Structure and Processing Properties of Nine Yam (Dioscorea opposita Thunb) Starches from South China: A Comparison Study.

In order to explore the processing and application potential of Chinese yam starch, nine kinds of Chinese yam starch (GY11, GY5, GY2, GXPY, LCY, SFY, MPY, SYPY, ASY) from South China were collected and characterized. The chemical composition, rheological properties, thermal properties, and in vitro starch digestion were compared, and the correlation between the structure and processing properties of these yam starches was analyzed using Pearson correlation. The results show that GY2 had the highest amylose content of 28.70%. All the yam starches were similarly elliptical, and all the yam starch gels showed pseudoplastic behavior. Yam starches showed similar pasting temperatures and resistant starch content, but SYPY showed the largest particle size (28.4 µm), SFY showed the highest setback (2712.33 cp), and LCY showed the highest peak viscosity (6145.67 cp) and breakdown (2672.33 cp). In addition, these yam starches also showed different crystal types (A-type, B-type, C-type), relative crystallinity (26.54-31.48%), the ratios of 1045/1022 cm-1 (0.836-1.213), pasting properties, and rheological properties, so the yam starches have different application potentials. The rheological and pasting properties were related to the structural properties of starch, such as DI, Mw, and particle size, and were also closely related to the thermodynamic properties. The appropriate processing methods and purposes of the processed products of these yam starches can be selected according to their characteristics.

Edible oleogels stabilized solely by stigmasterol: effect of oil type and gelator concentration.

BACKGROUND: Phytosterols are considered to be one of the most promising gelators for obtaining oleogel because of their additional health benefits and natural coexist with vegetable oils. Previous studies have confirmed that individual phytosterols are not capable of structuring vegetable oils unless they act synergistically with other components. However, based on the self-assembly properties of stigmasterol (ST) in organic solvents, we speculate that it can also structure vegetable oils as a gelator alone. RESULTS: For the first time, the present study confirmed the feasibility of using ST alone as a gelator for structuring of vegetable oils, including rapeseed oil (RSO), olive oil (OLO) and flaxseed oil (FSO). RSO had the lowest ST gelation concentration (4%, w/w), and the oil-binding capacity and firmness value of the oleogels were the highest. The rheological results showed that all the samples were gelatinous (G' > G″). The results of differential scanning calorimeter and X-ray diffraction further confirmed that the properties of RSO-based oleogels are superior to those prepared by OLO and FSO. The microscopic results also confirmed that the crystal structure of RSO oleogels was more uniform, smaller and more densely distributed. CONCLUSION: The structural properties of the oleogels were positively correlated with the ST concentration, and various analysis indicators showed that the performance of the oleogel based on RSO was better than that of OLO and FSO. In summary, the present study used ST as a gelator to successfully prepare oleogels with excellent properties, which provides a feasible reference for researchers in related fields. © 2022 Society of Chemical Industry.

Novel Biocompatible Polysaccharide-Based Eutectogels with Tunable Rheological, Thermal, and Mechanical Properties: The Role of Water.

The natural deep eutectic solvent (NADES) is an excellent solvent for insoluble natural products and medicines. Eutectogels formed by gelation of NADESs are interesting materials that deserve attention. In this study, xanthan gum was used as a gelator to gel choline chloride-xylitol with different water contents in virtue of the excellent solubility of choline chloride-xylitol (1:1) to quercetin. We observed that water was critical to the formation of eutectogels. An MTT assay indicated that our eutectogel had excellent biocompatibility as its corresponding hydrogel. According to rheological tests, xanthan gum-based eutectogels had better viscoelastic properties, higher thermal stability, and more defined shear thinning behavior than its corresponding hydrogel. Texture profile analysis showed that eutectogels with less water content had higher hardness and adhesiveness. Meanwhile, Differential scanning calorimeter (DSC) results suggested that the various rheological and texture properties of eutectogels could be attributed to changes in the water state, which was influenced by the hydrogen bonding network of NADES. This biocompatible eutectogel with tunable properties was expected to find applications in novel drug delivery vehicles, which are widely used in the fields of medicine and food.

The Impact of Oil Type on the Performance of ß-Amyrin-Based Oleogels: Formation, Physicochemical Properties, and Potential Correlation Analysis.

