Properties and extraction of pectin-enriched materials from sugar beet pulp by ultrasonic-assisted treatment combined with subcritical water

Optimization of subcritical water extraction for pectin extraction from cocoa pod husks using the response surface methodology

This study optimized subcritical water extraction (SWE) conditions to maximize pectin yield from cocoa pod husk (CPH) and compared the characteristics of CPH pectin extracted through SWE with those of CPH pectin obtained through conventional extraction (CE) with citric acid. The Box-Behnken experimental design was employed to optimize SWE and examine the influence of process parameters, including temperature (100 °C-120 °C), extraction time (10-30 min), and solid:liquid ratio (SLR) (1:30-2:30 g/mL), on pectin yield. The maximum pectin yield of 6.58% was obtained under the optimal extraction conditions of 120 °C for 10 min with 1:15 g/mL SLR and closely corresponded with the predicted value of 7.29%. Compared with CE, SWE generated a higher yield and resulted in a higher degree of esterification, methoxyl content, and anhydrouronic acid value but a lower equivalent weight. The extracted pectin was pure, had low-methoxyl content, and similar melting and degradation temperatures.

Cocoa by-products: A comprehensive review on potential uses, waste management, and emerging green technologies for cocoa pod husk utilization

Cocoa is considered to be one of the most significant agricultural commodities globally, alongside Palm Oil and Rubber. Cocoa is the primary ingredient in the manufacturing of chocolate, a globally popular food product. Approximately 30 % of cocoa, specifically cocoa nibs, are used as the primary constituent in chocolate production., while the other portion is either discarded in landfills as compost or repurposed as animal feed. Cocoa by-products consist of cocoa pod husk (CPH), cocoa shell, and pulp, of which about 70 % of the fruit is composed of CPH. CPH is a renewable resource rich in dietary fiber, lignin, and bioactive antioxidants like polyphenols that are being underutilized. CPH has the potential to be used as a source of pectin, dietary fibre, antibacterial properties, encapsulation material, xylitol as a sugar substitute, a fragrance compound, and in skin care applications. Several methods can be used to manage CPH waste using green technology and then transformed into valuable commodities, including pectin sources. Innovations in extraction procedures for the production of functional compounds can be utilized to increase yields and enhance existing uses. This review focuses on the physicochemical of CPH, its potential use, waste management, and green technology of cocoa by-products, particularly CPH pectin, in order to provide information for its development.

Hot-air drying vs. lyophilization of sugar beet flakes for efficient pectin recovery and influence of extraction conditions on pectin physicochemical properties

This study assessed the influence of drying pretreatment and extraction conditions (type of acid and particle size of plant material) on the yield and physicochemical properties of pectin from sugar beet flakes resulted as by-product of sugar beet processing in the sugar industry. The results indicated that the drying conditions (hot-air drying and lyophilization) affected the extraction yield, the chemical composition of pectin, its color, degree of methylation and acetylation, molecular weight, and its rheological and emulsifying properties. The best results for pectin yield (16.20%), galacturonic acid content (91.19 g/100 g), degree of methylation and acetylation (66.93 and 23.87%), and molecular weight (3.89 × 105 g/mol) were obtained when sugar beet flakes were pretreated by hot-air drying, and the extraction was made with citric acid using plant material with particle sizes of 125-200 μm. This pectin also had high emulsion activity (51.42%) and emulsion stability (88.03%). The FT-IR spectra were similar, while pectin thermal behavior was affected by the drying pretreatment and extraction conditions. The results of this study showed that from this by-product of the sugar industry it can be extracted high quality pectin with rheological and emulsifying properties that are superior to commercial citrus and apple pectin.

An eco-friendly extraction method to obtain pectin from passion fruit rinds (Passiflora edulis sp.) using subcritical water and pressurized natural deep eutectic solvents

This work evaluated the efficiency of Subcritical Water Extraction (SWE) and Pressurized Natural Deep Eutectic Solvents (P-NaDESs) under different temperatures (100, 120, 140 and 160 °C) in obtaining pectin from Passion Fruit Rinds (PFR) and its residual biomass (PFR - UAPLE), and compare the results with those of Conventional Extraction (CE). The highest pectin yields, 19.1 and 27.6 %, were achieved using P-NaDES (Citric Acid:Glucose:Water) at 120 °C for PFR and its PFR-UAPLE, respectively. Regarding the Degree of Esterification (DE), pectin obtained with SWE and CE had DE below 50 %, while with P-NaDES (Citric Acid: Glucose:Water), DE was above 50 %. Higher Molecular Weights (MW) (98 and 81 kDa) were obtained with SWE and P-NaDES from PFR compared to PFR-UAPLE and CE. Galacturonic acid was the most abundant (74 to 78 %) monosaccharide obtained by SWE. In terms of morphology, water extraction provided pectin with more uniform textures, whereas extraction with acidified mixtures led to more heterogeneous surfaces. Overall, comparing SWE and P-NaDES, the obtained pectins differed in terms of monomeric composition, MW and DE. These results indicate that pectins obtained by both methods can have different applications depending on their structural characteristics.

