Lintnerization of Two Amylose-free Starches of A- and B-Crystalline Types, Respectively
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| Format: | Article |
| Language: | English Slovak |
| Online Access: | http://www.viks.sk/chk/star_5_04_167_180.doc |
| Abstract: | Summaries. Waxy maize starch (WMS) and potato amylopectin starch (PAPS), representing amylose-free A- and B-crystalline granules, respectively, were subjected to hydrolysis in diluted hydrochloric acid (lintnerization). The solubilization rate of the granules was dependent on the temperature, but there were only small differences between the samples. The compositions of the lintners obtained at 29°C were also similar, though the sensitivity to enzymatic debranching was different. The degree of debranching increased significantly if pullulanase and isoamylase were used successively. Because some branches remained resistant to enzymatic attack, the degree of scattered branching was difficult to estimate. The amount and composition of p-limit dextrins suggested, however, that both starches contained scattered branches. Long chains and the shortest chains in the amylopectin molecules were sensitive to lintnerization and therefore probably located outside the crystallites. The composition of the PAPS lintners was dependent on the temperature of the lintnerization, whereas that of WMS lintners was not. The composition of a lintner from normal potato starch was compared with PAPS, and it is concluded that the presence of amylose has a higher effect than the type of crystallinity on the lintnerization results. Conclusions. There are only small differences between amylose-free granular starches of A- and B-crystalline types regarding their sensitivity to acid hydrolysis. Both types give rise to dextrins of mostly linear (DP 9-21) and singly branched (DP > 21) species. Both groups contain, however, also very short branch chains after lintnerization, mostly positioned at the reducing end side of the dextrins. Isoamy-lase and pullulanase possess different action patterns against the lintners and, even though both enzymes are used successively, some branches always remain inaccessible. The extent of scattered branching is therefore difficult to estimate. Resistant branches appear also in the (3-amylolysis mixtures of the lintners. The long chains of amylopectin (CL > 35), as well as the shortest chains with DP 6-8, are attacked by the acid, which suggests that both groups of chains are in the amorphous phase. B-crystalline starch is sensitive to the temperature at which the lintnerisation is performed, suggesting a higher mobility of the amylopectin chains in the granules compared to A-crystalline starch. The presence of amylose has a more dramatic effect on the lintnerization result than the type of crystallinity possessed by the amylopectin in amylose-free starches. Amylose retards the rate of lintnerization and decreases the amount of acid resistant double helices. However, the helices are comparatively more resistant to enzymatic debranching. |
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| ISSN: | ISSN 0038-9056 |
