Influence of Low Acyl and High Acyl Gellan Gums on Pasting and Rheological Properties of Rice Starch Gel

Interaction of anthocyanins, soluble dietary fiber and waxy rice starch: Their effect on freeze-thaw stability, water migration, and pasting, rheological and microstructural properties of starch gels

This study aimed to investigate the effect of the interaction of black rice anthocyanins (BRA), soluble dietary fiber from extruded rice bran (ES) and waxy rice starch (WRS) on the physicochemical properties of starch gels, including gelatinization properties, rheological properties, freeze-thaw stability, water migration, molecular structure and gel microstructure. The results showed that the pasting temperature (PT) of the mixtures was increased, and the peak viscosity (PV), trough viscosity (TV), final viscosity (FV) and setback viscosity (SV) were significantly reduced when ES and BRA were added to WRS in different proportions (ES:BRA, 4:0, 4:0.4, 4:1, 4:2, 8:0, 8:0.8, 8:2, 8:4). Both ES and BRA could enhance the viscosity of WRS gels, and ES exhibited strong ability on improving the strength of gels. The presence of ES and BRA improved the water retaining capacity of WRS gels, but weakened the freeze-thaw stability. ES, BRA and WRS formed non-covalent bonds (hydrogen bonds) through hydrophilic groups during gelatinization, which improved the gel properties. In addition, the steric hindrance formed by ES and BRA inhibited starch retrogradation. These results might contribute to the development of starch-based food formulations with good quality.

A novel edible solid fat substitute: Preparation of biphasic stabilized bigels based on glyceryl monolaurate and gellan gum

Solid fats contribute to a delicate and pleasant flavor for food, but its excessive intake increases the risk of cardiovascular disease. Bigel is considered a promising solid fat substitute as it significantly reduces fat content while meeting consumer demands for food flavor and a balanced diet. In this study, bigels were prepared by mixing glyceryl monolaurate-based oleogel (10 wt%) and gellan gum-based hydrogel (0.8 wt%) at ratios of 1:3, 1:1, and 3:1. The microscopic results indicated that the oleogel/hydrogel ratios influenced the structure of bigels, forming oil-in-water, bi-continuous, and water-in-oil bigels with the increase of oleogel proportion, respectively. All bigels presented a semi-solid structure dominated by elasticity, and their hardness, gumminess, chewiness, and cohesiveness increased with the enhancement of hydrogel proportion. Among them, the bigels (S25:L75 and S25:H75) prepared with an oleogel/hydrogel ratio of 1:3 showed excellent freeze-thaw stability, maintaining an oil holding capacity of >95 % after three freeze-thaw cycles. Meanwhile, they also presented good oxidative stabilities, where the peroxide values and malondialdehyde contents were below 0.07 g/100 g and 1.5 mg MDA/kg at 12 d, respectively. Therefore, S25:L75 and S25:H75 are expected to be green, low-cost, healthy, and sustainable alternatives to solid fats.

Impact of Guar Gum and Locust Bean Gum Addition on the Pasting, Rheological Properties, and Freeze-Thaw Stability of Rice Starch Gel

Improving the gel texture and stability of rice starch (RS) by natural hydrocolloids is important for the development of gluten-free starch-based products. In this paper, the effects of guar gum and locust bean gum on the pasting, rheological properties, and freeze−thaw stability of rice starch were investigated by using a rapid visco analyzer, rheometer, and texture analyzer. Both gums can modify the pasting properties, revealed by an increment in the peak, trough, and final viscosities, and prevent the short-term retrogradation tendency of RS. Dynamic viscoelasticity measurements also indicated that the starch−gum system exhibits superior viscoelastic properties compared with starch alone, as revealed by its higher storage modulus (G′). Compared with the control, the hysteresis loop area of the guar gum-containing system and locust bean gum-containing system was reduced by 37.7% and 24.2%, respectively, indicating that the addition of gums could enhance shear resistance and structure recovery properties. The thermodynamic properties indicated that both gums retard short-term retrogradation as well as long-term retrogradation of the RS gels. Interestingly, the textural properties and freeze−thaw stability of the RS gel were significantly improved by the addition of galactomannans (p < 0.05), and guar gum was more effective than locust bean gum, which may be due to the different mannose to galactose ratio. The results provide alternatives for gluten-free recipes with improved texture properties and freeze−thaw stability.

Polymer-Solvent Interactions in Modified Starches Pastes-Electrokinetic, Dynamic Light Scattering, Rheological and Low Field Nuclear Magnetic Resonance Approach

Starch paste is a very complex dispersion that cannot be clearly classified as a solution, colloid or suspension and many factors affects its properties. As these ambiguities constitute a barrier to technological development, the aim of this study was to investigate the interaction of starch macromolecules with water by analysing the results of rheological properties, low field nuclear magnetic resonance (LF NMR), dynamic light scattering (DLS) and ζ potential analyses. Starch pastes with a concentration of 1%, prepared with distilled water and buffered to pH values of 2.5, 7.0 and 9.5 were analysed. It was proved that the pH buffering substantially decreased the values of consistency index but the pH value itself was not significant. LF NMR studies indicated that the dissolution of starch in water resulted in a reduction in spin-lattice as well as spin-spin relaxation times. Moreover, changes in relaxation times followed the patterns observed in rheological studies. Electrokinetic and DLS analyses showed that potential values are primarily influenced by the properties of the starches themselves and, to a lesser extent, by the environmental conditions. The conducted research also showed complementarity and, to some extent, substitutability of the applied research methods as well as exclusion chromatography (a method not used in this work).

Tailormade Wheat Arabinoxylan Reveals the Role of Substitution in Regulating Gelatinization and Retrogradation Behavior of Wheat Starch

To elucidate the role of substitution of arabinoxylan (AX) in the characteristics of wheat starch, this study prepared AX with a well-defined structure by targeted enzymatic hydrolysis and comparatively investigated the effects of AX with different degrees of substitution on gelatinization and retrogradation behavior of starch. Removal of major arabinofuranosyl (Araf) of mono- or disubstituted xylopyranosyl (Xylp) of both low-molecular-weight (Mw: 62.5 kDa, Araf/Xylp: 0.61) and high-molecular-weight AX (Mw: 401.2 kDa, Araf/Xylp: 0.61) reversed the decreased gelatinization viscosity and recrystallization of amylose induced by AX to a similar extent. Upon retrogradation for 30 days, the Araf of mono- and disubstituted Xylp contributed to the water distribution and the effect depended on the molecular chain length. The C3-linked Araf of disubstituted Xylp was more involved in prohibiting the retardation of recrystallization of amylopectin, while the presence of Araf of monosubstituted Xylp might hinder the interactions between AX and amylopectin.