Application of ultrasound technology for the effective management of waste from fruit and vegetable

Food waste presents a continuous challenge for the food industry, leading to environmental pollution and economic issues. A substantial amount of waste, including by-products from fruits and vegetables, non-edible food items, and other waste materials, is produced throughout the food supply chain, from production to consumption. Recycling and valorizing waste from perishable goods is emerging as a key multidisciplinary approach within the circular bio-economy framework. This waste, rich in raw by-products, can be repurposed as a natural source of ingredients. Researchers increasingly focus on biomass valorization to extract and use components that add significant value. Traditional methods for extracting these bio-compounds typically require the use of solvents and are time-consuming, underscoring the need for innovative techniques like ultrasound (US) extraction. Wastes from the processing of fruits and vegetables in the food industry can be used to develop functional foods and edible coatings, offering protection against various environmental factors. This comprehensive review paper discusses the valorization of waste from perishable items like fruits and vegetables using US technology, not only to extract valuable components from waste but also to treat wastewater in the beverage industry. It also covers the application of biomolecules recovered from this process in the development of functional foods and packaging.

Eat your beets: Conversion of polysaccharides into oligosaccharides for enhanced bioactivity

Bioactive oligosaccharides with the potential to improve human health, especially in modulating gut microbiota via prebiotic activity, are available from few natural sources. This work uses polysaccharide oxidative cleavage to generate oligosaccharides from beet pulp, an agroindustry by-product. A scalable membrane filtration approach was applied to purify the oligosaccharides for subsequent in vitro functional testing. The combined use of nano-LC/Chip Q-TOF MS and UHPLC/QqQ MS allowed the evaluation of the oligosaccharide profile and their monosaccharide complexity. A final product containing roughly 40 g of oligosaccharide was obtained from 475 g of carbohydrates. Microbiological bioactivity assays indicated that the product obtained herein stimulated desirable commensal gut bacteria. This rapid, reproducible, and scalable method represents a breakthrough in the food industry for generating potential prebiotic ingredients from common plant by-products at scale. INDUSTRIAL RELEVANCE: This work proposes an innovative technology based on polysaccharide oxidative cleavage and multi-stage membrane purification to produce potential prebiotic oligosaccharides from renewable sources. It also provides critical information to evidence the prebiotic potential of the newly generated oligosaccharides on the growth promotion ability of representative probiotic strains of bifidobacteria and lactobacilli.

Production, structural and functional characteristics of soluble dietary fiber from fermented okara by Penicillium expansum

Soluble dietary fiber (SDF), an important prebiotic, has attracted growing attention, due to its great health effects and wide application. This study focused on the preparation of SDF from fermented okara. The yield of SDF obtained through Penicillium expansum fermentation (FSDF) reached 45.63 % (w/w) under the optimal conditions (pH 6.7, inoculum size 9.5 %, and time 29 h) by response surface methodology, which were 1.92 and 4.43 times higher than those of phosphate-citric acid treatment and untreated okara. Infrared spectra and X-ray diffraction indicated that three SDFs had similar spectral distribution and crystalline region. Moreover, FSDF displayed looser and more porous microstructures. Meanwhile, the composition ratio of monosaccharides has changed. FSDF exhibited higher water solubility (97.46 %), glucose adsorption capacity (203.73 mg/g), sodium cholate adsorption capacity (13.07 mg/g), cholesterol adsorption capacity (6.69- 7.62 mg/g) and radical (ABTS+, hydroxyl and DPPH) scavenging capacity. Additionally, three SDFs didn't degrade by upper gastrointestinal tract and could improve the proportion of beneficial intestinal flora in vitro, such as Lactobacillus and Bifidobacterium. Overall, the FSDF prepared in this study was a functional ingredient with great potential in foods.

Comparisons of pulsed ultrasound-assisted and hot-acid extraction methods for pectin extraction under dual acid mixtures from onion (Allium cepa L.) waste

