Effect of calcium chloride on emulsion stability of methyl-esterified citrus pectin

Influence of pH on the emulsifying property of high methyl-esterified citrus pectin in the presence of calcium cations

High methyl-esterified citrus pectin (HMCP) is often used as a thickness in food products and is considered a poor emulsifier, especially in neutral pH solutions. Our previous findings show that the emulsifying capacity of HMCP could be significantly enhanced by calcium cations. Besides, the pH of the solution decreased in the presence of calcium cations. However, the impact of solution pH on HMCP emulsifying capacity in the presence of calcium cations is unclear. In this study, the pH of the HMCP solution was adjusted from 3.00 to 8.00 before adding calcium cations. The solution properties and emulsifying properties were analyzed in light of the existence of calcium cations. The results showed that the pH of the HMCP solutions decreased after bringing calcium cations into them. Calcium cations could change the solution rheological properties, particle size distributions and morphologies, and the particle microenvironmental hydrophobic areas in HMCP solutions while increasing the pH of HMCP solutions, contributing to improving the emulsifying capacity of HMCP. HMCP had the best emulsifying ability when the pH of the HMCP solutions was kept at a neutral level. This research gives us new ideas to adjust the emulsifying property of HMCP.

Interfacial Behavior and Long-Term Stability of the Emulsions Stabilized by Sugar Beet Pectin-Ca2+ Complexes with Different Cross-Linking Degrees

Recent studies showed that sugar beet pectin exhibited more excellent emulsifying properties than traditional citrus peel pectin and apple pectin ascribed to the higher content of neutral sugar, protein, ferulic acid, and acetyl groups. It is precisely because of the extremely complex molecular structure of pectin that the emulsifying properties of the pectin-Ca2+ complex are still unclear. In this study, SBP-Ca2+ complexes with different cross-linking degrees were prepared. Subsequently, their interfacial adsorption kinetics, the resistance of interfacial films to external perturbances, and the long-term stability of the emulsions formed by these SBP-Ca2+ complexes were measured. The results indicated that the highly cross-linked SBP-Ca2+ complex exhibited slower interfacial adsorption kinetics than SBP alone. Moreover, compared with SBP alone, the oil-water interfacial film loaded by the highly cross-linked SBP-Ca2+ complex exhibited a lower elasticity and a poorer resistance to external perturbances. This resulted in a larger droplet size, a lower ζ-potential value, a larger continuous viscosity, and a worse long-term stability of the emulsion formed by the highly cross-linked SBP-Ca2+ complex. This study has very important guiding significance for deeply understanding the emulsification mechanism of the pectin-Ca2+ complex.

Amino acid regulated citrus pectin-based emulsion stability mediated by pH

BACKGROUND

Citrus residuals are rich in nutrients like pectin, essential oil, and amino acids, which are wasted in the food industry. Moreover, citrus components often coexist with amino acids during emulsion preparation and application.

RESULTS

Adding glutamic or arginine after emulsification resulted in a stable emulsion compared with adding them before emulsification. Adding glycine before or after emulsification had no effect on the emulsion stability. Emulsion stability was improved by adding glutamic acid at pH 6. Ionic interaction and hydrogen bonding were the main forms of bonding. The rhamnogalacturonan II domain was the potential binding site for the amino acids.

CONCLUSIONS

The emulsions prepared by adding acidic amino acids or basic amino acids after emulsification were stable relative to those in which the amino acids were added before emulsification. However, the order in which neutral amino acids were added did not affect the emulsion stability after storage for 7 days. With an increase in the pH level, droplet size increased and emulsion stability decreased. All the results could be attributed to changes in the structure and properties of citrus pectin, as well as the interaction between citrus pectin and amino acids. This study may expand the application of citrus-derived emulsions in the food industry. © 2023 Society of Chemical Industry.

