Characterization and emulsifying ability evaluation of whey protein-pectin conjugates formed by glycosylation.

Glycosylation is a method that enhances the functional properties of proteins by covalently attaching sugars to them. This study aimed at preparing three conjugates (WP-HG, WP-SBP, and WP-RGI) by dry heating method to research the influence of different pectin structures on the functional properties of WP and characterize properties and structures of these conjugates. The research results manifested that the degree of glycosylation (DG) of HG, SBP and RGI were 13.13 % ± 0.07 %, 23.27 % ± 0.3 % and 36.39 % ± 0.3 % respectively, suggesting that the increase of the number of branch chains promoted the glycosylation reaction. The formation of the conjugate was identified by the FT-IR spectroscopy technique. And SEM showed that WP could covalently bind to pectin, resulting in a smoother and denser surface of the conjugates. The circular dichroism analysis exhibited that the glycosylation reaction altered the secondary structure of WP and decreased the α-Helix content. This structural change in the protein spatial conformation led to a decrease in the hydrophobicity of protein surface. But the addition of pectin further regulated the hydrophilic-hydrophobic ratio on the surface of the protein, thus improving the emulsification properties of WP. In addition, the glycosylation could improve the stability of the emulsion, giving it a smaller droplet size, higher Zeta-potential and more stable properties. In a word, this study pointed out the direction for the application of different pectin structures in the development of functional properties of glycosylation products in food ingredients.

Salt adopted in soaking solution controls the yield and starch digestion kinetics of intact pulse cotyledon cells.

Intact cellular powders have gained attention as a functional ingredient due to their lower glycemic response and potential benefits in colon. The isolation of intact cells in the laboratory and pilot plant settings is mainly achieved through thermal treatment with or without the use of limited salts. However, the effects of salt type and concentration on cell porosity, and their impact on the enzymic hydrolysis of encapsulated macro-nutrients such as starch, have been overlooked. In this study, different salt-soaking solutions were used to isolate intact cotyledon cells from white kidney beans. The use of Na2CO3 and Na3PO4 soaking treatments, with high pH (11.5-12.7) and high amount of Na ion (0.1, 0.5 M), greatly improved the yield of cellular powder (49.6-55.5 %), due to the solubilization of pectin through ß-elimination and ion exchange. Intact cell walls serve as a physical barrier, significantly reducing the susceptibility of cell to amylolysis when compared to white kidney bean flour and starch counterparts. However, the solubilization of pectin may facilitate enzyme access into the cells by enlarging cell wall permeability. These findings provide new insights into the processing optimization to improve the yield and nutritional value of intact pulse cotyledon cells as a functional food ingredient.

Recent advances in polysaccharides from Rose roxburghii Tratt fruits: isolation, structural characterization, and bioactivities.

Rosa roxburghii Tratt fruit (RRF), known commonly as Cili in China, is a highly valued fruit that contains abundant functional and nutritional constituents with a variety of health-promoting benefits. Polysaccharides (RRFPs) are regarded as one of the crucial biological compounds in RRF. Existing literature has shown that RRFPs possess various remarkable biological activities, such as antioxidant, hypoglycemic, antitumor, anti-inflammatory, and gut microbiota modulation capabilities. In recent years, isolation and purification methods, structural characteristics, and biological activities of RRFPs have been drawing increasing attention. However, there is no up-to-date review of research progress on this front. In this review, recent advances in RRFPs, including their isolation, purification, structural characterization, biological activity, and the structure-activity relationship are summarized and discussed. In addition, this review highlights the challenges and prospects of RRFPs. Overall, this review provides useful research underpinnings and updated information for the further development and utilization of RRFPs in the fields of health, food, and medicine.

Effect of V-type crystallinity and starch particle structure on the oil loading capacity and anti-oxidation.