The aim of this study is to compare the physicochemical properties and yields of pectins extracted from onion waste under hot acid (HAE) and pulsed ultrasound-assisted extraction (PUAE) methods using different organic-inorganic acids, their mixtures, and pure water. The extraction temperature for experiments carried out under HAE was kept at 90°C for 90 min, whereas PUAE experiments were accomplished at RT in 15 min. In general, HAE gave better pectin yields compared with PUAE due to the significance of the increasing extraction temperature for the release of pectin from the plant matrix. While the maximum pectin yield from onion waste was 16.22% for HAE, the highest yield for PUAE was 9.83%. PUAE provides less time- and energy-consuming extraction of pectin within 15 min and thus seems to be more economic compared with the HAE. According to the physicochemical properties (equivalent weight (EW), degree of esterification (DE), methoxyl (MeO), and galacturonic acid (Gal-A) contents) of obtained pectins, extracted pectins were mostly high methoxy pectin. While the DE and MeO values of pectins extracted in organic acid conditions under HAE were higher, these values were found to be higher for pectins extracted in inorganic acids under PUAE. For acid mixtures, the DE and MeO values of pectins under HAE were mostly found to be lower than those under PUAE. Sequential PUAE and HAE methods for the extraction of pectin from onion waste were also found to be useful in terms of obtaining higher yields and better physicochemical properties. The highest pectin yield was 20.32% for the sequential PUAE and HAE methods. FT-IR analyses of the extracted pectins by both HAE and PUAE methods showed similar vibration bands compared with those of commercial citrus pectin.

Physicochemical, structure properties and in vitro hypoglycemic activity of soluble dietary fiber from adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) bran treated by steam explosion

To enhance the content of adlay bran soluble dietary fiber (SDF) and improve its functionality, we investigated the influences of steam explosion (SE) on the physicochemical, structural properties, and in vitro hypoglycemic activities of adlay bran SDF. The cellulose, hemicellulose, and lignin contents of adlay bran decreased significantly after SE treatment. When the SE strength was 0.8 MPa for 3 min, the SDF content was 9.37%, which was a significant increase of 27.48% compared to the control. Under these conditions, SDF showed the highest oil-holding capacity (OHC) (2.18 g/g), cholesterol adsorption capacity (CAC) (27.29 mg/g), glucose adsorption capacity (GAC) (15.54 mg/g), glucose dialysis retardation index (GDRI) (36.57%), and α-Amylase activity inhibition ratio (α-AAIR) (74.14%). Compared with SDF from untreated adlay bran, SDF from SE-treated adlay bran showed lower weight molecular. In addition, differential scanning calorimetry (DSC) measurement showed that the peak temperature of SDF from adlay bran treated by SE increased by 4.19°C compared to the untreated SDF sample. The structure of SDF from adlay bran treated by SE showed that the SDF surface was rough and poriferous and the specific surface areas increased. In conclusion, SE pretreatment increases the content of SDF in adlay bran and improves its physicochemical, structural properties, and biological activities, which will be beneficial for the further exploitation of adlay bran.

Isolation, structures, bioactivities, application and future prospective for polysaccharides from Tremella aurantialba: A review

Since ancient times, Tremella aurantialba has been proposed to have medicinal and food benefits. Modern phytochemistry and pharmacological studies have demonstrated that polysaccharides, the main components from T. aurantialba appear to be an all-round talent resisting a variety of chronic inflammatory diseases and protecting against different types of tumors, diabetes and cardiovascular diseases. These health and pharmacological benefits have gained much attention from scholars around the world. Further, more and more methods for polysaccharides extraction, purification, structure identification have been proposed. Significantly, the bioactivity of fungus polysaccharides is affected by many factors such as extraction and purification conditions and chemical structure. This paper provides an overview of recent advances in the isolation, structural features and biological effects of polysaccharides derived from T. aurantialba, covers recent advances in the field and outlines future research and applications of these polysaccharides.

Systematic evaluation on the physicochemical characteristics of a series polysaccharides extracted from different edible lilies by ultrasound and subcritical water

A series polysaccharide samples extracted from three edible lilies (Lilium davidii var. willmottiae, Lilium brownii var. viridulum, and Lilium lancifolium) by subcritical water and ultrasound-assisted extraction were systematically compared. The results showed that extraction method was a more important factor than lily species. Subcritical water extracted lily polysaccharides (S-LP) with higher yield, molecular weight, neutral glucose and uronic acid content as well as apparent viscosity. Ultrasound-assisted extracted lily polysaccharides (U-LP) with higher reducing sugars and protein content. Moreover, due to the degradation of glycosidic bonds, ultrasonic extraction was easier to obtain lower molecular weight polysaccharides. In addition, the extraction method significantly affected the monosaccharide proportion of polysaccharides, but had no effect on type. Glucose was the main component in S-LP, and glucose and mannose were the main components in U-LP. The micromorphology of different polysaccharide samples was similar, and the scanning electron microscope (SEM) images showed regular/irregular particle clusters with different particle sizes. Overall, the relationships between extraction methods, lily species and polysaccharide properties were preliminarily elucidated, providing a reference for the targeted extraction of specific lily polysaccharides (LP).

