Pectin Acid Research Articles

Structure formation mechanism of pectin-soy protein isolate gels: Unraveling the role of peach pectin fractions.

This study investigated the macro & micro properties of the composite gels formed by soy protein isolate (SPI) and peach pectin fractions: water-soluble pectin (WSP), chelator-soluble pectin (CSP), and sodium carbonate soluble pectin (NSP). Specially, the interaction between pectin fractions and SPI was studied to explain the formation mechanism of the composite gels. WSP, as a high methoxyl pectin, exhibited rich branching (sugar ratio B=3.10). CSP, as a low methoxyl pectin, depicted a high linearity. NSP, with low linearity (sugar ratio A=6.14), contained numerous side chains. Due to the strong interaction between pectin fractions and SPI, the new composites with excellent dense network microstructures were formed, accompanied by increased apparent viscosity, higher G' and G'', and reduced particle size. XRD and FT-IR analysis highlighted the modifications in gel structures. SEM-dispersive X-ray spectroscopy observed elemental distribution and framework composition in pectin-SPI gels. Hydrophobic interaction was the most important chemical force in pectin-SPI binding. Molecular docking results indicated that galacturonic acid in pectin bound more strongly to 7S than to 11S, with tighter hydrogen bonds. Notably, WSP-SPI showed the lowest turbidity, indicating enhanced solubility and particle dispersion, which helped prevent aggregation. CSP-SPI demonstrated the highest G' and G'', ascribing to the high linearity and abundant carboxyl groups in CSP. NSP-SPI showed the highest apparent viscosity and irregular structure. Overall, the texture properties of pectin-SPI gels were driven by pectin's structure properties, which would provide new and valuable information for texture control in gel formulation.

Dietary Pectin from Premna microphylla Turcz Leaves Prevents Obesity by Regulating Gut Microbiota and Lipid Metabolism in Mice Fed High-Fat Diet.

The present study was designed to investigate the protective effects of pectin extracted from Premna microphylla Turcz leaves (PTP) against high-fat-diet (HFD)-induced lipid metabolism disorders and gut microbiota dysbiosis in obese mice. PTP was made using the acid extraction method, and it was found to be an acidic pectin that had relative mole percentages of 32.1%, 29.2%, and 26.2% for galacturonic acid, arabinose, and galactose, respectively. The administration of PTP in C57BL/6J mice inhibited the HFD-induced abnormal weight gain, visceral obesity, and dyslipidemia, and also improved insulin sensitivity, as revealed by the improved insulin tolerance and the decreased glucose levels during an insulin sensitivity test. These effects were linked to increased energy expenditure, as demonstrated by the upregulation of thermogenesis-related protein UCP1 expression in the brown adipose tissue (BAT) of PTP-treated mice. 16S rRNA gene sequencing revealed that PTP dramatically improved the HFD-induced gut dysbiosis by lowering the ratio of Firmicutes to Bacteroidetes and the quantity of potentially harmful bacteria. These findings may provide a theoretical basis for us to understand the functions and usages of PTP in alleviating obesity.

Aqueous Acidic Pectin‐based Solution as Electrolyte and Pretreatment Solution for Zinc Ion Battery Anodes

While considerable progress has been achieved in aqueous mildly acidic Zn‐ion batteries (AZIBs), the development of metallic Zn anodes remains challenging due to dendritic growth and side reactions on the Zn surface in mildly acidic aqueous environments. Herein, we utilize pectin in two ways: firstly, as an additive for the acidic ZnSO4 electrolyte with pectin (referred to as ZSP); and secondly, as a component in the pretreatment solution for Zn electrode. The ZSP electrolyte can prevent the formation of inactive Zn4(OH)6(SO4)·5H2O byproduct on Zn electrode and enable stable cycling under challenging conditions at 10 mA h cm−2. Interestingly, the immersion of the Zn foil in the acidic pectin solution resulted in the uniform removal of the bumpy oxides/carbonates layer on the Zn metal surface. The cells with treated Zn electrode in pectin solution exhibited lower overpotentials and effectively inhibited cell failure. Our findings indicate that utilizing an organic‐based acidic ZnSO4 electrolyte shows promise as both an effective electrolyte and a pretreatment solution for the development of stable and cheap aqueous AZIB electrolytes.