Starch-based carriers have a great potential in functional oil encapsulation because of their mild preparation conditions, but the oil loading capacity and underlying anti-oxidation mechanism remain unclear. Here V-type starches were applied to fabricate flaxseed oil powder. Particle size analysis and scanning electron microscopy showed a loose aggregation microstructure of normal maize starch (NMS) prepared using the anti-solvent (AS) precipitation method, with an average size of 24.9 µm. Differential scanning calorimetry displayed a good thermo-oxidation resistance of NMS-derived V-type starch prepared via AS precipitation. Principal component analysis revealed that the oil loading capacity, related closely to V-type crystallinity and D50, has a significant positive correlation with the onset oxidation temperature and a negative correlation with the peroxide, thiobarbituric acid, and ρ-anisidine values. Our original study reveals the effects of V-type crystallinity and aggregation microstructure on the oil loading capacity and anti-oxidation, providing theoretical guidance for developing novel, starch-based carriers.

Multi-scale structures and physicochemical properties of waxy starches from different botanical origins.

The multi-scale structures and physicochemical relationships of three different types of waxy starches (maize, tapioca, and potato) were investigated. The maize and tapioca starches exhibited A-type crystalline polymorph compared to potato starch (B-type). The WMS showed higher amorphous content (5.56 %) than other waxy starches. The WTS exhibited a low tendency of retrogradation with its high fa (DP 6-12) and low fb3 (DP ≥ 37) proportion of chains. Double helix content of WPS was observed highest with a high pasting viscosity (952.3 BU). Low fa (DP 6-12) and high fb3 (DP ≥ 37) chain proportions of the WPS retrograded easily. The compactness of the semi-crystalline aggregation structure influenced the retrogradation properties of waxy starches with a positive correlation. Furthermore, the peak viscosity of pastes was correlated with the proportion of fb3 (DP ≥ 37) chains, mass fractal dimension, and double helix content. The results provide guidance to design the application of waxy starches in the production of clean-labels.

The interfacial behavior and long-term stability of emulsions stabilized by gum arabic and sugar beet pectin.

Gum arabic (GA) is the most widely used natural emulsifier in food industry. However, due to its high price and unstable market supply, the search for substitutes of gum arabic has attracted the attention of researchers. Recent studies have shown that sugar beet pectin (SBP) has great potential as a natural emulsifier. However, the mechanisms and differences of GA- and SBP-stabilized emulsions are still unclear. In this study, the interfacial behavior of GA and SBP on the oil-water interface was studied and compared through dissipative quartz crystal microbalance and interfacial dilatational rheology. Then, droplet size, zeta-potential and viscosity of the emulsion stabilized by GA and SBP were measured. Meanwhile, the long-term stability of GA- and SBP-stabilized emulsions was evaluated and compared through a LUMiSizer stability analyzer. The study showed that at the same concentration, SBP-stabilized emulsion had significant advantages of a smaller droplet size, a larger viscosity, a thicker and more elastic interfacial layer, and better long-term stability. A comparison of the long-term stability of SBP2.0%- and GA15.0%-stabilized emulsions, evidenced that the elasticity of the interfacial layer plays a crucial role in the long-term stability of emulsions. This research may provide useful information for finding alternatives to GA.

Starch-lauric acid complex-stabilised Pickering emulsion gels enhance the thermo-oxidative resistance of flaxseed oil.

Hydrophobic-modified starch complexes have the potential to form Pickering emulsions and improve the oxidative stability of flaxseed oil. Here, V-type starch-lauric acid complexes (SLACs) were fabricated via solid encapsulation within 0.5-12 h and applied in flaxseed oil Pickering emulsions. Complexing index, X-ray diffraction and differential scanning calorimetry analyses confirmed that the degree of complexation increased with the reaction time. Pickering emulsion gels stabilised by SLACs generated with reaction times of 6 h and 12 h exhibited good storage stability and high yield stress, G' values and apparent viscosity. Confocal laser scanning microscopy and cryo-scanning electron microscopy revealed a gelation mechanism involving increased interface roughness and enhanced droplet-droplet interaction. In comparison to pure flaxseed oil, higher thermo-oxidative resistance was observed at 130 °C, with a markedly longer oxidation induction for emulsions and emulsion gels stabilised by SLACs. Our findings could assist in the design of hydrophobic-modified starch and provide a new paradigm for delaying oil oxidation.

Starch retrogradation in potato cells: Structure and in vitro digestion paradigm.

