Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

NST 108 > MIDTERM 1 REVIEW > Flashcards

MIDTERM 1 REVIEW Flashcards

1
Q

objective vs sensory evaluation

A

objective: quantitative, unbiased, uses instruments

sensory: subjective, human experience, qualitative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

objective measurements

A

physical measurements:
- mass (g), volume, (L), density (g/L), specific gravity
- moisture: pressing, wettability
- texture: tensile strength, puncture strength, torque % sag
- color: standardized systems

chemical measurements:
- pH, nutrient analysis, sugar concentration, saltiness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

physiology of sensory evaluations

A

olfactory receptor neurons (10 mil)
- volatile/aromatic compounds

taste receptors (10 thous)
- sweet, salty, sour, bitter, umami
- umami: amino acid, savory

other flavors
- astringency, coolness, heat, glucosinolates

subthreshold levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

affect of salt, acid, sugar

A

salt
- inc sweetness
- dec sourness

acid
- increase saltiness

sugar
- decrease saltiness
- decrease bitterness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

types of sensory tests

A
  1. single sample (acceptability)
  2. descriptive (scoring of attributes)
  3. affective (preference)
  4. difference test
    a. paired comparison which has greater amt of characteristic
    b. duo-trio (which sample of two is diff from control)
    c. triangle test (3 samples, which is diff)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

proteins in food

A

foam, thickening, structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

protein stcuture

A

contains amino group (NH3), carboxyl group (COOH… carbonyl + OH + R); held together by peptide bonds

  • primary: sequence of a chain of AA
  • secondary: sequence of AA linked by hydrogen bonds (pleated sheets; alpha helix)
  • tertiary: attractions present between alpha helices and pleated sheets
  • quaternary: protein consisting of more than one AA chain

***secondary protein structure:
- necessary for function
- lowers thermodynamic state
- prevents aggregation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

types of proteins

A

globular protein (varying solubility)
- enzymes
- hormones
- transport proteins

fibrous proteins (insoluble in water)
- structural proteins (ex: collagen)

conjugated proteins
- bound to lipids
- carbs
- metals
- phosphorous
- (ex: lipoprotein)

*** what type of protein would you expect rennin to be?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

denaturation & coagulation in food science

A

1) heating/beating leads to denaturation
- tertiary structure lost
- inc viscosity, dec solubility
- dec water holding capacity
- inactivate enzymes

  1. (continued) heating/beating leads to coagulation
    - R groups: crosslink: aggregation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

coagulation: isoelectric point

A
  • point at which protein carries no electrical charge
  • protein is least soluble at isoelectric point

*** (1) a positive charge on each molecule keeps them apart (2) when molecule loses charge they clump together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

hydrolysis

A
  • heat of pH to break peptide bonds
  • inc solubility
  • dec thickening
  • meat tenderizing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

egg structure

A
  • yolk, germinal disc, vitelline membrane
  • chalaza, air cell
  • thick albumen, thin albumen
  • inner membrane, outer membrane, cuticula
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

egg formation

A
  1. development of ovum in ovary
  2. possible fertilization
  3. egg white develops as it moves through oviduct
  4. shell forms in oviduct
  5. bloom (cuticula) forms
  6. intestine merges and egg is laid through same pathway feces are excreted
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

egg nutrition

A

white
- *3.2 g protein
- trace amount of fat

yolk
- 2.4 g protein
- *4.6 g fat (half saturated)

*overall
- 186 mg cholesterol in large egg
- fat soluble vitamins
- B12
- minerals
- sometimes omega 3s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

proteins in egg albumin

A

*ovalbumin: 54% of protein
conalbumin: binds metals if uncooked
ovamucoid: inhibits trypsin if uncooked
lysozymes: breakdown bacteria
ovamucin: thick albumin
avinid: binds biotin if uncooked

