Food Composition: An Overview

Chapter 1: Overview of Food Composition

• Food is defined as a necessity for health, growth, and normal bodily functions.
• In practice, food is a mixture of chemical substances.
• Food can be classified based on its chemical composition.
• Carbohydrates, fats/lipids, proteins/amino acids, vitamins, minerals, and water comprise over 99.9% of food.
• Other substances found in food are food additives or flavor enhancers.

Food Composition

• The study of the chemical nature of food became a primary focus in the 18th and 19th centuries to improve dietary standards, health, and prosperity.
• Carbohydrates, fats, and proteins were the first to be thoroughly described due to their high concentration in foods.
• Trace components like pigments, vitamins, and odor compounds required sophisticated 20th-century extraction and analysis techniques.
• Later studies focused on how food components change during storage, processing, cooking, and digestion.
• In the 1990s, two factors related to food gained increased attention: unrestricted food consumption due to affordability, and the rise of obesity in Western countries.
• Growing awareness of food chemicals and safety issues prompted more research in food chemistry and the food industry.

Contemporary Trends

• Recent interest in health and nutrition has led to a demand for functional and fortifying foods with good taste.
• Eating habits are shifting towards healthier and more nutritious foods.
• There is a growing preference for natural and plant-based foods.
• This trend drives the food industry to develop, produce, and supply nutritious plant-based foods to meet consumer demand.

Composition Variability

• Most foods are mixtures of various chemical compounds.
• These mixtures are typically not fixed.
• The chemical composition of fruits varies by variety, stage of ripening, climate, plant health, location on the plant, and even atmospheric pressure in some cases.

General Composition

• Data on the proportion of substances in food is usually only an average, and can differ depending on what specific food is being analyzed.
• Except for dried or highly concentrated food, water is the largest component of most foods, often comprising 80-90% of its mass.
• Aside from water and minerals, the remaining the substances in food are organic.
• The inorganic components of food contain the minerals necessary to maintain health and are vital to the body, despite their extremely small proportion of the total mass.
• Pigments, odors and acids are natural chemical components in food that are related to consumer tastes.

Food Additives

• Most manufactured or processed foods contain additives for distinct purposes.
• Specific food components are made of many miniature elements.
• A fruit's odor is composed of more than 100 components.

Carbohydrates

• Three key natural organic ingredients are the basis for plants and animals, these being carbohydrates, lipids, and proteins.
• The 3 carbohydrates, lipids, and proteins are essential nutrients. Also includes minerals and vitamins.
• Carbohydrates contain only carbon, hydrogen, and oxygen, with a 2:1 hydrogen-to-oxygen ratio.
• Their general formula is Cₓ(H₂O)ᵧ.
• Only natural carbohydrates are relevant to food chemistry with 6 or multiples of 6 carbon elements being particularly important.
• Familiar examples: Glucose (C₆H₁₂O₆), Sucrose (C₁₂H₂₂O₁₁), Starch ((C₆H₁₀O₅)ₙ)
• The simpler carbohydrates, called sugars, are crystalline solids which dissolve in water to give a sweet solution.

Carbohydrate Functions in Body

• Carbohydrates provide energy for physical activities and rest.
• Each gram of carbohydrates produces approximately 4.2 calories, often rounded to 4 calories.
• Apart from providing energy, carbohydrates act as macromolecules that help sustain the structure and function of the organism.
• Carbohydrates are needed for proper function of the central nervous system, kidneys, brain, and muscles (including the heart).
• Carbohydrates can be stored in the muscles and liver to supply energy when required.
• Carbohydrates are important for digestion and waste elimination.
• Carbohydrates come predominately from foods rich in flour (such as grain and potatoes), fruits, milk, and yogurt. Vegetables, beans, nuts, and cheese contain lower amounts of carbohydrates.
• According to USDA recommendations, 45-65% of daily calories should come from carbohydrates.

Fats (Lipids)

• Lipids dissolve in organic solvents but not in water.
• They belong to the ester group, formed through the reaction between an acid and alcohol.
• Lipids are glycerol esters of trihydric alcohol.
• Three hydroxyl groups can combine with fatty acids to make an ester called triglyceride or triacylglycerol.
• The most simplistic triglyceride occurs when 3 acids are of the same molecule.
• An illustration of a chemical reaction states when stearic acid reacts with one molecule of glycerol, the fat created is tristearin.
• The importance of lipids in nutrition and physiology relies on their role as a fuel and supply of essential fatty acids and vitamins.
• 1 gram of fat supplies around 9.5 calories of energy, but usually 9 calories are used.
• According to the USDA, 20%-35% of calories should come from fats.