The consumption of foods with intact cellular structure is recognized to lower the glycemic index. Studies have focused on the gelatinization and digestibility of starch in intact cells. However, the effects of intact cells on starch retrogradation and digestibility are still unclear. Mild acid and alkali soaking were used to isolate intact potato cells and hydrothermal treatment (73 °C for 30 min) followed by retrogradation (4 °C for 0-15 days). The retrogradation period of 0-15 days increased the crystallinity and enthalpy change, while decreased the digestion rate and extent in potato cell and starch ghost samples. Furthermore, the existence of cell wall (potato cell) lowered the starch digestion rate and extent than potato starch ghost. It was concluded that the ghost structure is the main factor that controls the starch retrogradation, whereas the intact cell wall structure provides the barrier for starch digestion and protects the ghost structure.

Identification of polyphenols from Rosa roxburghii Tratt pomace and evaluation of in vitro and in vivo antioxidant activity.

Rosa roxburghii Tratt pomace (RRTP) has increasingly attracted attention due to its various nutritional ingredients and health benefits. In this study, the free phenolic fraction (RRTP-FPF) and bound phenolic fraction (RRTP-BPF) were extracted from RRTP by solvent extraction method and alkaline hydrolysis method, respectively. The composition of polyphenols in RRTP-FPF and RRTP-BPF were identified by ultra-high performance liquid chromatography equipped with an electrospray ionization and quadrupole time-of-flight mass spectrometry (UHPLC-ESI-QTOF-MS/MS). In vitro antioxidant assays indicated that RRTP-FPF and RRTP-BPF could scavenge radicals in a dose-dependent manner, and RRTP-BPF exhibited better scavenging activity than RRTP-FPF. In addition, RRTP-FPF and RRTP-BPF (20 âˆ¼ 100 µg/mL) treatment for 24 h could significantly increase the survival rate and decrease reactive oxygen species (ROS) level of paraquat-exposed nematodes through improving the activities of superoxide dismutase (SOD) and catalase (CAT). These results suggest that RRTP could be as a good and cheap source of natural antioxidants.

Ultra-high Pressure Treatment Controls In Vitro Fecal Fermentation Rate of Insoluble Dietary Fiber from Rosa Roxburghii Tratt Pomace and Induces Butyrogenic Shifts in Microbiota Composition.

Dietary fiber has been considered a key element in shaping the beneficial host-microbe symbiosis. In the present study, we identified Rosa roxburghii Tratt fruits as a promising dietary fiber source. The physicochemical properties and in vitro fermentability by human fecal microbes of R. roxburghii pomace water insoluble dietary fiber (RIDF) obtained from ultrasonic extraction and ultrahigh pressure (90 MPa)-treated RIDF (RIDF-90) were compared to those of R. roxburghii Tratt pomace (R). Ultrahigh pressure modification significantly increased the water holding, oil holding, and swelling capacity of RIDF-90 in comparison to R and RIDF. RIDF-90 displayed the slowest fermentation rate yet yielded the highest butyrate production. The superior butyrogenic properties of both RIDF-90 and, in part, RIDF were reflected by increased Coprococcus and Ruminococcus levels, demonstrating that ultrasonic extraction and/or further ultrahigh pressure treatment of insoluble fibers promotes the prebiotic value of R. roxburghii Tratt.

Polysaccharide from Rosa roxburghii Tratt Fruit Attenuates Hyperglycemia and Hyperlipidemia and Regulates Colon Microbiota in Diabetic db/db Mice.

This study was aimed at investigating the hypoglycemic and hypolipidemic effects of a polysaccharide (RTFP) isolated from Rosa roxburghii Tratt fruit on type-2 diabetic db/db mice. The results indicated that the oral administration of RTFP could significantly decrease the body weight, fat, and liver hypertrophy and the levels of fasting blood glucose, serum insulin, and serum lipids of the db/db mice. Histopathological observation showed that RTFP could effectively protect the pancreas, liver, and epididymal fat against damage and dysfunction. Real-time quantitative polymerase chain reaction analysis confirmed that the gene expression levels of peroxisome proliferator-activated receptors-γ (PPAR-γ), sterol regulatory element-binding protein-1 (SREBP-1c), acetyl-CoA carboxylase-1 (ACC-1), fatty acid synthase (FAS), and glucose-6-phosphatase (G6 Pase) were significantly down-regulated in the liver of db/db mice after treatment with RTFP. Moreover, RTFP treatment reversed gut dysbiosis by lowering the Firmicutes-to-Bacteroidetes ratio and enhancing the relative abundances of beneficial bacteria including Bacteroidaceae, Bacteroidaceae S24-7 group, and Lactobacillaceae. These findings suggest that RTFP can be used as a promising functional supplement for the prevention and treatment of type-2 diabetes mellitus.

