79
that absorb to oilewater interfaces and facilitate the formation of small oil droplets
during homogenization, and increase their long term stability during storage.
Acetylation of starch has been shown to increase its hydrophobicity, reduce swelling ability, and enhance resistance to enzymatic hydrolysis, which are useful attributes for development of delivery systems for pharmaceutical agents (Xu et al.
2009) and food ingredients (Pu et al. 2011).
Other Applications of Starch
Starches from different sources exhibit uniqueness in functional and physiochemical characteristics. These attributes, in association with the non-toxic, biocompatible and biodegradable nature of starch, makes it a versatile ingredient that
can be used in food and biomedical applications. Properties of starch such as gelatinization, swelling index, mechanical behavior, enzymatic digestibility, and solubility have been greatly exploited to tailor its use in a particular biomedical or
pharmaceutical application. Native starches, their characteristics, and interactions
with other ingredients during product development have been studied and reported
from time to time. Due to an increased demand of value-added products, researchers
have shown keen interest in isolation and characterization of starches from novel
sources. However to be applicable industrially, starch in its native form has certain
limitations. These include high tendency towards retrogradation and low thermal
resistance, shear stress resistance, thermal decomposition. Starches when modified
physically and chemically exhibit improved stability, clarity and resistance to retrogradation and can be used to tailor specific applications. Different treatments have
been adopted for production of modified starches commercially, including grafting,
self-association, crosslinking, substitution and others (Shefer et al. 1992; Van Soest
and Vliegenthart 1997; Malafaya et al. 2006). The mode of treatment for starch
modification varies with the application of starch, whether for food or pharmaceutical use. The applications of starch as a matrix for controlled drug release, as a
hydrogel for wound dressing and in bone fixation are presently widely recognized
and different types of modified starches like hydroxyethyl starch (HES), cadexomer
iodine (CI), and oxidized starch (OS) are being used for biomedical purposes.
Modified Starches Used in Biomedical Applications
(a) Hydroxyethyl starch (HES): hydroxyethyl starch (HES) or hetastarch is a naturally derived nonionic polysaccharide obtained by hydrolysis of amylopectin
following stabilization by hydroxyl ethylation. The hydroxyethyl is substituted
at carbon 2, 3 and 6 in the glucose ring. The degree and type of hydroxylation
determines the pharmacokinetics of HES. It is usually produced by the reaction
of starch with ethylene oxide at temperatures below 50 °C in aqueous slurries in
Recent Advances in the Application of Starch and Resistant Starch
that absorb to oilewater interfaces and facilitate the formation of small oil droplets
during homogenization, and increase their long term stability during storage.
Acetylation of starch has been shown to increase its hydrophobicity, reduce swelling ability, and enhance resistance to enzymatic hydrolysis, which are useful attributes for development of delivery systems for pharmaceutical agents (Xu et al.
2009) and food ingredients (Pu et al. 2011).
Other Applications of Starch
Starches from different sources exhibit uniqueness in functional and physiochemical characteristics. These attributes, in association with the non-toxic, biocompatible and biodegradable nature of starch, makes it a versatile ingredient that
can be used in food and biomedical applications. Properties of starch such as gelatinization, swelling index, mechanical behavior, enzymatic digestibility, and solubility have been greatly exploited to tailor its use in a particular biomedical or
pharmaceutical application. Native starches, their characteristics, and interactions
with other ingredients during product development have been studied and reported
from time to time. Due to an increased demand of value-added products, researchers
have shown keen interest in isolation and characterization of starches from novel
sources. However to be applicable industrially, starch in its native form has certain
limitations. These include high tendency towards retrogradation and low thermal
resistance, shear stress resistance, thermal decomposition. Starches when modified
physically and chemically exhibit improved stability, clarity and resistance to retrogradation and can be used to tailor specific applications. Different treatments have
been adopted for production of modified starches commercially, including grafting,
self-association, crosslinking, substitution and others (Shefer et al. 1992; Van Soest
and Vliegenthart 1997; Malafaya et al. 2006). The mode of treatment for starch
modification varies with the application of starch, whether for food or pharmaceutical use. The applications of starch as a matrix for controlled drug release, as a
hydrogel for wound dressing and in bone fixation are presently widely recognized
and different types of modified starches like hydroxyethyl starch (HES), cadexomer
iodine (CI), and oxidized starch (OS) are being used for biomedical purposes.
Modified Starches Used in Biomedical Applications
(a) Hydroxyethyl starch (HES): hydroxyethyl starch (HES) or hetastarch is a naturally derived nonionic polysaccharide obtained by hydrolysis of amylopectin
following stabilization by hydroxyl ethylation. The hydroxyethyl is substituted
at carbon 2, 3 and 6 in the glucose ring. The degree and type of hydroxylation
determines the pharmacokinetics of HES. It is usually produced by the reaction
of starch with ethylene oxide at temperatures below 50 °C in aqueous slurries in
Recent Advances in the Application of Starch and Resistant Starch