Effects of black bean cell wall pectin by exogenous calcium ions: Insight into the metabolomics, physicochemical properties and anti-digestive capacity

In this work, the metabolomics, physicochemical and in vitro digestion properties of black beans influenced by different calcium ion solutions (0, 0.5 %, 1 %, and 2 %) were explored. The addition of calcium ions had a significant effect on the metabolic processing of black beans, including 16 differential metabolites and 4 metabolic pathways related to the cell wall. From the results of FT-IR and ICP-OES, it was confirmed that calcium ions can interact with COO− in non-methylated galacturonic acid in pectin to form calcium carboxylate strengthening the middle lamellae of the cell wall. Based on this mechanism, the soaked beans with an intact and dense cell structure were verified by the analyses of SEM and CLSM. Compared with other soaked beans, BB-2 exhibited lower cell permeability with electrical conductivity value decreased to 0.60 μs·cm−1. Additionally, BB-2 demonstrated slower digestion properties with digestion rate coefficient at 0.0020 min−1 and digestion extent only at 30.83 %, which is attributed to its increasingly compact cell wall and densely cellular matrix. This study illustrates the effect of calcium ions on the cellular structure of black beans, providing an effective process method for low glycemic index diets.

Extraction of pectin from jelly fig shell using microwave heating extraction: pectin physicochemical properties and antioxidant activities

Abstract Jelly fig is a crop of high economic value; however, the processing by-product of jelly fig, “jelly fig shell”, is not well utilized. In this study, jelly fig shell pectin was extracted through the microwave extraction technique. Then, galacturonic acid content, degree of esterification, molecular weight, functional group properties, and antioxidant activity were determined. The highest pectin yield (21.6 ± 0.1 %) was obtained at 200 mM citric acid and microwave power of 800 W, with extraction time of 4 min. The content of galacturonic acid in pectin was greater than 65 %, which meets the specifications of food-grade pectin. In terms of antioxidant ability, the IC50 of 2,2-diphenylpicrylhydrazyl (DPPH) free radical scavenging rate of jelly fig shell pectin was 175.1 μg/mL. These results suggest that, comparing to the extracted jelly fig seed pectin, jelly fig shell has stable quality under more desirable extraction conditions, and has better physicochemical properties.

In vitro fermentation characteristics and interaction of neutral and acidic polysaccharides from Lycii fructus on human gut microbiota

In this study, the microbial fermentation characteristics and effects of neutral and acidic Lycii fructus polysaccharides (LFPs) on gut microbial composition were investigated using pure cultures of selected probiotic strains and mixed cultures of human fecal microflora in vitro. The results revealed that LFPs could significantly promote the growth of probiotics, with a faster proliferation rate in the early stages of fermentation. When LFPs were degraded and utilized by the gut microbiota, neutral arabinogalactans were more easily fermented, while acidic pectin polysaccharides exhibited a higher degree of anti-fermentation. LFPs were selectively modulated by microbiota; acidic polysaccharides promoted the growth of potentially beneficial bacteria, such as Lachnospira and Bacteroides vulgatus, while neutral polysaccharides significantly improved the relative abundances of Bifidobacterium longum and Bifidobacterium pseudocatenulatum. In summary, the results revealed that different types of LFPs regulate the gut microbiota in a structure-dependent manner, with uronic acid play a key role in selective regulation. This study aimed to better understand the fermentation characteristics and saccharide preferences of gut microbes for LFP structures and provide a theoretical basis for the relationship between the chemical structural and probiotic effects of LFPs.

