Enhance the resistance of probiotics by microencapsulation and biofilm construction based on rhamnogalacturonan I rich pectin.

Microcapsules were always used as functional material carriers for targeted delivery and meanwhile offering protection. However, microcapsule wall materials with specific properties were required, which makes the choice of wall material a key factor. In our previous study, a highly branched rhamnogalacturonan I rich (RG-I-rich) pectin was extracted from citrus canning processing water, which showed good gelling properties and binding ability, indicating it could be a potential microcapsule wall material. In the present study, Lactiplantibacillus plantarum GDMCC 1.140 and Lactobacillus rhamnosus were encapsulated by RG-I-rich pectin with embedding efficiencies of about 65 %. The environmental tolerance effect was evaluated under four different environmental stresses. Positive protection results were obtained under all four conditions, especially under H2O2 stress, the survival rate of probiotics embedded in microcapsules was about double that of free probiotics. The storage test showed that the total plate count of L. rhamnosus encapsulated in RG-I-rich pectin microcapsules could still reach 6.38 Log (CFU/mL) at 25 °C for 45 days. Moreover, probiotics embedded in microcapsules with additional incubation to form a biofilm layer inside could further improve the probiotics' activities significantly in the above experiments. In conclusion, RG-I-rich pectin may be a good microcapsule wall material for probiotics protection.

Changes in physiochemical properties and in vitro digestion of corn starch prepared with heat-moisture treatment.

To investigate the effect of heat-moisture treatment (HMT) on the physiochemical properties and in vitro digestibility of corn starch, the pasting behavior, viscoelasticity, thermal properties, long/short range structure, morphology and in vitro digestion of corn starch treated with different HMT conditions (HMT-20, 25, 30, 35 and 40 %) were characterized. Results indicated that after HMT, the pasting and disintegration behaviors of corn starch were affected and correlated with the moisture content. The dynamic viscoelasticity of corn starch was changed, and when glassy conditions were reached, the elastic properties decreased with increasing moisture while the viscous properties increased, especially for the HMT-40 %. The thermal stability of starch was improved by HMT, although the enthalpy of pasting (ΔH) was reduced. Additionally, the HMT processing also promoted the conversion of RDS to SDS and/or RS (SDS and RS increased to 39.80 % and 31.68 % for HMT-40 %, respectively), which might attribute to the rearrangement of free starch molecules. The present work provides a potential approach to make functional starches with healthy properties.

Preparation and physicochemical properties characterization of hesperetin-grafted pectin conjugate.

Different ratios of hesperetin (HT) were successfully grafted onto pectin from basic water (PB) molecules via free radical-induced reaction. The structure of PB-HT conjugates was characterized by ultraviolet spectroscopy, infrared spectroscopy, X-ray diffraction and scanning electron microscopy. Results indicated that HT was successfully grafted onto pectin molecules, and PB-HT-0.5 showed the highest HT content (103.18 ± 2.76 mg/g). Thermogravimetric analysis indicated that HT crystals showed good thermal resistance and could improve the thermal stability of PB-HT conjugates. Additionally, PB-HT conjugates showed good cytocompatibility and blood compatibility. This study provides a novel and efficient method to synthesize hesperetin-grafted pectin conjugate, which showed potential application in the fields of functional foods in the future.

Effect of annealing treatment on the physicochemical properties and enzymatic hydrolysis of different types of starch.

Annealing treatment on the physicochemical properties and hydrolysis of maize, potato and pea starch were investigated in present study. Results indicated that annealing treatment did not change the morphology of the starch. However, the relative crystallinity of maize and potato starch showed a peak trend as the annealing time extended, while pea starch showed a lower relative crystallinity. Besides, all the annealed starch showed a decrease in peak viscosity and an increase in pasting time. Little difference in the rapidly digestive starch (RDS) and resistant starch (RS) contents of annealed maize starch and pea starch were observed after annealing, while annealed potato starch (72 h) showed an increased RS content (23.37 ± 5.36 %) and a decreased RDS content (52.60 ± 6.14 %), respectively. The obtained results may provide a better understanding of the physicochemical properties and enzymatic hydrolysis of annealed starch with different semi crystalline type.

