Molecular Structure of Selected Tuber and Root Starches and Effect of Amylopectin Structure on Their Physical Properties

Abstract

The objectives of this study were to characterize starches isolated from potato, canna, fern, and kudzu, grown in Hangzhou, China, for potential food and nonfood applications and to gain understandings of the structures and properties of tuber and root starches. Potato and canna starches with B-type X-ray patterns had larger proportions of amylopectin (AP) long branch chains (DP g37) than did fern (C-type) and kudzu (CA-type) starches. The analysis of Naegeli dextrins suggested that fern and kudzu starches had more branch points, R-(1,6)-D-glycosidic linkages, located within the double-helical crystalline lamella than did the B-type starches. Dispersed molecular densities of the C-and CA-type APs (11.6-13.5 g/mol/nm3) were significantly larger than those of the B-type APs (1.4-6.1 g/mol/nm3) in dilute solutions. The larger proportion of the long AP branch chains in the B-type starch granules resulted in greater gelatinization enthalpy changes (ΔH). Retrograded kudzu starch, which had the shortest average chain length (DP 25.1), melted at a lower temperature (37.9 °C) than the others. Higher peak viscosities (550-749 RVU at 8%, dsb) of potato starches were attributed to the greater concentrations of phosphate monoesters, longer branch chains, and larger granule sizes compared with other tuber and root starches. KeywordsCenter for Crops Utilization and Research, Amylose, amylopectin, molecular weight, dispersed molecular density, gelatinization, retrogradation, pasting The objectives of this study were to characterize starches isolated from potato, canna, fern, and kudzu, grown in Hangzhou, China, for potential food and nonfood applications and to gain understandings of the structures and properties of tuber and root starches. Potato and canna starches with B-type X-ray patterns had larger proportions of amylopectin (AP) long branch chains (DP g37) than did fern (C-type) and kudzu (C A -type) starches. The analysis of Naegeli dextrins suggested that fern and kudzu starches had more branch points, R-(1,6)-D-glycosidic linkages, located within the double-helical crystalline lamella than did the B-type starches. Dispersed molecular densities of the C-and C A -type APs (11.6-13.5 g/mol/nm 3 ) were significantly larger than those of the B-type APs (1.4-6.1 g/mol/nm 3 ) in dilute solutions. The larger proportion of the long AP branch chains in the B-type starch granules resulted in greater gelatinization enthalpy changes (∆H). Retrograded kudzu starch, which had the shortest average chain length (DP 25.1), melted at a lower temperature (37.9°C) than the others. Higher peak viscosities (550-749 RVU at 8%, dsb) of potato starches were attributed to the greater concentrations of phosphate monoesters, longer branch chains, and larger granule sizes compared with other tuber and root starches.

Physicochemical properties of starch isolated from eight different varieties of Korean sweet potatoes

“…In contrast, Shinchunmi AP had 28.1% short chains (DP6‐12). Although Juhwangmi and Shinchunmi showed A‐types and Shinjami, Yeonwhangmi, and Jeungmi showed C‐types, the percentages of short chains (DP6‐12) and long chains (DP ≥ 37) differed from the Yoo et al results. Starches with a higher proportion of shorter AP chains (around DP10) showed slower retrogradation, whereas starches with a higher proportion of longer chains (around DP15) show faster retrogradation.…”

“…The branch chain length distributions of AP are summarized in Table . Apart from other tuber and root starches , all APs except Shinchunmi AP showed the peak at DP12. Juhwangmi AP had the highest of 33.2% short chains (DP6‐12), and the average number and average weight of DP were of the lowest values, 13.7 and 16.1, respectively.…”

“…Pasting properties are influenced by the size and shape of granules, AM content, branched chain‐length distribution of AP, DP, phosphate‐monoester derivatives, and lipids. The AP contributes to the swelling of starch granules, and amylose–lipid complexes inhibit swelling . Jane and Chen reported that the AM molecular size and AP branch chain‐length distribution produced synergistic effects on viscosity of starch pastes.…”

C‐type starches and their derivatives: structure and function

“…The C‐type starch pattern is a mixture of A‐ and B‐types owing to the presence of both A‐ and B‐polymorph crystallites and is considered to be more complicated . Amylopectin in C‐type starch granules has relatively intermediate chain lengths and both short and long chains …”

Isolation and characterization ofAlstroemeria hookerissp.hookeristarch in comparison with potato starch

“…It can be seen that potato starch had the higher proportion of intermediate/short chains (DP 13‐24) and Alstroemeria starch had the higher proportion of long chains (DP ≥ 37). Yoo et al studied the effect of chain length distribution on swelling and pasting behavior of six native tuber and root starches. They found that high‐ M w AP molecules increased swelling (see Table ) as can be seen for Alstroemeria .…”