Digestive Property and Bioactivity of Blackberry Polysaccharides with Different Molecular Weights.

In the present study, the digestion and fermentation of blackberry polysaccharides (BBPs) with different molecular weights (Mw) were investigated. The results showed that the Mw decrease rates of BBP, BBP-8, BBP-16, and BBP-24 were 77.48, 69.61, 56.87, and 52.89%, respectively. The antioxidant and α-glucosidase inhibitory activities of BBPs were decreased under gastrointestinal condition, which might be due to the variation of Mw during digestion. The bile acid-binding ability of BBPs showed an Mw-dependent manner for higher Mw polysaccharides with higher viscosity. Through fermentation, the BBPs affected the ecosystem of the intestinal tract by promoting the production of short-chain fatty acids, lowering the pH of colon, and decreasing the ratio of Firmicutes to Bacteroidetes. All BBPs showed almost a similar modulation effect on the gut bacteria, but the lower Mw polysaccharide was more easily utilized by bacteria.

Preparation and properties of ferulic acid-sugar beet pulp pectin ester and its application as a physical and antioxidative stabilizer in a fish oil-water emulsion.

A ferulic acid-sugar beet pulp pectin complex (FA-SBPP) was prepared using an immobilized enzyme (Novozym 435®) as the catalyst at 60 °C in a vacuum-controlled system. The structure of FA-SBPP was characterized by FT-IR and NMR (1H and 13C). In addition, the antioxidant activity of FA-SBPP was evaluated according to the DPPH free radical scavenging ability and ORAC values. Moreover, the physical and oxidation stability of the emulsion was evaluated by particle size distribution, cream index (CI), peroxide value (POV), and 2-thiobarbituric acid reactive substance (TBARS) formation. The results showed that esterification between FA and SBPP was confirmed, and the reaction mainly occurred at the C-2, C-3, and C-6 positions. When the concentration was 1.0 mg/mL, the DPPH scavenging activity and total antioxidant activity of FA-SBPP-3 were 80.03% and 355.72 µmol TE/g, respectively. Compared with SBPP, FA-SBPP-stabilized emulsions exhibited significant smaller droplet sizes and lower CIs, POVs and TBARS amounts. Thus, the introduction of FA changed not only the chemical reactivity but also the polarity of SBPP, thereby improving its antioxidant ability and affinity for the oil-water interface. Thus, we provide a multifunctional stabilizer that can reduce the dose of antioxidants or even replace them in oil-in-water emulsions.

Comparative assessment of phytochemical profiles and antioxidant and antiproliferative activities of kiwifruit (Actinidia deliciosa) cultivars.

The present study was designed to analyze and compare phytochemical activities of four different cultivars of kiwifruit. Among all investigated varieties, Hua You (HY) and Cui Xiang (CUX) displayed the maximum concentration of phytochemical content, and the highest total phenolic results were observed in HY and CUX cultivars with 220.20 ± 1.12 mg GAE/100 g and 218.04 ± 1.11 mg GAE/100 g FW, respectively. Likewise, the richest total flavonoids results were estimated in red kiwifruit (RKF) and CUX varieties with 49.082 ± 0.14 mg CE/100 g FW and 48.327 ± 0.14 mg CE/100 g FW, respectively. Moreover, tests for oxygen radical scavenging capacity (ORAC) and peroxyl radical scavenging capacity (PSC) were observed maximum in RKF cultivar showing 131.229 ± 5.91 µM Trolox equivalent/g FW and 85.957 ± 11.75 µM vitamin C equivalent/g FW, respectively. Furthermore, the highest cellular antioxidant activity (CAA) with No PBS wash protocol was depicted in RKF 237.544 ± 4.12 µM QE equivalent/g FW with the lowest EC50 0.0128 mg/ml. In addition, high-performance liquid chromatography (HPLC) analysis confirmed the presence of ferulic acid, naringin, gallic acid, syringic acid, caffeic acid, rutin, protocatechuic acid, salicylic acid, and catechin in kiwifruit. Catechin as one main content in our study is consistent with the recent reports. The result suggested that the phytochemical profile and bioactivities were significantly affected by the type of cultivars. PRACTICAL APPLICATIONS: Kiwifruit is widely consumed over the world for its rich nutritious and medicinal values. Currently, phytochemicals are considered as one of the main bioactive components of kiwifruits, which are responsible for lots of bioactivities, such as antitumor, anti-inflammatory, antioxidant, hypoglycemic, and hypolipidemic activities. There are varieties of kiwifruits, and the bioactive components and bioactivities are greatly affected by the cultivars. But there have been no comparative studies on the phytochemicals from different varieties. This study aimed to make a comprehensive assessments of the free, bound, and total phenolics and flavonoids, as well as the chemical-based and cell-based antioxidant activities of four different subspecies of kiwifruit. This work would be beneficial to elucidate the function differences of different kiwifruit phytochemicals, promote its further research, as well as provide a basis for selecting cultivars.