Regulation of mineral elements in Hordeum brevisubulatum by Epichloë bromicola under Cd stress

In this study, wild barley (Hordeum brevisubulatum) infected (E+) and uninfected (E-) by Epichloë bromicola were used for hydroponic experiments during the seedling stage. Various attributes, such as the effect of fungal endophyte on the growth and development of wild barley, the absorption of cadmium (Cd) and mineral elements (Ca, Mg, Fe, Mn, Cu, Zn), subcellular distribution, and chemical forms were investigated under CdCl2 stress. The results showed that the fungal endophy significantly reduced the Ca content and percentage of plant roots under Cd stress. The Fe and Mn content of roots, the mineral element content of soluble fractions, and the stems in the pectin acid or protein-chelated state increased significantly in response to fungal endophy. Epichloë endophyte helped Cd2+ to enter into plants; and reduced the positive correlation of Ca-Fe and Ca-Mn in roots. In addition, it also decreased the correlation of soluble components Cd-Cu, Cd-Ca, Cd-Mg in roots, and the negative correlation between pectin acid or protein-chelated Cd in stems and mineral elements, to increase the absorbance of host for mineral elements. In conclusion, fungal endophy regulated the concentration and distribution of mineral elements, while storing more Cd2+ to resist the damage caused by Cd stress. The study could provide a ground for revealing the Cd tolerance mechanism of endophytic fungal symbionts.

Microwave and ultrasound assisted extraction techniques with citric acid of pectin from Pomelo (Citrus maxima) peel

This current research attempted to obtain pectin from Pomelo (Citrus maxima) peels using conventional heating, microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE) techniques with organic citric acid. In order to characterize pectin extracted using conventional heating, MAE, and UAE, yield, pH, solubility, ash content, equivalent weight, anhydrouronic acid content, degree of esterification methoxyl content were taken into consideration. On physicochemical properties, the extraction techniques had a significant effect. The findings demonstrated that the MAE method produced the highest amount of pectin (26.63 ± 0.21 %). On the basis of the Degree of Esterification (DE) value, pectins were all classified as high-methoxypectins (HMP). According to anhydrouronic acid (AUA) content, the extracted pectins were extremely pure. Fourier transform infrared (FT-IR) spectroscopy was used to structurally characterize pectin that was extracted using three different methods, and the results revealed that pectin has functional groups between 1740 and 800 cm-1 spectrally.

Relaxation temperature and storage stability of the functionalized cell wall material residue from lemon peel

Lemon peel cell wall material (CWM) residue obtained after acid pectin extraction can be functionalized into a texturizing ingredient using mechanical treatments such as high-pressure homogenization. The application of CWM as a texturizing ingredient is most likely through a dry powder and thus the stability of its functionality (rheological property) during storage becomes an obvious question. However, studies on the glass transition properties of this CWM residue and it's relation to storage stability are largely lacking. This study aims to first evaluate the potential of two methods, i.e. DSC analysis and combined TMCT-DMTA (thermal mechanical compression test – dynamic mechanical thermal analysis) to measure the Tg and relaxation temperature of lemon peel CWM and subsequently relate the results to the stability of the material's rheological property. The results showed that DSC-based Tg measurements may not be the most appropriate indicator for storage stability of the lemon peel CWM residue, despite being the most commonly used method to explain state transition in materials. On the other hand, the structural relaxation phenomena elucidated by the change in mechanical properties measured by TMCT-DMTA correlated with the results of storage stability of the material. To ensure the stability of the CWM residue, storage should be carried out at conditions (temperature and moisture content) before the onset of tan δ curve change. In conclusion, relaxation phenomena observed through the measurement of mechanical properties, in particular the tan δ curve from DMTA, provides a suitable starting point for inferring the stability of the functionalized CWM residue.

Changes in the physicochemical characteristics and biological activities of polysaccharides from Panax ginseng during defense against red-skin disease

