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Abstract Sweet potato is an important starch resource and has different colored root tubers due to different genotype backgrounds. However, it is unclear whether starch properties are related to the color of root tuber. In this study, 3 white, 3 yellow, and 3 purple sweet potato varieties were planted in the same environment. The dry root tubers of white varieties had the highest starch ranging from 61.5 to 67.5% and the lowest soluble sugar ranging from 13.1 to 18.0%, and those of yellow varieties had the lowest starch ranging from 45.8 to 53.1% and the highest soluble sugar ranging from 28.9 to 31.5%. Starches from different varieties had different granule sizes (D[4,3] 12.3–18.1 μm) and amylose contents (24.1–27.2%), but all exhibited C A -type crystalline structure. The relative crystallinity ranged from 22.3 to 25.5%, and the IR absorbance ratios of 1045/1022 and 1022/995 cm−1 ranged from 0.665 to 0.775 and from 0.846 to 0.944, respectively, among 9 varieties. The starches from the same or different colored varieties had differences in swelling power, water solubility, gelatinization temperature, pasting viscosity, and digestion properties. The cluster analysis based on starch property parameters indicated that starch properties of sweet potato had no relationship with the color of root tuber but were determined by the genotype background of variety. Graphical abstract Image 1 Highlights • Starch properties were measured in 3 white, 3 yellow and 3 purple sweet potatoes. • The white and yellow varieties contained the highest and lowest starch, respectively. • The starches from the same or different colored varieties had different properties. • The cluster analysis of different colored varieties was based on starch properties. • Characteristics of starch had no relationship with the color of root tuber. [ABSTRACT FROM AUTHOR]

Abstract The extra-long chain (ELC) of amylopectin influences molecular compositions of starch. In this study, starches were isolated from 22 rice varieties with different ELCs. Molecular compositions of starch were determined, and their relationships with crystalline structure, gelatinization properties, pasting properties, and enzyme hydrolysis were analysed. The results showed that the starches with different ELCs had significantly different structural and functional properties. The ELC was significantly positively related to setback viscosity and negatively related to relative crystallinity, lamellar peak intensity, swelling power, gelatinization enthalpy, and rapidly digestible starch of retrograded starch. The true amylose content was significantly positively related to retrogradation and negatively related to peak viscosity and hydrolysis degree by α-amylase and amyloglucosidase. The short branch-chain of amylopectin was significantly positively related to lamellar peak intensity, swelling power, hydrolysis degree by α-amylase, and rapidly digestible starch of retrograded starch and negatively related to setback viscosity and resistant starch of retrograded starch. The ratio of short to long branch-chain of amylopectin was significantly positively related to swelling power and hydrolysis degree by α-amylase. The principal component analysis and partial least squares discriminant analysis demonstrated that the low-ELC starches were distinguished from the middle- and high-ELC starches, the middle-ELC starches basically clustered together, but the high-ELC starches were highly dispersed. The above results would provide some new information for rice quality breeding and starch applications by changing the ELC in starch. Graphical abstract Image 1 Highlights • Starches from 22 rice varieties had different extra-long chains (ELC) of amylopectin. • GPC profiles of debranched starch and amylopectin measured molecular compositions. • Gelatinization and pasting properties and enzyme hydrolysis of starch were measured. • PLSR showed interrelationship between molecular compositions and starch properties. • PCA and PLS-DA revealed the differences among rice varieties with different ELCs. [ABSTRACT FROM AUTHOR]