Polysaccharide from Hemerocallis citrina Borani by subcritical water with different temperatures and investigation of its physicochemical properties and antioxidant activity

Hemerocallis citrina Borani as a low-cost vegetable, has various health benefits. However, the industry of H. citrina Borani is in the state of primary processing, with poor economic benefits. This study aimed to investigate the physicochemical properties, and the antioxidant activity of H. citrina Borani polysaccharide (HCBP) using subcritical water extraction (SWE) at different temperatures, to expand the value of H. citrina Borani. HCBP mainly composed of nine monosaccharides (glucose, galactose, rhamnose, fucose, mannose, arabinose, xylose, galacturonic acid, and glucuronic acid), among which the content of neutral sugar was higher and uronic acid was lower. HCBP contained glycosidic bond of β-configurations and trace quantities protein. The molecular weight of HCBP decreased with increasing temperature. Shear thinning occurred in HCBP with the increase of shear rate (0.01-1 s-1), and the apparent viscosity of HCBP decreased at higher temperature (150-160°C) with the increase continuously of shear rate (1-10 s-1), but almost remained constant at lower temperature (130-140°C). Scanning electron microscope showed that HCBP had rough surface, loose structure, obvious particle gap, and irregular shape. In addition, HCBP extracted at 160°C had strong FRAP activity, and HCBP extracted at 130 and 140°C had better ABTS radical scavenging activity. This study suggests that HCBP extracted by SWE could provide a cheap raw material as food thickening agent and natural antioxidants.

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.

Ultrasound-assisted extraction of highly nutritious date sugar from date palm (Phoenix dactylifera) fruit powder: Parametric optimization and kinetic modeling

Alternative sweeteners to white sugar with a lower calorie content and glycemic index obtained through date palm fruits is of great interest to the food industry. In this study, ultrasound-assisted extraction of nutritive sugar from date fruit powder was investigated through Box-Behnken design. A maximum total sugar content (TSC) of 812 mg glucose eq./g of DFP was obtained with a sugar extraction yield (SEY) of 81.40 ± 0.27 % under the following optimal extraction conditions: extraction temperature of 60 °C, extraction time of 30 min, and L/S ratio of 7.6 mL/g. Various modern techniques were used to characterize the obtained extracts and associated residues. The results showed that the extract contained fructose, glucose, and sucrose and had good thermal stability. Furthermore, SEM and TSC analysis revealed that ultrasonic treatment of the biomass improved mass transfer diffusion due to acoustic or ultrasonic cavitation, resulting in a higher sugar yield.

Polysaccharide from Hemerocallis citrina Borani by subcritical water: Bioactivity, purification, characterization, and anti-diabetic effects in T2DM rats

Hemerocallis citrina Borani (daylily) has various health benefits. However, the structural characterization and hypoglycemic effects of its polysaccharide remain unclear. Here, we first report for the first time, the effects of subcritical water extraction temperature on bioactivity of Hemerocallis citrina Borani polysaccharide (HCBP). HCBP extracted at 160 °C had better scavenging ability of free-radical and pancreatic lipase inhibition. This study aimed to investigate the structural characterization and anti-diabetic effects of aforementioned HCBP. HCBP was separated into three fractions using a DEAE-Sepharose Fast Flow. HCBP-1 was the major component with lower molecular weight, HCBP-2 was the least abundant component, HCBP-3 was the component with higher uronic acid and molecular weight. HCBP treatment significantly decreased the concentrations of fasting blood glucose, insulin, total cholesterol, triglyceride, and low density lipoprotein, as well as improved glucose intolerance and insulin resistance in type 2 diabetes mellitus (T2DM) rats. HCBP also protected the kidneys and pancreatic organs by histopathology and immunohistochemical analyses in T2DM rats. In addition, HCBP significantly increased the antioxidant enzymes activities and decreased the level of malonaldehyde to alleviated the oxidative stress injury. The results indicate HCBP extracted by subcritical water is promising functional food ingredients and could be used in T2DM treatment.

Optimization and Rheological Study of an Exopolysaccharide Obtained from Fermented Mature Coconut Water with Lipomyces starkeyi

The current research aimed to solve the environmental pollution of mature coconut water by Lipomyces starkeyi and provide a study of its high value utilization. The innovation firstly investigated the rheological properties and interface behavior of a crude exopolysaccharide and provided a technical support for its application in food. A response surface methodology was performed to ameliorate the fermentation factors of the new exopolysaccharide with mature coconut water as a substrate, and the consequences suggested that the maximum yield was 7.76 g/L under optimal conditions. Rotary shear measurements were used to study the influence of four variables on the viscosity of the exopolysaccharide solution. The results illustrated that the exopolysaccharide solution demonstrated a shear-thinning behavior and satisfactory thermal stability within the test range. The viscosity of the exopolysaccharide solution was significantly affected by ionic strength and pH; it reached the peak viscosity when the concentration of NaCl was 0.1 mol/L and the pH was neutral. The adsorption behavior of the exopolysaccharide at the medium chain triglyceride–water interface was investigated by a quartz crystal microbalance with a dissipation detector. The results demonstrated that the exopolysaccharide might form a multilayer adsorption layer, and the thickness of the adsorption layer was at its maximum at a concentration of 1.0%, while the interfacial film was the most rigid at a concentration of 0.4%. Overall, these results suggest that the exopolysaccharide produced by Lipomyces starkeyi is an excellent biomaterial for usage in drink, makeup and drug fabrications as a thickening and stabilizing agent.

