Development of Hydrophobic Starch

Abstract

The aim of this work was a systematic investigation of the preparation conditions for stable aqueous dispersions of hydrophobic starch. Samples of benzylated starch were therefore synthesised and then converted into hydrophobic dispersions by fragmentation. In the study, the type of starch and process parameters such as the degree of hydrophobic substitution and fragmentation method were varied. It was shown that the type of derivatisation process (i.e. heterogeneous in a slurry or homogeneous in an autoclave) had a crucial influence on the dispersion properties. Dilution from homogeneous solution and steam‐jet cooking were explored as fragmentation methods for the starch derivatives. The resulting dispersions were comprehensively characterised in relation to the molecular properties of the soluble fraction and sediment. Significant differences in dispersion properties were caused by the type of starch used (i.e. potato or maize) and the derivatisation process, for a similar degree of benzylation.

Preparation and characterization of modified and functional starch (hexadecyl corboxymethyl starch) ether using reactive extrusion

“…Moreover, increased hydrophobic groups decreased association of water molecules and starch molecules while prompting loosely packed starch molecules that may be responsible for higher volume and viscosity . Furthermore, a higher DS could increase the starch intramolecular hydrophobic association to such an extent that the starch molecular chain would crimp and contract, reducing the hydrodynamic volume and resulting in a reduced apparent viscosity . However, our results show that this effect was reversed with sodium hydroxide addition that probably acts as a catalyst to maintain the acid‐base balance with increasing DS.…”

Amino Starches as pH‐Sensitive Coatings: Synthesis and Application

“…For the determination of the DS values the three peak integrals were varied until consistency of the results. The chemical shift of the aromatic protons of the O-Bn group (, 7.5 ppm) is known from detailed investigations of benzyl starches [13]. The aromatic N 1 -Bn protons at , 7.65 ppm give the DS (0.15) of the cationic moiety.…”

Physico-chemical properties of solvent based etherification of sago starch

“…For benzylated starches, introduction of the benzyl group in the starch molecular chain repels moisture and thus imparts a hydrophobic behaviour of the starches (Bohrisch et al, 2004). However, according to Fig.…”

“…Since then, many researchers have studied the characteristics of the benzylated starch intensively. The process is an S N 2-nucleophilic substitution process (Williamson reaction) at the hydroxyl functional group of starch (Berkhout and Guns, 1973;Cho and Lim, 1998;Pieters et al, 2003;Bohrisch et al, 2004;Jaspreet et al, 2007;Sarka et al, 2012). Prior to etherification process, the starch was protonated by aqueous alkaline metal hydroxide, e.g., sodium hydroxide or potassium hydroxide, to form an alkoxide ion (RO − ) (Banks and Greenwood, 1975;Pieters et al, 2003).…”

“…However, as the concentration of sodium hydroxide solution increases, gelatinization of starch molecule could occur (Maher, 1983;Han and Lim, 2004;Junli et al, 2012). Bohrisch et al (2004) reported that, even though benzylation of starch could occur in gelatinized states (paste), the final starch dispersion will have lower substitution degree. Thus, an inhibitor such as inorganic salt was used to minimize the gelatinization process (Foster, 1965;Hjermstad et al, 1969;Kaur et al, 2011).…”