Problem 90 - Chemistry: The Central Science in SI Units, Global Edition

Question

(a) Which releases the most energy when metabolized, \(1 \mathrm{~g}\) of carbohydrates or \(1 \mathrm{~g}\) of fat? (b) A particular chip snack food is composed of \(12 \%\) protein, \(14 \%\) fat, and the rest carbohydrate. What percentage of the calorie content of this food is fat? (c) How many grams of protein provide the same fuel value as \(25 \mathrm{~g}\) of fat?

Step-by-Step Solution

Answer

(a) 1 gram of fat releases more energy when metabolized than 1 gram of carbohydrates, as it contains 9 calories compared to 4 calories in carbohydrates. (b) Approximately 26.8% of the calorie content in the food product is fat. (c) 56.25 grams of protein provide the same fuel value as 25 grams of fat.

Step 1: (a) Comparing Energy Release from Carbohydrates and Fats

To determine which releases the most energy when metabolized, we can simply compare the calorie values of carbohydrates and fats: Carbohydrates: 1 gram = 4 calories Fats: 1 gram = 9 calories Since 9 calories (from fats) is greater than 4 calories (from carbohydrates), 1 gram of fat releases more energy when metabolized than 1 gram of carbohydrates.

Step 2: (b) Fat Percentage of Calorie Content in Food Product

We have the following information about the food product: - 12% protein - 14% fat - The rest carbohydrate Let's first find the percentage of carbohydrates in the food product: 100% - 12% (protein) - 14% (fat) = 74% carbohydrates Now, we'll calculate the calorie contribution of each component (protein, fat, and carbohydrates) per 100 grams of the food product: Protein: \(0.12 \times 100 \mathrm{~g} \times 4 \mathrm{~cal/g} = 48 \mathrm{~cal}\) Fat: \(0.14 \times 100 \mathrm{~g} \times 9 \mathrm{~cal/g} = 126 \mathrm{~cal}\) Carbohydrates: \(0.74 \times 100 \mathrm{~g} \times 4 \mathrm{~cal/g} = 296 \mathrm{~cal}\) Total calorie content: \(48 \mathrm{~cal} + 126 \mathrm{~cal} + 296 \mathrm{~cal} = 470 \mathrm{~cal}\) To find the percentage of the calorie content that is fat, calculate the proportion of fat calories to the total calorie content: Fat percentage: \(\frac{126 \mathrm{~cal}}{470 \mathrm{~cal}} \times 100\% \approx 26.8\%\) Thus, approximately 26.8% of the calorie content in this food product is fat.

Step 3: (c) Protein Equivalent of 25 grams of Fat for Fuel Value

First, we calculate the fuel value provided by 25 grams of fat: 25 grams of fat: \(25 \mathrm{~g} \times 9 \mathrm{~cal/g} = 225 \mathrm{~cal}\) Next, we determine how many grams of protein provide the same fuel value (225 calories): Let x = grams of protein \(x \times 4 \mathrm{~cal/g} = 225 \mathrm{~cal}\) Solve for x: \(x = \frac{225 \mathrm{~cal}}{4 \mathrm{~cal/g}} = 56.25 \mathrm{~g}\) Therefore, 56.25 grams of protein provide the same fuel value as 25 grams of fat.

Key Concepts

Energy Metabolism

Energy metabolism refers to the processes by which the body converts food into the energy necessary for daily activities. When we speak about metabolizing macronutrients, we are referring to how the body breaks down carbohydrates, fats, and proteins to produce energy. Each macronutrient has a different energy yield:

• Carbohydrates provide 4 calories per gram.
• Fats offer 9 calories per gram.
• Proteins, much like carbohydrates, provide 4 calories per gram.

These differences arise due to the molecular structures and chemical bonds within each nutrient, which determine the amount of energy that can be extracted during metabolism. Understanding energy metabolism helps individuals optimize their dietary choices to meet energy requirements for various physical activities, enhance athletic performance, or manage weight effectively.

Macronutrients

Macronutrients are the building blocks of our diet and consist of three primary categories: carbohydrates, proteins, and fats. Each plays vital roles in maintaining bodily functions and health.

• Carbohydrates are primarily a source of energy, especially important for brain and muscle function. They are found in foods like bread, grains, and fruits.
• Proteins are crucial for building and repairing tissues, making hormones, and supporting immune functions. They are present in meats, dairy products, legumes, and nuts.
• Fats provide essential fatty acids and act as energy reserves. They are found in oils, butter, avocados, and fatty fish.

By understanding macronutrients, individuals can tailor their diets to ensure they get the right balance of these essential nutrients for overall health and well-being.

Caloric Content

The caloric content of food is a measure of the amount of energy that food provides. Foods are composed of macronutrients, and each one contributes differently to the total caloric content. To calculate the calorie content of a food product, consider the macronutrient composition: - Multiply the grams of each macronutrient by their caloric value per gram (carbohydrates and proteins = 4 calories per gram; fat = 9 calories per gram). - Sum these values to determine the total calorie content. For example, in a food product containing 12% protein, 14% fat, and the rest carbohydrates, calculating each macronutrient component's contribution reveals how each contributes to the total calories. Understanding caloric content allows people to make informed decisions about their energy intake, tailored to personal health goals or lifestyle needs.

Nutritional Chemistry

Nutritional chemistry explores how the chemical composition of foods impacts their nutritional value and how these nutrients interact within our bodies. It's a field that combines the principles of chemistry and biochemistry in analyzing food components and their role in maintaining health. Key areas include:

• Understanding nutrient interactions: How vitamins and minerals impact the metabolism of macronutrients.
• Impact of cooking on nutrients: How cooking methods affect the availability and digestibility of nutrients like proteins, carbohydrates, and fats.
• Food additives and processing: How additives affect the safety, flavor, and calorie count of foods.

Nutritional chemistry provides insights into how to enhance nutrient intake from foods and how food processing can alter nutrient values, thereby influencing health and wellness.