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

egg grading and inspection

A

with age
- inc air cell, inc pH
- thinning of albumin
- vitelline membrane breakdown

candling
- air cell size, yolk stabalility

grading (voluntary
- AA grade (small air cell), A grade, B grade (large air cell)

inspection (required)
- wholesome, unaltered, truthfully labeled
- USDA Poultry Division
- restricted aggs: cracked, dirty, greenish whites

17
Q

egg safety

A

salmonella enteriditis
- from ovary (yolk), from intestine (shell)

prevention
- cooking to 160 deg and refrigerate
- pasteurization: heating to high temp without denaturing proteins (required for eggs out of shell)

18
Q

egg color

A
  • egg yolk color due to carotenoids (provitamin A): lutein, zeaxanthin, carotene
  • color is largely influenced by diet
19
Q

egg emulsifying

A

yolk proteins act as emulsifiers
- lecithin (contains phosphatidylcholine)
- lysolecithin

phospholipids: P and NP regions (P, hydrophilic head)

substitutes: mucilaginous polysaccharides (flax seed)
- egg white + synthetic yolk
- other proteins or starches

20
Q

egg binding and thickening

A

thickening via denaturation and coagulation
- ex: custard

coagulation is influenced by
- the source of protein (yolk, whole egg, white)
- rate of heating (tempering eggs)
- other added ingredients (custard)

21
Q

foam formation

A

uses: leavening, texture, structure

  1. beating causes proteins to denature and introduces air
  2. proteins rest of surface of liquid
    a. hydrophilic groups: face into air
    b. hydrophobic groups: bind to water

foamy > soft peaks > firm peaks > over beaten
- protein most stable at soft peaks
- coagulation occurs when over beaten
- syneresis (loss of water) when over beaten

22
Q

foam stability

A

increases when:
- liquids have lower vapor pressure
- liquids have lower surface tension
- proteins solidify at the surface of air bubble

other factors impacting stability:
- temperature of eggs/equipment
- using copper equipment
- additional ingredients (fat, sugar, liquid, salt, acid, amount of thin & thick white albumin)

23
Q

heating foams

A
  1. air cells expand
  2. egg proteins coagulate (ovalbumin unaffected by agitation)
  3. firm, stable structure created (covalent bonds)
24
Q

food processing methods

A

mechanical (hand mixer)
- generated by creaming, beating, mixing
- transformed into a modest amount of heat energy
- thermal denaturation of egg white and other proteins

chemical (ceviche; acid cooking meat)
- hydrolysis using acids and water
- fermentation using enzymes and microbes
- dehydration in drying ovens
- oxidation in drying ovens
oxidation when food is air dried

electromagnetic/radient (microwave)
- radiant thermal processing (fire, broiling, sun)
- UV sterilization
- gamma irradiation
- microwaves for heating/cooking food

25
Q

food heating methods

A

microwave
- rapid vibration of water, fat, or sugar molecules creating friction between dipoles (and generating heat within the food)
- magnetron tube generates microwave
- remainder of food heated via conduction

induction
- cooktop creates changing MF that interacts with iron in cookware to induce electric current and generate MF that heats pan
- food heated via conduction (contact with hot surface)

conduction (transferring heat)
- energy transferred from heat source to metal molecules in pan
- thermal heat eventually transferred to food in pan
- requires time, energy is lost in heating pan and air (cast iron & al are best pans)
- water, fat, and air can also conduct hear (ex: sous vide)

convection (oven)
- accelerate air circulation
- shorten baking time
- promote browning

mass transfer (frying)
- movement of food into/out of food being heated
- frying temp must be controlled
- frying can cause loss of water into oil and loss of water-soluble vitamins

