Interactions of hsian-tsao polysaccharide with corn starch to reduce its in vitro digestibility.

Hsian-tsao polysaccharide (HP) with preferable bioactivities was used to produce starchy gel foods. This study elucidated how interactions of HP (0-0.6 %, w/v) with gelatinized corn starch (CS, 6 %, w/v) reduced in vitro digestibility of CS. The CS digestibility (82.85 %, without HP) was reduced to 68.85 % (co-heated) and 74.75 % (non-co-heated) when 0.6 % HP was added, demonstrating that HP reduced the CS digestibility to a larger extent under co-heating by both HP-CS interactions and inhibiting digestive enzyme activities by HP which was dominated under non-co-heating. Moreover, when co-heated, HP bonded to the amylose of CS via physical forces with a composite index of 21.95 % (0.4 % HP), impeded CS swelling and promoted CS aggregation with the average particle size increased to 42.95 µm (0.6 % HP). Also, the HP-CS complexes formed strong association network structures that increased their apparent viscosity and digestive fluid viscosity. Additionally, HP enhanced the short-range ordered structure and crystal structure of CS. These results evidenced that HP-CS interactions significantly reduced the CS digestibility by forming physical barriers, viscosity effects, and ordered structures, to hinder the enzymes from accessing starch matrices. This laid a foundation for applying HP to starchy foods with a low predicted glycemic index.

Effects of hsian-tsao polysaccharide on myosin gel structure and its binding capacity to flavor compounds.

Hsian-tsao polysaccharide (HTP) with preferable biological activities was explored to improve the gel qualities of surimi. This study investigated the effects of HTP (0-1.0 mg/mL) on structural changes, in vitro digestibility, and fishy odor binding capacity of heat-induced myosin gels (30 mg/mL). HTP promoted the unfolding of myosin structure with transitions from α- helixes to ß-sheets, accompanied by the enhancement of hydrophobic bonds, hydrogen bonds, and non-disulfide covalent bonds dominated within gel networks. Moreover, HTP facilitated the formation of compact gel structures of myosin with superior elastic properties (G' > G'') and apparent viscosity, but without affecting the final in vitro digestibility. Moreover, the microstructure of gels markedly affected the adsorption rate of flavor compounds, with a lower adsorption rate obtained for myosin-HTP gels with compact gel networks embedded with evenly small cavities. Additionally, HTP affected the flavor-binding capacities of myosin gels by increasing hexanal and heptanal, but reducing nonanal and 1-octen-3-ol, in relation to the combined effects of myosin structural changes and newly formed gel networks. This work provides a new prospect for application of HTP to regulate the adsorption rate and binding capacity of myosin gels to fishy odors, critical for improvement of gel properties in surimi products.

Physicochemical properties and in vitro hypoglycemic activities of hsian-tsao polysaccharide fractions by gradient ethanol precipitation method.

Hsian-tsao polysaccharides fractions (HPs), including HP20, HP40, HP60, and HP80, were fractioned by gradient precipitation of 20 %, 40 %, 60 %, and 80 % (v/v) ethanol, respectively. Their physicochemical properties and in vitro hypoglycemic activities (inhibitory activities on α-amylase and α-glucosidase, glucose adsorption capacity, and glucose diffusion retardation) were determined. The results showed that, with ethanol upward, the average particle size, molecular weight, and apparent viscosity of HPs were decreased while carbohydrate and uronic acid contents, absolute zeta potential, and thermal stability were increased. Each of the HPs contained Rha, Ara, Gal, Xyl, Man, and GalA with different molar ratios, indicative of anionic heteropolysaccharides with uronic acid. HPs, with diverse structures and surface morphologies as proved by FTIR and SEM, whose solutions were pseudoplastic fluids, exhibited elastic behavior of weak gel networks at concentrations of >1 %. Moreover, HPs showed inhibitory activities on α-amylase and α-glucosidase, of which HP80 was the strongest. For α-amylase, HP20 and HP60 behaved as mixed inhibitors, while HP40 and HP80 were non-competitive. For α-glucosidase, HPs acted as mixed inhibitors. Additionally, HPs possessed glucose adsorption capacity and glucose diffusion retardation, with the best for HP20. These results suggested that HPs possessed hypoglycemic activities, which could be developed as functional food or hypoglycemic drugs.

Interactions involved in heat-induced gelatin gel containing hsian-tsao gum, and mechanisms to improve its properties.

BACKGROUND: Hsian-tsao gum (HG) has unique gel-promoting and nutritional properties; however, its use in processed foods is limited to starchy foods, partially due to a lack of knowledge related to its interaction with proteins. This study elucidated the interaction mechanism of heat-induced gelatin (G) (50 g kg-1 ) gel fortified with HG (0 ~ 20 g kg-1 ) using rheology, Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), large deformation tests, low-field nuclear magnetic resonance (LF-NMR), and confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM). RESULTS: Heating promoted synergistic interactions between G and more HG molecules with enhanced apparent viscosity and higher storage modulus G' than loss modulus G″, thus shortening the gel time (tg ) of G-HG sols into gels. Fourier-transform infrared spectroscopy and DSC also confirmed the chemical interactions that occurred, facilitating the formation of ß-sheet structures of G. The microstructure of G gradually formed separate, coarse strands, and aggregated as HG was added, as observed by CLSM and SEM. This accelerated the gel formation rate and changed the textural properties. Although HG caused a disruptive decrease in the helix structure of G, it was possible to compensate for this by accelerating synergistic interactions, including depletion attractions and Maillard reactions, by heating. CONCLUSION: Hsian-tsao gum interacted synergistically with G as a result of heating and this accelerated the gel formation rate and improved the gel properties. Novel complex gels could be designed by blending HG to improve the gel properties of G in the heat processing of the food gel formulation. © 2022 Society of Chemical Industry.

Elucidation of interactions between gelatin aggregates and hsian-tsao gum in aqueous solutions.

Interactions between gelatin aggregates (G, 0.5 wt%) and an anionic polysaccharide hsian-tsao gum (HG, 0-0.25 wt%) in aqueous solutions were investigated at 25 °C using zeta potentiometry, turbidimetric analysis, dynamic light scattering, confocal laser scanning microscopy (CLSM), fluorescence spectra and circular dichroism measurements. The results indicated that soluble and insoluble G-HG complexes formed mainly through electrostatic interactions followed critical pH-dependent structure-forming events. The phase transition points (pHφ1, pHopt and pHφ2) shifted to lower pH with HG increased, whereas pHc kept constant. Conformational transitions of G from α-helix to ß-sheet were promoted by interacting with HG, concurrent with changes in environment of hydrophobic residues. Additionally, CLSM evidenced phase transitions of G from homogeneity to separation occurred by interaction with HG, forming G-HG complexes with G centered and HG absorbed on the periphery. Findings aided in understanding interactions mechanism between G and HG to further apply HG in designing new food matrixes.