Bioaccessibility, antioxidant activity and modulation effect on gut microbiota of bioactive compounds from Moringa oleifera Lam. leaves during digestion and fermentation in vitro.

This study aims to investigate the bioaccessibility, bioactivity and gut microbiota modulation effect of Moringa oleifera Lam. leaves after in vitro gastrointestinal digestion and colonic fermentation. A total of 24.95 ± 0.91 mg GAE per g DM and 21.66 ± 1.41 mg RE per g DM of phenolics and flavonoids were released during digestion. The HPLC-ESI-TOF/MS analysis showed that the major phenolic compound 6,8-di-C-glucosylapigenin was released during oral digestion, catechin during gastric digestion, and quercetin-3-O-ß-d-glucoside and ferulic acid during small intestine digestion. The antioxidant activity of Moringa oleifera Lam. leaves during the whole digestion process was in line with the release of phenolics and flavonoids. In addition, the fermentation of Moringa oleifera Lam. leaves induced the production of acetic, propionic, and n-butyric acids leading to a decrease in pH, as well as the growth of beneficial colonic bacteria. The results suggested that Moringa oleifera Lam. leaves are a promising candidate for healthy food.

Controlled gelatinization of potato parenchyma cells under excess water condition: structural and in vitro digestion properties of starch.

Modulation of the starch digestion rate and extent is a major target for increasing nutritional value of potato-based food. In order to understand the effect of controlled gelatinization on the structure and in vitro digestion properties of whole potato food, intact parenchyma cells were isolated as a model through soaking in mild acid and alkali solutions, and then hydrothermally treated at different incubation temperatures in excess water. The morphological and structural changes of entrapped starch granules as well as in vitro starch digestion properties were investigated. Three classes of starch digestion of potato cells are identified: (1) when the temperature of hydrothermal treatment was set at 55 °C or 60 °C, the efficient physical barrier of intact cell walls resulted in a limited starch digestion extent; (2) when the temperature is set at 65 °C, the cell wall structures apparently reduced the digestion rate but only slightly reduced the final extent compared to the starch counterpart, probably because starch swelling weakens the physical barrier; (3) at 70-95 °C, the damaged cell wall still reduced the digestion rate but did not reduce the digestion extent compared to the starch counterpart. The results suggest that controlling hydrothermal processing temperature is a viable approach to develop potato ingredients with enhanced nutritional functionality.

A comparison study on polysaccharides extracted from Fructus Mori using different methods: structural characterization and glucose entrapment.

In this study, the structure characteristics and the hypoglycemic and antioxidant activities of mulberry fruit polysaccharides obtained by the commonly used hot water (MFPh)-, ultrasonic (MFPu)-, acid (MFPc)- and alkali (MFPa)-assisted extraction methods were investigated. NMR analysis indicated that the four polysaccharides had similar glycosidic linkage patterns. Scanning electron microscopy analyses showed that the surface morphology of the polysaccharides was greatly affected by the extraction methods. The results of the bioactivity assays indicated that MFPh exhibited stronger antioxidant and α-amylase inhibitory activities than the other polysaccharides. Moreover, all the polysaccharides showed good α-glucosidase inhibitory activities except for MFPu with the lowest molecular weight. These results suggested that acid, alkali, and ultrasonic-assisted extractions have different effects on the degradation of polysaccharides without changing the main structure compared with hot water extraction. In addition, the molecular weight of polysaccharides plays a key role in the bioactivity of the mulberry fruit polysaccharides.

