midterm Flashcards
Orthonasal olfaction
smelling an aroma that enters your nose via your nose
Retronasal olfaction
smelling an aroma that enters your nose via your mouth
The 5 Tastes
Sweet Sour Bitter Salty Umami (Glutamic acid → monosodium glutamate (MSG))
Four Major Food Molecules
Carbohydrates
Proteins
Lipids (oils and fats)
Water
Scientific Method
Hypothesis
- Becomes scientific hypothesis when it can be tested through experiments (testable guess)
- Scientific law
- Scientific theory
Hypothesis
a suggested observation for an observable phenomenon
Scientific law
when a hypothesis has been tested and supported by experimental data over and over again and has not been contradicted
Scientific theory
a well-tested hypothesis that unifies a broad range of observations within the natural world
Carbohydrates
- Main function: provide energy
- Provides 4 calories of energy per gram
- Glucose = blood sugar = sugar your body uses to get energy
- Categories: sugars, starches, and cellulose
- Produced by plants for structural material (cellulose)
Simple carbs
Monosaccharides
disaccharides
Monosaccharides
(1 unit) - ring: 6 members
Glucose
Fructose
Disaccharides
(2 mono together) - ring: 5 members
Sucrose
Lactose
Complex carbs
Polysaccharides (many)
- Starch: produced by plants to store the glucose formed during photosynthesis
- —2 types: Amylose, Amylopectin
- Glycogen
- Cellulose
Physical Properties
observable properties that do NOT involve a substance’s potential for undergoing some type of change in chemical makeup
Chemical Properties
properties that DO involve a potential for change in a sample’s chemical makeup
Ways to tell if a Chemical Reaction (change) has occurred
Heat released or absorbed Color change Gives off light Forms a precipitate Gives off a gas
Atom
simple unit of which all matter is composed
Element
a substance on periodic table of one type of atom
Molecule
2 or more atoms connected together
Compound
2 or more atoms of different elements (combined in a specific ratio)
Solid
close interaction, little movement (do not fill container)
Liquid
move relative to each other (spreads to fill boundaries of container)
Gas
move independently (fills entire container, far apart)
Pure Substance
chemical that cannot be separated into simpler components by ordinary physical means
- Atoms, elements, molecules, compounds
Mixtures
2 or more pure substances mixed together
Homogeneous mixture
same throughout down to molecular level
heterogeneous mixture
different throughout
Colloid
a special type of heterogeneous mixture that is so finely particulated, it appears homogeneous
Density
a measure of how tightly matter is packed
Mass / volume
Temperature
A measure of molecular motion
Temp of liquid usually higher than solid because of more molecular movement
Polarity
- one oxygen and 2 hydrogen atoms share electrons unevenly
- Creates slightly positive and slightly negative regions, and opposite charges attract
- So, water molecules are very attracted to each other, and to other molecules that contain charges
Hydrogen bonding
dotted lines show attractions between water molecules
Can occur between an O, N, or F atom, and an H that is attached to a different O, N, or F atom
Every atom in water can participate in H bonding
Properties of water based on structure
- Solid water (ice) is less dense than liquid water
- Water has an abnormally high boiling point (for its size)
- Liquid water absorbs a lot of heat as it vaporizes into steam; steam releases a lot of heat as it condenses into liquid water
- Water is good at dissolving other substances
Acids
- chemical compounds that generate H3O+ ions when dissolved in water
Hydrophobic
High HC to hetero ratio
Molecules that have aromas
Fat- soluble
“Blooming spices”
Hydrophilic
water- soluble
low HC to hetero ratio
Lipids
Chemicals necessary for life that dissolve on organic (hydrophobic) solvent
Provides 9 Cal/gram
Smoke point
- decomposition and combustion of oil under high heat
- Related to shape and size of oil
- Lower than boiling point
Phospholipid
Hydrophobic tail (non-polar, “water fearing”) Hydrophilic head (ionic, “water loving”)
Emulsification
By high rate of stirring/ shear
Chemical ingredient - emulsifier
Ex: Mayonnaise
Hydrophobic attractions
between nonpolar molecules
Weaker interactions between molecules ( ~ similar sizes, by # of carbons)
Hydrophilic attractions
Hydrogen bonding
Attractions between ions and polar molecules
Attractions between polar molecules
Physical properties:
The greater the interactions between molecules (hydrophilic), the higher the:
Boiling point
Melting point
Viscosity
Solubility also affected (like dissolves like)
Types of attractions between molecules
- Attractions between polar molecules
- Attractions between ions and polar water
- If molecule contains F, O, and/or N, and a second molecule contains F, O, or N, then those molecules can hydrogen bond
Acids
Taste sour
- Have pH < 7
- If organic, contain carboxylic acid group (COOH)
- H in front or a COOH in back of formula
- React with carbonate- containing compounds to make
- CO2 and H2O and a salt
- React with bases to make salt and water
- Generate H3O + in water
Bases
- Taste bitter
- Have pH > 7
- Generate OH - ions in water
- If organic, contain an amine group (N with 3 single bonds, but not C=O)
- React with acids to make a salt and water
Organic Acids
Contain a carboxylic acid group - COOH or CO2H
*** RECOGNIZE STRUCTURE
Acetic acid ** (in vinegar)
“Strong” vs. “Weak” acids
Dissociation: “breaks into ions”
Strong: 100% dissociation
HCl (stomach acid)*
Weak: «< 100% dissociation
Acetic acid (food) HCN?
Difference between a strong and a weak acid:
Strong: put HCl into water, get a lot of H, a lot of Cl, and no HCl
Weak: put HCN into water, small amount break into H + and CN -, and most will remain as HCN
Acid-Base indicator
- substance that changes color in a specific pH range
- Tend to be big molecules
- Lots of double bonds→ color
- Different forms of indicators have different colors
Ex: cabbage juice indicator dye from activity
Lactase enzyme lab
acidity increases enzyme activity
enzymes break down their specific sugars better than other sugars
warm temperature increases enzyme activity
