food composition Flashcards
What is water?
A chemical compound made of 3 atoms covalently bonded.
Water is the most abundant compound on Earth.
What are the four types of water in food?
- Free
- Bound
- Entrapped
- Metabolic
What is free water?
Water that can be easily obtained from food.
What is bound water?
Water molecules that are bonded to other molecules in the food and not readily available to be removed.
What is entrapped water?
Water that remains between large cells.
What is metabolic water?
Water produced as a byproduct from the destruction of glucose during metabolism.
How much water do we need to drink daily?
1,000 ml (4 cups)
What is the main driver of thirst?
Osmolarity (ion concentrations).
True or False: The thirst mechanism is always reliable.
False.
What are the impacts of water’s special atomic properties?
- Partially positive hydrogens available for hydrogen bonds
- Very good solvent
- Impacts boiling temperatures, heat transfer, surface tension, density
What are good solvents for polar substances?
Water readily dissolves electrolytes and sugars to form solutions.
What is colloidal dispersion?
A mixture where larger molecules stay suspended in water.
What are electrolytes?
Minerals that carry an electric charge
- Positive ions (e.g., sodium, potassium)
- Negative ions (e.g., chloride, phosphate)
What is intracellular water volume?
Fluid within cells.
What is extracellular water dehydration?
A condition where the body’s fluids have less concentrated salts, causing water to move out of cells.
What are carbohydrates primarily composed of?
Hydrogen, oxygen, and carbon.
What are monosaccharides?
The simplest carbohydrates, e.g., glucose (C6 H12 O6).
What is the structure formula for monosaccharides?
Cn H2n On
What are disaccharides?
Carbohydrates made of two monosaccharides, e.g., glucose + fructose.
What is lactose?
A disaccharide made of galactose + glucose.
What are polysaccharides?
Carbohydrates that contain 10 or more monosaccharides.
What happens when glycogen is depleted?
The body begins to burn fat for energy.
What is fiber?
Indigestible substances, including plant cell walls.
What are the two types of fiber?
- Soluble fiber
- Insoluble fiber
What does soluble fiber do?
Soaks up water, partially digestible, and reduces cholesterol levels.
What is an example of high fiber foods?
- Corn bran
- Legumes
- Fruits
- Vegetables
What is the role of insoluble fiber?
Speeds up food passage through the body and adds bulk to stool.
What are the defining characteristics of lipids?
Insoluble, plant and animal in origin
What does ‘Total Fat’ on food labels refer to?
The total amount of fats present in the food item
What distinguishes fats from oils?
Fats are solid at room temperature; oils are liquid at room temperature
How many kilocalories do lipids provide per gram?
9 kc/gram
What is the energy yield of carbohydrates per gram?
4 kilocalories per gram
What is the energy yield of proteins per gram?
4 kc/gram
What is the energy yield of alcohol per gram?
7 kc/gram
What structural feature makes lipids hydrophobic?
Long carbon chains with few oxygen-hydrogen bonds
What are the three main types of lipids?
- Triglycerides: Energy storage
- Phospholipids: Cell membrane
- Steroids and Waxes: Hormones and cell signaling
What is the most common saturated fatty acid?
Palmitic acid
What is the most common fatty acid found in nature?
Oleic acid
How does the melting temperature of fatty acids change?
Melting temperature increases with the length of the carbon chain
What is the state of saturated fatty acids at room temperature?
Solid (e.g., Coconut oil)
What is the state of polyunsaturated fatty acids at room temperature?
Liquid (e.g., Canola oil, walnut oil, flaxseed oil)
What are trans-fats produced by?
Hydrogenation (chemical processing)
What effect do trans-fats have on cholesterol levels?
Raise LDLs and lower HDLs
What is the lipid content percentage in cow’s milk?
4-5%
What is the lipid content percentage in human milk?
4-5%
What is the lipid content percentage in seal milk?
50%
Which vitamins require lipids for uptake?
- A
- D
- E
- K
What is the primary function of spices?
Taste, temperature, flavor enhancers
Spices are not necessary for nutrition.
When do the earliest records of spice trades date back to?
10,000 B.C.
What percentage of US spices are imported?
About 60%
Define ‘spices’.
Sometimes individual additive (ex: pepper)
Define ‘seasonings’.
Mix or blend of spices
Define ‘flavorings’.
Extracts added to food to change flavor (ex: strawberry ice cream)
How do we detect flavors?
Through smell (olfactory receptors) and taste (taste buds)
How many taste buds do humans have?
5,000 to 10,000
True or False: Children have more taste buds than older adults.
True
How often do taste receptors regenerate?
Every 10 days
List the five types of taste receptors.
- Unami (savory)
- Sweet
- Sour
- Salty
- Bitter
How many types of bitter receptors do humans have?
25 types
What are the three types of aroma notes?
- Top Notes
- Middle Notes
- Bottom Notes
How many unique olfactory receptors do humans have?
About 400
What mineral is commonly known as table salt?
