Comparison of structural and in vitro digestive properties of autoclave-microwave treated maize starch under different retrogradation temperature conditions.

Retrogradation is a critical step in the physical production of resistant starch. This study aimed to examine the effects of isothermal and temperature-cycled retrogradation on the structural, physicochemical properties, and digestibility of resistant starch type-III (RS3) under various thermal conditions. To create RS3, normal maize starch (NM) and Hylon VII (HAM) were treated by autoclave-microwave and then retrograded at isothermal (4 °C) or various temperature conditions (4/10 °C, 4/20 °C, 4/30 °C, 4/40 °C, and 4/50 °C). We found that temperature-cycled retrogradation possessed greater potential than isothermal retrogradation for producing short-range ordering and crystalline structures of RS3. Also, retrograded starch prepared via temperature cycling exhibited higher double helix content, lower amorphous content, reduced swelling power, and less amylose leaching in water. Furthermore, the starch digestibility was affected by structural alterations, which were more significant in HAM-retrograded starch. While, HAM-4-40 (39.27 %) displayed the highest level of resistant starch (RS).

The effect of heat-moisture treatment changed the binding of starch, protein and lipid in rice flour to affect its hierarchical structure and physicochemical properties.

This study investigated the effect of removing proteins, lipids and starch on the structure, physicochemical properties and digestion properties of rice flour (with 30% moisture) treated with heat moisture treatment (HMT). According to the results, HMT caused the adhesion and agglomeration of the rice flour, promoted the binding between starch, protein and lipid molecular chains and led to the formation of complexes (especially starch-lipid complexes), which hindered the removal of non-starch components. Compared to the untreated rice flour, the HMT treated lipid-removal rice flour had small changes in their crystallinity, gelatinization temperature and viscosity property. After removing protein, the crystallinity, peak viscosity, final viscosity, breakdown and starch digestibility were sharply increased. In particular, the peak viscosity increased from 811 cP to 1746 cP and the enthalpy change increased from 5.33 J/g to 10.18 J/g. These findings are helpful in understanding the contribution of removing endogenous proteins and lipids to the physicochemical changes of HMT treated rice flour during its heating process and thus can be helpful in controlling the quality of rice flour through HMT.

The Influence of Temperature Changes on the Rice Starch Structure and Digestive Characteristics: One and Two-Step Annealing.

This study investigated the effects of annealing on the structural and physicochemical properties of rice starch below the onset temperature (To) by 5 °C and 15 °C. The results revealed that annealing improved the gelatinization temperature of rice starch, decreased the swelling power, solubility, and paste viscosity of rice starch, and had no significant effects on the morphological structure and crystal configuration of rice starch. In one-step annealing, the annealing temperature of 60 °C is more conducive to the rearrangement of starch molecules, so its crystallinity, short-range ordered structure, and gelatinization temperature are higher than at 50 °C; however, its RDS, SDS, and RS contents will be increased. During the two-step annealing treatment, the temperature change is not conducive to the molecular chain rearrangement and to the formation of perfect crystalline structure, which increases the sensitivity of enzymes to starch, so the RDS content of starch increases significantly, while the RS content decreases.

Effects of Reheating Methods on Rheological and Textural Characteristics of Rice Starch with Different Gelatinization Degrees.

Pregelatinized starch (PGS) is often used to improve the processing quality of foodstuffs, but little attention has been paid to the effects of different reheating methods and degree of starch gelatinization (DSG) on their rheological and textural properties. In this study, pregelatinized rice starches (RS) with gelatinization degrees ranging from 58% to 100% were prepared via different Rapid Visco Analyser (RVA) heating procedures and reheated in various methods, including high-power microwave (HM), low-power microwave (LM), and water bath. The rheological behavior and textural properties were explored, and the results demonstrated that the consistency, gel strength, hardness, and springiness of PGS in all tested samples decreased significantly after reheating. The storage modulus (G') of PGS increased dramatically while the thermal stability decreased. Interestingly, the reheating methods possessed various effects on the starch of different DSG.

Advances in Electrochemical Energy Devices Constructed with Tungsten Oxide-Based Nanomaterials.

