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fdn 2232 > 9 > Flashcards

9 Flashcards

1
Q

nutrition: FAT CONTAINS

fat: 9kcal/g
essential f.a (definition):
___ : vit
for which organs

A
  • cannot produce them oruselves, get from food
  • linoleic (omg6) vs linolenic (omg3)
  • antioxidants: vit E & C
  • for brain nerve retinal cell; also impact eye health
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2
Q

classification- 3

can be either @ roomp temp
which has double bond?

A

sat = no DOUBLE BOND; solid @ roomp temp
monounsat: at least one; liquid

cis H atoms on same side; trans OPP

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3
Q

id test to find the unsat degree of fat

A

= iodine values
sat fat’d take no idoine while polyunsat fat will take lots

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4
Q

qualities:
______
f.a attract
- if symmetrical & _______, crystals

A

polymorphic = can take on many forms
_____ van der waal forces to bond crystal as it cools
& similar C length, form more crystals

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5
Q

3 main forms of crystals: __ & ____ & ____
het vs homo (all 3 f.a chains in glycerol backbone all =)
give an e.g

e.g milk fat vs lard

A

forms: alpha, beta, beta-prime to determine which fat work best in specific food
het (diff) yield more beta prime crystal
e.g in milk at when makign forsting -> creamy txture

homo: mroe beta crystals i.e in lard

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6
Q

melting point depends on___
influenced by type of fat
assym fat have lower MP

A

strength of bonding forces btw f.a: < attraction, easier to crystalise -> higher MP

  • (l) fat have lower mP vs (s): longer chain; higher MP
  • cis fat has more kinks -> less energ to melt vs sat fat highrr MP
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7
Q

smoke point =
depends on what?
higher SP

A

temp @ which smoke comes form fat surface when heated

  • depends on thermal stability when contact air
  • depends on ease of glycerol hydrolysis & # of free glycerol:

higher SP _> better for high temp COOKING i.e baking

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8
Q

what happens in heating of fat & smoke?

A

due to excess heating & smoke, free glycerol demp to H20 + acrolein

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9
Q

compare flash point vs fire point

A

flash point = temp of volatines being ignited; cannot sustain combust
fire point = ___sustaining combus

oil once heated reach SMOKE point 0-> FLASH point -> Fire point

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10
Q

plasticity =
like

A

= when it doesnt change shape permanently til stress or force applied
like solid fat, beta prime crystals in het fat

if compsoed of liquid & crystal, flexible
bt the small combo of (l) & (s) allow fat to flex

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11
Q

general abt refining:
remove the phospholipid, carb protein water

A

start w/ crude oil,
wannt oxidative stable (so not susceptible to rancidity), provide nutr w/ function aspect

…..bt keep essential f.a, antioxidants, vit

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12
Q

additives to protect quality in prolong storage?

3f parta

A

lecithin as emulsifier
citric acid (metal chelating) to inhibit oxidation
polyclyerol ester: to inhibit crystalisation

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13
Q

rendering

A

extract fat from lve stock by melting down or reprocessing meat bone / animal byproduct
via heat or steam

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14
Q

tallow: deoderised vs undeodorised
use of yellow grease_

A

is the result of rendering cattle & sheep

  • deoderise (doesnt impac the taste) vs udeo (to enhance food flavour)

there is edible and indedible tallwo (or yellow grease) -> make bioful, soap & detergent

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15
Q

what is so good abt marine oil?

A

typically long polyunsat fat
high in vit D & A, susceptible to oxidation
source of EPA & DHA

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16
Q

which fat has 4 fat crystals?

most fat are in small_____

A

milk fat- alpha, beta, beta prime 1 & 2
most fat’re in smal globulel, surrounded by protein ^ phospholipid bilayer membrane

17
Q

what is butter

A

a phase invert
cream oil in water emulsion -> agitated -> form butter as water in oil emulsion
smaller crystal -> harder butter
winter butter harder than spring bcs seasonal cattle feed

18
Q

compare hydrolytic vs oxidative randicity?

hydrolytic: what are the catalysts?

