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Crystalline Properties of Starch

Svensson, Erik (1996)
Abstract (Swedish)
Popular Abstract in Swedish

Den första delen av denna avhandling behandlar teoretiska aspekter på stärkelsens kristallina egenskaper. Vår förståelse av dessa egenskaper är baserad på modeller som erhållits via kristallografiska undersökningar av modifierad amylos. Mycket tyder på att dessa modeller är direkt överförbara till amylopektin som utgör den kristallina komponenten i stärkelse. En stor del av diskussionen riktas mot de föreslagna enhetscellerna (de minsta kristallografiska enheterna) som förekommer i litteraturen för stärkelse.



Den andra delen är inriktad på praktiska undersökningar av de kristallina egenskaperna hos stärkelse. Dels diskuteras faktorer som påverkar kristalliniteten i det nativa... (More)
Popular Abstract in Swedish

Den första delen av denna avhandling behandlar teoretiska aspekter på stärkelsens kristallina egenskaper. Vår förståelse av dessa egenskaper är baserad på modeller som erhållits via kristallografiska undersökningar av modifierad amylos. Mycket tyder på att dessa modeller är direkt överförbara till amylopektin som utgör den kristallina komponenten i stärkelse. En stor del av diskussionen riktas mot de föreslagna enhetscellerna (de minsta kristallografiska enheterna) som förekommer i litteraturen för stärkelse.



Den andra delen är inriktad på praktiska undersökningar av de kristallina egenskaperna hos stärkelse. Dels diskuteras faktorer som påverkar kristalliniteten i det nativa tillståndet, dels behandlas förändringar i de kristallina egenskaperna som sker vid olika grad av upphettning i närvaro av vatten.



Fosfatgrupper som är direkt kopplade till amylopektin i position C-6 kan reducera kristalliniteten hos potatisstärkelse. Genom härdning, d.v. s. en kombinerad värme/vattenbehandling vid låg temperatur, kan man få dessa grupper att orientera sig mot områden där de orsakar mindre störningar hos amylopektin.



Kombinerade data från undersökningar med hjälp av röntgen och differentiell svepkalorimetri visade att de kristallografiska egenskaperna hos stärkelse är mycket beroende på den tillgängliga mängden vatten under gelatiniseringen. Resultaten i denna undersökning visar även att gelatiniseringsprocessen bör diskuteras i nära relation till den glasomvandling som tidigare föreslagits i litteraturen.



Det initiala skedet av kristallisationsförloppet efter gelatinisering för främst amylos har undersökts med mikrokalorimetri. Denna metod har även använts för att studera komplexbildningen mellan amylopektin och lipider. Komplexbildningen mellan amylopektin och en anjonisk ytaktiv substans, SDS, har även undersökts med en ytspänningsmetod. Denna komplex-bildning anses vara den verkliga mekanismen som fördröjer åldrandet i många stärkelsebaserade produkter, men kan ej påvisas med hjälp av röntgen för finstrukturanalys då komplexet ej har tillräckligt hög grad av ordning. (Less)
Abstract
The crystalline properties of starch constitutes a puzzling area of research. Our understanding of the crystalline structure of amylopectin, that is the crystalline component in starch, is based on the observations from investigations on modified amylose. The first part of this thesis includes a discussion of the unit cells (the smallest crystalline units) suggested in the literature. The different unit cells are discussed in relation to each other, and also to what could be reasonable to find in nature.



The second part of the thesis is focused on how the crystalline properties of starch are influenced by factors in the native state, and during processing, i.e., heating and cooling. Phosphate groups located at the C-6... (More)
The crystalline properties of starch constitutes a puzzling area of research. Our understanding of the crystalline structure of amylopectin, that is the crystalline component in starch, is based on the observations from investigations on modified amylose. The first part of this thesis includes a discussion of the unit cells (the smallest crystalline units) suggested in the literature. The different unit cells are discussed in relation to each other, and also to what could be reasonable to find in nature.



The second part of the thesis is focused on how the crystalline properties of starch are influenced by factors in the native state, and during processing, i.e., heating and cooling. Phosphate groups located at the C-6 position of potato starch were observed to influence the degree of crystallinity. The effect of these bulky phosphate groups can be altered by annealing, i.e., careful heat treatment in excessive amounts of water. Potato starches with a high content of phosphate groups were observed to have the largest shift in gelatinization enthalpies over the examined annealing period. This is not an effect of hydrolysis but rather their orientation towards positions causing less dislocations in the clusters.