Red-skin roots are a common disease symptom in cultivation of Panax ginseng, which strongly affects its quality and production. Differences in polysaccharides between red-skin and healthy ginseng were examined for the first time to elucidate their function as resistance to disease and explore their potential as active ingredients. Fluorol Yellow 088 and ruthenium red staining revealed changes in the distribution and composition of ginseng polysaccharides during defense against red-skin disease. Acid pectin content was observed to increase significantly in cell walls of the diseased epidermal tissue. Furthermore, targeted extraction approaches were used to obtain water-solution polysaccharides (WPS) and pectic polysaccharides (PP) which marked different characteristics with the health group. WPS from red-skin roots exhibited novel pectic characteristics, consisting of 32.25% GalA which is 10 times more than the healthy sample, accompanied by a sharp decrease in starch content (approximately 50%). Another study on the adsorption and gel properties of PP indicated that it played an important role in disease resistance by reducing metal toxicity and increasing the strength of the cell wall. For further analysis of the abnormal pectic composition, DEAE-52 purification was used and various pectic fractions (WPS-1,2,3) consisting of the RG-Ⅰ pectic domain were obtained. The analysis of antioxidant and immunoactivity was performed to explore the effect of characteristic changes on biological activities. Higher radical scavenging ratios of DPPH and ABTS indicated that red-skin fractions had stronger antioxidant activities. Stronger promotion effect on Raw264.7 secretion of TNF-α and IL-1α represented the higher immunological activities. Therefore, the red-skin ginseng polysaccharides could be utilized in the pharmaceutical industry to compensate for the value loss caused by red-skin roots.

Chemical and microstructural characterization of easy- and hard-to-cook Jack bean (Canavalia ensiformis (L.) DC.) collections

Differences in the microstructure and the chemical composition of pectic polymers were investigated from three Jack bean collections with different hard-to-cook (HTC) levels, as confirmed by the optimal cooking time analysis. These collections showed different cell and starch granule sizes, where the hardest-to-cook bean (Jombang collection) had the smallest maximum cell perimeter (285 μm), the smallest starch granule perimeter (98 μm), and the highest frequency of small intercellular space indicating more linkage in the middle lamella. No significant difference was observed in the frequency of small intercellular spaces between Malang and Cilacap despite having different optimal cooking times. Jack bean cotyledon cell walls were mainly composed of insoluble polysaccharide rich in arabinose and galactose. The beans contained high covalently bound pectin fractions (NEF) ranging from 78% to 83%. Higher bound phenolics (ferulic acid) were found with the increase in the optimal cooking times of the collections. Overall, the findings suggest the occurrence of cell wall linkage and highlight the importance of ferulic acid pectin crosslink in HTC Jack bean. This study could help develop strategies to reduce cooking time to promote the utilization of Jack bean.

Pharmaceutical Assessment of the Impact of the Method of Extraction on the Suitability of Pectin from Plantain (Musa paradisiaca) Peels as a Suspending Agent in Oral Liquid Formulations.

Natural polymers such as pectin have gained increased utilization in pharmaceutical and biotechnology sectors because they are affordable, easily accessible, nontoxic, and chemically modifiable, with the potential to be biodegradable and biocompatible. Musa paradisiaca (plantain) peels make up 30-40% of the overall weight of the fruit. The extraction of pectin from these residues can therefore be viewed as a possible waste of wealth. This study, therefore, focused on evaluating the suspending properties of pectin obtained from Musa paradisiaca (plantain) peels (through acid and alkaline extraction) and presented an alternative suspending agent in the pharmaceutical formulation of suspensions. The unripe peels of Musa paradisiaca were acquired and authenticated at the Department of Pharmacognosy, Faculty of Pharmacy and Pharmaceutical Sciences, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana. Pectin was extracted from the peels using both acid and alkaline extraction processes, respectively, characterized, and evaluated for its phytochemical properties. Different concentrations of the acid and alkaline pectin extracts were employed as a suspending agent in paracetamol suspensions, using acacia gum as a standard. The pectin yields obtained were 4.88% and 7.61% for the acid and alkaline extraction processes, respectively, while phytochemical screening revealed the presence of glycosides, tannins, saponins, and phenols in both extracts. The alkaline pectin extract recorded higher equivalent weight, degree of esterification, ash content, and crude content than the acid pectin extract, while FTIR identified similar functional groups in both acid and alkaline pectin extracts. The test suspensions reported significant differences (P < 0.05) in flow rates, ease of redispersion, sedimentation volumes, and rates compared with acacia gum. Moreover, when the acid and alkaline pectin extracts were compared, significant differences (P < 0.05) were observed in sedimentation rates and sedimentation volumes, suggesting that the extraction method may affect suspending properties. Ultimately, the alkaline pectin extract had better suspending properties than the acid pectin extract; however, they both can be used as an alternative to acacia gum as a suspending agent.

