation 1
Within our bodies, the energy released by the combustion of food molecules is converted to heat energy (to maintain our constant body temperature), mechanical energy (to move our muscles), and electrical energy (for nerve transmission). The total amount of energy released by the digestion and metabolism of a particular food is referred to as its calorie content and is expressed in units of nutritional Calories (note the uppercase C). A nutritional Calorie, abbreviated Cal, is equivalent to a unit of energy called a kilocalorie, or 1000 calories (note the lower case c). One calorie is defined as the amount of heat required to raise the temperature of 1 gram of water by 1 °C. (This is also the definition of the specific heat of water.) The calorie content of most prepared foods is listed on their nutritional information labels.
Nutritionists and food