Sodium chloride
What does table salt often contain?
Iodine
What is the heat in pepper primarily attributed to?
Piperidine
What is black pepper made from?
Unripe green berries that are fermented and sun dried
What distinguishes white pepper from black pepper?
White pepper is picked ripe, and the outer skin is removed.
Define ‘herbs’.
Wide range of herbaceous plants used for their aromatic properties
List common sources of sugar.
- Honey
- Jackfruit
- Mango
- Passion Fruit
- Dates
- Figs
- Cherries
- Tangerines
- Goji Berries
- Grapes
- Bananas
- Apples
What percentage of the world’s sugar production comes from sugarcane?
About 80%
What is refined cane sugar primarily composed of?
> 99% sucrose
What is the sucrose content of sugar beets?
~5%
What is high fructose corn syrup primarily made from?
Corn
True or False: Added sugars have nutritional value.
False
What is stevia?
Sugar substitute made from leaves of the stevia rebaudiana plant
How much sweeter is stevia compared to table sugar?
200 to 400 times sweeter
List the most common artificial sweeteners.
- Aspartame (NutraSweet & Equal)
- Sucralose (Splenda)
- Saccharin/cyclamate (Sweet’N Low)
What is the Maillard reaction?
Non-enzymatic browning that occurs when protein and sugars are heated
What happens during caramelization?
Produces a brown coloring by removing water and breaking down sugars
What is a characteristic of sugar alcohols?
Reduced calorie sweeteners
What are examples of food additives?
Emulsifiers
Surfactants
Preservatives
Anti-caking agents
Anti-foaming agents
Food dyes
Why are food additives used?
Reduce production costs or improve perceived quality
First additive was salt (used as a preservative)
Increased use during the industrial revolution
What is a trend in food additives related to natural substances?
Even natural additives can be problematic (e.g., Safrole from sassafras)
Safrole was used in root beer and candy until 1960
Oils containing Safrole cannot be added to foods
How does food coloring influence food?
Color affects perceived taste
Can offset color loss
Both natural and artificial food colors are used and must undergo safety testing
What are examples of natural food coloring?
Betanin: magenta (from beets)
Anthocyanin: red to blue (depends on pH)
Beta-carotene: yellow to orange
What are examples of artificial food coloring?
Indigo carmine = Blue
Allura Red AC = Red
Quinoline Yellow WS = Yellow
What are anti-caking agents?
Compounds that prevent clumping in substances like salt, baking powder, sugars
Absorb water and oil
Typically used in small amounts (e.g., <1% in salt)
What are emulsifiers/surfactants?
Improve or maintain texture in foods with oil and water
Have both hydrophobic and hydrophilic ends (amphiphilic)
Examples: lecithins, monoglycerides, diglycerides, polysorbates, eggs
What are foaming and anti-foaming agents?
Foaming agents: Create foam (e.g., egg whites, gelatin)
Anti-foaming agents: Reduce foam (e.g., egg yolks, Polydimethylsiloxane)
What are preservatives used for?
Prevent microbial growth or oxidative spoilage (antioxidants)
Old preservatives: salt, sugar, vinegar
Modern preservatives: sodium benzoate, calcium propionate, potassium sorbate
What are antioxidants used for?
Prevent oxidative damage
Natural antioxidants: berries, herbs/spices (rosemary, dill)
Synthetic antioxidants: BHA, BHT, PG, TBHQ
What is the role of emulsifiers in food products?
Emulsifiers help mix and stabilize substances that don’t naturally combine (like oil and water)
They improve texture and consistency in foods like ice cream, mayonnaise, and chocolate
How do anti-caking agents work?
They prevent clumping by absorbing moisture and oil
Commonly used in powdered food products (e.g., salt, dried milk, flour)
Why are synthetic food colorings often preferred over natural ones in food production?
Synthetic colors are typically cheaper to produce than extracting natural colors
They offer more stability and longer shelf life
Why was Safrole banned in food products?
Safrole was found to be a potential carcinogen, leading to its removal from foods and drinks like root beer in the 1960s
How did the Food and Drug Act of 1906 impact food additives?
Reduced the number of approved additives to seven
Introduced testing requirements, including animal studies and toxicology tests
What are some common uses of preservatives in modern foods?
Preservatives like sodium benzoate, calcium propionate, and potassium sorbate prevent microbial growth and extend shelf life
What is the difference between natural and synthetic antioxidants? natural
Natural antioxidants come from foods like berries and herbs
Synthetic antioxidants, like BHA and BHT, are chemically manufactured to prevent oxidative spoilage
Why are preservatives like salt and vinegar effective?
Salt and sugar reduce water availability, making it harder for bacteria to grow
Vinegar (acetic acid) prevents microbial growth by lowering the pH of the food
What makes emulsifiers “amphiphilic”?
Emulsifiers are amphiphilic because they have both hydrophobic (water-repelling) and hydrophilic (water-attracting) parts, allowing them to mix oil and water effectively