C-type starches isolated from different colored root tubers of sweet potatoes were investigated to reveal the distribution of A- and B-type crystals using differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and hot stage microscopy. The results showed that starches from different colored sweet potatoes all exhibited C A -type XRD patterns and wide DSC thermal peak curves. The thermal peaks could be highly fitted into three peaks, defined as Peak 1, 2 and 3, according to their gelatinization temperatures (GTs) from low to high. When starch was gelatinized in KCl solution, the peak temperature of Peak 1 increased slightly and then decreased, but those of Peak 2 and 3 increased first rapidly and then slowly with increasing KCl concentration. Starch was gelatinized from the interior to exterior of granules, and could be divided into three groups, defined as Group 1, 2 and 3, according to their GTs from low to high, corresponding to Peak 1, 2 and 3 of DSC thermogram, respectively. The starch granules in Group 2 had significantly wider GT range than those in Group 1 and Group 3. The starch granules with increasing GT exhibited XRD patterns from C A - to A-type and DSC thermograms from wide three-peak to narrow single peak. B-type starch granules had higher short-range ordered structure than A-type starch granules. The above results indicated that B-, C-, and A-type starch granules with GT from low to high coexisted in root tubers of sweet potato. Image 1 • C-type starches from different colored sweet potatoes had wide thermal peak curves. • 3 peaks with different gelatinization temperatures (GTs) were fitted from peak curve. • 3 groups of starch granules with different GTs were also detected during heating. • Starches with low and high GTs were B- and A-type starch granules, respectively. • Starch with middle GT had both A- and B-type crystals coexisted in the same granule. [ABSTRACT FROM AUTHOR]

The multi-scale structural dynamics of amylopectin-only barley starch (APBS), normal barley starch (NBS), and amylose-only barley starch (AMBS) digested with amylolytic enzymes for 120 min were investigated in this study. For all starches, 0–20 min was identified as a rapid digestion stage, followed by a 20–120 min slow digestion. For APBS and NBS, the content of short chains (DP ≤ 12) and the thickness of crystalline and amorphous nano-lamellae increased, whereas the crystallinity decreased, and pores were generated on the granular surface during the rapid digestion stage. At the following slow digestion stage, the branching degree and relative amount of double helices increased, the crystalline and lamellar structures were lost, and the hydrolyzed starch segments aggregated. For AMBS, the rapid digestion stage was characterized by an increased content of short chains (DP ≤ 8) and B-type crystals and decreased amounts of V-type crystals. Furthermore, the lamellar and granular structures were lost, and digestion residues aggregated during the first stage of AMBS, which were formed in the second digestion stage of APBS and NBS. The second slow digestion stage of AMBS was characterized by an increased branching degree and a decreased relative content of single helices. It is suggested that the aggregated digestion residues at the initial digestion stage are the main reason for the overall low digestibility of AMBS. [Display omitted] • Amylose barley starch (AMBS) lost granular structure at initial digestion stage. • AMBS reorganized immediately and was thereafter hydrolytic resistant. • Single helices and the V-type crystals decreased in AMBS upon hydrolysis. • Amylopectin barley starch (APBS) first generated pores and then reorganized. • APBS had a high content of double helices after digestion. [ABSTRACT FROM AUTHOR]

Sweet potato starch has great edible and economic value and has been widely studied. Starches from different varieties have significantly different properties. Previous studies are focused on white, yellow and orange sweet potato. In this study, starches were isolated from purple sweet potato variety Ningzi 1 and six advanced breeding lines with different genotypes, their structural and functional properties were investigated and compared. Seven starches all had round, polygonal, oval and semi-oval shapes with central hila, but showed different granule sizes. The starch content in dry root tubers varied from 40.1 to 55.1%. The apparent amylose content ranged from 24.6 to 31.0%. The seven sweet potatoes all had C A -type starch. The swelling power and water solubility at 95 °C ranged from 22.5 to 29.0 g/g and 13.1 to 16.9%, respectively. The starches displayed a two peak gelatinization thermogram, the first peak temperature ranged from 64.1 to 69.0 °C and the second peak temperature ranged from 73.5 to 80.8 °C. The peak viscosity, hot viscosity, breakdown viscosity and setback viscosity varied from 2535 to 3750 mPa s, 1517 to 2450 mPa s, 1018 to 1622 mPa s, and 474 to 1036 mPa s, respectively. The seven starches had different hydrolysis degrees to porcine pancreatic α-amylase and Aspergillus niger amyloglucosidase. All the starches had high resistance to the in vitro digestion. This study could provide important information for the utilization of purple advanced breeding lines in breeding and food and nonfood industries. [ABSTRACT FROM AUTHOR]