Fructus mori L. polysaccharide-iron chelates formed by self-embedding with iron(iii) as the core exhibit good antioxidant activity.

Mulberry fruit polysaccharide (MFP) was obtained from Morus alba L. by a hot water extraction method, and mulberry polysaccharide fractions named MFP1, MFP2 and MFP3 were isolated by DEAE cellulose-52 column chromatography. Monosaccharide analysis of MFP1, MFP2 and MFP3 showed that the three components had the same monosaccharide compositions with different ratios, and galacturonic acid was the main monosaccharide component. Molecular weight measurements showed that MFP1 and MFP2 are heteropolysaccharides and MFP3 is a homogeneous polysaccharide. In addition, the chelate mechanism of iron(iii) and polysaccharide is proposed in which iron(iii) as a core is enwrapped by the polysaccharide as a ligand by hydroxyl and carboxyl groups, which induces a morphology change from flat sheets to rods and increases the size. Furthermore, the polysaccharides showed strong antioxidant activity to eliminate hydroxyl radicals and inhibit MDA production in healthy mouse liver homogenate. Also, the polysaccharide-iron(iii) chelates exhibited stronger superoxide radical scavenging ability than the polysaccharides. These results suggest that the polysaccharides derived from Morus alba L. are promising candidates for fabricating organic iron supplements with good antioxidant activity.

Structure and in vitro hypoglycemic activity of a homogenous polysaccharide purified from Sargassum pallidum.

This study aimed at investigating the structure, hypoglycemic activity and the underlying mechanism of a homogeneous polysaccharide (PSP-2) purified from Sargassum pallidum. Structural characterization revealed that PSP-2 with a molecular weight of 144.8 kDa was composed of fucose (21.6%), arabinose (2.5%), galactose (22.4%), glucose (2.2%), xylose (18.8%), mannose (1.2%), glucuronic acid (7.7%) and galacturonic acid (23.6%). The backbone chain of PSP-2 was composed of →1)-ß-d-Xylp-(3→, →1,3)-ß-l-Fucp-(4→, →1)-α-d-Galp-(6→, and →1)-α-d-GlcpNAc-(2→, and the side chains were composed of →1,3,6)-α-d-Galp-(2→, →3)-ß-l-Fucp-(1,4→, ß-d-GalpNAc-(1→, and α-d-Manp-(1→. In vitro hypoglycemic assays indicated that PSP-2 could significantly enhance glucose consumption, glycogen synthesis, and pyruvate kinase (PK) and hexokinase (HK) activities of insulin-resistant HepG2 cells. Furthermore, the underlying mechanistic studies revealed that PSP-2 could ameliorate insulin resistance by up-regulating the expression levels of insulin receptor substrate-1 (IRS-1), glycogen synthase (GS), phosphoinositide-3-kinase (PI3K) and glucose transporter-4 (GLUT4). These results suggested that PSP-2 may be a potential candidate for the prevention and treatment of Type 2 diabetes mellitus.

CO2 inclusion complexes of Granular V-type crystalline starch: Structure and release kinetics.

Granular V-type crystalline starch (V-type starch) was prepared using different starch varieties by alcoholic-alkaline treatment. Carbon dioxide was encapsulated into V-type starch using a solid encapsulation method. The morphological and structural properties of the inclusion complexes (ICs) were characterised using scanning electron microscopy and X-ray diffraction. Fourier-transform infrared spectroscopy and 13C Nuclear Magnetic Resonance proved that CO2 was successfully encapsulated. The encapsulation capacity of V-type starches was determined by head space gas chromatography, and ICs made from normal maize starch achieved the highest CO2 concentration (2.55%, w/w). The controlled release characteristics of ICs were also determined at various temperatures and relative humidity, and ICs made from normal potato starch exhibited slower release characteristics. The release kinetics showed that the release of CO2 from ICs was accelerated by increasing temperature or RH. V-type starch is a renewable, inexpensive material for encapsulation of gasses such as CO2.