Valorization of sugar beet pulp to value-added products: A review

The processing of sugar beet in the sugar production industry releases huge amounts of sugar beet pulp as waste which can be considered a valuable by-product as a source of cellulose, hemicellulose, and pectin. Valorization of sugar beet pulp into value added products occurs through acid hydrolysis, hydrothermal techniques, and enzymatic hydrolysis. Biochemical conversion of beet pulp into simple fermentable sugars for producing value added products occurs through enzymatic hydrolysis is a cost effective and eco-friendly process. While beet pulp has predominantly been used as a fodder for livestock, recent developments in its biotechnological valorization have unlocked its value as a feedstock in the production of biofuels, biohydrogen, biodegradable plastics, and platform chemicals such as lactic acid, citric acid, alcohols, microbial enzymes, single cell proteins, and pectic oligosaccharides. This review brings forward recent biotechnological developments made in the valorization of sugar beet pulp into valuable products.

Protein Hydrolysis by Subcritical Water: A New Perspective on Obtaining Bioactive Peptides

The importance of bioactive peptides lies in their diverse applications in the pharmaceutical and food industries. In addition, they have been projected as allies in the control and prevention of certain diseases due to their associated antioxidant, antihypertensive, or hypoglycemic activities, just to mention a few. Obtaining these peptides has been performed traditionally by fermentation processes or enzymatic hydrolysis. In recent years, the use of supercritical fluid technology, specifically subcritical water (SW), has been positioned as an efficient and sustainable alternative to obtain peptides from various protein sources. This review presents and discusses updated research reports on the use of subcritical water to obtain bioactive peptides, its hydrolysis mechanism, and the experimental designs used for the study of effects from factors involved in the hydrolysis process. The aim was to promote obtaining peptides by green technology and to clarify perspectives that still need to be explored in the use of subcritical water in protein hydrolysis.

Review of ultrasound combinations with hybrid and innovative techniques for extraction and processing of food and natural products

Ultrasound has a significant effect on the rate of various processes in food, perfume, cosmetic, pharmaceutical, bio-fuel, materials, or fine chemical industries, despite some shortcomings. Combination with other conventional or innovative techniques can overcome these limitations, enhance energy, momentum and mass transfer, and has been successfully demonstrated in many recent studies. Various ultrasound combined hybrid and innovative techniques are systematically summarized in this review for the first time. Ultrasound can be combined with diverse conventional techniques including Soxhlet, Clevenger, enzyme, hydrotropes, ionic liquids, Deep Eutectic Solvents (DES) or Natural Deep Eutectic Solvents (NADES), to enhance mixing and micro-mixing, reduced thermal and concentration gradients, and selective extraction. Moreover, combinations of ultrasound with other innovative techniques such as microwave, extrusion, supercritical fluid, subcritical and pressure liquids, Instant controlled pressure drop (DIC), Pulsed Electric Field (PEF), Ultra-Violet (UV) or Infra-Red (IR) radiations, Counter-current chromatography (CCC), or centrifugal partition chromatographs (CPC) can enable reduced equipment size, faster response to process control, faster start-up, increased production, and elimination of process steps. The theories and applications of these ultrasound combined hybrid and innovative techniques as well as their advantages and limitations are compared, and further perspectives are proposed. This review provides new insights into advances in ultrasound combined techniques and their application at research, educational, and industrial level in modern food and plant-based chemistry.

Sugar beet pectin extracted by ultrasound or conventional heating: a comparison

The yield and quality of sugar beet pulp pectin obtained by ultrasound-assisted extraction (UAE) were compared to those obtained by conventional heating. Extraction temperature (70-90) °C, extraction time (2-4) h and pH (1-1.5) were considered as the variables for the conventional extraction while ultrasound frequency (20-60) kHz, time (10-30) min and amplitude (60-100%) were considered as the variables for UAE. The optimal conditions for maximum yield of pectin for conventionally and ultrasonically extracted pectin were determined by the central composite design and the Box Behnken design, respectively. The optimum conditions of conventional extraction were the temperature of 90 °C, time of 4 h and pH of 1. The optimum conditions of UAE were ultrasound frequency of 20 kHz, time of 10 min, and ultrasound amplitude of 96%. Extraction using the optimized conditions of conventional heating and UAE achieved the best yield of 20.75% and 20.85%, respectively. The degree of methyl esterification, ferulic acid content and molecular weight of UAE pectin were higher than conventionally extracted pectin but the content of galacturonic acid in UAE pectin was lower than that of conventionally extracted pectin. The infrared spectra of both pectins revealed the occurrence of polysaccharide component. The pectin achieved by UAE had higher lightness value than conventionally extracted pectin, confirming its application in different products partially in bright food products. The UAE pectin possessed higher viscosity than conventionally extracted pectin. The addition of UAE pectin increased all of the DSC gelatinization parameters. Overall, UAE could be a promising scalable and economical approach to obtain pectin with unique characteristics.

