Lufeng Wang

Acid-induced gelation behavior of soybean protein isolate with high intensity ultrasonic pre-treatments.

High intensity ultrasonic (HUS, 20 kHz, 400 W) pre-treatments of soybean protein isolate (SPI) improved the water holding capacity (WHC), gel strength and gel firmness (final elastic moduli) of glucono-δ-lactone induced SPI gels (GISG). Sonication time (0, 5, 20, and 40 min) had a significant effect on the above three properties. 20 min HUS-GISG had the highest WHC (95.53 ± 0.25%), gel strength (60.90 ± 2.87 g) and gel firmness (96340Pa), compared with other samples. Moreover, SH groups and non-covalent interactions of GISG also changed after HUS pre-treatments. The HUS GISG had denser and more uniform microstructures than the untreated GISG. Rheological investments showed that the cooling step (reduce the temperature from 95 to 25 °C at a speed of 2 °C/min) was more important for the HUS GISG network formation while the heat preservation step (keep temperature at 95 for 20 min) was more important for the untreated GISG. HUS reduced the particle size of SPI and Pearson correlation test showed that the particle size of SPI dispersions was negatively correlated with WHC, gel strength and gel firmness.

Adsorption–desorption properties and characterization of crosslinked Konjac glucomannan-graft-polyacrylamide-co-sodium xanthate

A new flocculant, based on Konjac-graft-poly (acrylamide)-co-sodium xanthate (CKAX), was synthesized in aqueous solution using epichlorohydrin (ECH) as the cross-linker and ceric ammonium nitrate (CAN) as the initiator. X-ray diffraction indicated the existence of strong interaction between KGM and reactant, including intermolecular and intramolecular hydrogen bonds. Microscopy images exhibited the appropriate pore size and distribution, which might be related to a higher capacity of flocculation and adsorption. Thermo gravimetric analysis showed that the synthetic polymer could improve the thermo-stability of the natural polysaccharides, and there was a positive correlation between polymer residual weight and flocculation. The adsorption and desorption properties for copper ions indicated that the adsorption rate could be described by a pseudo-second-order rate model, and the Freundlich model provides the best fit for the resulting adsorption isotherm. The flocculant can be regenerated in HNO(3) solution.

Physicochemical and functional properties of micronized jincheng orange by-products (Citrus sinensis Osbeck) dietary fiber and its application as a fat replacer in yogurt

Abstract Orange by-products from juice extraction are generally discarded or used in animal feed due to their low market value. However, orange by-products show potential as dietary fiber (DF) and fat replacers in products such as yogurt. This study assessed the benefits of using orange by-products in DF-enriched materials such as DF powders (OP) and micronized DF with ball-milling (MDF). The study also investigated the effects of adding different levels of OP and MDF on the quality of low-fat yogurt. Results show that MDF showed better physicochemical and functional properties than OP, and that 2% MDF as a fat replacer in yogurt retained most of the textural and sensory properties of full-fat yogurt. Therefore, this study showed that MDF is a promising alternative as a fat replacer in low-fat yogurt, without sacrificing good taste and other qualities of full-fat yogurt.

Effect of Grinding Methods on Structural, Physicochemical, and Functional Properties of Insoluble Dietary Fiber from Orange Peel

This study evaluated the effect of grinding methods (regular laboratory milling, ultra centrifugal rotor milling, and ball milling) on structural, physicochemical, and functional properties of insoluble dietary fiber (IDF) fraction from orange peel. The results demonstrated that both ultra centrifugal milling and ball milling could effectively decrease average particle size of IDF fraction (81.40 μm and 19.63 μm, resp.). The matrix structure of IDF fraction was destroyed but FTIR structure had no major change after grinding. As particle size decreased, the bulk density and lightness of IDF fraction increased and a redistribution of fiber components from insoluble to soluble fractions was observed. Furthermore, ball milled IDF fraction exhibited significantly higher capacity to retard glucose diffusion and inhibit α-amylase activity (35.09%). This work would give useful insight into effect of grinding methods on properties and functions of orange peel IDF in food industry.

Preparation and prebiotic potential of pectin oligosaccharides obtained from citrus peel pectin

Pectin oligosaccharide (POS) fractions were obtained by controlled chemical degradation of citrus peel pectin. By adjusting trifluoroacetic acid (TFA) concentration, three oligosaccharides were obtained, of molecular weight (Mw) range 3000-4000 Da, 2000-3000 Da and lower than 2000 Da. Varying hydrogen peroxide (H2O2) concentration and reaction time produced oligosaccharides of 3000-4000 Da and 2000-3000 Da. The relative proportions of acidic monosaccharide increased from 68.58% to 89.93% (TFA) and from 63.74% to 83.26% (H2O2) as the reaction conditions intensified. Prebiotic activity scores were used to quantify POS ability to promote selective growth of specific probiotics. Sample POSH1 from H2O2 degradation showed the highest prebiotic potential with prebiotic activity score 0.41 for Lactobacillus paracasei LPC-37 and 0.92 for Bifidobacterium bifidum ATCC 29521.

Rheological, sensory, and microstructural properties of fresh and frozen/thawed mashed potatoes enriched with different proteins

ABSTRACT In this study, the effect of the addition of soybean protein isolate (SPI), whey protein isolate (WPI), whole milk powder (WMP), and sodium caseinate (SC) on the rheological, physical, sensory, and structural properties of fresh and frozen/thawed mashed potatoes formulated with added cryoprotectants [kappa-carrageenan (κ-C) and xanthan gum (XG)] was compared. Steady shear flow rate curves indicated a non-Newtonian fluid and exhibited typical shear thinning (pseudoplastic) behavior (n < 1) with all added proteins. The results showed that there is no significant change in the apparent viscosity (ηapp) of fresh mashed potatoes (FMP) and frozen/thawed mashed potatoes (F/TMP) with added WMP and SC at a concentration of 5 g/kg. While the addition of SPI at a concentration of 10 g/kg increased the ηapp and pseudoplasticity, which indicates that the SPI behaves as harder fillers. Based on the sensory evaluation results, WPI and WMP could incorporate to FMP without losing the sensory quality of the product. F/TMP samples with addition of SPI were judged more acceptable than other processed samples, evidencing the ability of this protein to reduce the influence of freeze/thaw process.

Influence of calcium lactate and pH on emulsification of low-methoxylated citrus pectin in a Pickering emulsion

ABSTRACT An emulsion was prepared by homogenizing 30% rapeseed oil with 70% (w/w) aqueous solution. The emulsion viscosity increased when the concentrations of calcium lactate and low-methoxylated citrus pectin (LMP) in the emulsion were increased. A stable emulsion was obtained when the concentrations of LMP and calcium lactate were 1% and 9 mM at pH 3, respectively. Optical microscopy and laser scanning confocal microscopy revealed that the stable emulsion was a Pickering emulsion. In the Pickering emulsion, LMP with calcium formed micro gels that can be absorbed on the oil surface. The emulsifying property of LMP could widen the applications of pectin. GRAPHICAL ABSTRACT