The document discusses the basic components of food, including the six major nutrient groups: water, carbohydrates, lipids, proteins, vitamins, minerals, and nonnutritive food components. It explains that living things are composed of six elements - carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur - which combine to form molecules and compounds. Water is essential for life and its heat is measured in calories. Carbohydrates, lipids, and proteins are the main sources of calories or energy in foods. Vitamins and minerals also play important roles in the body despite containing no calories.

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Understanding Food Principles and Preparation • Fifth Edition
AMY BROWN
© Cengage Learning 2015
Chemistry of Food
Composition
3

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• Living things are made up of six elements
(CHNOPS)
– Carbon, hydrogen, nitrogen, oxygen,
phosphorus, and sulfur
• Elements combine to form molecules or
compounds
Basic Food Chemistry

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Basic Food Chemistry (cont’d.)

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Basic Food Chemistry (cont’d.)

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• Essential for life
• One oxygen atom flanked by two
hydrogen atoms (H2O)
• Heat
– Moves water through its cycles
– Is measured in calories or kilocalories
Water

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Water (cont’d.)

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Water (cont’d.)

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Water (cont’d.)

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• Water boils at a lower temperature at
altitude than at sea level
• Hard water has a higher concentration of
calcium and magnesium
• Soft water has a higher concentration of
sodium
Water (cont’d.)

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Water (cont’d.)

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Water (cont’d.)

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Water (cont’d.)

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• Food preservation decreases
microorganisms
• Dehydration occurs in warm temperatures;
hydration in cool temperatures
• Water activity (aw) determines how quickly
food decays
– More water means quicker decay
• Solutes reduce water activity via osmosis
Water (cont’d.)

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• Sugars, starches, and fibers of food
• Mostly found in plants
– Made during photosynthesis
• Made up of carbon, hydrogen, and oxygen
Carbohydrates

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Carbohydrates (cont’d.)

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• Ribose: found in nucleosides and vitamin
B2
• Arabinose: part of the structure of plants
• Glucose: starch and sugar; called dextrose
when refined
• Fructose (fruit sugar)
• Galactose: rare in nature; part of lactose
Monosaccharides

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• Sucrose: table sugar
• Lactose: milk sugar; not digestible by
some
• Maltose: malt sugar; found in beer, cereal,
some infant formulas
Disaccharides

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• Raffinose and stachyose
– Found in dried beans
– Digesting them produces gas
• Fructo-oligosaccharides
– Found in fruits and vegetables
– Prebiotics
• Used as bulking agents and fat replacers
in commercial foods
Oligosaccharides

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• Starch
– Amylose and amylopectin
– Stored energy for plants
– Digestible by humans
• Glycogen
– Stored energy for animals
– Digestible by humans
– Turned into lactic acid during slaughter
Polysaccharides

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• Fiber
– Undigestible by humans
– Only found in plant-originated food
– Soluble fiber vs. insoluble fiber
• Both have benefits
– Cellulose
– Hemicelluloses
– Pectic substances
– Others (vegetable gums, inulin, lignin)
Polysaccharides (cont’d.)

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• Commonly called fats
• Fats vs. oils
– Fats are solid at room temperature; oils are
liquid (exception: coconut, palm, and fish oils)
– Fats are generally from animals; oils generally
from plants
• Made of carbon, hydrogen, and oxygen
• Not water soluble (except for acetic acid)
Lipids

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• Triglycerides: three fatty acids
– 95% of lipids in foods
• Fatty acids
– Length determined by number of carbon
atoms
– Saturation determined by number of double
bonds between carbon atoms
• Saturation = no double bonds
Lipids (cont’d.)

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Lipids (cont’d.)

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Lipids (cont’d.)

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• Phospholipids
– Contains phosphorus, which makes them
water soluble
– Used as emulsifiers (e.g., lecithin)
• Sterols
– Cholesterol only found in animal foods
– Plant sterols can lower risk for coronary heart
disease
Lipids (cont’d.)

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• Contain nitrogen atoms (unlike
carbs/lipids)
– The human body can manufacture most of the
carbohydrates and lipids needed for survival,
but can only synthesize about 50% of proteins
• Made from amino acids
• Complete vs. incomplete proteins
– Most animal proteins are complete
– Most plant proteins are incomplete (protein
complementation)
Proteins

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Proteins (cont’d.)

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• Functions of proteins in food
– Hydration
– Denaturation/coagulation
– Enzymatic reactions
– Buffering
– Browning
Proteins (cont’d.)

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Proteins (cont’d.)

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• Vitamins
– Organic (carbon-containing)
– Can be destroyed by heat, light, or oxygen
– No kcalories
• Minerals
– Nonorganic; found on periodic table
– Cannot be destroyed by heat, light, or oxygen
– No kcalories
Vitamins and Minerals

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Vitamins and Minerals (cont’d.)

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Vitamins and Minerals (cont’d.)

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• Functions of vitamins and minerals in food
– Enrichment and fortification
– Antioxidants
– Salt
Vitamins and Minerals (cont’d.)

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Vitamins and Minerals (cont’d.)

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• Food additive: any substance added to
foods
• Over 3,000 food additives, including:
– Sugar
– Salt
– Corn syrup
Nonnutritive Food Components

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• Purposes of food additives
– Improve appeal
– Extend storage life
– Maximize performance
– Protect nutrient value
Nonnutritive Food Components (cont’d.)

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• How to improve appeal
– Color compounds
• Certified colors vs. natural colors
– Flavor compounds
– Texture compounds
Nonnutritive Food Components (cont’d.)

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• Plant compounds
– Beneficial (phytochemicals)
– Harmful (natural toxins)
• Caffeine in excess
Nonnutritive Food Components (cont’d.)

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Nonnutritive Food Components (cont’d.)

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• The six major nutrient groups
– Water
– Carbohydrates
– Lipids
– Proteins
– Vitamins
– Minerals
– And nonnutritive food components
Chapter Summary