9 Flashcards
nutrition: FAT CONTAINS
fat: 9kcal/g
essential f.a (definition):
___ : vit
for which organs
- 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
classification- 3
can be either @ roomp temp
which has double bond?
sat = no DOUBLE BOND; solid @ roomp temp
monounsat: at least one; liquid
cis H atoms on same side; trans OPP
id test to find the unsat degree of fat
= iodine values
sat fat’d take no idoine while polyunsat fat will take lots
qualities:
______
f.a attract
- if symmetrical & _______, crystals
polymorphic = can take on many forms
_____ van der waal forces to bond crystal as it cools
& similar C length, form more crystals
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
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
melting point depends on___
influenced by type of fat
assym fat have lower MP
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
smoke point =
depends on what?
higher SP
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
what happens in heating of fat & smoke?
due to excess heating & smoke, free glycerol demp to H20 + acrolein
compare flash point vs fire point
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
plasticity =
like
= 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
general abt refining:
remove the phospholipid, carb protein water
start w/ crude oil,
wannt oxidative stable (so not susceptible to rancidity), provide nutr w/ function aspect
…..bt keep essential f.a, antioxidants, vit
additives to protect quality in prolong storage?
3f parta
lecithin as emulsifier
citric acid (metal chelating) to inhibit oxidation
polyclyerol ester: to inhibit crystalisation
rendering
extract fat from lve stock by melting down or reprocessing meat bone / animal byproduct
via heat or steam
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
what is so good abt marine oil?
typically long polyunsat fat
high in vit D & A, susceptible to oxidation
source of EPA & DHA
which fat has 4 fat crystals?
most fat are in small_____
milk fat- alpha, beta, beta prime 1 & 2
most fat’re in smal globulel, surrounded by protein ^ phospholipid bilayer membrane
what is butter
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
compare hydrolytic vs oxidative randicity?
hydrolytic: what are the catalysts?
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
processing: first 3-
third is neutralise
- 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
processing: second 3-
bleach / ____ / distill steam related
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
add H+ til sat
can increase the
hydrogenation:
take (l) fat turn int into solid or plastic
=> < thermal and oxidative staibility
=> for shortening
why is partial hydrogenation bad?
create trans f.a NOT ALLOWED
H2 bubbled through (l) oil in the presence w/ nickel catalyst -> trad hydrogenation
interesterification
diff btw inter vs intra?
add f.a or rearrange glycerol backbone -> create new trig
bronds broken on f.a & reesterified on = glycerol (intra) or diff (inter)
how to reduce trans f.a by 50%
low temp
high P
catalyst
separate trigly by difference in MP, solubility & volatility
fractioning
for processing palm oil
what does antioxidant do? what are they specifically?
veggie fats/ synergists
donate H+ to free radical
in veggie fat- stripped during processing
- VIT E C b-carotene / BHA BHT propyl gallate
synergists < its effeciveness by chelating w/ metals
milk fat can 1) destabilize & coaslesce vs flocculate vs partial coalesce
crytal (liquid) fat
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.
changes during frying
3. surfactats: easier to xodiate
- polymerization: polyun f.a form large molec of polymers
< viscosity & darken fat - SF lowers
- surfactants: lower surface tension -> allow O to interact more w/ oil -> oxidate -> help w. heat transfer
- darken
some words on chocoalte,
3/4 of it comes from west africa
cacao beans ripen on treees ____
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
first step of choc processing
___ bitter ___ acid taste
ferment & dry:
- remoes pulp, forms flavour precursor
- ferment via yeast, bacteria fungi
- then sun dryL to essen the bitter, astringent, acid taste
what are acrylamides
colorless, crystalline solids prolly carcinogenic
formed by high temp or frying using sillicone
BT boiling/ steaming/ microwaving doesnt form acylamides
T or F: roast cocoa nibs in 150-200C for 30 min.
F: 105 to 150. dvlop flavour through maillard browning
choc processing
winnow, grind, mill, refine
pass through rolelr
- 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
what is special abt duch processed cocoa powder
alkaline treated, ph 6-8
less bitter less polyphenols w. brown reddish color
milk choc vs yt choc
milk choc contains milk sugar vs yt chocl has cocoa butter w/ no cocoa solids
conching vs tempering
tempering produce which type of fat crystal?
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
temporary vs permant emulsion
an emulshion when shaken then separate like vinegar dressing vs need an emulsifier like mayo
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
- oil is added too quickly or too much to water
- not enonugh agitation
to reverse use a new yolk or add tbs of H20 / vingefar
an emulfifier can be _____ & _____
less than 6 / bigger than 8
- amphiphilic : both attract to fat & oil
more attrac to water in oil in water emulsion & vice versa - HLB (hydrophilic lipolhilic balance) - sacle of 1-20
less than 6 in water in oil emulsion; bigger than 8 in opp