Fats' Role in Body

• Although fats are seen as an ingredient that can cause weight gain, some fats are essential for life.
• We need the fat we ingest for: Normal growth and development, Energy (fat is the most concentrated energy source), Vitamin absorption (A, D, E, K, and carotenoids), Cushioning for tissues, Maintaining cell membranes, Taste, consistency, and stability of foods.

Proteins

• Proteins are the most complex compounds.
• They have high average molecular weights, around 60,000, and no melting point.
• Proteins contain the elements C, H, O, N, and sometimes S and P. Note that protein is technically C,H,O and N.
• They are formed from numerous molecules of 20 different amino acids linked by peptide bonds.
• One gram of protein provides 4.1 calories of energy (used 4 calories).
• Proteins directly contribute to the taste of food and are precursors to aromatic compounds and the colors produced during heating or enzymatic reactions in food production, processing, and preservation.
• Direct protein affects physical traits in food through gel formation, foam stabilization, emulsification, and networking of structural products.

Protein Molecular Mass

• A monosaccharide like has a molecular weight of 180 and the formula is C6H12O6, while a simple protein such as lactoglobulin has a molecular weight of 42,000 with the approximate formula C1864H3012O576N468S21.
• Proteins can reach molecular weights of millions.

Protein Intake

• According to USDA recommended dietary intake, (10%-35%) of total caloric intake should come from protein.

Reasons To Consume Protein

• Growth (especially important for children, adolescents, and pregnant women)
• Tissue repair
• Immune function
• Creation of essential hormones and enzymes
• Energy when there is a lack of carbohydrates
• Maintaining lean muscle mass

Minerals

• Minerals are elements other than C, H, O, and N, often forming salts and remaining as ash after the body is burned.
• The main elements found in ash, accounting for 4% of total body weight, include Na, Mg, P, S, Cl, K, Ca, and Fe.
• The body needs minerals in smaller amounts compared to macronutrients.
• Minerals needed in diet include: Macronutrients (Na, K, Ca, S, Mg, and P) and Micronutrients (Fe, Cu, Zn, Se, Mn, Co, Ni, and Mo)

How Body Uses Minerals

• Structurally firm components of the body: Ca, P and Mg are utilized in bones.
• Soft tissue components of the body: Potassium.
• Body fluid components:
• Potassium ions help control the pH of intracellular fluid and maintain osmotic pressure inside cells.
• Phosphate is also important in intracellular fluid, and energy release.
• Na and Cl are the main minerals in body fluids outside the cells.

Water

• Water is a chemical compound with the formula H₂O.
• A water molecule consists of one oxygen atom and two hydrogen atoms bonded by covalent bonds.
• Water is a liquid under standard conditions, and also often exists next to its state on earth in a solid, and gas form.
• Water is essential for all living organisms, from the most simple plants and single cellular organism, to the most complex of plant and animal life.
• Living organisms can exist for a considerable length of time while without what is considered essential nutrients, but will die rapidly if without water.
• Living organisms contain a remarkable amount of water, never less than 60% of total body weight and occasionally up to 95%.
• Human body water content percentages range 55%-78%, depending on someone's typical body size.

Water Intake

• To ensure the body works, one and - seven liters of water is needed each day to avoid fluid loose while under activity.
• Most water is introduced into the body either through food contents, or water beverages.
• Most scientists agree that at least 2 liters , or six to seven water glasses of water are adequate to maintain hydration.
• The most broad study infers that 1 liter of liter is for the average male, this includes added need lost during athletics.
• It plays a primary function in the body due to the physical activities, and is heavily linked to nutritional function, due that water transports nutrition, dissolves, and maintains in a liquid form.

Water Roles

• Only a few sections within the body such as bones, teeth and hair have minimal water content.
• Unlike other nutrients water usually does not undergo changing chemical states in the body.
• Water can react with various food ingredients, creating problems related to the properties of the food system.
• Regardless, water is an important property in food.

Vitamins

• Vitamins are organic compounds found in many foods in small amounts.
• Most all vitamins contain intricate chemical structures and are from many different areas.
• Vitamins are necessary in a diet because the body cannot synthesize them from other nutrients.
• Vitamins are small, but they perform crucial tasks.
• The B-group vitamins form coenzymes, which are essential for maintaining good health.
• Although Vitamin qualities are not known, other vitamins are necessary.
• The body only requires a tiny amount of vitamins