Chapter 3 Chemistry Of Food Composition Flashcards
The fundamental purpose of eating and drinking is to ______.
Replace nutrients and obtain calories
All foods and humans consist of what 6 basic nutrients?
Water, carbohydrates, lipids, proteins, vitamins, minerals
Humans are composed of ___% water, ___% fat, ___% protein, & ___% minerals
60-70% water, 15-25% fat, 15% protein, 12% minerals
Biochemistry
The study of chemistry that occurs in living organisms
All living things contain what 6 key elements? Why are they important?
Carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur; they are the building blocks for organic material
Are there calories in carbohydrates? Protein? Fiber? Alcohol? Vitamins? Minerals? Fat? Water? If yes, how much per gram?
Carbs=4 kcal per gram, protein=4 kcal per gram, fat=9 kcal per gram, alcohol=7 kcal per gram. The rest are no’s
___ grams = 1 teaspoons
5 grams
_______grams = 1 ounce
28.35 grams
____ grams = 1/2 cup of liquid
100 grams
Inorganic Compounds
Substances that do not contain carbon and cannot provide calories (ie water and minerals)
This nutrient is the simplest, and most important
Water
Explain the rule of 3
Three days without water, three minutes without air, three weeks without food
Water is necessary for _______.
All functions
The human body is a medium for ______.
Every metabolic process (which uses water)
Water content of fruits and vegetables (%)
70-95%
Water content of whole milk (%)
80%
Water content of most meats (%)
Just under 70%
What are the two possible forms of water in food?
Free & Bound
Free Form of Water
It is the largest form of water in foods and can be separated from food (like when squeezing a peach or orange)
Bound Form of Water in Food
Smallest form of water in food, cannot be separated (like bread, you cant squeeze the water out of it)
What is the chemical composition of water?
H2O (one oxygen atom flanked by two hydrogen atoms)
Heat is measured in the form of ______
Calories
In calories, uppercase C means ___________. Lowercase c means _________.
C = amnt of energy to raise 1kg of water by 1 degree celsius c = amnt of energy to raise 1g of water by 1 degree celsius
1 kcal = ____ calories
1,000
Specific Heat
The amount of heat required to raise the temperature by 1 degree celsius
Freezing Point
The temperature at which a liquid turns into a solid. Water becomes less dense. Occurs at 32 degrees F, or 0 degrees celsius
Heat of Solidification
The removal of heat
Melting Point
The temperature at which water turns from a solid to a liquid. 32 degrees F or 0 degrees celsius
Boiling Point
Temperature at which water boils. 212 degrees F or 100 centigrade
Heat of Vaporization
The amount of heat required to turn a liquid into a gas
As altitude increases, boiling point _______. Why does this happen?
Decreases; Occurs because there is less pressure.
Artificial pressure can be created by pressure cookers, which does what to your heating time?
Speeds it up
______ determine whether water is HARD or SOFT.
Minerals
Hard Water
Contains more calcium and magnesium minerals
Soft Water
Contains higher sodium content
Does the hardness or softness of water affect the boiling point?
Nope!
The 2 most important functions of water in food? What are twp other functions that are not necessarily as important?
It is a transfer medium for heat, and it is a universal solvent.
It is an agent in chemical reactions, and it is a factor in perishability/preservation of food.
Define moist-heat cooking, and name the methods
A cooking method that uses water to transfer heat.
Boiling, simmering, steaming, stewing, and braising
Define dry-heat cooking, and name the methods
Cooking method that uses heat in a form of radiation.
Baking, grilling, broiling, and frying
Microwaves use ______ & _______ cooking methods. Explain why.
Moist AND dry heat methods. Radiation heats up the water that is in the food, which then heats the food
Solvent
Liquid (like water) which solute (like NaCl) is added to
Solute
Substance that is added to a solvent
Solubility
The amount of solute at a specific temperature
Solution
Completely homogenous mixture of a solute (usually a solid) dissolved in a solvent (usually a liquid)
Biochemical interactions could not occur in _________.
absence of solvent environment
Colloids
A particle too large to completely dissolve (ie protein, starch, and fat)
The 2 types of dispersions in a universal solvent
Suspension and emulsion
Suspension
Particles are too large to dissolve so they just kinda hang out in the solution
Emulsion
Liquid is dispersed into another liquid (not completely mixed, like oil and water)
When particles dissolve in solvent, solution is either ______ or ______.
Molecular or Ionic
Molecular Solution
Cations and anions stay intact
Ionic Solution
Cations and Anions separate
pH scale
Measure of acidity or basicity based on a scale of 1-14. Below 7 is considered acidic, above 7 is considered basic. Center is neutral.
Hydrolysis
Chemical breakdown of a compound due to an interaction with water
Carbon dioxide release
Using baking soda in water (important for bread to rise)
Water Activity
Amount of water available for microbial growth. Most molds grow at .85 and above
To extend shelf life of foods, you _______.
Take water out of the food
Osmosis and Osmotic Pressure
Osmosis is the movement of water from an area of high water concentration to an area of lower water concentration.
Osmotic pressure is the pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis, often used to express the concentration of the solution.