Subcritical Water Extraction of Natural Products

Subcritical water refers to high-temperature and high-pressure water. A unique and useful characteristic of subcritical water is that its polarity can be dramatically decreased with increasing temperature. Therefore, subcritical water can behave similar to methanol or ethanol. This makes subcritical water a green extraction fluid used for a variety of organic species. This review focuses on the subcritical water extraction (SBWE) of natural products. The extracted materials include medicinal and seasoning herbs, vegetables, fruits, food by-products, algae, shrubs, tea leaves, grains, and seeds. A wide range of natural products such as alkaloids, carbohydrates, essential oil, flavonoids, glycosides, lignans, organic acids, polyphenolics, quinones, steroids, and terpenes have been extracted using subcritical water. Various SBWE systems and their advantages and drawbacks have also been discussed in this review. In addition, we have reviewed co-solvents including ethanol, methanol, salts, and ionic liquids used to assist SBWE. Other extraction techniques such as microwave and sonication combined with SBWE are also covered in this review. It is very clear that temperature has the most significant effect on SBWE efficiency, and thus, it can be optimized. The optimal temperature ranges from 130 to 240 °C for extracting the natural products mentioned above. This review can help readers learn more about the SBWE technology, especially for readers with an interest in the field of green extraction of natural products. The major advantage of SBWE of natural products is that water is nontoxic, and therefore, it is more suitable for the extraction of herbs, vegetables, and fruits. Another advantage is that no liquid waste disposal is required after SBWE. Compared with organic solvents, subcritical water not only has advantages in ecology, economy, and safety, but also its density, ion product, and dielectric constant can be adjusted by temperature. These tunable properties allow subcritical water to carry out class selective extractions such as extracting polar compounds at lower temperatures and less polar ingredients at higher temperatures. SBWE can mimic the traditional herbal decoction for preparing herbal medication and with higher extraction efficiency. Since SBWE employs high-temperature and high-pressure, great caution is needed for safe operation. Another challenge for application of SBWE is potential organic degradation under high temperature conditions. We highly recommend conducting analyte stability checks when carrying out SBWE. For analytes with poor SBWE efficiency, a small number of organic modifiers such as ethanol, surfactants, or ionic liquids may be added.

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.

Study on the Relationship between Emulsion Properties and Interfacial Rheology of Sugar Beet Pectin Modified by Different Enzymes

The contribution of rheological properties and viscoelasticity of the interfacial adsorbed layer to the emulsification mechanism of enzymatic modified sugar beet pectin (SBP) was studied. The component content of each enzymatic modified pectin was lower than that of untreated SBP. Protein and ferulic acid decreased from 5.52% and 1.08% to 0.54% and 0.13%, respectively, resulting in a decrease in thermal stability, apparent viscosity, and molecular weight (Mw). The dynamic interfacial rheological properties showed that the interfacial pressure and modulus (E) decreased significantly with the decrease of functional groups (especially proteins), which also led to the bimodal distribution of particle size. These results indicated that the superior emulsification property of SBP is mainly determined by proteins, followed by ferulic acid, and the existence of other functional groups also promotes the emulsification property of SBP.

Valorization of Bio-Residues from the Processing of Main Portuguese Fruit Crops: From Discarded Waste to Health Promoting Compounds

Food processing generates a large amount of bio-residues, which have become the focus of different studies aimed at valorizing this low-cost source of bioactive compounds. High fruit consumption is associated with beneficial health effects and, therefore, bio-waste and its constituents arouse therapeutic interest. The present work focuses on the main Portuguese fruit crops and revises (i) the chemical constituents of apple, orange, and pear pomace as potential sources of functional/bioactive compounds; (ii) the bioactive evidence and potential therapeutic use of bio-waste generated in the processing of the main Portuguese fruit crops; and (iii) potential applications in the food, nutraceutical, pharmaceutical, and cosmetics industries. The current evidence of the effect of these bio-residues as antioxidant, anti-inflammatory, and antimicrobial agents is also summarized. Conclusions of the revised data are that these bio-wastes hold great potential to be employed in specific nutritional and pharmaceutical applications.

