Structural properties of the intra- and interhelical cavities of V6-type crystalline starches

Chemical characterization of single helical mung bean amylopectin

The distinctive chemical properties of amylopectin are attributable to the single and double helical structures that are characteristic of the polysaccharide. In the extant literature, amylopectin is generally described as a combination of these two structural forms, with limited studies focusing exclusively on the chemical properties of the single helical ones. In this paper, the single/double helical mung bean amylopectin (SMBA/DMBA) was prepared by the innovative methodology developed in-house and its chemical properties were characterized by molecular weight, chain length distribution, light micrographs, FT-IR、13C Solid-state NMR, XRD, and DSC. The results indicated that the primary branch diameter of SMBA aggregates was approximately half that observed in the double helical structure. Furthermore, the number-average molecular weight (Mn) of SMBA was found to be 123,538 g/mol, with a higher proportion of chains with 1, 10-13 glucose residues. The wavenumbers of 1022.6 and 1020.6 cm-1 represented the amorphous structure composed of SMBA and DMBA, respectively. In comparison with DMBA, the resonances of carbon atoms, excluding C4, in SMBA exhibited a lower field shift. The diffraction angles of single-helix mung bean amylopectin were found to be 2θ at 17.54 o and 22.28 o. The findings of this study provide a reliable marker for the identification of single helix in starch and its influence on the properties of starch.

Fabrication and characterization of decanoyl chloride/curcumin-modified potato starch nanoparticles and the potential application in the stabilization of flaxseed oil-in-water Pickering emulsions

In the current study, gelatinized potato starch was modified by decanoyl chloride and curcumin via esterification and pH-driven method at two pH levels (pH 8 and 12), respectively, followed by precipitation and formation of anionic nanoparticles. The effects of modifications on the various properties of starch nanoparticles were investigated. A decrease in mean particle diameter and branching degree as well as an increase in product mass, fatty acid substitution degree (0.043 to 0.049), curcumin encapsulation efficiency (83.0 % to 86.7 %), and absolute zeta-potential value (-30.3 to -41.2 mV) were observed at pH 12 compared to pH 8. The starch esterification process was confirmed by FTIR and 1H NMR analyses. XRD results revealed changes in the crystallinity index and the crystal pattern from B-type in native starch to V-type in modified starch nanoparticles. Contact angle values of different modified nanoparticles ranged from 85.9° to 130.9°. Pickering emulsions with a mean diameter of 6.79 μm and a zeta-potential value of -30.5 mV were stabilized by decanoyl chloride/curcumin-modified starch nanoparticles. Bright-field microscopy and confocal Raman spectral mapping of Pickering emulsion droplets confirmed the adsorption of modified starch nanoparticles at the interfacial layer. Tailored particle size and hydrophobicity might provide potential advantages for tuning the properties of Pickering emulsions stabilized by these nanoparticles.

Formation of the rosette-like starch with enhanced V-type crystallization via modified solvent-shifting method

This research investigated the effect modified solvent-shifting method on the formation, ordered structure, and morphology of V-type starch. Ionic liquid (IL) dissolution and hot ethanol aqueous incubation in gradient concentrations from 30 % to 80 % (v/v) were applied to optimize the relative crystallinity of V-type starch. The results showed that this new method worked in producing V-type conformation, and higher ethanol concentration tended to yield V-type starch with higher crystallinity and more disk-like shape structure within the ethanol range of 30-50 % (v/v). Notably, the crystalline order of V-type starch reached the maximum with a specific rosette-like morphology under the condition of an ethanol concentration of 50 % (v/v). While the grown crystals organized into small-size flower-like assemblies and this morphology even disappeared accompanied by the V-type crystallization weakening when starch chains co-crystallized with the ethanol concentrations of 60 %-80 % (v/v). The molecular structure analysis indicated no significant correlation between the relative crystallinity of V-type starch and its fine structure. IL served to promote the formation of V-type starch, while it didn't participate in the formation process and could be removed during the washing process. The findings can provide new insights into developing a bottom-up pathway for regulating crystallization and morphology of V-type starch.

Effects of different fatty acids on the structure, physicochemical properties, and in vitro digestibility of Chinese yam resistant starch-lipid complexes

Nine CYRS-FA complexes were prepared by resistant starch in Chinese yam (CYRS) and nine fatty acids (FAs) with different chain lengths and degrees of unsaturation. CYRS-myristic acid and CYRS-palmitic acid showed higher complexing index (CI) and relative crystallinity (RC); CYRS-myristic acid and CYRS-oleic acid exhibited lower estimated glycemic index (eGI). Chain lengths of FAs showed significantly positive correlations with CI and contact angle (CA), and yet, unsaturation degree of FAs was negative correlated with both CI and CA. The eGI exhibited positive relations with solubility, and negative correlations with CI and RC. Therefore, the results indicated that chain lengths and unsaturation degrees of FAs were key factors for complexation of the CYRS-FA complexes, which influenced the structural, physicochemical and digestive properties. The findings were expected to provide a theoretical foundation for the interactions between starch and lipids in food processing, and elevate the high-tech values of Chinese yam.

