Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
even at low DS values (0.023 to 0.099). Some of these inhibit growth of Escherichia
coli, Bacillus subtilis, and Aspergillus niger. Long-chain and aromatic-ring sulfones
are available by reacting starch with sultones. Sulfoethylaminated starches have also
been described. Thiosulfates of starch reported in the literature include benzoylthiosulfate
and benzoyloxy thiosulfate, produced by treating starch with the corresponding
thiosulfate in an aqueous suspension at room temperature.
Silylated starches are designed as glues, binders, coatings, water-repellent sizes,
and glass-fiber sizes. Polysiloxanes react with starch in the presence of alkali aluminate,
alkali hydroxide, or urea, and also with thiourea. Several modifications of
silylated starches are achieved by the use of silanes having the general structure
R(CH 2) n Si(Me) m(OR 1 ) 3 – m, where R = NH 2, H, Me, Cl, CH=CH 2, SH, O, glycidoxy,
CH 2=CHMeCOO; R 1 = C 1 –C 6 alkyl; n = 10–20; and m = 0– 2. Such derivatives are
biodegradable.
Acylation of starch improves several of its functional properties, particularly
with respect to food cooking applications. Starch acylation is used to reduce setback
viscosity, and control gelatinization time, stability at low pH, freeze–thaw stability,
storage characteristics, and other characteristics.
Starch esters are used as emulsifying agents, thickeners, and sizes; binders for
coal briquets; and additives for hydraulic binders, paper coatings, and adhesives.
Starch acetate having a degree of esterification above 0.03 is blended with diluted
alkali and urea to produce an adhesive. Starch acetate has been used in wastewater
treatment, especially in applications involving food processing. Starch dodecanoate
having a degree of substitution above 2 has been patented as a base for
chewing gum, and starch hexadecanoate is a component of shampoos. Esters of
higher fatty acids are used to produce special optical effects in photographic films.
Acylation of hydrolyzed starch with acid anhydrides in pyridine gives products of
interest for medical and cosmetic use, and also has applications similar to those
of acylated starches.
Esters from unsaturated fatty acid chlorides are usually viscous or limpid oils
soluble in hydrocarbons and turpentine, whose primary applications are as varnishes,
films, artificial threads, aqueous emulsions, and rubber-like plastics. Heating them
in an inert gas produces insoluble products caused by polymerization involving
double bonds in the acyl moieites. As mentioned in the section on nitrates, acetates
of amylose are less compact than amylopectin acetate. Esters of unsaturated acids
have also been proposed as remoistenable adhesives.
Mixed esters are proposed for use as petrochemical dispersants and cardboard
adhesives. They are also compounded with starch and borax for use in processing
corrugated board.
19.3.7 HALOSTARCHES
6-Iodoethylated starch resulting from the reaction of (hydroxypropyl)starch with Niodosuccinimide
in the presence of triphenylphosphine is cited as a potential contrast
material for medical imaging by computed tomography.
Preparation of a chlorostarch for improved pigment retention in paper has been
reported. Acetalation of chlorinated starches leads to a high-strength paper size.