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.

Physicochemical, Thermal and Rheological Properties of Pectin Extracted from Sugar Beet Pulp Using Subcritical Water Extraction Process

The objective of this study was to characterize the properties of pectin extracted from sugar beet pulp using subcritical water (SWE) as compared to conventional extraction (CE). The research involved advanced modeling using response surface methodology and optimization of operational parameters. The optimal conditions for maximum yield of pectin for SWE and CE methods were determined by the central composite design. The optimum conditions of CE were the temperature of 90 °C, time of 240 min, pH of 1, and pectin recovery yield of 20.8%. The optimal SWE conditions were liquid-to-solid (L/S) ratio of 30% (v/w) at temperature of 130 °C for 20 min, which resulted in a comparable yield of 20.7%. The effect of obtained pectins on viscoamylograph pasting and DSC thermal parameters of corn starch was evaluated. The contents of galacturonic acid, degree of methylation, acetylation, and ferulic acid content were higher in the pectin extracted by SWE, while the molecular weight was lower. Similar chemical groups were characterized by FTIR in both SWE and CE pectins. Color attributes of both pectins were similar. Solutions of pectins at lower concentrations displayed nearly Newtonian behavior. The addition of both pectins to corn starch decreased pasting and DSC gelatinization parameters, but increased ΔH. The results offered a promising scalable approach to convert the beet waste to pectin as a value-added product using SWE with improved pectin properties.

Citrus pectin modified by microfluidization and ultrasonication: Improved emulsifying and encapsulation properties

In this study, modified citrus pectin treated with a combination of microfluidization and ultrasonication was compared to the original and ultrasonication treated pectin on hydrodynamic diameter, molecular weight, polydispersity, zeta potential, apparent viscosity, Fourier-transform infrared spectroscopy (FTIR), 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging capacity, scanning electron microscope (SEM), atomic force microscopy (AFM), their emulsifying properties and encapsulation properties. Modified pectin treated with a combination of microfluidization and moderate ultrasonication (MUB) was found to have lowest hydrodynamic diameter (418 nm), molecular weight (237.69 kDa) and polydispersity (0.12), and relatively low apparent viscosity among all pectin samples. Furthermore, it showed significantly higher DPPH radical scavenging capacity than the original pectin although only slightly higher than that of ultrasonication treated one (UB). MUB showed a thin fibrous morphology and decreased degree of branching from SEM and AFM. Emulsion stabilized by MUB had highest centrifugal and thermal stability compared to emulsions stabilized by UB and the original pectin. This could be attributed to higher interfacial loading of MUB (17.90 mg/m²) forming more compact interfacial layer observed by confocal laser scanning microscopy (CLSM). Moreover, both MUB and UB exhibited improved encapsulation functionality to protect cholecalciferol (vitamin D₃) from UV degradation compared to the original pectin.

Platelet Anti-Aggregant Activity and Bioactive Compounds of Ultrasound-Assisted Extracts from Whole and Seedless Tomato Pomace

Tomato paste production generates a residue known as tomato pomace, which corresponds to peels and seeds separated during tomato processing. Currently, there is an opportunity to use tomato pomace to obtain a functional extract with antithrombotic properties, such as platelet anti-aggregant activity. The aim of this study was to evaluate the yield and inhibitory activity of different extracts of tomato pomace on in vitro platelet aggregation, comparing this activity with commercial cardioprotective products, and quantify bioactive compounds. Aqueous or ethanolic/water (1:1) extracts of whole tomato pomace, seedless tomato pomace, tomato pomace supplemented with seeds (50% and 20%), and only seeds were obtained with different ultrasound-assisted extraction times. The inhibition of platelet aggregation was evaluated using a lumi-aggregometer. The quantification of bioactive compounds was determined by HPLC-MS. From 5 g of each type of tomato pomace sample, 0.023-0.22 g of a dry extract was obtained for the platelet aggregation assay. The time of sonication and extraction solvent had a significant role in platelet anti-aggregant activity of some extracts respect the control. Thus, the most active extracts decreased adenosine diphosphate (ADP)-induced platelet aggregation from 87 ± 6% (control) to values between 26 ± 6% and 34 ± 2% (p < 0.05). Furthermore, different ultrasound-assisted extraction conditions of tomato pomace fractions had varied concentration of flavonoids and nucleosides, and had an effect on extract yield.

