Iodine binding property of a ternary complex consisting of starch, protein, and free fatty acids

Impacts of transglutaminase on the processing and digestion characteristics of glutinous rice flour: Insight of the interactions between enzymic crossing-linked protein and starch

Glutinous rice is extensively consumed due to its nutritious content and wonderful flavor. However, glutinous rice flour has a high glycemic index, and the storage deterioration of sweet dumplingsissevere. Transglutaminase (TG) was used to cross-link glutinous rice protein and improve the characteristics of glutinous rice products. The findings demonstrated that TG significantly catalysed protein cross-linking to form a dense protein network, reduced the viscosity of glutinous rice paste and improved the thermal stability. The protein network may physically block the access of starch granules to digestive enzymes to lower the digestion rate of starch, and attenuate the damage of ice crystal molecules to the starch structure to improve the freezing stability of starch gels. The cracking rate and water loss of sweet dumplings prepared using glutinous rice flour with TG treated for 60 min reduced significantly. In conclusion, this study broadened the application of TG in starch products.

Preparation, structure, and in-vitro hypoglycemic potential of debranched millet starch-fatty acid composite resistant starch

Currently, the preparation methods and basic physicochemical properties of starch-FA complexes have been widely studied; however, no in-depth research on the regulatory mechanism of the digestive properties of debranched starch-unsaturated FA complexes has been conducted. Therefore, six fatty acids with different carbon chains and different degrees of unsaturation were complexed with de-branched millet starch in this research, using the microwave method. Microwave millet starch-linoleic acid complex (MPS-LOA) had the highest resistant starch (RS) content, and the structure and physicochemical properties of MPS-LOA were determined using various molecular techniques. The results indicate that MPS-LOA had a resistant starch (RS) content of 40.35% and the most notable fluorescence. The characteristic UV peaks of MPS-LOA were blue-shifted, and new IR peaks appeared. The crystalline structure changed to V-type crystals, the crystallinity increased, and the molecular weight decreased. The enthalpy and coagulability of MPS-LOA increased, and the swelling force decreased. Additionally, MPS-LOA showed enhanced α-glucosidase and α-amylase inhibition, and in-vitro hydrolysis kinetics analysis of MPS-LOA showed a hydrolysis index of 53.8 and an extended glycemic index (eGI)I of 54.6, indicating a low eGI food suitable for consumption by people with type II diabetes. These results provide a theoretical basis for the preparation of amylopectin- and starch-based foods with an anti-enzyme structure and a low glycemic index (GI).

Dietary compounds slow starch enzymatic digestion: A review

Dietary compounds significantly affected starch enzymatic digestion. However, effects of dietary compounds on starch digestion and their underlying mechanisms have been not systematically discussed yet. This review summarized the effects of dietary compounds including cell walls, proteins, lipids, non-starchy polysaccharides, and polyphenols on starch enzymatic digestion. Cell walls, proteins, and non-starchy polysaccharides restricted starch disruption during hydrothermal treatment and the retained ordered structures limited enzymatic binding. Moreover, they encapsulated starch granules and formed physical barriers for enzyme accessibility. Proteins, non-starchy polysaccharides along with lipids and polyphenols interacted with starch and formed ordered assemblies. Furthermore, non-starchy polysaccharides and polyphenols showed robust abilities to reduce activities of α-amylase and α-glucosidase. Accordingly, it can be concluded that dietary compounds lowered starch digestion mainly by three modes: (i) prevented ordered structures from disruption and formed ordered assemblies chaperoned with these dietary compounds; (ii) formed physical barriers and prevented enzymes from accessing/binding to starch; (iii) reduced enzymes activities. Dietary compounds showed great potentials in lowering starch enzymatic digestion, thereby modulating postprandial glucose response to food and preventing or treating type II diabetes disease.

