Starch granule hydrolysis

Another likely commercial starch is that from amaranth seed, an expanding crop for food use, particularly its flour. Amaranth starch granules (1—3 micrometers dia) have potential for numerous food appHcations, one of which is as a fat replacer because of their small size and especially after minor surface hydrolysis with a-amylase or glucoamylase to produce a fluffy surface (see Fat replacers). 

Oates, C. G. (1997). Towards and understanding of starch granule structure and hydrolysis. 

Putaux, J. -L., Molina-Boisseau, S., Momaur, T., Dufresne, A. (2003). Platelet nanocrystals resulting from the disruption of waxy maize starch granules by acid hydrolysis. Biomacromol, 4,1198-1202. 

Srichuwong, S., Isono, N., Mishima, T., Hisamatsu, M. (2005). Structure of linterized starch is related to X-ray diffraction pattern and susceptibility to acid and enzyme hydrolysis of starch granules. Int. J. Biol Macromol, 57,115-121. 

Presence of native starch crystals. In plant materials, starch exists as semicrystalline, granular entities. Starch molecules, both amy-lose and amy lopectin, with their many intermo-lecular hydrogen bonds, give structure to the starch granule (Zobel, 1988). The crystalline regions formed by this intermolecular hydrogen bonding are somewhat resistant to enzyme hydrolysis and need to be broken prior to enzyme treatments. 

The structure of starch granules is of essential importance. Amoiphous zones of irradiated granules undergo hydrolysis prior to hydrolysis in their crystalline areas.104 Irradiation of granules of maize starch causes them to break along radial and concentric lines. An increase of dose makes the granules more crunchy. These... 

The susceptibility of starch granules to hydrolysis catalyzed by a-amylase can be quantified by following the degree and the manner in which erosion and corrosion take place. Most starch granules are first hydrolyzed superficially. Granules of some... 

Figure 5.14 Transmission electron micrograph ofwaxy maize starch granule after a-hydrolysis showing internal canal of corrosion. In the outer shell diameter, the size of the thin canalicles is about 25 nm. (Gallant, unpublished)...

After extensive acid-catalyzed hydrolysis, the crystallites of starch granules are detached. With mild attrition, the starch granules break into small particles.307 The size of the small-particle starch varies with the conditions of the acid hydrolysis ... 

The porous internal structures of A-type starch granules agree with known features for example, A-type starches exhibit faster chemical penetration and derivatization reactions,325 have weak points, are more susceptible to enzyme-catalyzed hydrolysis,38... 

Kimura and Robyt201 made a kinetic study of the hydrolysis of seven types of starch granules from normal maize, waxy maize, barley, tapioca, amylomaize-7, shoti and potato by R. nievus glucoamylase-I. The different types of starch granules had... 

Even a very mild acid-catalyzed hydrolysis (0.5 hour with 1M HC1 at 40°C), followed by heating at 95°C, induced considerable changes in the oat starch granule, viz., a breaking down of the granule structure and formation of a continuous phase of amylopectin. 13The tendency for aggregation decreased when oat starch was annealed.15... 

---