Adsorption mechanism of key off-odor compounds of oyster peptide by V-type starch in the solid-phase environment

V-type starch was employed to adsorb key off-odors (heptanal and 1-octen-3-ol) of oyster peptide (OP), and the adsorption mechanism was investigated. The off-odor content was quantified using gas chromatography (GC), and the successful inclusion complexes (ICs) between the key off-odors of OP and V-type starches were detected by X-ray diffraction, differential scanning calorimetry, Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy. In FTIR spectra, the appearance of new peaks and the shifts of characteristic peaks in ICs indicated the successful formation of ICs between V-type starches and heptanal or 1-octen-3-ol. The results of thermodynamic analysis showed that the endothermic peaks of ICs in the range of 113-116 °C corresponded to the formation of V-type II complexes. The GC results suggested that V6a- and V7a-type starches exhibited selective adsorption of heptanal and 1-octen-3-ol, respectively, which was attributed to the size compatibility between starches and guest molecules. Furthermore, the correlation analysis exhibited that the encapsulation efficiency and loading efficiency of V-type starches for heptanal and 1-octen-3-ol were correlated with the enthalpy, short-range order degree and relative crystallinity. The research findings demonstrate the good adsorption effects of V-type starches on characteristic off-odors of OP, which could effectively improve the flavor of OP.

Impact of magnetic field-assisted freezing on the physicochemical properties and starch structure of cooked rice: Effects of magnetic types, intensities, and cryostasis time

A magnetic field-assisted freezing system was developed to mitigate the degradation of taste quality in frozen cooked rice (FCR). The physicochemical properties and starch structure were analyzed under varying magnetic field types, intensities, and cryostasis time. The analysis of freezing characteristics indicated that treatments with 10 mT static magnetic fields (SMF) and 6 mT alternating magnetic fields (AMF) yielded optimal results, significantly reducing the duration of the maximum ice crystal generation zone by approximately 18 min. Compared to no magnetic field (NMF) treatment, a 16-day frozen storage experiment showed significant improvements in the texture characteristics of cooked rice treated with magnetic fields. However, the moisture content of rice treated with AMF closely resembled those of freshly cooked rice, with a slight increase in yellowness compared to SMF treatment. Throughout the storage period, the crystallinity for the AMF treatment exceeded that of the SMF treatment by 2.99 %. Furthermore, compared to SMF treatment, water molecules in FCR treated with AMF are more tightly bound. Given the superior sensory scores in the AMF treatment, it can be concluded that while SMF reduces color degradation, AMF is more effective in preserving moisture, and structural density. Hence, magnetic fields, especially AMF, emerge as a promising auxiliary technology for FCR, offering a theoretical basis for advancing cold chain logistics technology for cooked rice.

Insights into impact of chlorogenic acid on multi-scale structure and digestive properties of lotus seed starch under autoclaving treatment

The interaction between polyphenols and starch is an important factor affecting the structure and function of starch. Here, the impact of chlorogenic acid on the multi-scale structure and digestive properties of lotus seed starch under autoclaving treatment were evaluated in this study. The results showed that lotus seed starch granules were destroyed under autoclaving treatment, and chlorogenic acid promoted the formation of loose gel structure of lotus seed starch. In particular, the long- and short-range ordered structure of lotus seed starch-chlorogenic acid complexes were reduced compared with lotus seed starch under autoclaving treatment. The relative crystallinity of A-LS-CA complexes decreased from 23.4 % to 20.3 %, the value of R1047/1022 reduced from 0.87 to 0.80, and the proportion of amorphous region increased from 10.26 % to 13.85 %. In addition, thermal stability, storage modulus and loss modulus of lotus seed starch-chlorogenic acid complexes were reduced, indicating that the viscoelasticity of lotus seed starch gel was weakened with the addition of chlorogenic acid. It is remarkable that chlorogenic acid increased the proportion of resistant starch from 58.25 ± 1.43 % to 63.85 ± 0.96 % compared with lotus seed starch under autoclaving treatment. Here, the research results provided a theoretical guidance for the development of functional foods containing lotus seed starch.

Insights into formation and stability mechanism of V7-type short amylose-resveratrol complex using molecular dynamics simulation and molecular docking

Pre-formed V-type amylose as a kind of wall material has been reported to carry polyphenols, while the interaction mechanism between V-type amylose and polyphenol is still elusive. In this work, the formation and stability mechanism of a V7-type short amylose-resveratrol complex was investigated via isothermal titration calorimetry, molecular dynamics, and molecular docking. The results presented that two stoichiometric ratios of resveratrol to short amylose were calculated to 0.120 and 0.800, and the corresponding main driving force was hydrogen bonding and hydrophobic interaction, respectively. The folding and unfolding conformation of V7-type short amylose chains appeared alternately during the simulation. Resveratrol tended to be bound in the short amylose helix between 40 ns and 80 ns to form a more stable complex. Hydrogen bonds between resveratrol molecule and O6 at the 22nd glucose molecule/O2 at the 24th glucose molecules and hydrophobic interaction between resveratrol molecule and glucose molecules (19th, 20th, 21st and 23rd) could be found.