Pentacyclic triterpenes show potential as oleogelators, but their combination with various vegetable oils has limited research. This study selected linseed, rapeseed, sunflower, coconut, and palm oils to combine with the triterpenoid compound ß-amyrin for the preparation of oleogels. The stability, crystal network structure, and other properties of each oleogel were evaluated. The correlation between different oil types and the properties of corresponding oleogels was explored. The results showed that ß-amyrin formed stable oleogels with five vegetable oils under suitable temperature conditions, wherein especially the LO-based oleogel not only exhibited higher oil-binding capacity and hardness, but also demonstrated excellent stability at the microscopic level and notable rheological properties. Further analysis revealed a close correlation between the physicochemical properties of the oleogels and lipid characteristics, indicating that oleogels prepared from long-chain highly unsaturated fatty acids exhibit high stability. The above results indicate that ß-amyrin can be a novel candidate oleogelator and that the oil type can modify the properties of ß-amyrin-based oleogels. This study provides the latest reference for the application of pentacyclic triterpenoids in food.

Effect of Digestion on Ursolic Acid Self-Stabilized Water-in-Oil Emulsion: Role of Bile Salts.

Exploring the effect of bile salts on the properties of emulsion carriers containing hydrophobic bioactive compounds is particularly critical to understanding the stability and bioavailability of these hydrophobic bioactive compounds in the digestive process. In this study, the effects of bile salts on the stability and digestive characteristics of the ursolic acid (UA) self-stabilized water-in-oil (W/O) emulsion were investigated via static and dynamic (with or without enzyme) in vitro simulated digestive systems. The results showed that under the static system, the basic conditions had less interference, while the bile salts had a significant effect on the appearance and microstructure of the emulsion. The primary mechanism of emulsion instability is hydrophobic binding and depletion flocculation. Under the dynamic condition, it was found that the low concentrations of bile salts can promote the release amount and the rate of free fatty acids via displacement, while high concentrations of bile salts inhibit the decomposition of lipid, which may be related to the secondary coverage formed at the interface by the bile salts. These findings provide a theoretical basis for understanding the digestive behavior of the UA emulsion and its interaction with bile salts, which are conducive to developing and designing new emulsions to improve the bioaccessibility of UA.

Effect and mechanism of edible oil co-digestion on the bioaccessibility and bioavailability of ursolic acid.

Ursolic acid (UA), a pentacyclic triterpenoid, has gained attentions due to its various health-promoting benefits, but exhibits poor bioavailability. This could be enhanced by changing the food matrix of UA in which it is present. In this study, several UA systems were constructed to investigate the bioaccessibility and bioavailability of UA in combination with in vitro simulated digestion and Caco-2 cell models. The results showed that the bioaccessibility of UA was significantly improved after adding rapeseed oil. Caco-2 cell models showed that the UA-oil blend was more advantageous than UA emulsion in total absorption. The results indicate that the location of UA distribution in oil determines the ease of UA release into the mixed micellar phase. This paper brings a new research idea and basis for the design of improving the bioavailability of hydrophobic compounds.

Water-in-oil Pickering emulsions stabilized solely by a naturally occurring steroidal sapogenin: Diosgenin.

In this study, stable water-in-oil emulsions stabilized solely by a naturally occurring steroidal sapogenin was reported for the first time. The results show that a concentrated emulsion with an internal water ratio of up to 60% can be obtained with only 3% of diosgenin concentration. The concentration of diosgenin had a significant effect on the microstructure and rheological properties of the emulsions. More importantly, the emulsion has excellent freeze/thaw stability and thermal stability. The results of polarized light microscopy, CLSM, and XRD indicate that the great structural properties and high stability of the emulsion can be attributed to the combined action of the diosgenin crystal shells on the droplet surface and needle-crystals in the continuous phase. That is, Pickering stabilization and network stabilization acting synergistically on stabilization of the emulsions. This novel food grade water-in-oil emulsions demonstrated great potential for application in food and biomedical-related fields.

Highly biodegradable, thermostable eutectogels prepared by gelation of natural deep eutectic solvents using xanthan gum: preparation and characterization.

As a possible alternative to hydrogels, eutectogels are formed by gelling natural deep eutectic solvents (NADESs) that may be closer to the intracellular environment than pure water. This study successfully prepared highly biodegradable and thermostable eutectogels based on polysaccharides and NADESs, and studied the possible mechanism of eutectogel formation. The results show that these eutectogels displayed excellent thermostability as both the G' and G'' values remained constant in the temperature range of 60-110 °C, and the weight of the eutectogels remained almost unchanged when held at 80 °C for 10 hours. Similar to the formation of xanthan gum-based hydrogels, water addition and annealing treatment are necessary for the preparation of xanthan gum-based eutectogels. XRD, DSC and FT-IR results show that the existence of xanthan gum affects the original hydrogen bonding network of the NADESs, which further indicate that the hydrogen bond interaction between xanthan gum and NADESs is an important cause of eutectogel formation and changes in gel properties. Rheological results show that the eutectogel is a weak gel with excellent thermostability and structure recovery. As it is more stable than hydrogels and greener than ion gels, the polysaccharide-based eutectogel is expected to be widely used in the fields of food, medicine and materials.

