Effect of high-pressure homogenization on the rheology, microstructure and fractal dimension of citrus fiber-oil dispersions

Effect of modifications on structure, physicochemical properties and lead ions adsorption behavior of dietary fiber of Flammulina velutipes

The health effects of dietary fiber have been widely concerned, which are closely related to physicochemical properties. This study focused on soluble dietary fiber of Flammulina velutipes (FDF), evaluated the effects of modifications on structural characterization, the physicochemical properties and the heavy metal adsorption characteristics, and further clarified underlying mechanisms on Pb2+ adsorption behavior of FDFs. The results showed the modifications of extrusion and cellulase improved the yield of FDFs, increased the release of active groups and enhanced the adsorption ability in vitro. Besides, Pb2+ adsorption altered porous structure and led to the presence of carboxylate. It was a spontaneous endothermic reaction and can be fitted by the pseudo-second-order kinetic equation. The Freundlich equation was suitable to describe the adsorption isotherm. These results highlighted potential applications of the dietary fiber modification and laid the theoretical foundation for the modification processing of F. velutipes and protection from food-derived heavy metal toxicity.

Sucrose ester alleviates the agglomeration behavior of bamboo shoot dietary fiber treated via high pressure homogenization: Influence on physicochemical, rheological, and structural properties

High-pressure homogenization (HPH) is a physical modification method that can rapidly reduce the particle size of bamboo shoot dietary fiber (BSDF), but it can lead to agglomeration. Therefore, the effects of the addition of sucrose ester (SE) to alleviate the agglomeration of BSDF during HPH were investigated. Compared with BSDF without added SE, BSDF obtained the smallest particle size (276.5 nm) and highest ζ-Potential (53.6 mV) when SE was 5 g/L. Water-holding capacity, oil-holding capacity, swelling capacity, and b* increased, whereas L* and a* decreased significantly with the addition of SE. The shear stress and viscoelasticity of BSDF solution were minimized when 5 g/L SE was added. SE reduced relative crystallinity and thermal stability of BSDF. SE could effectively alleviate the aggregation of BSDF through the mechanism of electrostatic repulsion. This study highlights an innovative and promising strategy for alleviating the agglomeration behavior of BSDF during HPH treatment.

Multi-fractal structure features of corn stalks and their correlation with pretreatment homogeneity and efficacy

Lignocellulose biomass is a natural porous medium with fractal characteristics, which tend to be distinct after certain pretreatment and relational with processing effects. In this work, multi-scale fractal features of corn stalks after steam explosion pretreatment were systematically characterized employing digital image processing and mercury intrusion porosimetry methodologies. The macroscopic surface fractal features (D_s: 2.8278 ∼ 2.8523) and microscopic pore fractal features (D_p: 2.3003 ∼ 2.8867) presented same variation tendency with pretreatment severity, revealing the self-similarity of processing results of corn stalks with the scale. In association with pretreatment homogeneity and efficacy, the decrease in fractal dimensions corresponded to morphologically homogeneous and structurally complex samples with preferable auto-hydrolysis degree of structural components, which led to high reactivity with enzymes. Quantitatively, there were strongly linear correlation between fractal dimensions and enzymatic digestibility with r² > 0.95. Fractal dimension was expected to theoretically guide the rational evaluation, prediction and promotion of the key pretreatment technique in biorefinery.

Applicable Plant Proteins and Dietary Fibers for Simulate Plant-Based Yogurts

Effects of plant proteins and dietary fibers on the physical properties of stirred soy yogurt were investigated. Buffering capacity against lactic acid was not affected by the protein concentration for any of the four proteins that were examined: isolate soy protein (ISP), pea protein (PP), rice protein (RP), and almond protein (AP). Three proteins other than AP exhibited an increase in buffering capacity (dB/dPH) following a physical treatment, whereas AP saw a decrease in buffering capacity. Furthermore, physically treated PP revealed a significant increase in viscosity, reaching up to 497 cp in the pH 6.0~6.2 range during the titration process. Following fermentation, PP produced the highest viscosity and coagulum strength with no syneresis. In the case of dietary fiber, Acacia Fiber (AF) was completely dissolved in the solvent and did not affect the physical properties of the fermented coagulum. Soy fiber (SF) was also not suitable for fermented milk processes because precipitation occurred after the physical treatment. In the case of citrus fiber (CF), however, syneresis did not occur during storage after the physical treatment, and the viscosity also increased up to 2873 cP. Consequently, PP and CF were deemed to be a suitable plant protein and dietary fiber for stirred soy yogurt, respectively.