Functional soluble dietary fiber from ginseng residue: Polysaccharide characterization, structure, antioxidant, and enzyme inhibitory activity

Ginseng (Panax ginseng C.A. Meyer) is the most famous edible Chinese herbal medicine. In the present study, soluble dietary fiber of ginseng (ginseng-SDF, 8.98% content) was extracted from ginseng residue, and its physicochemical characterization, structure, and biological activities were studied. Ginseng-SDF was an acidic heteropolysaccharide (uronic acid, 4.42% content) rich in protein, amino acids, and mineral elements. Glucose was its main monosaccharide composition (58.03%). Ginseng-SDF had a porous microstructure, a typical cellulose I structure and a large number of hydroxyl functional groups. These chemical composition and structural characteristics gave ginseng-SDF a good water solubility (98.56%), oil-holding capacity (OHC) (3.01 g/g), and biological activities, as the antioxidant activity (13.35 μM TE/g, 105.17 μM TE/g, 54.20 μM TE/g for DPPH, ABTs, and FRAP assays, respectively), glucose diffusion retardation index (GDRI, 33.33%-7.43%), and α-amylase/α-glucosidase inhibitory activities (IC₅₀ , 6.70 mg/ml, and 4.89 mg/ml, respectively). The results suggested that ginseng residue is a valuable source of functional dietary fiber, and the ginseng-SDF has a potential use in antioxidant and hypoglycemic foods. PRACTICAL APPLICATIONS: Ginseng has long been popular as a health food in Asia, North America, and Europe. Ginseng residue is rich in polysaccharides, dietary fiber, proteins, and other components, which is also of great research value. However, there are few studies focus on the soluble dietary fiber of ginseng at present. The research shows that ginseng residue is a valuable source of functional dietary fiber. The chemical components and structural characteristics give ginseng-SDF a noteworthy antioxidant activity and enzyme inhibitory activity in vitro. These properties and biological activities indicate that ginseng-SDF has application value in antioxidant and hypoglycemic foods.

Effect of ultrasonic treatment on rheological and emulsifying properties of sugar beet pectin

The effects of ultrasonic treatment on rheological and emulsifying properties of sugar beet pectin were studied. Results indicated that intrinsic viscosity ([η]) and viscosity average molecular weight ([M v]) decreased with the increased time from 0 to 30 min but increased when the duration prolonged to 45 min. The change of apparent viscosity with shear rate of all pectin solutions could be well described by Sisko model (R 2 ≥ .996) and the infinite-rate viscosity (η ∞) and the consistency coefficient (k s) values decreased after ultrasonic treatment. Ultrasonic treatment could have an effect on dynamic moduli and activation energy of sugar beet pectin solutions. Particle size of pectin emulsions decreased and absolute zeta potential increased with increased time from 0 to 20 min. Excessive ultrasonic duration (30 and 45 min) could result in the aggregation of oil droplets in pectin emulsion and decrease in emulsifying stability. It could be concluded that ultrasonic treatment could affect the rheological and emulsifying properties of sugar beet pectin. The results have important implications for understanding the ultrasonic modification of sugar beet pectin.

Extraction of Low Methoxyl Pectin from Fresh Sunflower Heads by Subcritical Water Extraction

Subcritical water extraction (SWE) of pectin from fresh sunflower heads was optimized using the response surface methodology (RSM). The optimal conditions for the maximum yield of pectin (6.57 ± 0.6%) were found to be a pressure of 8 bar, temperature of 120 °C, time of 20 min, and liquid-solid ratio (LSR) of 7 mL/g. The degree of esterification (DE) of pectin was analyzed by titrimetry and Fourier transform infrared (FTIR) methods, which was low methoxyl pectin. The molecular weight (M _w), galacturonic acid (GalA) content, and surface tension of pectin were 11.50 kDa, 82%, and 45.38 mN/m (1.5% w/v), respectively. Moreover, thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis confirmed that pectin had excellent thermal stability. FTIR and ¹H NMR spectra confirmed its structure. This study demonstrated that SWE could be used as a productive and environmentally friendly method for extracting pectin from fresh sunflower heads.

Extraction of Polysaccharide from Dendrobium nobile Lindl. by Subcritical Water Extraction

Subcritical water extraction (SWE) uses hot compressed water as an effective solvent for both polar and nonpolar compounds and has been developed as an environmentally benign extraction technology for natural materials. Polysaccharides as one of the main ingredients in Dendrobium plants showed obvious biological activity. Thus, SWE of polysaccharides obtained from Dendrobium nobile Lindl. was investigated in this work. The response surface methodology (RSM) was combined with a Box-Behnken design to evaluate the influence that the three independent variables had on the response. The optimal extraction conditions (determined via RSM) were 129.83 °C extraction temperature, 16.71 min extraction time, and 1.12 MPa extraction pressure. The maximum predicted polysaccharide yield was 20.67%, which corresponded well with the experiential extraction (21.88%). The polysaccharides obtained from either the stirring extraction, refluxing extraction, ultrasound extraction, or SWE methods were compared, and the extraction processes were modeled. The molecular weight, monosaccharide composition, and antioxidative activities of the polysaccharides were analyzed.