Influence of Hofmeister anions on structural and thermal properties of a starch-protein-lipid nanoparticle

A self-assembled soluble nanoparticle, composed of common food biopolymers (carbohydrate, protein) and lipid, was previously reported by our laboratory. Although carrying capacity of valuable small molecules was demonstrated, physical functional properties are also important. Given the stabilization or destabilization characteristics of Hofmeister anion on macromolecular structures, mainly on proteins, here, we investigated the effects of different sodium salts composed of different Hofmeister anions on the structural and thermal properties of these self-assembled nanoparticles for improved functionalities. The salts were added into the mixture that was prepared in a diluted system during nanoparticle formation. Increased concentration of kosmotropic anions, in contrast to the chaotropic anion tested, resulted in nanoparticles with higher molar mass, hydrodynamic radius, and molecular density with more compact arrangement. The nanoparticles produced in presence of kosmotropic anions dissociated at higher temperatures and required higher enthalpies compared to the control sample. Spherical nanoparticles were formed for the kosmotropes with shear thinning behavior, contrary to rod-like nanoparticles for the chaotrope with near-Newtonian behavior. These findings help to gain an understanding of the effect of altering environmental conditions on the nanoparticles with an aim of producing desired structures for applications.

Biodegradable Binary and Ternary Complexes from Renewable Raw Materials

The aim of this paper is to investigate the interactions between polysaccharides with different electrical charges (anionic and neutral starches) and proteins and fats in food ingredients. Another objective is to understand the mechanisms of these systems and the interdependence between their properties and intermolecular interactions. At present, there are not many studies on ternary blends composed of natural food polymers: polysaccharides of different electrical charge (anionic and neutral starches), proteins and lipids. Additionally, there are no reports concerning what type of interactions between polysaccharide, proteins and lipids exist simultaneously when the components are mixed in different orders. This paper intends to fill this gap. It also presents the application of natural biopolymers in the food and non-food industries.

Cationic surfactants as a non-covalent linker for oxidised cellulose nanofibrils and starch-based hydrogels

Rheological properties of hydrogels composed of TEMPO-oxidised cellulose nanofibrils (OCNF)-starch in the presence of cationic surfactants were investigated. The cationic surfactants dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB) were used to trigger gelation of OCNF at around 5 mM surfactant. As OCNF and DTAB/CTAB are oppositely charged, an electrostatic attraction is suggested to explain the gelation mechanism. OCNF (1 wt%) and soluble starch (0.5 and 1 wt%) were blended to prepare hydrogels, where the addition of starch to the OCNF resulted in a higher storage modulus. Starch polymers were suggested to form networks with cellulose nanofibrils. The stiffness and viscosity of OCNF-Starch hydrogels were enhanced further by the addition of cationic surfactants (5 mM of DTAB/CTAB). ζ -potential and amylose-iodine complex analyses were also conducted to confirm surface charge and interaction of OCNF-starch-surfactant in order to provide an in-depth understanding of the surfactant-induced gel networks.

Self-assembled nanoparticle of common food constituents that carries a sparingly soluble small molecule

A previously reported nanoparticle formed through the self-assembly of common food constituents (amylose, protein, and fatty acids) was shown to have the capacity to carry a sparingly soluble small molecule (1-naphthol) in a dispersed system. Potentiometric titration showed that 1-naphthol locates in the lumen of the amylose helix of the nanoparticle. This finding was further supported by calorimetric measurements, showing higher enthalpies of dissociation and reassociation in the presence of 1-naphthol. Visually, the 1-naphthol-loaded nanoparticle appeared to be well-dispersed in aqueous solution. Molecular dynamics simulation showed that the self-assembly was favorable, and at 500 ns, the 1-naphthol molecule resided in the helix of the amylose lumen in proximity to the hydrophobic tail of the fatty acid. Thus, sparingly soluble small molecules, such as some nutraceuticals or drugs, could be incorporated and delivered by this soft nanoparticle carrier.