Improving Regulation of Polymeric Proanthocyanidins and Tea Polyphenols against Postprandial Hyperglycemia via Acid-Catalyzed Transformation.

A novel protocol was established to synthesize novel α-glucosidase inhibitors (prodelphinidin B gallates) from proanthocyanidins from Chinese bayberry leaves (BLPs) and epigallocatechin gallate (EGCG) via acid-catalyzed transformation, which had improved regulation against postprandial hyperglycemia. Their structural-activity relationship was clarified by enzymatic kinetics, multispectroscopic method, molecular docking analysis, and sucrose loading test. ProDB MG and DG were noncompetitive inhibitors of α-glucosidase with IC50 values of 7.82 and 7.52 µg/mL, respectively. They bound with α-glucosidase spontaneously through van der Waals force and hydrogen bonding interaction, inducing the change of spatial conformation and secondary structure of α-glucosidase. Molecular docking studies suggested that proDB MG and DG attached to another one nonactive pocket with strong affinity. ProDB DG exerted significant improvement of postprandial hyperglycemia in a dose-dependent manner. Hence, proDB MG and DG, potential antidiabetic compounds, alleviate postprandial hyperglycemia by inhibiting α-glucosidase.

Proanthocyanidins from Chinese bayberry leaves reduce obesity and associated metabolic disorders in high-fat diet-induced obese mice through a combination of AMPK activation and an alteration in gut microbiota.

Regulating host energy metabolism and re-shaping gut microbiota are effective strategies against high-fat diet (HFD)-induced obesity and related metabolic disorders. A special type of proanthocyanidin extracted from Chinese bayberry leaves (BLPs) was studied for its effects and mechanisms in preventing HFD-induced obesity in mice. BLPs significantly reduced body weight, ameliorated inflammation and regulated gut dysbiosis in HFD-fed mice. BLPs activated AMP-activated protein kinase (AMPK) in the liver and white adipose tissue (WAT), which led to the downregulation of genes related to lipogenesis (ACC, FAS and SREBP-1c), and the upregulation of genes related to ß-oxidation. Furthermore, BLPs improved HFD-induced gut dysbiosis by sharply decreasing the percentage of an endotoxin-producing bacteria - Desulfovibrionaceae, and enabling some distinct bacteria, such as Peptococcaceae, Clostridiaceae and Desulfovibrio. BLPs also reduced the circulated endotoxin and maintained the gut barrier's integrity. Further antibiotic treatment revealed that depleting the gut microbiota abrogated the anti-obesogenic effects of BLPs, yet did not affect AMPK activation. Collectively, these results suggest that BLPs reduce obesity and associated metabolic disorders in HFD-fed mice through a combination of AMPK activation and an alteration in gut microbiota.

Enzyme-extracted raspberry pectin exhibits a high-branched structure and enhanced anti-inflammatory properties than hot acid-extracted pectin.

To characterize the structure of purified raspberry pectin and discuss the impact of different extraction methods on the pectin structure, raspberry pectin was extracted by hot-acid and enzyme method and purified by stepwise ethanol precipitation and ion-exchange chromatography isolation. Enzyme-extracted raspberry pectin (RPE50%-3) presented relatively intact structure with molecular weight of 5 × 104 g/mol and the degree of methylation was 39%. The 1D/2D NMR analysis demonstrated RPE50%-3 was a high-branched pectin mainly containing 50% homogalacturonan, 16% branched α-1,5-arabinan and α-1,3-arabinan, 18% ß-1,4-galactan and ß-1,6-galactan. Acid-extracted raspberry pectin (RPA50%-3) contained less arabinan than RPE50%-3. Moreover, RPE50%-3 inhibited the nitric oxide (NO), TNF-α, IL-6 production of lipopolysaccharide-induced macrophages by 67%, 22% and 46% at the dosage of 200 ug/mL, while the inhibitory rate of RPA50%-3 were 33%, 9%, and 1%, respectively. These results suggested that enzyme-extracted raspberry pectin contained more arabinan sidechains and exhibited better immunomodulatory effect.

