7 Flashcards
starch (___) = a polysacc that is made up of ___
act as ___/ binding/ __ agent
__ stores energy as starch
is hydrocolloid = able to ____
2 types: __
carb / glucose
thickener / jelling
plant
large vol of h20
native & modified
to break down starch,
2 process
w/ amylase, breaks into maltose
w/ maltase, breaks into glucose
source of starch in food
1. cereal grains (corn __ __ rice)
2. ___
3. __ & tubers: potato, __ arrowroot
why is boba brown?
- what oat
- legumes
- root: tapioca
boba is brown bcs brown sugar or added caramel flavour
describe the wet milling process?
- clean
- grind
- slurry
- separate
- dry
define refined starch
remove other components i.e protein, vit/min
add it to toher food as thickening/ bulking/ stabilising agent
e.g of wet milling process
corn
for corn, native grain is separated from roots ^ tubers
corn starch + germ = corn boil
how to reach the gelatinisation point for starch
is the final product a colloid >
ingre: water /s tarch / heat
when u add starch + water, have salt
apply heat: granule’ll swell, mixture thickens -> have gel @ gelatinisation point
this is a colloid
plan
plant store energy as starch….
which is deposited in organised unit called granules.
=> size and shape depends on source
am. ^ am. lyose pectin is tightly packed within there
define birefringence
how to see that cross pattern of granule?
= wgen starch molec is observed via microscope under polarised light
light is rotated, see the corss pattern of each granule
this pattern dissapears once granule is heated to gelatinsation point
pure starch isolated from og plant material. elaborate.
native starch
- dvloped through trad plant breeding & genetic engineering
-not physc or chem mod
is “improved”
define modified starch
native starch that is physc and chem modified to help food prep
chem modified starch: hydrolysis or avcid converted
mix starch + H20 + acid -< dry it
make a low viscous paste & stiff gell ‘
for confectionary
chem modified starch: cross linked
think abt how it’s better from hydrolysis
better viscosity and texgture
higher temp for hydration -> nore heat resistane
also resistance to shear
=> useful for canned soup & sphagetti sauce
chem modified starch: substitution:
for frozen starch thickened food
more susceptible if…
amylose
prevents retrogradation which leads to syneresis:
when whip (l) into cooked starch, H20 pushed out of jell network => create this water-beading effect on surface
more susceptible if food has more amy. bcs it realigns
gel vs colloid
gel = solid to semi-solid stage of colloidal solution
colloid = intermediate btw small particles in solution and large particles in suspension
**physc **modified strach
instant or pregelatinisation = by cooking starch in H20, or w/ drum dryer (low temp to dry liquid)
for instant dry mix, gravies, sauce
**physc **modified strach
pregelatin: __intergrity___smooth
cold water swelling = pregelatin: stach’s intergrity is retained, can swell in room temp water
=> smooth txture
**physc **modified strach
heat
heat treated: starch heated beyond gelatinisation point
not enough water to increase viscosity ^ stability
4 types of resistant staarch, which is not digsted by the **human **body
potato, whole wheat bread, green banana
RS1: reist digestion e.g whole grains
RS2: same thing due to compact structure i.e green banana
RS3: retrograded
RS4: only 1 chem modified starch
=> to add fibre
what is the effect of dry heat?
dextrin
starch becomes more soluble, can thicken less
dvlop a brown, toasty nutty flavour
dextrinization -> starch broken down into dextrins
e.g toast
what is the effect of moist heat?
colloid / starch paste
starch becomes less soluble in cold watrer
w/ heat, produce colloid
when H20 dispension is heated, make starch paste!
changes w/ moist heat
1. gelatinisation
2. more swelling -> leaching of ___ parts
3. ____ or ___ formation
4. ____
- pasting = heat starch + h20 well beyond gelatinisation / soluble
- gel formation or gelation
- retrograd = amylose realign (freezing or thawing encourage this)
factors of starch paste
- time & temp of heating: less smooth & silky (think bad custard)
- slick & pasty mouthfeel
- ph
- agitation or stirring: if excess, disrupt the granule
- fragmentation or hydrolysis (if pH <4, thin starch)
factors of starch paste
sugar
fat & protein: viscosity
sugar compete w/ starch for H20
=> delay swelling, raise temp of gelatinisation
___-delay hydration of starch, lower rate of viscosity
2 things ijmpt in food when combine starch + hot (l)
- roux: blend melted fat to liquid
- slurry: blend flour to cold water -> add to hot (l) while stirring
list 5 basic mother sauce
fat, flour, what’s different. what’s special abt tomato?
- bechamel: fat, flour, MILK
- veloute: fat, flour, veal/chicken/fish stock
- espagnole: fat, flour, BEEF stock
- tomaro: the only one thickened w/ emulsion; rest, roux
- hollandise: emulsifying egg
how to cook cream soup
celelry and carrot
use mirepoix for flavouring
thicken w/ slur / roux or pureed starchy veggie
how to cook dessert
cook starch mix before add eggs: sgtarch can handle higher temp
=> after gelatinisation, , add egg to temper
=> less coagulate
compare gel vs sol
impact…
gel = liquid trapped in solid
contain polymer cross linked to that trapped liuid
impact temp / syneresis . pH
sol = liquid; can convert into gel
polymers tht form gel:
1/ amylose
2/
3/
4/ ___ mold
1/ starch thickened pudding
2/ egg protein: egg custard
3/ pectin
4/ gelatin
to prep unflavoured gelatin
cold -> hot -> cold -> swell
- soak in cold water
- raise temp above 35C by adding or suspend over hot water
- remain (l) add cold
- after gelatin swells, add fruit acid or suag
to prep flavoured gelatin
add hot H20 to dissolve
how to industrial manufacture of gelatin?
- isolate collage from other components
- purify, then refine in dry form
in dry form, getlain has a high/low bacterial count. if add water, __ bacteria activity
low / increase
what does gelation mean for felatin and starch?
gelatin: molec link tgt to form a gel-typical structure
vs
starch: carb gel formation
what is gelatin?
hydrolysed from animal tissues: hides, skin, bones
low protein, essential am.a => p much monessential
effect of temp on gelatin:
1. below and above dispersion temp
2. rapid and slow cooling
- all gelatin needs to cool below the dispersion temp 35C
above 40C, weaker gell strength - rapid cooling -> sets gel faster -> softer gell
effect of concentration on gelatin:
yields a faster rate of setting & firmer gel (usual % is 1.5 to 2)
effect of pH on gelatin solution:
diced fruits can_____
acidic-> soft gel, prevents gelation VS less acidic: stiff gel
lemon juice & vinegat have strong effect
diced fruits can break up gel
effect of ___ on gelatin
salt: __ gel strength
sugar:
enzyme:
salt & sugar has a different effect
salt < gel strength while sugar yields a slower rate of setting
E: bromelain a protease found in pineapple kiwi papaya
can hydrolyse gelatin
to balalnce, heat the protease first / use canned, heated processed frutis
usage of gelatin
- foam ___ in whipped products
_____ in pudding & pies - ___
control of ___ ___ in frozen __ & ____
as a basic gel (tasteless & ordourless)
stabiliser
thickener
candy
crystal size / desserts / syneresis