High-intensity pulsed electric field-assisted acidic extraction of pectin from citrus peel: Physicochemical characteristics and emulsifying properties

Sustainable innovation seeks more energy-efficient processes for producing highly demanded products from industrial by-products. This study follows this endeavor. Comparisons were made on two processes for producing pectins from citrus peel as well as the two derived pectin products: a high-intensity pulsed electric field (HIPEF) pretreatment of citrus peel powder followed by a milder acidic extraction (pH 2, heating at 70 °C for 1 h; pectin termed HIPEF-CP), and a conventional direct hot-acid extraction (pH 2, heating at 90 °C for 2 h; pectin termed CP). HIPEF-assisted extraction significantly improved pectin yield (by 8.48%) and production efficiency (by 100.23%) while reducing energy consumption. Both were low-methoxyl pectins with similar branching degrees and contents of rhamnogalacturonan-I (RG-I), protein, phenolic compounds, total alkaloids and vitamin C. Compared with CP, HIPEF-CP contained higher homogalacturonan content, higher galactose content, higher galacturonic acid content, lower arabinose content, lower xylose content, slightly lower degree of methyl esterification, higher linearity, lower side chain size, higher molecular weight, and wider molecular weight distribution. The antioxidant, emulsifying and emulsion-stabilizing abilities of HIPEF-CP were superior to those of CP, though both pectins were satisfactory emulsifiers, exhibiting good antioxidant activities and emulsifying capacities at pectin concentrations not lower than 1.0%. The HIPEF pretreatment of citrus peel made the subsequent acidic pectin extraction feasible under milder conditions, to produce pectin with desired antioxidant and emulsifying capacities.

Ultrasound‐assisted enzymatic extraction of orange peel pectin and its characterisation

SummaryCitrus processing waste (CPW) accumulates in vast amounts worldwide during fruit processing and its disposal through landfilling is environmentally damaging. However, CPW is also a renewable source of economically and medically relevant compounds such as pectin. There is a need for new methods of extracting pectin from CPW, as conventional methods are unsustainable. Therefore, this study proposed a new environmentally friendly method, which combines ultrasound cavitation with cellulase preparation, Celluclast) into one extraction procedure (UAE), and compared it to conventional acid extraction. The yield and productivity of each method were measured and the extracts were analysed for composition and structural characteristics. UAE and acid extraction pectin yields (26.9 vs. 22.1%) and productivity (0.10 vs. 0.09%/min) values were comparable. The extracts consisted mainly of galacturonic acid and galactose residues, but the ratio was different for each method; 1: 0.34 and 0.84: 1 for acid and UAE‐extracted pectin, respectively. FTIR was used to estimate the degree of esterification of the pectin extracts; 8% and 55% for acid and UAE‐extracted pectin, respectively. TGA revealed a higher ash content in UAE pectin, while XRD revealed similar degrees of polymer crystallinity. Viscosimetry revealed that the acid pectin had a higher molecular weight (70.22 kDa) compared to UAE pectin (197.78 kDa). In conclusion, the UAE procedure is a viable alternative to acid extraction.

Modulating temperature and pH during subcritical water extraction tunes the molecular properties of apple pomace pectin as food gels and emulsifiers

