FOOD CHEM PART 1 Flashcards
what are the six elements that make up almost all living things
carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur
how are molecules/compounds formed
when elements combine
what are the six groups of molecules/compounds
protein, lipid, vitamins, minerals, water, carbs
what is the most important nutrient
water
why is water essential for life
needed for digesting, absorbing, transporting, metabolizing, and excreting nuutrients
how much of the human body is water
60-70%
what foods have the most water
fruits/veggies (70-95%), milk (90%), (meats 70%)
describe the chemical structure of water
one oxygen atom covalently bound to two hydrogen atoms; O -2 charge and H+1 charge so neutral overall charge, but the charges aren’t uniformly disturbed
describe hydrogen bonds
noncovalent bonds that form between the slightly positive H of one molecules and slightly negative O of another molecules
how many H-bonds can one water molecule form
up to 4
what would happen to water without H-bonds
would be gas at room temp
when does water form H-bonds?
with other polar components in foods (sugars, proteins, etc)
what are the unique properties of water that H-bonding gives rise to
high specific heat + high latent heat
whats high specific heat
amount of heat required to raise the temp of 1g of substance 1C and water’s is 4.186 joule/gram which is higher than any other common substance
describe high latent heat
amount of energy released or absorbed for a substance to undergo a phase change
what happens when you increase temp of water
increases kinetic energy
whats the relationships between elevation and boiling point
increasing elevation decreases boiling point
how does cooking change at higher elevatiions
lower pressure, takes longer to cook
whats boiling point
temp at which vapor pressure of liquid = external pressure surrounding the liquid
describe BP dropping
drops 1F for every 500 ft inc
what do pressure cookers do
reduce cooking time buy increasing pressure and allowing liquid water to reach higher temps
describe dispersions + name the three types
mixtures containing particles (solid, liquid, gas) dispelled in a continuous phase; true solutions, colloids, suspensions
what are true solutions
smallest particles size; solutes completely dissolve and will not precipitate (like carbonated water or alcohol)
what are colloids
particles too large to truly dissolve (emulsions, gels, foams)
what are suspensions
biggest particle size; very unstable, particles will eventually settle out (like oil and vinegar dressing)
what are ionizations
solutes ionize into electrically charged ions, so like NaCl -> Na + Cl
what are pH changes
water can participates in ace-base rxns
whats hydrolysis
water breaks chemical bond
whats CO2 release
baking powder needs water to release CO2
differentiate between bound and free water
bound water incorporated into chemical structure of other food components, not readily removed or available
what are the functions of water in food
heat transfer medium (because of water’s high specific heat), solvent, medium for chemical rxns
what are carbs
sugars, starches and fibers of food; contribute to sweetness, color, texture and fermentatin
what is the primary source of carbs
plants
how are carbs synthesized
through photosynthesis
what are carbs made up of + how are they classified
CHO, mono, di, sligo (3-10), poly saccharides (more than 10)
what are the two categories of polysacchardes
digestible + undigestible
what are some digestible carbs
starch (plants) - amylose and amylopectin
glycogen (animals)
what are some undigestible carbs
fiber (cellulose, pectin, gums)
what are the four categories of monosaccharides
pentoses (5 C), hexoses (6C), fructose, galactose
what are the types of pnetose
ribose + arabinose
what are the types of hexose
glucose
what are the types of fructose
free form in fruits and honey; sweetest
whats galactose
rarely in free form; part of lactose
what are the three types of disaccharides +DESCRIBE
sucore (glucose + fructose - table sugar), lactose (glucose + galactose - milk sugar), maltose (glucose + glucose - malt sugar)
what are the most common oligosaccharides
raffinose and stachyose (found in beans, not well digested)
what are fructo-oligosacchardies
short chains of fructose founf in fruits and veggies; prebiotic
what are olgosaccharides
used as bulking agents and fat replacers in commercial foods