A

hydrolytic: hydrolyzing f.a from glycerol backbone, make free f.a needs H20
w/ heat & lipase as catalysts + H20, release free f.a w. no OFF odour & taste unless short chain f.a

oxidative: has an OFF flavour & taste; w/ O exposure, in heat or light

19
Q

processing: first 3-

third is neutralise

A
  • settle: separate crude oil from phospholipid, carb protein fat
  • degum: remove the gum -> which can darken
  • neutralise: remove free F.A w/ NaOH & residual phospholipid
    => leftover can be used to make soap
20
Q

processing: second 3-

bleach / ____ / distill steam related

A

bleach: the chlorophyll
winterisation or dewax: filter f.a -> improve the clarity
oil can look cloudier depending on trigly: bcs some molec has higher MP, crystalize -> filter
deodourisation: distill steam w/ low P to remove voltaile comp; which can vaporise

21
Q

add H+ til sat

can increase the

A

hydrogenation:

take (l) fat turn int into solid or plastic
=> < thermal and oxidative staibility
=> for shortening

22
Q

why is partial hydrogenation bad?

A

create trans f.a NOT ALLOWED
H2 bubbled through (l) oil in the presence w/ nickel catalyst -> trad hydrogenation

23
Q

interesterification

diff btw inter vs intra?

A

add f.a or rearrange glycerol backbone -> create new trig
bronds broken on f.a & reesterified on = glycerol (intra) or diff (inter)

24
Q

how to reduce trans f.a by 50%

A

low temp
high P
catalyst

25
Q

separate trigly by difference in MP, solubility & volatility

A

fractioning
for processing palm oil

26
Q

what does antioxidant do? what are they specifically?

veggie fats/ synergists

A

donate H+ to free radical
in veggie fat- stripped during processing

  1. VIT E C b-carotene / BHA BHT propyl gallate

synergists < its effeciveness by chelating w/ metals

27
Q

milk fat can 1) destabilize & coaslesce vs flocculate vs partial coalesce

crytal (liquid) fat

A

1) irreversible < in fat globule size by clumping and clustering; bt loose your id
2) is reversible clustering of fat globules w/ no loss to id

partial: fat globules are held tgt by crystal and (l) fat as long as crystal structure is maintained.

28
Q

changes during frying
3. surfactats: easier to xodiate

A
  1. polymerization: polyun f.a form large molec of polymers
    < viscosity & darken fat
  2. SF lowers
  3. surfactants: lower surface tension -> allow O to interact more w/ oil -> oxidate -> help w. heat transfer
  4. darken
29
Q

some words on chocoalte,
3/4 of it comes from west africa
cacao beans ripen on treees ____

A

comes from cacao on cacao tree: contains theobromine, a mild stimulant

cacao beans ripen on trees til pods have golden orange - red color: inside nibs, polyphenol

30
Q

first step of choc processing
___ bitter ___ acid taste

A

ferment & dry:
- remoes pulp, forms flavour precursor
- ferment via yeast, bacteria fungi
- then sun dryL to essen the bitter, astringent, acid taste

31
Q

what are acrylamides

A

colorless, crystalline solids prolly carcinogenic
formed by high temp or frying using sillicone
BT boiling/ steaming/ microwaving doesnt form acylamides

32
Q

T or F: roast cocoa nibs in 150-200C for 30 min.

A

F: 105 to 150. dvlop flavour through maillard browning

33
Q

choc processing

winnow, grind, mill, refine

pass through rolelr

A
  • winnow: crack the bean, separate the shell -> yield the nibs
  • pass through a grinder: heat melst he fat -> choc mass/liquour

if press, remove cocoa butter -> dry cake
if grind, cocoa powder

34
Q

what is special abt duch processed cocoa powder

A

alkaline treated, ph 6-8
less bitter less polyphenols w. brown reddish color

35
Q

milk choc vs yt choc

A

milk choc contains milk sugar vs yt chocl has cocoa butter w/ no cocoa solids

36
Q

conching vs tempering

tempering produce which type of fat crystal?

A

stirring of cocoa mass @ controlled temp for up to 3 days
aeration dvlop flavor

= control temp to make stable, beta, V fat crystal
this glossy, stable, snappy choc

37
Q

temporary vs permant emulsion

A

an emulshion when shaken then separate like vinegar dressing vs need an emulsifier like mayo

38
Q

when an emulsion breaks, it coaslece and separates into 2 layers: oil & H20. this is more likely to occur if____

oil stirring and to fix

A
  1. oil is added too quickly or too much to water
  2. not enonugh agitation

to reverse use a new yolk or add tbs of H20 / vingefar

39
Q

an emulfifier can be _____ & _____

less than 6 / bigger than 8

A
  1. amphiphilic : both attract to fat & oil
    more attrac to water in oil in water emulsion & vice versa
  2. HLB (hydrophilic lipolhilic balance) - sacle of 1-20

less than 6 in water in oil emulsion; bigger than 8 in opp

fdn 2232 (18 decks)

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