Freeze dried oven dried

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ALPHA HELIX
B E
E
B E
BETA SHEET
Freeze dried oven dried butanol ethanol
butanol ethanol
Spray dried ethanol
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MAINLY HELICAL
MAINLY SHEET
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Heat treatment during the extraction and drying
process appears to cause denaturation and
aggregation of kafirin, decreasing solubility.
Kafirin films, where the ?-helical structure of
the native protein has been retained, are
better quality, smoother and more transparent,
than those containing aggregated proteins with a
greater ?-sheet content. Denatured/aggregated
kafirins give less homogeneous films showing
phase separation
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FT-IR spectra of kafirin films with sorghum
condensed tannin
a unmodified film, b 5 , c , 10 , d 15
, e 20 level of modification
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Tannic acid and sorghum condensed tannins
stabilised the kafirin a-helical structure and
decreased ß-sheet formation Tannic acid
cross-linking decreased the mobility of the
kafirin polypeptide chains
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PREDICTED VALUE
RAW DATA
WITH DEUTERATED GLYCEROL
CORRECTED FOR MOBILE PROTEIN
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GLYCEROL INCREASES THE ALPHA HELICAL CONTENT OF
THE PROTEIN AND CAUSES MORE MOBILE MATERIAL TO
APPEAR THAN CAN BE EXPLAINED SIMPLY BY THE AMOUNT
OF PLASTICISER ADDED. Glycerol must also act
as solvent
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heat
solvent
Hydrophobic interiors unwind slightly And
coagulation takes place. Degree of unwinding/
coagulation is determined by the thermal history
of the sample
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dry
Tannin dry
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plasticiser



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Some absorption of glycerol
plasticiser

More plasticiser
MOSTLY IMMOBILE
RIGID CORE Remains alpha helical
MOBILE Reverts to random coil or alpha helix
Glycerol acts at as a solvent for the unwound
region.









Highly mobile region