Extraction of pectin from watermelon and pomegranate peels with different methods and its application in ice cream as an emulsifier

Pectin extraction from watermelon peel (WP) and pomegranate peel (PP) was carried out using three different extraction methods: classical solvent extraction (CSE), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE). Extraction parameters (pH, temperature, time, and speed/amplitude/power) were optimized to target maximum crude pectin yield (CPY), while the sample-to-solvent ratio (SS) was determined to be fixed at 1:10 w/v at all experiments. CPY was increased by low pH, high temperature, and long time. The pectins obtained at optimum conditions were characterized regarding the physicochemical and rheological properties, and the pectin solutions were found to be typical pseudoplastic fluids. WP pectin extracted with MAE and PP pectin extracted with UAE were determined to have the best emulsifying properties and added to the ice cream formulations. MAE had the maximum CPY of 9.40% for WP (pH = 1.3, 6 min, 596 W) and the best emulsifying properties. UAE had the best emulsifying properties for PP and the CPY was 11.56% in conditions of pH = 1.5, a temperature of 69°C, an extraction time of 29 min, and a 32% amplitude. The use of PP pectin resulted in a significant increase in the apparent viscosity of ice cream mix and also the first dripping time and the hardness of ice cream over commercial emulsifier. Melting properties and hardness values of ice cream with WP pectin were comparatively closer to those of ice cream with commercial emulsifier. On the other hand, the first dripping time and hardness value of ice cream with PP pectin having 60.25 min and 3.84 N, respectively, were higher than those of commercial ice cream having 53.75 min and 2.14 N, respectively. Practical Application: The utilization of WP and PP, which are good sources for pectin production, benefits both a sustainable environment and a sustainable food industry. Pectin extracted from WP and PP as an emulsifier in ice cream can ensure the production of ice creams with good melting properties. Pectin can be used as a healthy, sustainable, and economical alternative emulsifier in the ice cream industry.

Valorization of Grape Pomace as a Renewable Source of Techno-Functional and Antioxidant Pectins

The food industry's increasing demand for new functional ingredients that meet both organoleptic and healthy requirements has driven the exploration of new sources of functional ingredients in agro-industrial by-products. The aim of this work was to valorize grape pomace (Vitis vinifera L. garnacha) as a source of pectins using food-grade extracting agents. Obtained pectins were evaluated for monomeric composition, methyl esterification, molecular weight, water retention, oil-holding capacity, and antioxidant properties. The relatively soft extraction conditions used permitted obtaining low methoxyl pectin (10-42%) enriched in homogalacturonan (38-45%) or rhamnogalacturonan (33-41%) with different branching degrees, molecular weight, and fewer impurities than those found in the scarce previous literature. The relationship between structure and functionality was studied. Among the different pectins obtained, the sample derived from the extraction with sodium citrate could resume the best characteristics, such as pectin purity and higher water retention and oil holding capacity. These results underscore the relevance of grape pomace as a viable alternative source of pectin.

Changes in the functional properties of casein conjugates prepared by Maillard reaction with pectin or arabinogalactan

The aim of this study was to prepare conjugates of casein (CA) with pectin (CP) or arabinogalactan (AG) by the Maillard reaction (wet-heating) and to investigate the effects of CP or AG on the structural and functional properties of casein. The results indicated that the highest grafting degree of CA with CP or AG was observed at 90 °C for 1.5 h or 1 h, respectively. Secondary structure showed that grafting with CP or AG reduced the α-helix level and increased the random coil level of CA. Glycosylation treatment of CA-CP and CA-AG exhibited lower surface hydrophobicity and higher absolute ζ-potential values, further significantly improving the functional properties of CA (e.g., solubility, foaming property, emulsifying property, thermal stability, and antioxidant activity). Accordingly, our results indicated that it is feasible for CP or AG to improve the functional properties of CA by the Maillard reaction.

