PubMed · 11736783
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P Young, M Blunt. 2001. Why KY?. https://doi.org/10.1046/j.1365-2044.2001.02369-11.x
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A family of L-lysine-based low-molecular-weight compounds with various positively charged terminals (pyridinium and imidazolium derivatives) was synthesized and its gelation behavior in water was investigated. Most of the compounds can be very easily synthesized in high yields (total yields >90 %), and they function as excellent hydrogelators that form hydrogels below 1 wt %; particularly, N(epsilon)-lauroyl-N(alpha)-[11-(4-tert-butylpyridinium)undecanoyl]-L-lysine ethyl ester (2 c) and N(epsilon)-lauroyl-N(alpha)-[11-(4-phenylpyridinium)undecanoyl]-L-lysine ethyl ester (2 d), which are able to gel water at concentration of only 0.2 wt %. This corresponds to a gelator molecule that entraps more than 20 000 water molecules. All hydrogels are very stable and maintain the gel state for at least 9 months. TEM observations demonstrated that these hydrogelators self-assemble into a nanoscaled fibrous structure; a three-dimensional network is then formed by the entanglement of the nanofibers. An FTIR study in [D(6)]DMSO/D(2)O and in CHCl(3) revealed the existence of intermolecular hydrogen bonding between the amide groups. This was further supported by a (1)H NMR study in [D(6)]DMSO/H(2)O. A luminescence study, in which ANS (1-anilino-8-naphtharenesulfonic acid) was used as a probe, indicated that the hydrogelators self-assemble into nanostructures possessing hydrophobic pockets at a very low concentration. Consequently, it was found that the driving forces for self-assembly into a nanofiber are hydrogel bonding and hydrophobic interactions.
The study was carried out in order to determine and establish the functional characters of starch extracted from yam bean (Pachyrhizus erosus (L) Urban) compared with cassava starch. Yam bean is a tropical tuber legume easily grown and holds a great potential as a new source of starch. Yam bean starch shows functional properties which are peculiar to those of most starch root crops. Gelatinization temperature (53-63 degrees C) and the pasting temperature (64.5 degrees C) are less than those of cereal starch, however, the swelling power is high (54.4 g gel/g dried starch). Yam bean starch paste presents a high viscosity profile, high retrogradation tendency and low stability on cooking. The functional properties of yam bean starch, similar to those of cassava starch, allows yam bean to be used as a potential new source of starch.
Rheological properties of intermediate moisture (35-45% wet basis) doughs from pregelatinized and raw wheat starch blends of various ratios were characterized using off-line capillary rheometry and online slit-die extrusion. In the case of capillary rheometer, viscosity of blends decreased by up to 50% as pregel starch concentration increased from 5 to 45%, whereas tests could not be conducted beyond 45% pregel starch concentration. For slit-die extrusion, viscosity was at a minimum at 60% pregel concentration, and it decreased by as much as 65% as pregel concentration increased from 0 to 60%. As pregel concentration increased (from 5 to 45% for the rheometer and from 0 to 60% for the extruder), the amount of water available in the system for gelatinization of existing raw starch granules decreased due to the stronger water-binding capacity of pregelatinized starch. This led to decreased additional conversion in the rheometer and extruder, which in turn caused a decrease in the volume fraction of starch and a reduction in viscosity.