Cross-linking Arenga pinnata starch and chitosan by citric acid: Structure and properties

In order to improve the processing and digestibility of the Arenga pinnata (Wurmb.) Merr. starch (APS), low concentration citric acid (CA) and chitosan (CS) were used for dual modification. The purpose of this study was to prepare APS and CS complexes with CA, the complexes (CA-CS-APS) physicochemical properties were investigated. The short-range ordered structure (DO), double helix structure (DO) and relative crystallinity (RC) were decreased; CA-CS resulted in the surface roughness of APS, but the particle integrity was preserved; the particle size of CA-CS-APS was increased. Compared with APS, the peak viscosity of CA-CS-APS was decreased from 2534 cP to 27 cP; CA-CS reduced the swelling power of APS, CA3%-CS-APS decreased from 19.00 g/g to 8.17 g/g. The gelatinization enthalpy was decreased after CA-CS modification from 3.25 J/g to 0.55 J/g. CA-CS-APS exhibits higher storage modulus and loss modulus (2067 Pa and 80 Pa). CA-CS significantly improved the anti-digestibility of APS, and the resistant starch (RS) content was increased from 32 % to 39 %. This study provided a simple and effective way to prepare modified starch, which had the potential as food additives or used as a base material for film preparation.

Modeling and investigation of swelling kinetics of sodium carboxymethyl cellulose/starch/citric acid superabsorbent polymer

Crosslinked hydrophilic polymers with high water absorption rates are known as superabsorbent polymers (SAPs). Most commercial superabsorbent polymers are made with acrylic acid, which is difficult to biodegrade. So, in this investigation, carboxymethyl cellulose (CMC) was utilized as a significant component in the synthesis of polysaccharide-based SAPs. Citric acid (CA) and starch were chosen as crosslinking agents because they are more eco-friendly, non-toxic, and biodegradable than traditional crosslinking agents. FTIR analysis revealed that the superabsorbent polymer product contains a crosslinked structure of CMC and starch with side chains that carry carboxylate functional groups. Superabsorbent weight loss and grafting data were satisfactorily studied using the TGA approach. Under optimum circumstances, the SAP2 water absorbency capacity in distilled water was 287.37 g.g-1 and SAP1 absorbency capacity in a solution containing 0.9 wt% NaCl was 52.18 g.g-1. Moreover, Schott's pseudo-second-order model was used to determine the kinetic swelling of the superabsorbent. The initial swelling rate of SAPs can be calculated using the Q∞ data acquired in the following order: SAP2 > SAP1 > SAP3 > SAP4 in distilled water and SAP1 > SAP2 > SAP3 > SAP4 in 0.9 wt% NaCl solution, respectively. The findings suggested that a small amount of citric acid introduced into the SAPs matrix could enhance the swelling rate of SAPs. The results of the cytotoxicity tests show that the extraction liquid of composite hydrogel fibers is less cytotoxic than the positive control. As well, SAP underwent in silico docking investigations on the DNA Gyrase enzyme. As the ligand is a monomer of SAP, it was a long chain of carbohydrate molecules with alcoholic groups, esters groups, and keto groups forms a strong binding interaction with DNA gyrase.

Impact of pH on physicochemical properties of corn starch by dry heat treatment

This study investigated the effects of temperature, pH, and starch genotype on starch characteristics after dry heat treatment (DHT). DHT starches were prepared according to 19 DHT conditions, constructed using a D-optimal design, and analyzed with respect to apparent amylose (AAM) content, X-ray diffraction (XRD) pattern, relative crystallinity (RC), solubility and swelling power (SP), thermal properties, and pasting viscosity. The DHT starches maintained their granular structures even after DHT at pH 3, although there was some damage to their granular surfaces. The DHT starches showed lower amylose content, RC, SP, gelatinization temperature and enthalpy, degree of retrogradation, and pasting viscosity, but higher solubility, compared to those of native starches. These DHT effects were more pronounced as pH decreased at each temperature, regardless of the starch genotype. Overall, DHT can be used to expand the physical functionality of high-amylose and highly crystallized starches with poor properties.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01353-7.