This study explores the cascade extraction of polyphenols and pectins from apple pomace and their potential application as food emulsifiers. The extraction of polyphenols was achieved by a simple method using ethanol and resulted in remarkable antioxidant activity. Pectic polysaccharides were sequentially extracted (5, 10 and 15 min) using subcritical water at two different temperatures (120 °C and 140 °C) and three different pH conditions (pH 3.0, 5.0 and 7.0). Acidic pH resulted in higher pectin yields when combined with higher temperature, whereas neutral conditions were less selective towards pectin. Pectin with different branching patterns could be isolated by tuning the process conditions. Linear homogalacturonan (HG) was preferentially isolated at milder conditions, whereas more branched rhamnogalacturonan (RG-I) populations required longer extraction times. Subcritical water enabled the extraction of pectins with different degrees of methoxylation (DM) depending on the extraction pH, which enabled the production of pectin acid gels with varying rheological properties. Low DM pectin was directly recovered from apple pomace at lower pH, eliminating the need for its conventional derivatization from high DM pectin. The emulsifying properties of two apple pomace pectin fractions with high and low methoxyl content were compared; the pectin with higher methoxyl content showed higher emulsifying capacity and stability. This study demonstrates that the relative abundance of the different pectic domains and the methoxylation of pectin can be controlled by subcritical water extraction, which has important implications for the valorization of pectic-rich agricultural wastes into valuable food ingredients.

Oil body extraction from high-fat and high-protein soybeans by laccase cross-linked beet pectin: physicochemical and oxidation properties.

Soybean oil bodies (SOB) are droplets of natural emulsified oil. Soybean oil emulsifies well but it is easily oxidized during storage. Beet pectin is a complex anionic polysaccharide, which can be adsorbed on the surface of liposomes to improve their resistance to flocculation. Laccase can covalently cross-link ferulic acid in beet pectin, and its structure is irreversible, which can improve the stability of polysaccharides. At pH2.5, laccase cross-linked beet pectin high-oil soybean oil body (HOSOB) and high-protein soybean oil body (HPSOB) emulsions showed obvious aggregation and severe stratification, and the oxidation of the emulsions was also high. The flocculation of emulsions decreased with an increase in the pH. The effect of pH on the flocculation of emulsion was confirmed by confocal laser electron microscopy. The ζ potential, emulsification, and rheological shear force increased with increasing pH whereas the particle size and surface hydrophobicity decreased with increasing pH. This experiment indicates that the physicochemical stability of the two composite emulsions was strongly affected under acidic conditions but stable under neutral and weakly alkaline conditions. Under the same acid-base conditions, the degree of oxidation of HPSOB composite emulsion changes substantially. The results of this study can provide a basis for the design of very stable emulsions to meet the demand for natural products. © 2023 Society of Chemical Industry.

Quantitative determination of galacturonic acid in pectin and pectin products by combined pectinase hydrolysis and HPLC determination

Pectin is a complex heteropolysaccharide with a predominantly galacturonic acid (GalA) main chain and various branching sugars, leading to some analytical and quantitative determination challenges. By comparison with various acid hydrolysis methods, an effective and precise hydrolysis method for GalA determination from pectin was investigated using a combination of pectinase hydrolysis (PH) and HPLC determination, which was named the PH-HPLC method. With a pectinase loading of 2250 U/g pectin, 4.0 g/L commercial pectin was almost completely hydrolysed to the intact and detectable GalA at 50 °C after 24 h, for quantitative determination by HPLC. Acid-catalysis methods showed obvious disadvantages in terms of GalA degradation or incomplete hydrolysis of pectin, resulting in imprecise determination results. Moreover, the PH-HPLC method was employed for the quantitative determination of GalA in three common natural pectin feedstocks and indicated 45.5–233.1% higher content of GalA than the acid hydrolysis method. Thus, the PH-HPLC method is demonstrated to be a precise approach for analysing and quantifying the GalA of pectin and respective feedstock.

Heterologous Expression and Characterization of a Novel Exo-Polygalacturonase from Aspergillus fumigatus Af293 and Its Application in Juice Extraction.

