Physicochemical properties of pectin from Malus domestica ‘Fălticeni’ apple pomace as affected by non-conventional extraction techniques

A review of sugar beet pectin-stabilized emulsion: extraction, structure, interfacial self-assembly and emulsion stability

In recent years, sugar beet pectin as a natural emulsifier has shown great potential in food and pharmaceutical fields. However, the emulsification performance depends on the molecular structure of sugar beet pectin, and the molecular structure is closely related to the extraction method. This review summarizes the extraction methods of pectin, structure characterization methods and the current research status of sugar beet pectin-stabilized emulsions. The structural characteristics of sugar beet pectin (such as degree of methylation, degree of acetylation, degree of blockiness, molecular weight, ferulic acid content, protein content, neutral sugar side chains, etc.) are of great significance to the emulsifying activity and stability of sugar beet pectin. Compared with traditional hot acid extraction method, ultrasonic-assisted extraction, microwave-assisted extraction, subcritical water-assisted extraction, induced electric field-assisted extraction and enzyme-assisted extraction can improve the yield of sugar beet pectin. At the same time, compared with harsh extraction conditions (too high temperature, too strong acidity, too long extraction time, etc.), mild extraction conditions can better preserve these emulsifying groups in sugar beet pectin molecules, which are beneficial to improve the emulsifying properties of sugar beet pectin. In addition, the interfacial self-assembly behavior of sugar beet pectin induced by the molecular structure is crucial to the long-term stability of the emulsion. This review provides a direction for extracting or modifying sugar beet pectin with specific structure and function, which is instructive for finding alternatives to gum arabic.

Hybrid techniques of pre and assisted processing modify structural, physicochemical and functional characteristics of okra pectin: Controlled-temperature ultrasonic-assisted extraction from preparative dry powders and its field monitoring

Diversiform okra dry powders were prepared and controlled-temperature ultrasonic-assisted extraction (CTUAE) was then utilized to obtain okra pectin (OP) from the preparative powders. During processing of hybrid techniques, 6 types of dry powders were prepared through different drying technologies (hot air drying, HD; freeze-drying, FD) and meshes (60, 80, 120 meshes) at first. Next, the extraction yield, physicochemical and function characteristics, and molecular structure of OP were analyzed with or without CTUAE technique. Meanwhile, the time-frequency domains of acoustic fields during extraction process of OP were monitored to analyze the effects of ultrasonic fields. Results showed that OP main chains with less cracking by FD than that by HD; the yield, GalA, esterification degree (DE), M_w and viscosity of OP increased, but its particle size decreased. Water holding capacity (WHC) and oil holding capacity (OHC) of OP by HD were more prominent. Secondly, HD OP had dendritic rigid chains, while FD OP had flexible chains with multiple branches. For HD OP, as meshes of okra dry powders decreased, GalA, viscosity and emulsification ability decreased; while gel strength and thermal stability increased. For FD OP, the reduction of meshes improved thermal stability. Above all, CTUAE technique increased the yield and GalA, and decreased DE, M_w and particle size of OP. In terms of functional characteristics, the technique also improved gel strength, resilience and viscoelasticity, enhanced emulsifying stability, WHC and thermal stability, and reduced viscosity. Finally, the correlation between functional and structural characteristics of OP was quantified, and some suggestions were made for its application in food areas.

Synthesis, physicochemical characterization, antibacterial activity, and biocompatibility of quaternized hawthorn pectin

Quaternized polysaccharides are considered as potential antimicrobial materials due to their antimicrobial activity, biodegradability, biocompatibility, and water solubility. In this work, hawthorn pectin (HP) was obtained by ultrasound‑sodium citrate assisted extraction, quaternized hawthorn pectin (QHP) derivatives (namely: QHP-1, QHP-2, QHP-3, and QHP-4) with different degree of substitution were produced using (3-Chloro-2-hydroxypropyl) trimethylammonium chloride under alkaline conditions. The structure, properties, and morphology of HP and QHP were characterized by FTIR, XRD, ¹H NMR, high-performance gel permeation chromatography (HPGPC), thermal analysis, and SEM. The results of FTIR and ¹H NMR demonstrated that the quaternary ammonium modification was successful, and the degree of substitution (DS) of derivatives was calculated through elemental analysis. The determination of the minimum inhibitory concentrations and biofilm inhibition assay exhibited that QHP has a certain inhibitory effect on Escherichia coli and Staphylococcus aureus. Acceptable values of QHP were obtained in cytotoxicity assay on human keratinocytes.