Water chestnut, rice, corn starches and sodium alginate. A comparative study on the physicochemical, thermal and morphological characteristics of starches after dry heating

Water chestnut (Trapa bispniosa), rice and corn starch were modified with sodium alginate and subjected to dry heating for 0,2 and 4 h for at 130 °C. The physicochemical, thermal and morphological properties of native as well as modified starches were determined. Thermal and morphological properties were studied using Differential Scanning Calorimeter (DSC) and Scanning Electron Microscopy (SEM). It was observed that the dry heating of starches with and without sodium alginate significantly reduce the swelling power, solubility, paste clarity whereas, water absorption and syneresis increased. The swelling power was higher for corn starch as compared to other starches while rice starch has higher syneresis. In the presence of sodium alginate the water absorption was increased in all starch samples upon heating. The onset temperature was found to be increased after dry heating of all starches. The maximum increased was noticed for rice starch. Morphological studies showed the damaging of granule surface with the accumulation of leached amylose and gum but total degradation was not observed. Peak viscosity, final viscosity, breakdown, and setback of RS- sodium alginate mixture were reduced on dry heating. Although pasting temperature of rice starch was not significantly changed.

Development and characterization of potato amylopectin-substituted starch materials

This study characterized the blends of corn starch with potato amylopectin (PAP) and PAP hydrolysates treated with branching enzyme (BR), pullulanase (PL), and BR-BL cocktail. PAP/PAP hydrolysates were deposited or bound (particularly in intact and PL-treated PAPs) on the surfaces of corn starch granules. Although PAP/PAP hydrolysates rarely affect the X-ray diffraction patterns of the blends, their relative crystallinities decreased. Relative to native starches, the swelling power was higher for all blends. Solubility was higher for normal starch-based blends but lower for waxy starch-based blends. All blends exhibited higher gelatinization temperatures and lower gelatinization enthalpies. Although the pasting viscosities of blends with intact PAP were higher than those of native starches, the opposite trends were found in blends with BR-, PL-, and BR-PL cocktail-treated PAPs. Overall, the PAP structures diversified the characteristics of the corn starch-PAP blends. BR- and BR-PL cocktail-treated PAPs could function as stabilizers for stable paste consistency.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-021-00919-7.

Characteristics of wheat starch-pectin hydrolysate complexes by dry heat treatment

The objective of this study was to characterize dry heat-induced wheat starch-pectin hydrolysate (WST/PH) complexes to develop the retrogradation-retarded starch. Native (N-) and protease-treated (P-) WST were used as starch sources. Pectin hydrolysates were mixed independently with N-WST and P-WST to a mixing ratio of 49:1 (based on total solid contents), followed by drying below 10% moisture and dry heat treatment at 130 °C for 4 h. The molar degrees of substitution (MS) was higher for WST/PH complexes than its mixtures, and apparent amylose contents decreased with their MS. Relative to WST/PH mixtures, solubilities were higher for WST/PH complexes, while swelling powers didn't differ. WST/PH complexes showed the lower degree of retrogradation, setback viscosities, slowly gelling tendency, and syneresis. These phenomena were more pronounced in WST/PH mixtures and complexes prepared with P-WST. Overall results suggest that dry heat-induced WST/PH complexes could be a potential retrogradation-retarded starch to replace chemically-modified starches.

Effect of dry heat treatment on the physicochemical properties and structure of proso millet flour and starch

Proso millet (Panicum miliaceum L.) flour and starch were heated in a dry state at 130°C for 2 or 4 h. The effects of dry heat treatment (DHT) on the pasting, morphological and structural properties of the samples were evaluated. Dry heat treatment had a more significant effect on the pasting viscosity of flour than starch; it increased the pasting viscosity of the flour while it only increased the final viscosity of the starch. After dry heating, the onset of gelatinization and the peak temperatures of the samples increased significantly while the endothermic enthalpy decreased. Scanning electron microscopy showed that the gel structure of the samples became more compact and the particles were plumper when compared with the native ones. Crystallinity of the samples decreased while the X-ray diffraction patterns remained the same after DHT.