Beneficial effects of high pressure processing on the interaction between RG-I pectin and cyanidin-3-glucoside.

In the present study, the effects of high-pressure processing (HPP) on the binding capacity, structural properties, antioxidant capacity and stability of rhamngalacturonan I (RG-I) pectin and cyanidin-3-glucoside (C3G) were investigated. HPP was found to have a positive effect on the binding between the two molecules, and the binding rate was increased by 32.8% after treatment (500 MPa/15 min). The increase in the binding rate is mainly due to the influence of high pressure on noncovalent effects such as hydrogen bonding and hydrophobicity. The results indicate that high pressure can be used to maintain the antioxidant capacity of C3G and improve the stability of C3G. The C3G retention rate is increased by 34.0% and 38.3% after heat treatment and simulated digestion, respectively. The results indicate that HPP improved stability of the C3G-RG-I pectin complex through interaction between C3G and RG-I pectin.

Simultaneous Extraction and Depolymerization of Condensed Tannins from Chinese Bayberry Leaves for Improved Bioavailability and Antioxidant Activity.

Biorefineries of polyphenols from plant leaves maximize their commercial value for developing biomedicines and nutrients. However, condensed tannins (CTs) constitute extensive polyphenols from plant leaves, which hinders the maximization due to extremely low bioavailability. Therefore, a simple, and sustainable one-step method was established to simultaneously extract polyphenols and depolymerize CTs with only endogenous flavan-3-ols from Chinese bayberry leaves via acid catalysis, which markedly improved the bioavailability of total polyphenols. Afterward, purification of polyphenols from depolymerized extract was studied with specific polymeric resins. Silica C18 showed the highest absorption efficiency of total polyphenols, while Amberlite XAD-7 and XAD-2 presented high selectivity toward polyphenols with high and low molecular weight, respectively. Combined depolymerization of CTs and purification with Amberlite XAD-2 showed the highest bioavailability and cellular free-radical scavenging activity of total polyphenols, which proved to be an ideal methodology for improving the bioavailability and activity of polyphenols from plant leaves.

Challenges of pectic polysaccharides as a prebiotic from the perspective of fermentation characteristics and anti-colitis activity.

Several studies are described that contribute to the systematic exploration of new aspects of digestion, fermentation, and biological activities of pectic polysaccharides (PPS) leading to a better understanding of prebiotics. Inflammatory bowel disease (IBD) is thought to be associated with the dysbacteriosis induced by different environmental agents in genetically susceptible persons. PPS are considered as an indispensable gut-microbiota-accessible carbohydrate that play a dominant role in maintaining gut microbiota balance and show a better effect in ameliorating IBD than some traditional prebiotics. The aim of this review is to summarize the fermentation characteristics of PPS, highlight its role in improving IBD, and propose a view that PPS may be a new and effective prebiotic.

High pressure processing accelarated the release of RG-I pectic polysaccharides from citrus peel.

High pressure processing (HPP) has become a promising strategy for extracting bioactive constituents. In this study, the impact of HPP treatment at various pH values (2.0, 8.0, and 12.0) on the macromolecular, structural, antioxidant capacity, rheological characteristics and gel properties of citrus pectic polysaccharide was investigated. The results showed that pressure and pH significantly affected the yield and Rhamnogalacturonan I (RG-I) characterizations. The yields of high pressure extraction at pH 12 (28.13 %-33.95 %) were significantly higher than the yields at pH 2 (14.85 %-16.11 %) and pH 8 (8.75 %-9.65 %). The yield of HPP (500 MPa/10 min) assisted alkali extraction is more than 2 times of that of HPP assisted acid extraction. The RG-I structure ratio of HPP-alkali extraction pectic polysaccharide (74.51 %) was significantly higher than that of traditional pectin (41.83 %). The results showed that HPP assisted alkali is a potential pectic polysaccharide extraction technology.

