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NUTR214 (Food fundamentals) > food composition, sensory evaluation, fruits > Flashcards

food composition, sensory evaluation, fruits Flashcards

1
Q

oligosaccharide ex?

A

raffinose and stachyose (dried beans digestion = gas)

fructo oligosaccharides (fruits and veg, prebiotics)

used as bulking agents and fat replacers

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2
Q

starch vs glycogen vs fiber

A

starch:

  • amylose and amylopectin
  • energy store for plants
  • digestible by humans

glycogen:

  • stored energy for animals
  • digestible by humans
  • fiber
  • cellulose, hemicellulose, pectic substances
  • undigestile by humans
  • in plant originated food
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3
Q

where are cholesterols found?

A

only animal foods

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4
Q

purposes of food additives

A

mprove appeal
Extend storage life
Maximize performance
Protect nutrient value

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5
Q

influences of food selection

A 
Sensory
Nutritional
Cultural
Religious
Psychological and sociological
Budgetary
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6
Q

sensory aspects of food

A 
appearance
odor
taste
texture
sound
flavor
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7
Q

describe odor and smells in sensory evaluation

A
  • detected first by olfactory epithelium (upper part of nasal cavity)
  • need a volatile molecule to make contact with olfactory receptors = sends impulses to brain
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8
Q

what is anosmia

A

lack of ability to smell

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9
Q

groups of odors:

A

6 groups:spicy, flowery, fruity, resinous, burnt, foul

4 groups:fragrant, acid, burnt, caprylic

2 groups:inedible vs. edible

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10
Q

describe taste in sensory evaluation?

papillae

taste bud life?

A
  • substance must be dissolved in liquid or saliva to seep into taste bud = nerve impulse to brain
  • taste buds distributed in papillae on tongue, palate, esophagus, cheek, epiglottis
  • papillae have microvillae
  • taste buds are regenerated within 2 weeks
  • humans: 10,000 taste buds
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11
Q

categories of taste?

A 
sweet (tip)
salty (tip of tongue)
sour (sides of tongue)
bitter (bck of tongue)
umami
oleogustus
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12
Q

what is the taste threshold

A

concentration necessary to elicit a taste respons

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13
Q

how is tactile character of food determined?

A

by shape = kinesthetic sensations = feeling of resistance to motion detected by nerves

assessed by mouth, tongue, jaws

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14
Q

what are factors affecting touch?

A

texture
consistency
astringency
chemsthesis

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15
Q

describe flavor in sensory evaluation

A

composed of aroma and mouthfeel

aroma: combination of odor and taste (independent of mouthfeel)
mouthfeel: sense of touch in mouth. influenced by: texture, consistency, astringency, chemsthesis

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16
Q

types of taste test

A

difference:

  • trained evaluators or untrained consumed
  • difference between protoypes of new product
  • they choose most preferred

acceptability tests:

  • consumer testing
  • is the product positively perceived by consumed
17
Q

types of flowers?

A

simple
aggregate
multiple

18
Q

fruit classification?

A
  1. simple fruits: derived from ovary of one pistil (ie. drupes and pomeS)
  2. aggregate fruits: formed by single flower with many stamens and pistils
  3. multiple fruits: formed from many flowers and remain together as single mass
  4. berries:
    - true berries: currants, tomatoes, cranberry, kiwi, banana, grapes, avocado
    - pepo: melon, squash
    - hesperidium: citrus. rind, juicy interior
19
Q

diff b/w animal and plant cells

A 
plant:
1. has primary cell wall. thin and contains:
-cellulose
-hemicellulose
-pectic substances
secondary cell wall:
-thin
-contains lignin (non carb material withbenzene derived structure)
  1. intercellular air: fills spaces between cell walls. gives volume, crispness, textural differences
20
Q

composition of plastids?

A

storage organells

  • lecuoplasts: starch and water. major digestile portion.
  • chloroplast: green color. CHO synthesis -chromoplasts: cartoene or xanthophyll
21
Q

describe skin of fruits

A

secretes waxy cutin ( protects surfaces. slows water loss)

additional wax is used commercially

22
Q

macro compoisition of fruits

A
  • 70-95% water
  • less than % protein
  • solid parts: mostly carbs
23
Q

phytochemicals in blueberries, cranberries, rasp, straw, watermelon,

A

blueberries: flavanoids: anthocyanins and flavinols
cranberries: proanthocyanins

rasp and straw: ellagitannins

watermelon, grapefruit, tomatoes: lycopene

24
Q

acidity of fruits?

A

pH below 5

least acidic fruits = more bland and sweet

veg are usually pH > 4.5

25
Q

pectic substances in fruit?

what does the food industry use it for?

A

polysaccharides
provides firmness and structure

protopectin: immature fruit ( no gel)
pectin: ripe fruit ( gells)

pectic acid: overripe fruit ( no gel)

food ind: used to emulsify, stabilize, thicken, texturize

26
Q

phenolic compounds in fruit?

A

causes browning and bruising (ie. in apples)

tannins

27
Q

how to decrease enzymatic browning

A

denature enzymes: boiling

add acid: acidic ph inhibits polyphenol oxidase

lower storage temp: cold slows enzyme inhibition

block o2: coat with sugar or water or antioxidants

28
Q

describe how fruits change during ripening

A
  1. vitamin content peaks at maturity
  2. organic acids decrease (pH increases). influences fruit flavor and pigments
  3. changes in color: carotenoids and anthocyanins. pigments become unmasked or synthesized
  4. starch decrease:
    - immature fruits: high starch
    - as fruit ripes, starch becomes sugar = sugar content increases
  5. texture softens: degredation of cementing pectic substances
  6. flavor substances develop
    - fruit becomes less tart as sugar content increases
    - organic acids decrease and astringency (polyphenol compounds) decrease
29
Q

how is fruit texture affected by cooking?

A

when heat is applied

  1. cell membranes are disrupted
    - air expulsion
    - protopectin becomes pectin
  2. loses selective permeability
    - protein denaturation
    - no more osmotic pressure. only simple diffusion for h2o and solutes to pass through membranes
30
Q

how are Ca2+ ions used in fruit cooking?

acids? alkali?

A
  • reduces tissue breakdown of fruits
  • Ca2+ reacts with polysacc in tissues = forms insoluble salts = strengthens tissues

acids: maintains firmer texture
alkali: solubilizes hemicellulose = mushy texture

NUTR214 (Food fundamentals) (10 decks)

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