Tungsten oxide-based materials have drawn huge attention for their versatile uses to construct various energy storage devices. Particularly, their electrochromic devices and optically-changing devices are intensively studied in terms of energy-saving. Furthermore, based on close connections in the forms of device structure and working mechanisms between these two main applications, bifunctional devices of tungsten oxide-based materials with energy storage and optical change came into our view, and when solar cells are integrated, multifunctional devices are accessible. In this article, we have reviewed the latest developments of tungsten oxide-based nanostructured materials in various kinds of applications, and our focus falls on their energy-related uses, especially supercapacitors, lithium ion batteries, electrochromic devices, and their bifunctional and multifunctional devices. Additionally, other applications such as photochromic devices, sensors, and photocatalysts of tungsten oxide-based materials have also been mentioned. We hope this article can shed light on the related applications of tungsten oxide-based materials and inspire new possibilities for further uses.

Preparation and characterization of broken-rice starch nanoparticles with different sizes.

Broken-rice starch nanoparticles with different mean particle diameters for 100, 200, 400 and 800 nm were prepared by nanoprecipitation, alkali freezing, cross-linking and H2SO4 hydrolysis methods respectively, and their structural, morphological and physicochemical properties were systematically characterized. The results showed that broken-rice starch nanoparticles had higher water absorption rate, and the maximum water absorption rate was obtained from the 100 nm starch granules being 91.53%, which means an increase about 2.07-fold in water absorption rate as compared with native rice starch. The stability of native rice starch is the worst, but the viscosity characteristic value is always higher than that of starch nanoparticles in the whole gelatinization process. The FT-IR spectrum showed that only starch nanoparticles prepared by cross-linking method showed the characteristic peak of secondary amide structure at 1714 cm-1, but the structure of was basically the same as native starch. The X-ray diffraction pattern revealed that there were obvious characteristic diffraction peaks near 2θ for 15°, 17°, 19° and 23° for the 800 nm starch nanoparticles and native rice starch, while the characteristic diffraction peaks of other starch nanoparticles disappeared in varying degrees due to the changed crystal structure.

Structural Features, Antitumor and Antioxidant Activities of Rice Bran Polysaccharides Using Different Extraction Methods.

In this study, rice bran polysaccharides (RBP) were extracted using the hydrothermal method (RBP-H), microwave-assisted extraction (RBP-M) and enzyme-assisted extraction (RBP-E). The prepared RBP samples exhibited the typical spectral patterns of polysaccharides, but differed in chemical composition, molecular features, antitumor and antioxidant activities. The molecular weights (Mw) of RBP-H, RBP-M, and RBP-E were 1.03 × 105 , 2.62 × 105 , and 0.46 × 105 g/mol, respectively. In vitro, all RBP samples significantly inhibited mouse sarcoma S180 cells viability in a dose-dependent manner. In vivo, RBP-M or RBP-E could not only inhibit the growth of the tumor, but also enhance the spleen index. In addition, RBP-E could induce an enhancement of superoxide dismutase (SOD) and glutathione peroxidase activities and a scavenging effect on malondialdehyde. This study demonstrated that the effective antitumor activity of RBP may be owed to its enhancement of antioxidant activity function. The present work suggested that RBP, especially RBP-E could be a safe and effective antitumor, bioactive agent or functional food. PRACTICAL APPLICATION: Polysaccharides is extracted from rice bran (RBP) using hydrothermal, microwave-assisted and enzyme-assisted extraction methods. The results suggested that the antitumor activity of RBP was associated with enhancement of immunization and antioxidant. RBP could be explored as a natural antitumor and antioxidant agent applied in medicines and functional foods.

Understanding the fine structure of intermediate materials of maize starches.

Here we concern the molecular fine structure of intermediate material (IM) fraction in regular maize starch (RMS) and Starpro 40 maize starch (S40). IM had a branching degree and a molar mass (Mw) somewhere between amylopectin (AP) and amylose (AM). Compared with AP, IM had more extra-long (Fr I) and long (Fr II) chains and fb3-chains (degree of polymerization (DP)>36), with a higher average chain length (CL). Also, IM contained less A-chains but more B-chains (both BS-chains with DP 3-25 and BL-chains with DP≥26), accompanied by longer B- and BL-chains, total internal chains (TICL) and average internal chains (ICL), and a similar average external chain length (ECL). Furthermore, relative to RMS-IM, the IM of S40 (with higher apparent amylose content than RMS) showed increases in relatively-long chains, e.g., Fr II, fb3-chains and BL-chains, but reductions in Mw, relatively-short chains (those with DP 6-12, etc.).