Dietary pectic substances enhance gut health by its polycomponent: A review.

Pectic substances, one of the cell wall polysaccharides, exist widespread in vegetables and fruits. A surge of recent research has revealed that pectic substances can inhibit gut inflammation and relieve inflammatory bowel disease symptoms. However, physiological functions of pectins are strongly structure dependent. Pectic substances are essentially heteropolysaccharides composed of homogalacturonan and rhamnogalacturonan backbones substituted by various neutral sugar sidechains. Subtle changes in the architecture of pectic substances may remarkably influence the nutritional function of gut microbiota and the host homeostasis of immune system. In this context, developing a structure-function understanding of how pectic substances have an impact on an inflammatory bowel is of primary importance for diet therapy and new drugs. Therefore, the present review has summarized the polycomponent nature of pectic substances, the activities of different pectic polymers, the effects of molecular characteristics and the underlying mechanisms of pectic substances. The immunomodulated property of pectic substances depends on not only the chemical composition but also the physical structure characteristics, such as molecular weight (Mw ) and chain conformation. The potential mechanisms by which pectic substances exert their protective effects are mainly reversing the disordered gut microbiota, regulating immune cells, enhancing barrier function, and inhibiting pathogen adhesion. The manipulation of pectic substances on gut health is sophisticated, and the link between structural specificity of pectins and selective regulation needs further exploration.

Synergistic gelling mechanism of RG-I rich citrus pectic polysaccharide at different esterification degree in calcium-induced gelation.

RG-I rich pectic polysaccharide is common in fruit and vegetable and possesses health benefits. However, it is removed during commercial pectin production because of poor gelling properties. Synergistic gelation can improve rheological properties of RG-I pectic polysaccharide and expand its application in functional food hydrocolloids. In the study, RG-I rich pectic polysaccharides at different degree of esterification was extracted from citrus membrane by sequential mild acidic (0.4% HCl, 28 °C) and alkaline (0.6% NaOH, 32 °C) treatment. The pectic polysaccharide from acid water (PA) composes of 41% RG-I and 44% HG with DM of 45%, while the pectic polysaccharide from basic water (PB) composed of 63% RG-I and 19% HG with DM of 15%. PA/PB blend gel under CaCO3-glucono-δ-lactone system showed improved rheological properties compared with pure gels. Ca-bridges connected pectin aggregates and promoted the three-dimensional structure of PA/PB blend gels, while neutral sugar side-chains prompted hydrogen bonds and strengthened gel network.

Physicochemical and macromolecule properties of RG-I enriched pectin from citrus wastes by manosonication extraction.

The properties of pectin extracted from mandarin citrus peels by manosonication extraction (MSp) were systematically studied and compared with pectin obtained by the conventional maceration method (CMp). The yield of MSp (25.5%) was significantly higher than that of CMp (18.3%), while MSp exhibited two Mw fraction distributions. Monosaccharide analysis demonstrated that MSp had more branched RG-I regions (78.3 mol%) than CMp (36.6 mol%) with a high content of arabinose and galactose. The branched-chain morphological characteristics of samples were directly imaged by atomic force microscopy. MSp exhibited a significantly lower degree of methoxylation than CMp by FT-IR and NMR analysis, but X-ray diffraction analysis showed little difference in the level of crystallinity. Moreover, MSp and CMp showed non-Newtonian behaviour, and the increasing order of apparent viscosities was 1.0 w/v% MSp < 1.0 w/v% CMp < 2.0 w/v% CMp < 2.0 w/v% MSp. Thermal analysis and weight loss measurements indicated MSp exhibited greater thermal stability. The results also indicated that both MSp and CMp significantly enhanced the emulsion activity at high concentrations; the emulsions containing 1.5 w/v% pectin showed no phase separation over 21 days, suggesting that MSp could be a potential effective stabiliser in the food and beverage industry.