Rheological and Microstructural Properties of Xanthan Gum-Based Coating Solutions Enriched with Phenolic Mango (Mangifera indica) Peel Extracts

Mango (Mangifera indica) is a tropical fruit highly desired for its vitamin content and flavor, but its peel is considered a byproduct or waste. However, mango peel contains some bioactive compounds that improve food quality matrix for the development of edible coatings or films. The effect of phenolic mango (Mangifera indica) peel extracts on the physicochemical, rheological, and microstructural properties of xanthan gum-based coating solutions was evaluated. The obtained solutions were stable during the study period and presented a non-Newtonian fluid type shear-thinning behavior described by Ostwald-de Waele. Moreover, viscoelastic properties revealed that the elastic modulus was higher than the viscous modulus, showing a characteristic of weak gels. The addition of extracts did not alter the shear rate and viscoelastic character of the solutions, preserving the pseudoplasticity and weak gel behavior of xanthan gum associated with spreadability and adherence of coatings; it modified the gel structure as a function of temperature. Furthermore, the coating solutions of xanthan gum and phenolic mango peel extracts are an alternative to develop complex food systems such as edible coatings, edible films, or delivery systems.

Nutritional, Physico-Chemical and Mechanical Characterization of Vegetable Fibers to Develop Fiber-Based Gel Foods

The aim of this research was to evaluate the nutritional and physico-chemical properties of six different vegetable fibers and explore the possibility of using them as a thickener or gelling agent in food. To determine the technological, nutritional and physical parameters, the following analyses were carried out: water-holding capacity, water retention capacity, swelling, fat absorption capacity, solubility, particle size, moisture, hygroscopicity, pH, water activity, bulk density, porosity, antioxidant activity, phenolic compounds and mineral content. Gels were prepared at concentrations from 4% to 7% at 5 °C and analyzed at 25 °C before and after treatment at 65 °C for 20 min. A back extrusion test, texture profile analysis and rheology were performed and the pH value, water content and color were analyzed. As a result, all the samples generally showed significant differences in all the tested parameters. Hydration properties were different in all the tested samples, but the high values found for chia flour and citrus fiber are highlighted in functional terms. Moreover, chia flour was a source of minerals with high Fe, Mn and Cu contents. In gels, significant differences were found in the textural and rheological properties among the samples, and also due to the heat treatment used (65 °C, 20 min). As a result, chia flour, citrus, potato and pea fibers showed more appropriate characteristics for thickening. Moreover, potato fiber at high concentrations and both combinations of fibers (pea, cane sugar and bamboo fiber and bamboo, psyllium and citric fiber) were more suitable for gelling agents to be used in food products.

Impact of high-pressure homogenization on the microstructure and rheological properties of citrus fiber

Citrus fiber dispersion with different concentrations (5–25 g/kg) was treated by high-pressure homogenization (90 and 160 MPa) for two cycles. The particle size distribution, hydration properties of powders, morphology and rheological measurements were carried out to study the microstructure and rheological properties changes by high-pressure homogenization (HPH). In conclusion, the HPH can reduce the particle size of fiber, improve the water holding capacity and water binding capacity. Furthermore, fiber shape can be modified from globular cluster to flake-like slices, and tiny pores can be formed on the surface of citrus fiber. The apparent viscosity, storage modulus and loss modulus were increased by HPH whereas the activation energy was reduced. The Hershcel–Bulkley model, Carreau model and Power Law mode were selected to evaluate the rheological properties.