Exo-polygalacturonase (exo-PG) hydrolyzes pectin acids and liberates mono-galacturonate, which plays an important role in juice extraction, and has rarely been reported. Exo-PG (AfumExoPG28A) from Aspergillus fumigatus belongs to the glycoside hydrolase 28 family. In this study, its gene was cloned and the protein was expressed and secreted in Pichia pastoris with a maximal activity of 4.44 U/ml. The optimal temperature and pH of AfumExoPG28A were 55°C and 4.0, respectively. The enzyme exhibited activity over almost the entire acidic pH range (>20.0% activity at pH 2.5-6.5) and remained stable at pH 2.5-10.0 for 24 h. The Km and Vmax values of AfumExoPG28A were calculated by the substrate of polygalacturonic acid as 25.4 mg/ml and 23.6 U/mg, respectively. Addition of AfumExoPG28A (0.8 U/mg) increased the light transmittance and juice yield of plantain pulp by 11.7% and 9%, respectively. Combining AfumExoPG28A (0.8 U/mg) with an endo-PG (0.8 U/mg) from our laboratory, the enzymes increased the light transmittance and juice yield of plantain pulp by 45.7% and 10%, respectively. Thus, the enzyme's potential value in juice production was revealed by the remarkable acidic properties and catalytic activity in fruit pulp.

Microbial communities that drive the degradation of flax pectin and hemicellulose during dew retting with Bacillus licheniformis HDYM-04 and Bacillus subtilis ZC-01 addition

In this study, the combined addition of Bacillus licheniformis HDYM-04 and Bacillus subtilis ZC-01 to flax degradation increased the degradation rates of pectin (74.7 %) and pectinic acid (59.3 %) and increased the maximum activities of pectinase (610.66 ± 7.03 U/mL) and mannanase (656.97 ± 13.16 U/mL). 16S rRNA sequencing showed that the added bacterial agent (Bacillus) was the dominant bacterium, and its addition increased the relative abundance (RA) of Firmicutes and decreased the RA of Bacteroidetes. The core bacterial community linked to degradation (Firmicutes) was determined by RDA. Network analysis showed that the number of bacteria related to pectin and hemicellulose degradation increased with the addition of the bacteria combination. SEM analysis showed that Bacillus was positively correlated with the degradation of pectic substances. These results provide new ideas for improving the utilization of agricultural waste resources and promoting sustainable development in modern agriculture.

Effect of ultrasonic pretreatments on the characteristics of pectin extracted from Salustiana orange cultivated in Argentina

AbstractThe use of direct and indirect ultrasound pretreatments was evaluated for the extraction of pectin enriched fractions with citric acid (pH 2.3, 85°C) from the albedo and pulp of Salustiana orange. The extractive method that produced the highest yield was the one involving a pretreatment with direct high‐power ultrasound (HPUS) (41 g isolated fraction/100 g albedo CM versus 30 g isolated fraction/ 100 g albedo CM for indirect treatment; 39 g isolated fraction/100 g pulp CM versus 26 g isolated fraction/100 g pulp CM for indirect treatment) and allowed extracting the highest amount of pectin from both albedo and pulp. The major neutral sugars found in all fractions were arabinose, galactose, and rhamnose. Pectins were obtained with weight average molecular masses of 566–729 kDa from the albedo and 663–739 kDa from the pulp. All fractions gelled in the presence of sucrose at acidic pH. Pretreatment with HPUS gave origin to the least elastic gels (albedo: G′ higher than 100 Pa, G″ higher than 20 Pa. Pulp: G′ higher than 70 Pa, G″ higher than 25 Pa), while indirect US produced fractions that formed more elastic gels (albedo: G′ higher than 1000 Pa, G″ higher than 250 Pa. Pulp: G′ higher than 500 Pa, G″ higher than 100 Pa). Ultrasound pretreatments allowed obtaining a variety of pectin enriched fractions with interesting characteristics for food formulation.Practical applicationsPectins are widely used as texture modifiers in the food industry. Commercial pectins are commonly obtained from waste from the citrus juice industry, using mineral acids at high temperatures, producing large amounts of polluting effluents. The study of the use of organic acids in combination with clean technologies such as ultrasound, which allow higher pectin yields to be obtained through less polluting processes, is of great interest as an environmentally friendly alternative. Likewise, it is important to demonstrate that the pectins obtained through such technologies are effectively useful for the industry as texture modifying additives. In this work it is proposed to study the effect of the use of indirect and direct ultrasound as pretreatments in the extraction with citric acid of Salustiana orange pectin.