Spectrophotometric determination of the formation constant of triiodide ions in aqueous-organic solvent or polymer mixed media both in absence and presence of a surfactant

The formation constant of triiodide ions from iodine-iodide equilibrium in aqueous-organic solvent or polymer mixed media have been determined spectrophotometrically at three different temperatures 20, 30 and 40°C. The organic solvents chosen for the study are ethylene glycol, 2-methoxy ethanol, and 2-ethoxy ethanol while the polymers include polyethylene glycol (PEG), hydroxypropyl cellulose (HPC) or polyethylene oxide (PEO). Effect of a surfactant on the formation of triiodide ions in the mixed media has also been investigated. Though presence of the organic solvents led to an increase in the triiodide formation except for 2-ethoxy ethanol mixed media at low percentage, the increase in presence of PEG or the other polymer mixed media even at very low percentage was much higher as compared to those in ethylene glycol or its homologues. The increase in the formation constant has been discussed in terms of changes in its solvation properties and the hydrophobic character of the mixed media besides the solvent dielectric effects. The sharp increase in triiodide formation in presence of the polymer under study suggests the possibility of iodine being present as triiodide or other higher polyiodides in the inclusion complexes of iodine with other polymers like starch or PVA. The decrease in the triiodide formation in presence of surfactant micelles may, however, be attributed to solubilization of iodine by the micelles. Iodine was found to be better solubilized in TX-100 micelles as compared to SDS micelles.

Inhibitory effects of Citrus flavonoids on starch digestion and antihyperglycemic effects in HepG2 cells

Flavonoids are a class of important bioactive natural products and are being extensively used in functional foods. In the present study, the effects of four Citrus flavonoids (i.e., hesperidin, naringin, neohesperidin, and nobiletin) on amylase-catalyzed starch digestion, major digestive enzyme activities (e.g., pancreatic α-amylase and α-glucosidase), and glucose use in HepG2 cells were investigated. The results showed that all of the tested Citrus flavonoids significantly inhibited amylase-catalyzed starch digestion. Moreover, naringin and neohesperidin mainly inhibited amylose digestion, whereas hesperidin and nobiletin inhibited both amylose and amylopectin digestion. However, these flavonoids showed weak inhibitory activities against digestive enzymes. Furthermore, glucose consumption, glycogen concentration, and glucokinase activity were significantly elevated, and glucose-6-phosphatase activity was markedly decreased by Citrus flavonoids. These results demonstrate that Citrus flavonoids play important roles in preventing the progression of hyperglycemia, partly by binding to starch, increasing hepatic glycolysis and the glycogen concentration, and lowering hepatic gluconeogenesis. This work suggests that Citrus flavonoids might be potentially used for the prevention of postprandial hyperglycemia.

Free fatty acids electronically bridge the self-assembly of a three-component nanocomplex consisting of amylose, protein, and free fatty acids

The self-assembly of a ternary complex, which is formed through heating and cooling of a mixture of amylose (1.0 mg/mL), whey protein isolate (50 μg/mL), and free fatty acids (FFAs, 250 μg/mL) was investigated. High-performance size-exclusion chromatography-multi-angle laser light scattering (HPSEC-MALLS) analysis showed that the complex is a water-soluble supramolecule (Mw = 6-7 × 10(6)), with a radius of gyration of 20-100 nm, indicating a nanoscale complex. Experimental results using 1-monostearyl-rac-glycerol (MSG) or cetyl alcohol that is similar to FFA in structure (except the headgroup) indicate that FFAs are the bridge between thermodynamically incompatible amylose and protein molecules and their functional carboxyl group is essential to the formation of the complex. Additionally, the effects of pH and salt treatments suggest that electrostatic interactions between negatively charged carboxyl groups of FFAs and polyionic protein are the foundation for the self-assembly of the complex. The fact that FFA is one important component in the self-assembled complex with an estimated molar ratio of 6:1:192 (amylose/protein/FFA, ∼4-5% FFA) demonstrates that it might be used as a nanocarrier for the controlled release of lipophilic functional materials to maintain their stability, bioactivity, and more importantly water solubility.