Pectin Stabilized Fish Gelatin Emulsions: Physical Stability, Rheological, and Interaction Properties

Pectin, a kind of natural polysaccharide, shows the attractive potential as a natural stabilizer for protein emulsion. The aim of this study is to investigate the effect of pectin on the physical stability, rheology, interface, and interaction properties of the fish gelatin (FG) emulsion, as pectin was utilized to improve the stability of FG, fish oil emulsion. During the study, when pH < 6, the FG-pectin emulsion displayed better storage stability and salinity tolerance. Analyzing the result, pectin could avoid phase separation at the freeze-thaw process and prevent the liquid-gel transition of FG emulsions during storage. On the other hand, when pH ≥ 6, the emulsion displayed high viscosity due to the complex flocculation and stratified during long-term storage. Electrostatic interactions, hydrophobic interactions, and hydrogen bonding of the FG-pectin complexes in the emulsion were all reduced. Overall, pectin improved the stability of FG emulsions through electrostatic repulsion, hydrophobic interactions, and steric hindrance.

Interaction mechanism between soybean protein isolate and citrus pectin

In this study, citrus pectin (CP) and soybean protein isolate (SPI) were used as raw materials to prepare a complex. The interaction mechanism and structural changes between SPI and CP were deeply studied by fluorescence spectroscopy and Fourier infrared spectroscopy. The results show that CP has a strong quenching effect on SPI's endogenous fluorescence, and with the addition of CP, the endogenous fluorescence intensity of SPI decreased from 13,565.2 to 6067.3. The CP quenching of SPI is static quenching, and the number of combined bits is 1.26. The results of three-dimensional fluorescence spectra showed that the addition of CP reduced the polarity of SPI amino acid residue microenvironment and changed the protein structure. Hydrophobic interaction exists between CP and SPI. The results of three-dimensional fluorescence spectra showed that the addition of CP reduced the polarity of the amino acid residue microenvironment of SPI and changed the protein structure. Fourier transform infrared spectroscopy shows that CP could change the secondary structure of SPI by decreasing the α-helix and β-sheet, increasing β-rotation and irregular curl, destroying the ordered structure of SPI and increasing the polarity of the amino acids exposed to the solution. The microstructure analysis shows that SPI-CP composite system has honeycomb structure and dense pores. From the perspective of reaction thermodynamics, it was found that the addition of CP could improve the thermal stability of SPI and increase the denaturation temperature of SPI from 119.73 to 132.97°C. This study can provide a theoretical basis for the preparation of protein-pectin complexes and provides reference for their application in food grade gels and Pickering emulsions.

Physicochemical characteristics and functional properties of high methoxyl pectin with different degree of esterification

Moderate alkali de-esterification can change the physicochemical characteristics and thus the functional properties of high methoxyl pectin (HMP). The results revealed that de-esterification could increase negative charges (Zeta potential from -21 to -31 mV), decrease molecular weight (from 448 to 136 kDa) and apparent viscosity of HMP. Homogalacturonan (HG) content decreased (from 62% to 49%) while rhamnogalacturonan Ⅰ (RG-Ⅰ) content increased (from 32% to 46%) after de-esterification. The group characteristics of HMP with different degree of esterification (DE) were similar and no obvious impact was made on degree of crystallinity by alkali de-esterification. A conformation transition of HMP molecule implied by Congo red test were occurred as the DE decreased. With the decrease of DE, the molecular structure of HMP became shorter and smaller, and the entanglement was weaker. The de-esterification caused slight decrease of thermal stability. Alkali de-esterification would weaken the gel property and the emulsifying ability of HMP.

Facile fabrication of multifunctional citrus pectin aerogel fortified with cellulose nanofiber as controlled packaging of edible fungi

Citrus pectin was used as a precursor and cellulose nanofibers as a reinforcing agent, a mixed aerogel with enhanced structural properties was prepared. Pickering emulsion was a template for aerogel formation, embedding thymol. Its potential application in humidity regulating packaging has been investigated. Results showed that emulsion gel containing cellulose nanofibers has slightly larger droplet diameter, better viscoelasticity and emulsification. Composite aerogel has larger pore size and thinner pore wall. Additionally, its tensile and compressive properties have been significantly improved. Moisture absorption was close to 100% of its own weight, thymol was released slowly. Compared with Escherichia coli, aerogel has better resistance to Staphylococcus aureus. When applied on fresh Agaricus bisporus. It was found that relative humidity in package can be stabilized at about 97%. Hardness, color, total phenol content, cell membrane integrity and total antioxidant capacity of Agaricus bisporus were maintained and fresh-keeping period was extended to 5 days.

