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1、Chapter 7 Starch processing 知识点知识点2 Starch propertiesStarch propertiesStarch propertiesRetrogradationSolubilisedstarchpolymerandremaininginsolublegranularfragmenttendtore-associateafterheating.There-associatingistermed“Retrogradation”.RetrogradationRetrogradationisaprocesswhichoccurswhenstarchchains
2、starttore-associateintoanorderedstructure.Initsinitialphase,twoormorestarchchainsmayformasimplejunctionpoint,whichthenmaydevelopintomoreextensivelyorderedregions.Ultimately,underfavourableconditions,acrystallineorderappears.Generally,amylose-containingstarchesshowgreaterretrogradation.Factors relati
3、ng to retrogradation include:Temperature4C.Moisturecontent20-60%.Amountofbranching.Highamylopectinstarches-e.g.,waxymaizeshowsnoretrogradationwhenfrozen.HydrogenbondingbetweenOHgroupsinamyloseingelatinisedstarchesduringcooling.Waterforcedoutofgelstructure(syneresis)&Starchinsolubilized.Factors relating to retrogradation include:Amylopectinalsoplaysaroleinretrogradationovertime.Short-termretrogradationislargelyassociatedwithamylose(whichreachesalimitin2days),whereaslong-termretrogradationisthoughttoinvolvedamylopectin(reachingalimitis40days).