The 3 types of carbohydrates
Monosaccharides, Disaccharides, and Polysaccharides
Monosaccharides are divided into what two groups? Name all of them in each group
Hexoses (6 carbons long): glucose, fructose, and galactose
Pentoses (5 carbons long): ribose, arabinose
Name the disaccharides
Sucrose, maltose, and lactose
Polysaccharides are separated into what two groups? Name them in each of the groups
Digestible: plant starch (amylose and amylopectin), animal starch (glycogen)
Undigestible: fiber (cellulose, hemicellulose, pectin, gums, insulin, etc)
Monosaccharides
The simplest of the sugars, classified by its number of carbons (pentose & hexose are the most common in food)
Glucose. What is it called when it is refined?
6-C sugar, called dextrose when refined
Fructose
Aka fruit sugar or levulose, found primarily in fruits and honey, sweetest of all sugars but not used in cooking because of problems such as stickiness and overbrowning.
Name 2 sugars a part of DNA and RNA
Ribose and Aravinose
What is the difference between the hexose carbohydrates?
Same chemical signature but different orientation of space
Sucrose is composed of _______.
Glucose and fructose
Lactose is composed of ______.
Galactose and Glucose
Maltose is composed of ______.
2 Glucose put together
Oligosaccharides
Made up of 3-10 monosaccharides
What are the two most common oligosaccharides and how many monosaccharides are they made of?
Raffinose (3 monosaccharides) & Stachyose (4 monosaccharides)
Oligosaccharides are used as _________, and the do not produce cavities and are therefore ________.
Agents in food; cariogenic
What are the most common polysaccharides in food?
Starch, glycogen, and fiber
Polysaccharides contain _____
Many monosaccharides linked together
These are sugar units held together by bonds that cant be broken down, and hence don’t provide energy
Fibers (polysaccharides)
Dietary Fiber
The undigested portion of carbohydrates remaining in a food sample after exposure to digestive enzymes
Soluble Fiber
Dissolves in water. (Insoluble fiber does not dissolve in water)
What kind of bonds are in fiber (polysaccharides)
1, 4 alpha bonds
What are the 3 common fibers? Where are they found?
Cellulose, hemicellulose, and pectic substances. Found in every cell in a plant food syste
Hemicellulose is composed of _____
A mixture of monosaccharides
What group do oils and fats belong to?
Lipids
How are oils and fats different?
- Fats are solid at room temp, oils aren’t
- Fats are usually from animal sources, whereas oils come from plants
EXCEPTIONS: coconut and palm oils are solid at room temp, and fish oils liquid at room temp
What are the three groups of edible lipids?
Triglycerides, phospholipids, sterols
Triglycerides make up about ____% of all lipids, and consist of the three fatty acids _____, ______, & ______.
95% ; saturated, monosaturated, polyunsaturated
How do you differentiate between the three fatty acids?
Carbon length and degree of saturation
How many double bonds in the carbon chain of a saturated fatty acid?
No double bonds
How many double bonds in the carbon chain of a monounsaturated fatty acid?
1 double bond
How many double bonds in the carbon chain of the polyunsaturated fatty acid?
2 double bonds
Name some good resources of saturated fatty acids
Meats, dairy (milk and butter), plants (coconut, coconut oil, palm oil)
Name some good resources for monounsaturated fatty acids
Olives, olive oil, peanuts, peanut butter, avocado
Name two good resources for polyunsaturated fatty acids
Vegetable oils and fish
Phospholipids are similar to triglycerides except that________.
One fatty acid is replaced with a compound containing phosphorus
What is the function of phospholipids in the human body?
To move water-soluble vitamins and hormones
Foods that contain phospholipids
Egg yolks, liver, soybeans, wheat germ, and peanuts
Best known phospholipid
Lecithin
Sterols
Large molecules, interconnected rings of carbon atoms with a variety of side chains attached
Name sterols that are within your body
Cholesterol, bile, testosterone, estrogen, adrenal hormones, vitamin D
Are sterols found in plants or animals?
Both
6 functions of lipids in our food
They contribute to:
- Heat transfer during food prep
- Tenderness
- Mixing (emulsifying)
- Texture
- Flavoring food
- Increases ones feeling of fullness after eating (satiety)
How many amino acids are there? How many of those are essential?
22; 9 essential
What is the major difference between lipids/CHOs and protein?
Protein contains nitrogen
5 Functions of protein in food
They allow the follwing during prep:
- Hydration
- Denaturation/coagulation
- Enzymic reactions
- Buffering (keeping acids and bases balanced)
- Browning
Meat is a good source of _____
B vitamins, iron, and zinc
Dairy foods are a good source of ______
Calcium (provide 80% of daily value)
Vitamin C is found _____
Only in plants
What are the fat-soluble vitamins? Where are they found?
Vitamins A, D, E, & K. Found in egg yolk
Where is vitamin B12 found?
Only in foods of animal origin or fermented foods
What are the two major sources of sodium?
Processed foods and saltshakers
The two major groups for vitamins and minerals
Fat soluble and water soluble
Two major groups for minerals
Macro (Ca), and micro (Fe)
What is the function of vitamins and minerals in our food?
They are antioxidants, a compound that inhibits oxidation which causes deterioration and rancidity. Antioxidants are used to neutralize free radicals (unstable molecules that can damage the cell)
The most important antioxidants
Vitamins A, C, and E, and the Mineral Selenium
The only mineral directly consumed
Sodium
What is sodium used for?
Preservative, enhances flavor
