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Research article2023Peer reviewedOpen access

Internal structure and thermal properties of potato starches varying widely in amylose content

Zhao, Xue; Hofvander, Per; Andersson, Mariette; Andersson, Roger

Abstract

The correlation between starch internal structure and thermal properties (gelatinisation and retrogradation) was studied in starches of wild-type potatoes and potatoes from the lines with altered starch synthase or branching enzyme activities (GBSS, SS, SBE), representing a range of amylose:amylopectin ratio from 2 to >99.5% amylopectin. The different potato lines were divided into Group 1-8 depending on the mutation targets. The internal chain distribution and building block composition of beta-limit dextrins (beta-LDs) in the whole starches were analysed by high-performance anion-exchange chromatography (HPAEC) and high-performance size -exclusion chromatography (HPSEC) based on a recently developed simplified method. The building blocks were categorised into five size groups (G2-G6). Thermal properties of the starches were investigated using differential scanning calorimetry (DSC). The proportion of fingerprint B-chains with the degree of polymerisation 4-7, and the composition of intermediate (G4) and large (G5 and G6) building blocks of starches generally decreased in the order of potato lines from Group 2 (full Sbe1 and partial Sbe2 mutated)>Group 1 (full Sbe1 mutated)>wild-type > Group 7 (full Gbss and Ss2, and partial Ss3 mutated)>Group 8 (full Gbss, Ss2, and Ss3 mutated). The starch of amylopectin-rich potato lines from Group 8 with multiple genes targeted and the highest degree of mutations showed the lowest enthalpy of gelatinisation (15.0 J/g of amylopectin) and retrogradation (3.1 J/g of amylo-pectin), compared to starches of potato lines from other groups. More intermediate and large building blocks led to higher gelatinisation temperatures. Retrogradation was favoured by dense structure of the amylopectins with many short internal chains.

Keywords

Potato; Starch; Amylopectin structure; Gelatinisation; Retrogradation

Published in

Food Hydrocolloids
2023, Volume: 135, article number: 108148Publisher: ELSEVIER SCI LTD