Characterization of Pectin from Grape Pomace: A Comparison of Conventional and Pulsed Ultrasound-Assisted Extraction Techniques

The yield, physicochemical and rheological parameters of grape pomace pectin (Fetească Neagră and Rară Neagră) obtained by conventional extraction (CE) were compared to those acquired by pulsed ultrasound-assisted extraction (PUAE). Extraction temperature (70–90 °C), pH (1–3) and time (1–3 h) were considered as independent variables for CE, while amplitude (20–100%), pH (1–3) and time (20–60 min) for PUAE. The optimal conditions for maximum yield and physicochemical parameters of pectin samples extracted by CE were temperature of 90 °C, pH 1.9 for 164 min (9.96% yield, 79.91 g/100 g of galacturonic acid (GalA) content, 81.28% of degree of esterification (DE) and 5.52 × 10⁴ g/mol of molecular weight (M_w) for Fetească Neagră (FN) pectin; 11.08% yield, 80.05 g/100 g of GalA content, 80.86% of DE and 5.59 × 10⁴ g/mol of M_w for Rară Neagră (RN) pectin), while for PUAE they were amplitude of 100%, pH 1.8 for 60 min (8.83% yield, 80.24 g/100 g of GalA content, 81.07% of DE and 4.19 × 10⁴ g/mol of M_w for FN pectin; 8.94% yield, 78.64 g/100 g of GalA content, 80.04% of DE and 4.23 × 10⁴ g/mol of M_w for RN pectin). The yield and physicochemical parameters of CE pectin were higher than PUAE pectin. The FT-IR spectra of pectin samples revealed the occurrence of polysaccharide compound, while rheology characteristics confirming its application in different food products.

Microwave-assisted extraction of pectin from grape pomace

The utilization of microwave technique for the pectin extraction from grape pomace (Fetească Neagră and Rară Neagră), its influence on yield, galacturonic acid content, degree of esterification and molecular weight of pectin were analyzed. The optimal conditions of the extraction process were microwave power of 560 W, pH of 1.8 for 120 s. The pectin samples extracted by MAE in optimal conditions were analyzed by comparing with commercial apple and citrus pectin based on FT-IR analysis, thermal behavior, rheological characteristics and microstructure. The FT-IR analysis established the presence of different functional groups which are attributed to the finger print region of extracted pectin, while the rheological behavior presented a good viscoelasticity of pectin solutions. The obtained data assumes that grape pomace has a great potential to be a valuable source of pectin which can be extracted by simple and quick techniques, while maintaining analogous quality to conventional sources of pectin.

New valorization approach of Algerian dates (Phoenix dactylifera L.) by ultrasound pectin extraction: Physicochemical, techno-functional, antioxidant and antidiabetic properties

To exploit the great fortune of date fruits, the current study aimed to valorize an Algerian common variety by extracting pectins. Response surface methodology (RSM) was applied as process optimization tool to achieve the highest yield using ultrasound-assisted extraction (UAE) as compared to conventional acid extraction (CAE). The experimental yield value (6.7%) was well matched with the predicted one (6.6%) at the optimum conditions (60 °C, 90 min, pH 1.5), confirming the validity of the model. The evaluation of the monomeric composition showed higher content of galacturonic acid and lower of neutral sugars in UAE pectin, as compared to CAE pectin. Conventional treatments decreased the molecular weight (Mw) of the extracted pectins (539 kDa) in a higher extent than ultrasound treatment (800 kDa). Fourier-Transform Infrared Spectroscopy (FT-IR) spectral analysis showed that both samples were low-methoxyl pectins. CAE gave rise to pectins with slightly upper technological samples in terms of water and oil holding capacity (5.2 and 3.8 g/g, respectively), and emulsifying activity (38.5 m²/g). Moreover, date pectins obtained by UAE presented enhanced antioxidant activity (24.3 and 61.0 mg/g DW for DPPH and FRAP assays, respectively), and in vitro antidiabetic properties, showing higher glucose adsorption capacity (4 mmol g^-1 at 200 min), as well as α-amylase inhibition (73.7%) and potential capacity to decrease glucose diffusion (1.4 mmol mM g^-1 at 150 min), which could improve the ability to retard starch digestion (0.1 mmol mM g-1 at 150 min), providing potential health-promoting properties.

