Effect of Soluble Dietary Fiber of Navel Orange Peel Prepared by Mixed Solid-State Fermentation on the Quality of Jelly.

The aim of this work was to prepare soluble dietary fibers (SDFs) from insoluble dietary fiber of navel orange peel (NOP-IDF) by mixed solid-state fermentation (M-SDF) and to investigate the influence of fermentation modification on the structural and functional characteristics of SDF in comparison with untreated soluble dietary fiber (U-SDF) of NOP-IDF. Based on this, the contribution of two kinds of SDF to the texture and microstructure of jelly was further examined. The analysis of scanning electron microscopy indicated that M-SDF exhibited a loose structure. The analysis of scanning electron microscopy indicated that M-SDF exhibited a loose structure. In addition, M-SDF exhibited increased molecular weight and elevated thermal stability, and had significantly higher relative crystallinity than U-SDF. Fermentation modified the monosaccharide composition and ratio of SDF, as compared to U-SDF. The above results pointed out that the mixed solid-state fermentation contributed to alteration of the SDF structure. Furthermore, the water holding capacity and oil holding capacity of M-SDF were 5.68 ± 0.36 g/g and 5.04 ± 0.04 g/g, which were about six times and two times of U-SDF, respectively. Notably, the cholesterol adsorption capacity of M-SDF was highest at pH 7.0 (12.88 ± 0.15 g/g) and simultaneously exhibited better glucose adsorption capacity. In addition, jellies containing M-SDF exhibited a higher hardness of 751.15 than U-SDF, as well as better gumminess and chewiness. At the same time, the jelly added with M-SDF performed a homogeneous porous mesh structure, which contributed to keeping the texture of the jelly. In general, M-SDF displayed much excellent structural and functional properties, which could be utilized to develop functional food.

Physicochemical Characteristics of Soluble Dietary Fiber Obtained from Grapefruit Peel Insoluble Dietary Fiber and Its Effects on Blueberry Jam.

Appropriate modification methods can increase the proportion of soluble dietary fiber (SDF). In this study, grapefruit peel insoluble dietary fiber (GP-IDF) was modified with the combined microwave and enzymatic method to obtain SDF. With regard to structural characterization, SDF from grapefruit peel IDF (GP-IDF-SDF) presented as a flat sheet with cracks, composed of a typical cellulose type I crystal, and had good stability below 200 °C. Galacturonic acid, arabinose and glucuronic acid were the main monosaccharide compositions, indicating that pectin might have been the principal component. Moreover, GP-IDF-SDF was excellent in water retention capacity (13.43 ± 1.19 g/g), oil retention capacity (22.10 ± 0.85 g/g) and glucose adsorption capacity (14.49 ± 0.068 mg/g). Thereafter, the effects of GP-IDF-SDF and commercial pectin addition on the color, rheology, texture and sensory properties of blueberry jam were compared. The results showed that the color of jam with GP-IDF-SDF was lighter. The addition of GP-IDF-SDF had less effects on the viscosity and gel strength of jam, but it enhanced the stability of jam. According to sensory data, the color, texture and spreadability of jam with GP-IDF-SDF or pectin were improved and more acceptable. Overall, GP-IDF-SDF had functional characteristics and played a positive role in jam, and it is expected to be a candidate for the development of functional food ingredients.

Bound Polyphenols from Insoluble Dietary Fiber of Defatted Rice Bran by Solid-State Fermentation with Trichoderma viride: Profile, Activity, and Release Mechanism.

This study is aimed at exploring the release of bound polyphenols (BP) from insoluble dietary fiber (IDF) and its mechanism by solid-state fermentation (SSF) via Trichoderma viride. The results indicated that BP released by SSF (5.55 mg GAE/g DW) was significantly higher than by alkaline hydrolysis. In addition, 39 polyphenols and catabolites were detected, and the related biotransformation pathways were speculated. Quantitative analysis showed that SSF released more ferulic acid, p-coumaric acid, and organic acids, which led to advances in antioxidant, α-amylase, and α-glucosidase inhibitory activities. Furthermore, structural characteristics (scanning electron microscopy, X-ray diffraction, thermos gravimetric analysis, and Fourier transform infrared spectroscopy) and dynamic changes of carbohydrate-hydrolyzing enzymes indicated that the destruction of hemicellulose and the secretion of xylanase were vital for releasing BP. Overall, this study demonstrated that SSF was beneficial to release BP from IDF, which could provide insight into utilizing agricultural byproducts in a more natural and economical way.

Comparison of structural, functional and in vitro digestion properties of bread incorporated with grapefruit peel soluble dietary fibers prepared by three microwave-assisted modifications.

In our previous study, three kinds of grapefruit peel soluble dietary fibers (SDFs) were prepared by microwave-assisted modifications, including microwave-sodium hydroxide treatment SDF (MST-SDF), microwave-enzymatic treatment SDF (MET-SDF) and microwave-ultrasonic treatment SDF (MUT-SDF). The present study aimed to investigate the structural, functional and in vitro digestion properties of three kinds of bread incorporated with SDFs, named MST-SDF bread (SB), MET-SDF bread (EB), and MUT-SDF bread (UB). Scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and texture profile analysis were used to determine the structural properties. In comparison with the SB and EB, the UB showed an ideal hardness and internal structure, and also significant improvement of the thermal stability. Meanwhile, the UB exhibited the highest overall acceptability in the sensory evaluation. In addition, the water holding capacity (WHC), cholesterol adsorption capacity (CAC) and nitrite ion adsorption capacity (NIAC) of UB were superior to those of the other two samples. Moreover, the in vitro digestive glucose release rates of breads were all significantly reduced by the addition of SDFs, especially that of UB. In summary, the present study showed that UB presented the best performance in terms of structural, functional and in vitro digestion properties, implying that MUT-SDF could be utilized in bread with high quality and low glucose release rate, and developed as a potential ingredient of functional food.

Ultrasound-assisted third-liquid phase-transfer catalyzed esterification of sodium salicylate in a continuous two-phase-flow reactor.

The esterification of sodium salicylate to synthesize butyl salicylate by third-liquid phase-transfer catalysis under ultrasound irradiation was investigated in a continuous two-phase-flow reactor. The reactor was designed to keep the third-liquid phase in the middle part and to have the aqueous and organic phases flowing through it in countercurrent. Using tetra-n-butylphosphonium bromide to prepare the third-liquid phase for this esterification, the product yield in the organic outlet (toluene) at 70 degrees C was 49.7% in silent condition, showing the reaction promoted simply by countercurrent mixing of the aqueous and organic phases. In the conditions of space time at 168 min, stirring at 150 rpm and ultrasound irradiation (28 kHz, 300 W), the product yield was greatly enhanced to 78.2%. As prepared, above 90% of the added catalyst existed in the third-liquid phase, and after 4-h on stream for a large excess of n-butyl bromide to sodium salicylate, the fraction of catalyst retaining in the reactor was reduced to around 80%. The distributions of catalysts between phases before and after reaction were analyzed. A kinetic model was proposed to estimate the apparent rate constants, and the feasibility for third-liquid phase-transfer catalysis assisted by ultrasound irradiation in a continuous flow reactor was demonstrated.