The crystallinity will be lost in a two-stage process during gelatinization at intermediate levels of water. The X-ray and DSC results in that investigation show that the gelatinization of starch must be discussed in relation a glass transition of a partially crystalline polymer system, as previously suggested in the literature. The gelatinization parameters of starch can be changed by addition of the anionic surfactant sodium dodecyl sulphate (SDS). A brightfield microscopy study confirmed that SDS has the capability to penetrate granules and cause an extensive swelling of the starch granules.



Ageing of starch based foods is a problem for the consumers´ acceptability of many products. The early retrogradation of mainly the amylose fraction was investigated by microcalorimetric investigations at 25°C. This method was also used to study the complex formation between different starches and glycerol-monolaurin or SDS. The complex formation between amylopectin from potato and SDS was quantified by surface tension measurements. The degree of binding between amylopectin and SDS was 6 to 7 surfactant molecules per 1000 glucose units. The inclusion complexes cannot form crystalline junction zones, but are believed to be the true anti-staling mechanism of many starch based foods. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Dr Biliaderis, Costas G., Department of Food Science and Technology, Aristotle University, Thessaloniki, Greece
publishing date
type
Thesis
publication status
published
subject
keywords
Livsmedelsteknik, Food and drink technology, gelatinization, retrogradation, annealing, phosphorylation, amylopectin-lipid complex, amylose-lipid complex, amylopectin, starch, amylose
pages
60 pages
publisher
Food Technology, Lund University
defense location
Lecture hall A, Chemical Center
defense date
1996-04-18 10:15
external identifiers
  • Other:ISRN: LUTKDH/TKL0-1025/1-60
language
English
LU publication?
no
id
e07979a3-792e-4676-838e-2df6d44f42c2 (old id 28318)
date added to LUP
2007-06-11 15:46:34
date last changed
2016-09-19 08:45:09
@misc{e07979a3-792e-4676-838e-2df6d44f42c2,
  abstract     = {The crystalline properties of starch constitutes a puzzling area of research. Our understanding of the crystalline structure of amylopectin, that is the crystalline component in starch, is based on the observations from investigations on modified amylose. The first part of this thesis includes a discussion of the unit cells (the smallest crystalline units) suggested in the literature. The different unit cells are discussed in relation to each other, and also to what could be reasonable to find in nature.<br/><br>
<br/><br>
The second part of the thesis is focused on how the crystalline properties of starch are influenced by factors in the native state, and during processing, i.e., heating and cooling. Phosphate groups located at the C-6 position of potato starch were observed to influence the degree of crystallinity. The effect of these bulky phosphate groups can be altered by annealing, i.e., careful heat treatment in excessive amounts of water. Potato starches with a high content of phosphate groups were observed to have the largest shift in gelatinization enthalpies over the examined annealing period. This is not an effect of hydrolysis but rather their orientation towards positions causing less dislocations in the clusters.<br/><br>
<br/><br>
The crystallinity will be lost in a two-stage process during gelatinization at intermediate levels of water. The X-ray and DSC results in that investigation show that the gelatinization of starch must be discussed in relation a glass transition of a partially crystalline polymer system, as previously suggested in the literature. The gelatinization parameters of starch can be changed by addition of the anionic surfactant sodium dodecyl sulphate (SDS). A brightfield microscopy study confirmed that SDS has the capability to penetrate granules and cause an extensive swelling of the starch granules.<br/><br>
<br/><br>
Ageing of starch based foods is a problem for the consumers´ acceptability of many products. The early retrogradation of mainly the amylose fraction was investigated by microcalorimetric investigations at 25°C. This method was also used to study the complex formation between different starches and glycerol-monolaurin or SDS. The complex formation between amylopectin from potato and SDS was quantified by surface tension measurements. The degree of binding between amylopectin and SDS was 6 to 7 surfactant molecules per 1000 glucose units. The inclusion complexes cannot form crystalline junction zones, but are believed to be the true anti-staling mechanism of many starch based foods.},
  author       = {Svensson, Erik},
  keyword      = {Livsmedelsteknik,Food and drink technology,gelatinization,retrogradation,annealing,phosphorylation,amylopectin-lipid complex,amylose-lipid complex,amylopectin,starch,amylose},
  language     = {eng},
  pages        = {60},
  publisher    = {ARRAY(0x7f44c20)},
  title        = {Crystalline Properties of Starch},
  year         = {1996},
}