The Influence of Extraction Conditions on the Yield and Physico-Chemical Parameters of Pectin from Grape Pomace

Grape pomace is one of the most abundant by-products generated from the wine industry. This by-product is a complex substrate consisted of polysaccharides, proanthocyanidins, acid pectic substances, structural proteins, lignin, and polyphenols. In an effort to valorize this material, the present study focused on the influence of extraction conditions on the yield and physico-chemical parameters of pectin. The following conditions, such as grape pomace variety (Fetească Neagră and Rară Neagră), acid type (citric, sulfuric, and nitric), particle size intervals (<125 µm, ≥125−<200 µm and ≥200−<300 µm), temperature (70, 80 and 90 °C), pH (1, 2 and 3), and extraction time (1, 2, and 3 h) were established in order to optimize the extraction of pectin. The results showed that acid type, particle size intervals, temperature, time, and pH had a significant influence on the yield and physico-chemical parameters of pectin extracted from grape pomace. According to the obtained results, the highest yield, galacturonic acid content, degree of esterification, methoxyl content, molecular, and equivalent weight of pectin were acquired for the extraction with citric acid at pH 2, particle size interval of ≥125−<200 µm, and temperature of 90 °C for 3 h. FT-IR analysis confirmed the presence of functional groups in the fingerprint region of identification for polysaccharide in the extracted pectin.

Ultrasound-Assisted Extraction and Characterization of Polyphenols from Apple Pomace, Functional Ingredients for Beef Burger Fortification

Currently, there is an increasing interest to valorise agri-food waste containing bioactive compounds with potential health benefits. In this paper, the recovery of functional molecules from apple pomace, the most abundant by-product of the apple processing industry, was carried out by ultrasound-assisted extraction (UAE) on fresh and freeze-dried samples. UAE extract, obtained by double extraction of freeze-dried apple pomace, was subjected to chromatographic and spectrophotometric characterization. It showed good levels of total phenol content, high antioxidant activity, and interesting antioxidant compounds (quercetin derivatives, chlorogenic acid, phloridzin). Subsequently, freeze-dried apple pomace, containing 40.19% of dietary fibre, was used as a fortifying agent for beef burgers (4% and 8%). The results concerning colour and sensory analysis of the fortified products were graded even better than the control (0%). The improved fibre and phenol content, together with the neutral flavour, represent the most interesting characteristics of fortified burgers. The results confirm that UAE was a successful technique for extracting phenol compounds and that the addition of apple pomace represents a valid approach to increase the health properties and palatability of beef burgers, including for consumers who do not like meat.

Challenges and solutions of extracting value-added ingredients from fruit and vegetable by-products: a review

Every year, huge amounts of fruit and vegetable by-products in the food processing factories are produced. These by-products have great potential to be used for different targets especially the extraction of value-added ingredients. The target of this study is to review the challenges of extraction of value-added ingredients from fruit and vegetable by-products on the industrial scale and to describe current trends in solving these problems. In addition, some strategies such as multi-component extraction as well as application of fermentation before or after the extraction process, and production of biofuel, organic fertilizers, animal feeds, etc. on final residues after extraction of value-added ingredients are discussed in this review paper. In fact, simultaneous extraction of different value-added ingredients from fruit and vegetable by-products can increase the extraction efficiency and reduce the cost of value-added ingredients as well as the final volume of these by-products. After extraction of value-added ingredients, the residues can be used to produce biofuels, or they can be used to produce organic fertilizers, animal feeds, etc. Therefore, the application of several appropriate strategies to treat the fruit and vegetable by-products can increase their application, protect the environment, and improve the food economy.