Effect of L-calcium lactate, zinc lactate, and ferric sodium EDTA on the physicochemical and functional properties of liquid whole egg

The study aimed to evaluate the physicochemical and functional properties of liquid whole egg (LWE) with L-calcium lactate (L-Ca), zinc lactate (L-Zn), and sodium ferric EDTA (NaFeEDTA), and to compare with NaCl addition to determine the application potential of these mineral supplements. Results showed that salts addition significantly influenced the foaming, emulsifying, and gelling properties of LWE, which was possible through affecting the pH, particle size, surface hydrophobicity, apparent viscosity, and solubility. The addition of all the four salts reduced pH but increased the d_4,3 diameter of LWE. Additionally, the addition of 200 mM L-Ca and 6 mM L-Zn significantly improved the emulsifying capacity by 41.73% and 13.6%, the foaming capacity by 26.57% and 10%, and the protein solubility by 13.89% and 12.70%, respectively. In the meantime, mineral supplements tend to produce lower hardness gel, especially with 25 mM L-Ca and 8 mM L-Zn, and the hardness was decreased from 2401.13 to 1138.29 and 1175.59 g, respectively. A relative decrease in hardness was desirable in gelled egg products. Moreover, the addition of NaCl and L-Ca showed a higher redness and yellowness, but the addition of NaFeEDTA showed an undesirable color in dark brown, which may be not accepted by the public. In summary, L-Ca and L-Zn had great potential for application in LWE, which was more appropriate than adding NaCl. This study provides a basis for improving the functional properties of LWE products in the future. PRACTICAL APPLICATION: The addition of L-Ca and L-Zn to liquid whole egg (LWE) could improve the foaming and emulsifying capacity of LWE as well as produce a lower hardness gel, which may be more conducive to the production of cake, custards, and meat products. Meantime, it is more in line with people's pursuit of a healthy diet.

Influence of cations, pH and dispersed phases on pectin emulsification properties

The cooperativity of six cations (Ca²⁺, Mg²⁺, Zn²⁺, Al³⁺, Cr³⁺ and Fe³⁺), three pectins (sugar beet, high and low methyl esterified), three dispersed phases (medium chain triglycerides (MCT), orange oil and hexadecane), time (30 days) and pH (2.0 and 6.0) has been investigated in the formation and stability against coarsening of oil-in-water emulsions. Cations generally influenced emulsion stability in the following order (most stable) Ca²⁺ ​> ​Mg²⁺ ​> ​Al³⁺ ​> ​Cr³⁺ ​> ​Zn²⁺ ​> ​Fe³⁺ (least stable). This order largely coincided with that of the strength of pectin-cation interactions showing that the higher the affinity of cation for pectin the less stable the emulsion. More stable emulsions were formed with sugar beet pectin, which was also unresponsive to the presence of cations, followed by high- and then low-methyl esterified samples. At pH 2.0 all pectins showed their best emulsification performance whereas shifting pH to 6.0 severely impaired emulsification capacity and longer term stability against droplet growth. Smaller droplets were created with hexadecane under all conditions studied followed by MCT and orange oil in agreement with their aqueous solubilities. The present results advance our understanding of the stabilisation of emulsions using pectin and allow us to tailor their functionality for applications in food, pharmaceutical and biomedical industries.

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Cations influence stability in the order: Ca²⁺ ​> ​Mg²⁺ ​> ​Al³⁺ ​> ​Cr³⁺ ​> ​Zn²⁺ ​> ​Fe³⁺.

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Pectins showed best emulsification performance at pH 2.0

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Pectins showed poor emulsification performance at pH 6.0

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Pectin stability order: sugar beet ​> ​high methoxy ​> ​low methoxy pectin.

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Oil stability order at pH 2.0: hexadecane ​< ​medium chain triglycerides ​< ​orange oil.

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 (M_w ) 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.