26
Q

states of matter

A

solid (low energy state)
- without flow under moderate stress
- molecules move slowly, tightly packed
- strong, non-covalent bonds
- crystalline solids: organized structure; amorphous: non-organized (dynamic)

liquid
- flow properties
- temp determines fluidity
- weaker transitory non-covalent bonds
- medium distance between molecules

gas (high energy state)
- large distances between molecules
- constant & fast movement of molecules
- increase in volume & pressure when heated

other
- vapor pressure: pressure when molecules in compound attempt to be gaseous rather than liquid
- evaporation: escape of liquid molecules into surrounding atmosphere
- surface tension: strength of bonds at surface of liquid, bonds broken during evaporation
- interfacial tension: molecules at surface of liquid remain with the liquid and not intersperse with a second liquid

27
Q

dispersions

A

A. true solutions
- unsaturated
- saturated
- supersaturated

B. colloidal dispersions
- emulsions
- sol
- gel
- foam

C. coarse suspensions

28
Q

emulsions

A
  • emulsifying agent
  • emulsion stability
  • permanent vs temporary emulsion
29
Q

milk proteins

A

whey and casein

*casein micelle: submicelle, calcium phosphate, k-casein peptide chain

30
Q

milk processing

A
  1. pasteurization
  2. homogenization
  3. fermentation
  4. other
    a. evaporated milk, condensed milk, dried milk, alternative milks
31
Q

milk processing examples (process + results)

A

fluid milk
- pasteurized; often homogenized; sometimes fat removal
- whole: 3.5%; reduced fat: 2%; lowfat: 1%; fat free

raw milk
- none; may be certified
- many touted benefits; rare but real risks

evaporated milk
- 60% water removed, sterilized
- 2x fat/pro; shelf stable

condensed milk
- 50% water removed, sugar added
- browns easily; shelf stable; thick; sweet

dried milk
- evaporated then blown as fine spray
- cheap; light; very shelf stable

fermented milk
- introduced microorganisms
- thicker; tarter; lower lactose

alternative milks
- varies: usually mechanically pressed nut/bean OR lactose added
- no lactose; vegan; varying nutrient values; often expensive

32
Q

milk gels

A

cheese
- coagulation of casein or whey (ricotta)

yogurt
- fermentation creates lactic acid and coagulation of casein
- whey protein coagulated via heat

33
Q

cheese production process

A
  1. curd formation: add acid or rennet, apply heat, bacteria
  2. curd cutting & drainage: increase SA to expel whey
  3. salting: controls bacteria, dehydrates curd, increases flavor
  4. pressing: expel whey, form shape
  5. aging: develops characteristic flavor, mold, bacteria added
    a. enzymes lead to further breakdown of casein to AA, which increases flavor
34
Q

yogurt

A
  1. production process (fermentation)
    a. heat to 180 deg or rolling boil
    b. cool to 115 deg
    c. whisk in bacteria
    d. heat for 8 hrs on low temp (108-112 deg)
  2. varieties
    a. skyr, greek yogurt, plant-based yogurt
35
Q

other related products

A
  1. tofu
  2. vegan cheeses
  3. nutritional yeast
  4. kefir
36
Q

milk foams

A

A. stability from protein
- agitation/beating or apply heat to denature proteins
- proteins wrap around air bubbles to stabilize
- hydrophilic: facing outward
- hydrophobic: inward touching air bubbles

B. milk vs egg whites

C. Maximizing stability
- concentration protein
- add acid
- use homogenized milk
- start with cold milk
- add fat, stabilizers, and sugar

37
Q

cream foams

A

stability from fat
- agitation/beating create air bubbles
- fat globules coagulate
- air bubbles are suspended in fat

maximize stability
- concentrate fat
- add acid
- use non-homogenized cream
- start with cold cream
- add sugar at end

38
Q

icecream

A
  • considered a foam-air dispersed in liquid
  • must contain at least 10% milk fat and 20% milk solids (proteins and lactose)
  • no more than 0.5% stabilizers (gels and gums)

overrun
- increase in volume due to incorporation of air
- gelato vs icecream (cost effective)

39
Q

butter

A

further disruption of fat globules (stage IV) –> excess coalescing –> air cells collapse –> BUTTER!

NST 108 (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions