Characterizations of a pectin extracted from Premna microphylla turcz and its cold gelation with whey protein concentrate at different pHs

Preparation of bovine serum albumin-arabinoxylan cold-set gels by glucono-δ-lactone and salt ions double induction

In order to investigate the effect of glucono-δ-lactone (GDL) and different salt ions (Na+ and Ca2+) induction on the cold-set gels of bovine serum albumin (BSA)-arabinoxylan (AX), the gel properties and structure of BSA-AX cold-set gels were evaluated by analyzing the gel strength, water-holding capacity, thermal properties, and Fourier Transform Infrared (FTIR) spectra. It was shown that the best gel strength (109.15 g) was obtained when the ratio of BSA to AX was 15:1. The addition of 1 % GDL significantly improved the water-holding capacity, gel strength and thermal stability of the cold-set gels (p < 0.05), and the microstructure was smoother. Low concentrations of Na+ (3 mM) and Ca2+ (6 mM) significantly enhanced the hydrophobic interaction and hydrogen bonding between BSA and AX after acid induction, and the Na+-induced formation of a denser microstructure with a higher water-holding capacity (75.51 %). However, the excess salt ions disrupted the stable network structure of the cold-set gels and reduced their thermal stability and crystalline structure. The results of this study contribute to the understanding of the interactions between BSA and AX induced by GDL and salt ions, and provide a basis for designing hydrogels with different properties.

Effects of Premna microphylla turcz polysaccharide on rheological, gelling, and structural properties of mung bean starch and their interactions

The aim of this study was to investigate the effects of Premna microphylla turcz polysaccharide (PMP) on the rheological, gelling, and structural properties of mung bean starch (MBS) and their potential interaction mechanism. Results showed that the addition of PMP significantly improved the pasting properties, rheological properties, water holding capacity, and thermostability of MBS. The texture tests showed a decrease in hardness, gumminess and chewiness, indicating the retrogradation of MBS was inhibited. Scanning electron microscopy (SEM) suggested the MBS-PMP composite gels expressed a denser microstructure with obvious folds and tears. Moreover, the results of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and interaction force tests revealed the main forces between MBS and PMP were hydrogen bonds and hydrophobic interactions to form composite gels with great gelling properties. These results facilitate the practical application of MBS and PMP, and provide some references for understanding the interaction mechanism between starch and polysaccharide.

Effect of apple high-methoxyl pectin on heat-induced gelation of silver carp myofibrillar protein

The effect of adding apple high-methoxy pectin (HMP) (0-3 mg∙mL-1) on heat-induced gel characteristics of low concentration silver carp myofibrillar protein (MP) (15 mg∙mL-1) was studied. It was found that the hardness of gel increased by 20.6 times with adding 2 mg∙mL-1 HMP. Besides, HMP aided in the development of disulfide bonds and the aggregation of hydrophobic groups. During gel formation, the maximal storage modulus (G') of samples supplemented with 2 mg·mL-1 HMP was raised by a factor of 2.7. Of note, the images of SEM showed that protein and water were tightly combined with a proper amount of HMP and made its pores more uniform and dense. Meantime, the addition of moderate amounts of HMP enabled the formation of gels with favorable texture and performance at low concentration of MP was identified, which could provide a theoretical reference for the design and production of flesh low-calorie food gel.

Soybean isolate protein complexes with different concentrations of inulin by ultrasound treatment: Structural and functional properties

The effects of ultrasound and different inulin (INU) concentrations (0, 10, 20, 30, and 40 mg/mL) on the structural and functional properties of soybean isolate protein (SPI)-INU complexes were hereby investigated. Fourier transform infrared spectroscopy showed that SPI was bound to INU via hydrogen bonding. All samples showed a decreasing and then increasing trend of α-helix content with increasing INU concentration. SPI-INU complexes by ultrasound with an INU concentration of 20 mg/mL (U-2) had the lowest content of α-helix, the highest content of random coils and the greatest flexibility, indicating the proteins were most tightly bound to INU in U-2. Both UV spectroscopy and intrinsic fluorescence spectroscopy indicated that it was hydrophobic interactions between INU and SPI. The addition of INU prevented the exposure of tryptophan and tyrosine residues to form a more compact tertiary structure compared to SPI alone, and ultrasound caused further unfolding of the structure of SPI. This indicated that the combined effect of ultrasound and INU concentration significantly altered the tertiary structure of SPI. SDS-PAGE and Native-PAGE displayed the formation of complexes through non-covalent interactions between SPI and INU. The ζ-potential and particle size of U-2 were minimized to as low as -34.94 mV and 110 nm, respectively. Additionally, the flexibility, free sulfhydryl groups, solubility, emulsifying and foaming properties of the samples were improved, with the best results for U-2, respectively 0.25, 3.51 μmoL/g, 55.51 %, 269.91 %, 25.90 %, 137.66 % and 136.33 %. Overall, this work provides a theoretical basis for improving the functional properties of plant proteins.

Characterization of a low-methoxyl pectin extracted from red radish (Raphanus sativus L.) pomace and its gelation induced by NaCl

There is an increasing demand for obtaining pectin from new sources. Red radish (Raphanus sativus L.) pomace pectin extracted by alkali was low-methoxyl pectin with esterification degree of 10.17 %, galacturonic acid content of 69.71 % (wt), and average molar weight of 78.59 kDa. The pectin primarily consisted of rhamnogalacturonan I and homogalacturonan domains. The predominant monosaccharides of the pectin were galacturonic acid (46.32 mol%), arabinose (16.03 mol%), galactose (10.46 mol%), and rhamnose (10.28 mol%), respectively. The red radish pomace pectin solution exhibited a shear-thinning behavior. NaCl could induce gelation of red radish pomace pectin, and the gel properties of red radish pomace pectin were considerably affected by the NaCl concentration. As the NaCl concentration (0.25-0.50 mol/L) increased, the rate of gelation accelerated, and the time to gelation point appeared earlier. There was an optimal NaCl concentration (0.50 mol/L) for the pectin to form a gel with the greatest solid-like properties, gel hardness (33.84 g) and water-holding capacity (62.41 %). Gelation force analysis indicated gel formation mainly caused by electrostatic shielding effect of Na+ and hydrogen bonding. This research could facilitate the applications of the red radish pomace pectin in the realm of edible hydrocolloids.

Pectin extracted from Premna Microphylla Turcz for preparation of a "sandwich" multi-property sensor film involved with deep eutectic solvent

An acidic deep eutectic solvent (DES, choline chloride/citric acid) was used to efficiently extract edible pectin from Premna microphylla Turcz (PMTP) and further prepare the film sensor with the purpose of "four birds with one stone" with the roles of extractant, coalescent, conductivity promoter and bacteriostatic agent. The optimized extraction process accorded with pseudo second-order kinetics, which was carried out at 78.2 °C for 1.29 h with the solid-liquid ratio of 1:34.66 g/mL with the yield up to 0.8210 g/g. After comprehensive characterizations of pectin product, a simple casting method was used to prepare the PMTP-DES based composite film. It showed that the composite film has promising compatibility, smooth surface, good breathability and ideal homogeneity. After 30 power on/power off cycles at 10 V, it exhibited satisfied conductivity stability. Moreover, the PMTP-DES film could be simply assembled as the flexible visual temperature sensor, with sensitive response at breathing or finger touch; it exhibited the highest sensitivity of 134 %/°C when the external temperature changed from 15 to 55 °C. Besides, the composite film also has preferable antimicrobial activity. The whole results and findings were aimed to contribute for the raw material, composition, preparation, and functions of the existing flexible functional materials.

Dietary fiber extraction from citrus peel pomace: Yield optimization and evaluation of its functionality, rheological behavior, and microstructure properties

Citrus fruits were widely used in processing and production, generating a large amount of peel pomace and a low utilization rate, resulting in substantial economic losses and environmental risks. It was important to extract compounds from citrus peel pomaces and find suitable preparation methods to improve their yield and physicochemical properties. Grapefruit peel pomace (GP) and navel orange peel pomace (OP) were used as raw materials in this study to prepare green and edible soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). Analysis was done on the effects of solid-liquid ratio, cellulase hydrolysis time, cellulase dosage, and ultrasonic time on dietary fiber (DF) yield. To obtain the best DF preparation conditions, we used range analysis, variance analysis, and orthogonal experimental design. We also analyzed the structural, physicochemical, and rheological characteristics of SDF and IDF. According to the study's findings, SDF and IDF showed a loose and expansive structure with reduced particle size, higher specific surface area, and noticeably better physical and chemical properties after treating GP and OP with ultrasound-assisted composite enzyme method. Both SDF solution and IDF suspension were discovered through rheological analysis to be non-Newtonian pseudoplastic fluids, which was advantageous for expanding their applications in the field of food packaging. In conclusion, DF prepared using the ultrasound-assisted composite enzyme method was an excellent source of edible packaging materials, offering a benchmark for the recycling of other citrus peel wastes and ultimately paving the way for new methods of recycling citrus waste.

Ultrasonic effects on molecular weight degradation, physicochemical and rheological properties of pectin extracted from Premna microphylla Turcz

The high molecular weight and poor solubility of pectin extracted from Premna microphylla Turcz (PEP) limits its application. Therefore, in this paper, the degradation effects of PEP under ultrasound irradiation and the influences of ultrasonic on the PEP processing characteristics were investigated. The results indicated that the M_w of PEP decreased significantly with a narrow distribution after ultrasonic treatment. The degradation kinetics of PEP at different ultrasound intensities were sufficiently described by the 2nd-order kinetics eq. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis suggested that ultrasonic treatment destroyed the ordered structure inside the PEP, resulting in a looser microscopic morphology. Compared with the control, the thermal stability of PEP was significantly boosted after ultrasonic treatment. Rheological analysis illustrated that the sonicated PEP presented lower apparent viscosities than the original PEP. While the elasticity and thermal reversibility of the degraded products was enhanced. Ultrasonic treatment prominently weakened its shear thinning fluid behavior and thixotropy, thus improved its processing quality. Therefore, desirable PEP can be prepared by ultrasonic irradiation. The results can provide a reference for the development and application of PEP.

Fabrication and characterization of ZnO nanofilms using extracted pectin of Premna microphylla Turcz leaves and carboxymethyl cellulose

The current study sought to fabricate pectin nano-films from Premna microphylla Turcz (PMTP) leaves using a combination of ZnO-carboxymethyl cellulose. The rheological and physical properties of fabricated nano-ZnO films were studied. Spectroscopy FT-IR, microscopic study (SEM), thermogravimetry (TG), and XRD were applied to characterize the fabricated film. The antibacterial activity of the nanofilm was determined using the antibacterial circle method. The findings showed that the addition of PMTP can reduce the nanofilm color, water solubility/hydrophilicity, air permeability, and ultraviolet light permeability of the nanofilm. Treatment CPN0.5 achieved the optimized Tensile strength (TS) of 4.50 Mpa, significant differences compared to CPN2 (3.99 Mpa) and CPN1 (3.65 Mpa). In addition, treatment CPN1 achieved the lowest WVP value (29.35) compared to the highest value (41.62) achieved by CPN0.5 treatment with no significant differences with CPN3 (29.7) and CPN1 (30.98) treatments. Elongation (E%) at break was the best for each CP10 (74.9) and CPN0.5 (73.03). Moreover, ZnO can enhance the nanofilm activity and the nanofilm water swelling ratio. Furthermore, adding ZnO to the nano-formula improved the antibacterial activity of the fabricated film against Staphylococcus aureus. In sum, nanofilms fabricated of PMTP and ZnO possess promising prospects as antibacterial agents in packaging applications.

The complex of whey protein and pectin: Interactions, functional properties and applications in food colloidal systems - A review

This review describes the mechanism of non-covalent/covalent interaction of whey protein-pectin (WPP) complexes, including electrostatic interaction, steric hindrance, cross-linking and Maillard reaction. The interaction between whey protein and pectin determines the form of the complex in the system, i.e. co-dissolution, precipitation, separation, complex coacervation and compounding. The interaction of WPP is affected by environmental conditions and its own properties, including several factors such as pH, polymer concentration and ratio, temperature, and ionic strength. In addition, the functional properties of WPP complexes are discussed through illustrative examples. The complexes with good emulsification, heat stability, gelling properties and biological activity have promising application prospects. WPP complexes have been widely studied for application in food colloidal systems, including protein beverages, delivery systems for bioactive substances, fat substitutes and food preservation films/coatings. The understanding of the interaction and functional properties of WPP complexes provides theoretical support for the improvement and design of new food colloidal systems.

Polysaccharides from Premna microphylla turcz ameliorate inflammation via the enhancement of intestinal resistance in host

ETHNOPHARMACOLOGICAL RELEVANCE

Premna microphylla turcz is traditionally used as a folk remedy. Its roots, stems and leaves can be invoked as medicines, which have the functions of detoxification, swelling and hemostasis. It belongs to the Premna in the Verbenaceae and is mainly distributed in the mountains of southeastern China. However, there are few reports of in-depth studies on the anti-inflammatory effects of polysaccharide, which was the main component in Premna microphylla turcz.

MATERIALS AND METHODS

The flies were fed with standard corn flour-yeast medium to cause inflammation by sodium lauryl sulfate (SDS). The treatment group contained Premna microphylla turcz polysaccharide (pPMTLs) extract. The survival rate was obtained by feeding a vial containing five layers of filter paper, which was infiltrated with the 5% sucrose solution contaminated with SDS or SDS polysaccharide. The microvilli and nucleus of the midgut epithelial cells of different treatments were observed by transmission electron microscope, and the expression of inflammation-related genes was detected by real-time quantitative PCR (qRT-PCR). Finally, 16S rDNA analysis was conducted on the differences in the composition of the intestinal microbes of Drosophila.

RESULTS

In the current study, we showed that pPMTLs significantly prolonged the life span of SDS-inflamed flies from 5 days to 6 days. And pPMTLs reduced the rupture of microvilli in the midgut and restored the nuclear structure. In addition, pPMTLs significantly improved expression level of immune-related genes in Inflammation Drosophila especially the defensin (4.32 ± 0.75 vs 9.97 ± 0.52 SDS-polysaccharide group: SDS group, p < 0.001). The analysis of intestinal microbiota showed that pPMTLs decreased the relative abundance of Raoultella while Wolbachia increased (p < 0.05).

CONCLUSIONS

Collectively, our results revealed the potential application of pPMTLs in enhancing inflammation defense, which would be enormous significance for the inflammation-related disorders treatment.

A novel self-crosslinked gel microspheres of Premna microphylla turcz leaves for the absorption of uranium

Premna microphylla turcz leaves (PMTL) is a resource-rich, biodegradable, renewable biomass. Here, a microsphere adsorbent was prepared from PMTL by a self-crosslinking method without any addition of chemical cross-linking agent, and characterized by SEM, FTIR, and XPS. The influence of preparation methods and conditions on the properties of the microspheres was studied and the self-crosslinking mechanism was analyzed. The effects of temperature, pH, contact time, uranium concentration, and adsorbent dosage on its adsorption performance toward to uranium were systematically explored. The results showed that PMTL endogenous pectin binding with endogenous Ca²⁺, Mg²⁺ and other metal ions to form an 'egg box' structure might be the mechanism of its self-crosslinking to form microspheres. The adsorption isotherms fitted well by the Freundlich model and the experimental maximum adsorption capacity of microspheres was 346.65 mg·g^-1 at pH of 5, and kinetics data correlated well with the pseudo-second order model. The adsorption mechanism might be the coordination bonding between the uranium and oxygen-containing groups (hydroxyl and carboxyl groups), and the ion exchange between the uranium and metal ions (mainly Ca²⁺ and Mg²⁺). The PMTL microspheres are promising in treating uranium-containing wastewater in a more cost-effective and environmentally friendly manner.