Inhibition effect of three common proanthocyanidins from grape seeds, peanut skins and pine barks on maize starch retrogradation.

The inhibition effect of three common proanthocyanidins (PA) on the retrogradation properties of maize starch was investigated (including grape seed proanthocyanidins (GSPA), peanut skin proanthocyanidins (PSPA), and pine bark proanthocyanidins (PBPA)). Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis showed that PA could significantly decrease the values of melting enthalpy of retrogradation (ΔHr) and the degree of relative crystallinity, suggesting that the starch re-crystallization was retarded by PA. Scanning electron microscope (SEM) characterizations illustrated that retrograded PA-starch samples formed a looser matrix with less appearance of continuous flakes during storage. Overall, 0.5 %-2.0 % of three PAs exhibited suppression of starch retrogradation after 21-day cooling storage, mainly resulting from the PA-starch interaction. Among them, PSPA showed the most substantial inhibition effect on starch retrogradation, which might be attributed to its structural features. This study suggested that PA could be a new type of inhibitor to suppress starch retrogradation.

Effect of Potato Pulp Pectic Polysaccharide on the Stability of Acidified Milk Drinks.

In order to broaden the application of potato pulp pectic polysaccharide (PPP) in stabilizing acidified milk drinks (AMDs) and investigate the stabilizing effect and physical properties of AMDs prepared with PPP, a comparative study was made among PPP, commercial high methoxyl pectin (HMP) and low methoxyl pectin (LMP). The zeta potential, rheology, particle size and serum separation of AMDs were evaluated after preparing with PPP, HMP and LMP, respectively. Results indicated that PPP led to lower serum separation than LMP (14.65% for AMDs prepared with 0.5% PPP compared to 25.05% for AMDs prepared with 0.5% LMP), but still higher than HMP (9.09% for AMDs prepared with 0.5% HMP). However, narrower particle size distribution and lower viscosity of AMDs was achieved by PPP than by LMP and HMP. PPP can electrostatically adsorb on the surface of casein and its abundant neutral sugar side chains would provide steric hindrance to prevent casein flocculation in AMDs. Our results might provide some new ideas for the application of PPP in improving the stability of AMDs.

Transcription-mediated tissue-specific lignification of vascular bundle causes trade-offs between growth and defence capacity during invasion of Solidago canadensis.

Allocation of more resources to growth but less to defense causing growth vigor of invasive alien plant populations contributes to successful invasion. However, few studies has addressed to relationship between vascular development variation and this mechanism. In this study, a common garden experimentwas established to compare the growth and vascular bundle development between native and introduced populations of Solidago canadensis, which is a wide-distributed invasive species in China. Our results suggested that the rapid growth of introduced populations could be explained by the well-developed and highly lignified xylem; while native populations present more developed and highly lignified phloem, which contributed more resistance to the infection of Sclerotiun rofsii compared with introduced populations. This difference was resulted from tissue-specific tradeoff distribution of lignification related gene expression between xylem and phloem, which is regulated by upstream MYB transcription factors. Our study gives a novel insight of mechanism that explain invasion success: lignin-related gene transcription-mediated tissue-specific lignification of vascular bundle contributes tradeoffs in resource allocation between growth and defence capacity during successful invasion of S. canadensis.

Structure-activity relationship of Citrus segment membrane RG-I pectin against Galectin-3: The galactan is not the only important factor.

