Cereal
1moisture-lower
moisture grains more expensive,less storages better,before milling
conditioning(10-15% moist)limits break-up&improves separation
2cellulose
3starch-largest,a-glucose
polymer.Must be heated to eat(Hbonds break)-gelatisation
4protein(12-14%)-protein
quality is the physical characteristics of gluten.High level of protein-good
yield of gluten-good for bread,but extensible gluten for
cakes.Gluten-gliadins(30%),glutenins(60%,coiled protein subunits linked by
disulphide links from oxidised cysteine).They are little ionic&are
insoluble.When water is added dough is formed(stronger when more glutein)
Kjeldahl
method determines protein content-grain digested in H2SO4,N2 leaves&is
measured
5some
fat
6vitamins+minerals
Processing
AWheat to
flour
1Conditioning
to uniform moisture by adding H2O&leaving
2Gristing
by blending together different wheats to adjust protein
3Milling&blending
to produce required protein+colour(endosperm colour,particle size,bran
contamination).Flour is broken by rolls to bran&endosperm
BAdditives
1CaCO3
to increase Ca content in diet
2Vitamins&Fe
3Improvers(KBrO3)to
control cross-linking
CFlour
to bread
1On
heating starch granules in the flour swell&take up large amounts of H2O
2Soluble
starch leaks out of granules&the suspension becomes more viscosious
3Added
yeast converts glucose>CO2+ethanol,that escapes,but CO2 is traped,makes to
rise
Bread
making properties improve with standing(unsaturated acids get oxidised by
peroxides),whiter&more elastic(SH>SO3H).Nowadays flour is bleached with
Cl or ClO2
Good
dough holds gas, made by kneading(glutein is stretched linearly to break
molecules,cystein exchanges disulphide).Improving agents become active when
water is added(vit,C,oxidises SH).Ca is added
In
dough amylase is hydrolysed to maltose.Starch on heating will dissolve&take
up H2O.Gelatinised starch is more readily hydrolysed by our body enzymes.Yeast
is added to produce CO2 that is trapped by gluten,that later in high t
coagulates.Salt is added to control rate of fermentation
In UK
Chorleywood Bread Process(instead of fermentation,high speed vacum,starch
damage,soft crumb,fast,cheap)
Gluten
test is SDS sedimentation(shake)
Gelatisation
temp.microscope or heat
Pour
2%iodine solution over wet flour.Blue with white spots,because ascorbic acid
reduces iodine to iodide,Add thiocyanate to flour,red spots appear where iron
is