Effect of Ultrasound-Assisted, Microwave-Assisted and Ultrasound-Microwave-Assisted Extraction on Pectin Extraction from Industrial Tomato Waste

This work aimed to study the effect of ultrasound-assisted (UAE), microwave-assisted (MAE), and ultrasound-microwave-assisted (UMAE) methods for pectin extraction from industrial tomato waste. The overall performance index from the fuzzy analytical method with three criteria, pectin yield, galacturonic acid, and lycopene content, was applied to evaluate the best extraction conditions by using the weight of 75, 20, and 5, respectively. The UAE conditions was performed at a temperature of 80 °C for 20 min with the variations in the extraction pH and the solid liquid (SL) ratio. The best UAE conditions with high pectin yield, and high total carboxyl group, as well as a lycopene content, was the pH of 1.5 and the SL ratio of 1:30. The MAE conditions was performed with variations in the microwave powers and times. The results showed that the best MAE conditions were 300 W for 10 min, which gave high pectin yield with high galacturonic acid and lycopene content. Various conditions of UMAE at the best conditions of MAE and UAE were performed and exhibited that the UAE had more positively affected the pectin yield. However, the FTIR spectra of obtained pectins from different extraction techniques showed a similar pectin structure.

Kinetic, Thermodynamic, Physicochemical, and Economical Characterization of Pectin from Mangifera indica L. cv. Haden Residues

The effect of temperature (60, 70, 80, and 90 °C) and time (30, 45, 60, 75, and 90 min) on citric acid extraction of Haden mango (Mangifera indica L. cv. Haden) peel pectin was evaluated in the present study. In order to obtain a better understanding of both the extraction process and the characteristics of the pectin (obtained from an agro-industrial waste) for a future scaling process, the following characterizations were performed: (1) Kinetic, with the maximum extraction times and yields at all evaluated temperatures; (2) thermodynamic, obtaining activation energies, enthalpies, entropies, and Gibbs free energies for each stage of the process; (3) physicochemical (chemical analysis, monosaccharide composition, degree of esterification, galacturonic acid content, free acidity, Fourier-transform infrared spectroscopy, thermogravimetric and derivative thermogravimetric analyses); and (4) economical, of the pectin with the highest yield. The Haden mango peel pectin was found to be characterized by a high-esterified degree (81.81 ± 0.00%), regular galacturonic acid content (71.57 ± 1.26%), low protein (0.83 ± 0.05%) and high ash (3.53 ± 0.02%) content, low mean viscometric molecular weight (55.91 kDa), and high equivalent weight (3657.55 ± 8.41), which makes it potentially useful for food applications.

Berry fruits as source of pectin: Conventional and non-conventional extraction techniques

Three non-conventional extraction techniques (enzyme-assisted with cellulase, citric acid ultrasound-assisted and enzyme-ultrasound-assisted treatment) and conventional citric acid extraction were applied to obtain pectin from raspberry, blueberry, strawberry and redcurrant, and were compared in terms of extraction yields and physicochemical properties of the extracted pectins. Except for pectin from raspberry, conventional citric acid extraction led to the highest extraction yield (~8%) and, for the same berries, the lowest pectin recovery was found for the extraction with cellulase (~4%). Regarding the structural characteristics of pectins, enzymatically extracted pectins from redcurrant and strawberry exhibited the highest levels of galacturonic acid (≥73%) whereas, in general, this monosaccharide was found from 51 to 69% in the rest of samples. Although, ultrasound-assisted extraction did not improve pectin yield, it minimized the levels of "non-pectic" components leading to the obtainment of purer pectin. The different monomeric composition and the wide range of molecular weight of the obtained pectins pointed out their usefulness in different potential food applications (e.g., thickening, gelling ingredients) and biological activities. This has been evidenced by the differences found in their physicochemical and techno-functional characteristics. Finally, it can be considered that the berries here studied are efficient sources of pectin.

Delineating the inherent functional descriptors and biofunctionalities of pectic polysaccharides

Pectin is a plant-based heteropolysaccharide macromolecule predominantly found in the cell wall of plants. Pectin is commercially extracted from apple pomace, citrus peels and sugar beet pulp and is widely used in the food industry as a stabilizer, emulsifier, encapsulant, and gelling agent. This review highlights various parameters considered important for describing the inherent properties and biofunctionalities of pectins in food systems. These inherent descriptors include monosaccharide composition, galacturonic acid content, degree of esterification, molecular weight, structural morphology, functional group analysis, and functional properties, such as water and oil holding capacity, emulsification, foaming capacity, foam stability, and viscosity. In this study, we also delineate their potential as a nutraceutical, prebiotic, and carrier for bioactive compounds. The biofunctionalities of pectin as an anticancer, antioxidant, lipid-lowering, and antidiabetic agent are also conceptually elaborated in the current review. The multidimensional characteristics of pectin make it a potential candidate for use in food and biomedical science.

