Starch granule phosphate

Blennow, A., Bay-Smidt, A. M., Olsen, C. A., Mailer, B. L. (2000). The distribution of covalently bound starch-phosphate in native starch granules. Int. J. Biol Macromol, 27, 211-218. 

Blennow, A.,Houborg,K.,Andersson,R.,Bidzihska,E.,Dyrek,K., Labanowska,M. (2006). Phosphate positioning and availability in the starch granule matrix as studied by ERR Biomacromolecules, 7,965-974. 

Intrinsic factors that may influence potato digestibility include the structure of the starch molecules, the structure of starch granules, the composition of the potato, the presence of phosphate in starch granules, tissue structure, and factors that may affect these, including agronomic and growth history, storage, maturity, and variety. 

Substances commonly found in starch granules are amylopectin, amylose, molecules intermediate between amylose and amylopectin, lipid (including phospholipids and free fatty acids), phosphate monoester and proteins/enzymes. The contents and the structures of amylopectin and amylose play major roles in the functional properties of starch. However, lipids, phospholipids and phosphate monoester groups have significant effects on starch functional properties, even though they are minor constituents. 

Although native starch granules from storage organs seem to be first eroded by amylases before other enzymes can further hydrolyze it, the chloroplastic phosphorylase can release labeled glucose 1-phosphate from 14C-labeled starch granules, at least in pea leaves (Kruger and ap Rees, 1983). 

Incubation of spinach leaf starch granules with extrachloroplastic phosphorylase resulted in the formation of glucose 1-phosphate (Steup et al., 1983). Hammond and Preiss (1983) reported a large increase in cytosolic phosphorylase from spinach leaf in a time course that approximates the time of leaf senescence (i.e., when starch chloroplast must be hydrolyzed and exported to active sinks). 

In addition to these major carbohydrate components, starch granules also contain minor noncarbohydrate components lipids from 0.01 to 0.80% (w/w) proteins, from 0.10 to 0.40% (w/w) and phosphate 0.09 to 0.63% (w/w). See Table 2 for the compositions of ten types... 

Starch granules have been cross-linked with phosphate by the reaction of an aqueous alkahne (pH 8-12) suspension reaction with phosphorus oxychloride [161]. Trimetaphosphate has also been used to produce phosphate cross-linkages. These reactions are primarily with the C-6-OH groups and only a minimal number with the C-3-OH groups [162]. Starch phospho esters can be obtained by phosphorylation with sodium triphosphate at pH of 8.5 [163]. 

FIG. 21-127 Power consumption for lactose, dicalcium phosphate, and dicalcium phosphate/starch mixtures (15 and 45 percent starch) granulated in a Fielder PMAT 25 VG. Impeller speed is 250 rpm, chopper speed 3000 rpm. [Holm et ai., Parts V and VI, Powder Technol., 43,213 (1985) Kristensen et al, Acta Pharm. Sci., 25,187 (1988). ]... 

In the plant kingdom, the biosynthesis of the starch granule remains the outstanding subject for investigation. This includes the mode of synthesis of the starch components, the variation in their proportion in different plants, and the occurrence of minor structural features (for example, phosphate groups and n-fructose residues). The relative importance of the enzymes catalyzing n-glucosyl transfer from uridine- and adenosine... 

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