Rhamnogalacturonan I (RG-I) pectin are regarded as strong galectin-3 (Gal-3) antagonist because of galactan sidechains. The present study focused on discussing the effects of more structural regions in pectin on the anti-Gal-3 activity. The water-soluble pectin (WSP) recovered from citrus canning processing water was categorized as RG-I pectin. The controlled enzymatic hydrolysis was employed to sequentially remove the α-1,5-arabinan, homogalaturonan and ß-1,4-galactan in WSP. The Gal-3-binding affinity KD (kd/ka) of WSP and debranched pectins were calculated to be 0.32 µM, 0.48 µM, 0.56 µM and 1.93 µM. Moreover, based on the more sensitive cell line (MCF-7) model, the IC30 value of WSP was lower than these of modified pectins, indicating decreased anti-Gal-3 activity. Our results suggested that the total amount of neutral sugar sidechains, the length of arabinan and cooperation between HG and RG-I played important roles in the anti-Gal-3 activity of WSP, not the Gal/Ara ratio or RG-I/HG ratio. These results provided a new insight into structure-activity relationship of citrus segment membrane RG-I as a galectin-3 antagonist and a new functional food.

Highly Branched RG-I Domain Enrichment Is Indispensable for Pectin Mitigating against High-Fat Diet-Induced Obesity.

Obesity is associated with gut microbiome dysbiosis. Our previous research has shown that highly branched rhamnogalacturonan type I (RG-I)-enriched pectin (WRP, 531.5 kDa, 70.44% RG-I, Rha/(Gal + Ara) = 20) and its oligosaccharide with less branched RG-I [DWRP, 12.1 kDa, 50.29% RG-I, Rha/(Gal + Ara) = 6] are potential prebiotics. The present study is conducted to uncover the impact of the content, molecular size, and branch degrees of RG-I on the inhibiting effect of high-fat diet (HFD)-induced obesity. The commercial pectin (CP, 496.2 kDa, 35.77% RG-I, Rha/(Gal + Ara) = 6), WRP, and DWRP were orally administered to HFD-fed C57BL/6J mice (100 mg kg-1 d-1) to determine their individual effects on obesity. WRP significantly prevented bodyweight gain, insulin resistance, and inflammatory responses in HFD-fed mice. No obvious anti-obesity effect was observed in either CP or DWRP supplementation. A mechanistic study revealed that CP and DWRP could not enhance the diversity of gut microbiota, while WRP treatment positively modulated the gut microbiota of obese mice by increasing the abundance of Butyrivibrio, Roseburia, Barnesiella, Flavonifractor, Acetivibrio, and Clostridium cluster IV. Furthermore, WRP significantly promoted browning of white adipose tissues in HFD-fed mice, while CP and DWRP did not. WRP can attenuate the HFD-induced obesity by modulation of gut microbiota and lipid metabolism. Highly branched RG-I domain enrichment is essential for pectin mitigating against the HFD-induced obesity.

Effect of anion type on enzymatic hydrolysis of starch-(thermostable α-amylase)-calcium system in a low-moisture solid microenvironment of bioextrusion.

The effect of six anions (Cl-, OH-, NO3-, SO42-, C6H10O62- and PO43-) on a starch (St)-enzyme (thermostable α-amylase, TαA)-calcium (Ca) system was investigated in a low-moisture solid state. Two levels of Ca salts (1 and 10 mmol/100 g St) added to potato starch with and without TαA were analyzed by FT-IR, DSC and SEM. The surface morphologies of the St-Ca complexes were different in the presence of various anions, and the residual Ca salts around the St granules might decrease the enzymatic action. For bioextrusion, TαA (0.5‰ and 1.5‰) were introduced for a relatively low Ca content (1 mmol/100 g). Significant differences in enzyme activity were observed, increasing the activity of TαA by SO42- (146.54 %) > C6H10O62- > Cl- > control > NO3- > OH- ≈ PO43- and C6H10O62- (123.20 %) ≈ Cl- ≈ SO42- > control > PO43 > OH- > NO3- for the low and high enzyme levels, respectively.