Effects of different extraction methods on structural and physicochemical properties of pectins from finger citron pomace

The functionality and property of pectin are correlated with its structure which is affected by the extraction method used. In this study, three different methods of extracting pectin, the microwave-assisted extraction (MAE), the ultrasonic-assisted extraction (UAE) and the conventional heating extraction (CHE), were used at three different temperatures with both an acid and alkali extraction solution. It was found that temperature mainly influenced pectin yield, while pectin structures and physicochemical properties were affected by the pH condition and extraction technology. The alkali-extraction with MAE and UAE at short time promoted the yield of low-ester pectin. Monosaccharide composition analysis showed a high galacturonic acid (GalA) content in the pectin derived from MAE and UAE. The high viscosity and desirable viscoelastic properties of the acid-MAE pectin were due to its large molecular weight and particle size. The results contribute to our understanding of the association among pectin extraction, structure and properties.

Apple pomaces derived from mono-varietal Asturian ciders production are potential source of pectins with appealing functional properties

Comprehensive chemical characterization of nine mono-varietal apple pomaces obtained from the production of ciders with PDO is described. They were rich in essential minerals, fibers (35-52.9 %), and polyphenols. High levels in GalA (11.8-21.6 %), revealed the suitability of these apple pomaces as efficient sources of pectins. Extracted pectins showed high variability in monomer composition, with degrees of methylesterification, strongly associated with pectins functional properties, ranging from 58 to 88 %. For a subset of apple pomace varieties, pectin extraction was accomplished by conventional acid heat treatment or ultrasound. Despite ultrasound-assisted extraction did not improve pectin yield, it minimized levels of "non-pectin" components as revealed by the low content of Glc/Man, leading to the obtainment of high-purity pectin. Our work highlights the key role played by the selection of the apple variety to streamline the potential food applications (gelling/thickening agents or prebiotics) of the extracted pectins that largely depend on their structural features.

Dietary Fiber from Underutilized Plant Resources—A Positive Approach for Valorization of Fruit and Vegetable Wastes

Agri-food industries generate enormous amounts of fruit and vegetable processing wastes, which opens up an important research area aimed towards minimizing and managing them efficiently to support zero wastes and/or circular economy concept. These wastes remain underutilized owing to a lack of appropriate processing technologies vital for their efficient valorization, especially for recovery of health beneficial bioactives like dietary fibers. Dietary fiber finds wide applications in food and pharmaceutical industries and holds high promise as a potential food additive and/or as a functional food ingredient to meet the techno-functional purposes important for developing health-promoting value-added products. Based on this, the present review has been designed to support ‘zero waste’ and ‘waste to wealth’ concepts. In addition, the focus revolves around providing updated information on various sustainability challenges incurred towards valorization of fruit and vegetable wastes for extraction of health promoting dietary fibers.

Microwave and ultrasound assisted extraction of pectin from various fruits peel

Pectin, found in the cell walls of fruits and vegetables, is a complex colloidal polysaccharide. In this study, pectin was extracted using ultrasound and microwave-assisted extraction methods from waste lemon, mandarin, and kiwi peel to investigate their use as alternative source of pectin. Hydrochloric acid (HCl) and nitric acid (HNO₃) were used as the extracting agents. The effects of microwave power (360-600 W) and irradiation time (1, 2, 3 min) for microwave-assisted extraction (MAE) and of temperature (60 and 75 °C) and sonication time (15, 30, 45 min) on ultrasound-assisted extraction (UAE) on the yield of extracted pectin from the peels were investigated. Optimum conditions were determined for the extraction of pectin from all of the peel samples with the two extraction methods. The produced pectin yield and the degree of esterification were determined and, FT-IR and SEM analyses were performed. Kiwi peel gave the highest yield of extracted pectin using HCl as the solvent with 17.30% yield via UAE at 75 °C for 45 min and 17.97% yield via MAE at 360 W for, 3 min. It was concluded that lemon, mandarin, and kiwi peels all contained pectin and that MAE gave a better yield than UAE and could thus be used as an efficient and rapid technique for the extraction of pectin from the peels. The chemical structures of the pectin obtained using the two different extraction methods were similar and showed a high degree of methoxylation.