Surface chemical functionalization of starch nanocrystals modified by 3-aminopropyl triethoxysilane.

A comparative experiment about the 3­aminopropyl triethoxysilane (APTES) modification of waxy potato starch nanocrystals (WPSNCs) and waxy maize starch nanocrystals (WMSNCs) was employed in the present study. The purpose of surface chemical functionalization was to introduce functional groups and improve hydrophobicity of SNCs for the extensive application. The degree of substitution (DS) of both SNCs displayed the upward trend with the increase of applied APTES, while WPSNCs showed higher DS than that of WMSNCs in the same dosage of APTES. XRD revealed the un-changed crystalline structure and decreased relative crystallinity after the modifications. The structure of silylated SNCs surface was characterized by FT-IR and XPS, which confirmed the presence of functional amino groups. The introduction of amino groups resulted in a simultaneous enhancement of zeta potentials for both SNCs relatively. The modified SNCs could be uniformly dispersed both in water and ethanol phase revealing improved hydrophobicity through wettability experiments.

Recrystallization kinetics of starch microspheres prepared by temperature cycling in aqueous two-phase system.

The recrystallization behavior of starch microspheres (SMs) prepared by temperature cycling in aqueous two-phase system (ATPS) was investigated. The SMs were carried out under the temperature-cycled treatment at 4°C, 30°C or 4/30°C for 2 to 20 days. X-ray diffraction (XRD) results showed that the crystalline structure of SMs were different from that of degraded cassava starch. Compared to degraded cassava starch, the relative crystallinity of SMs under different temperature decreased, and the increase in relative crystallinity with the storage time was observed. All gelatinization temperature parameters (To, Tp and Tc) and enthalpy of gelatinization (ΔH) of SMs decreased compared with degraded cassava starch. However, these values of SMs stored at 30°C were higher than that of SMs stored at 4°C and 4/30°C. The Avrami equation was applied to analysis the recrystallization behaviors of SMs. The stability test showed that the samples stored at 30°C were more stable than that stored at 4 °C and 4/30°C.

Effect of molecular weight of starch on the properties of cassava starch microspheres prepared in aqueous two-phase system.

Starch microspheres (SMs) were fabricated in an aqueous two-phase system (ATPS). A series of starch samples with different molecular weight were prepared by acid hydrolysis, and the effect of molecular weight of starch on the fabrication of SMs were investigated. Scanning electron microscopy (SEM) showed that the morphologies of SMs varied with starch molecular weight, and spherical SMs with sharp contours were obtained while using starch samples with weight-average molecular weight (M¯w)≤1.057×105g/mol. X-ray diffraction (XRD) results revealed that crystalline structure of SMs were different from that of native cassava starch, and the relative crystallinity of SMs increased with the molecular weight of starch decreasing. Differential scanning calorimetry (DSC) results showed peak gelatinization temperature (Tp) and enthalpy of gelatinization (ΔH) of SMs increased with decreased M¯wof starch. Stability tests indicated that the SMs were stable under acid environment, but not stable under α-amylase hydrolysis.

Preparation of starch nanospheres through hydrophobic modification followed by initial water dialysis.

Starch nanospheres smaller than 200 nm were produced from hydrophobically modified starch by using initial water dialysis method. The hydrophobic modification of starch was performed by using octenyl succinic anhydride (OSA). The resultant starch nanospheres were characterized by using Fourier transformation infrared (FTIR) spectroscopy, (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy and fluorescence spectroscopy, scanning electron microscopy (SEM) and dynamic light scattering (DLS). Effects of degree of substitution (DS) in OSA-starch, initial water content and OSA-starch concentration on morphology and particle size of starch nanospheres were evaluated. The SEM micrographs showed that starch nanospheres with spherical shape and sharp edge can be produced at DS values ≧0.67. The particle size of starch nanospheres decreased significantly (P<0.05) with increase in DS of OSA-starch and increase in the initial water content, whereas the particle size increased significantly (P<0.05) with the increase in the concentration of OSA-starch. These OSA-starch nanospheres can be preferentially used to microencapsulate hydrophobic drugs.