Differences in physicochemical properties of pectin extracted from pomelo peel with different extraction techniques.

In order to obtain high yield pomelo peel pectin with better physicochemical properties, four pectin extraction methods, including hot acid extraction (HAE), microwave-assisted extraction (MAE), ultrasound-assisted extraction, and enzymatic assisted extraction (EAE) were compared. MAE led to the highest pectin yield (20.43%), and the lowest pectin recovery was found for EAE (11.94%). The physicochemical properties of pomelo peel pectin obtained by different methods were also significantly different. Pectin samples obtained by MAE had the highest methoxyl content (8.35%), galacturonic acid content (71.36%), and showed a higher apparent viscosity, thermal and emulsion stability. The pectin extracted by EAE showed the highest total phenolic content (12.86%) and lowest particle size (843.69 nm), showing higher DPPH and ABTS scavenging activities than other extract methods. The pectin extracted by HAE had the highest particle size (966.12 nm) and degree of esterification (55.67%). However, Fourier-transform infrared spectroscopy showed that no significant difference occurred among the different methods in the chemical structure of the extracted pectin. This study provides a theoretical basis for the industrial production of pomelo peel pectin.

Ultrasonic-assisted extraction to enhance the recovery of bioactive phenolic compounds from Commiphora gileadensis leaves.

The "ultrasonic-assisted extraction (UAE)" method was utilized in this work to assess how different process parameters affected the yield and recovery of phenolic compounds from the leaf of Commiphora gileadensis, which is one of the medicinal plants with a variety of biological functions. Its leaf is used for a various of therapeutic applications, such as the treatment of bacterial infections, inflammation, and wound healing. The "One-Factor-At-a-Time (OFAT)" approach was employed to examine the impacts of various UAE process parameters on the process of extraction, which include time of extraction, sample/solvent ratio, ultrasonic frequency, and solvent (ethanol) concentration. The extracts were then investigated for the presence of several phytochemicals using analytical techniques such as "Gas Chromatography-Mass Spectroscopy (GC-MS)" and "Fourier Transform Infrared Spectroscopy (FTIR)" studies. The findings showed that the maximum extraction yield, the total phenolic content (TPC), and the total flavonoids content (TFC) of the ethanolic extract of the leaves of C. gileadensis using the UAE method were at 31.80 ± 0.41 %, 96.55 ± 2.81 mg GAE/g d.w. and 31.66 ± 2.01 mg QE/g d.w. accordingly under a procedure duration of 15 min, ultrasonic frequency of 20 kHz, solvent/sample ratio of 1:20 g/mL, and solvent concentration of 40 % v/v. The leaves extract of C. gileadensis included 25 phenolic compounds that were previously unreported, and GC-MS analysis confirmed their presence. Hence, it follows that the UAE technique can successfully extract the phytochemicals from C. gileadensis for a variety of therapeutic uses.

Sustainable green extraction of anthocyanins and carotenoids using deep eutectic solvents (DES): A review of recent developments.

Recently, deep eutectic solvents (DES) have been extensively researched as a more biocompatible and efficient alternative to conventional solvents for extracting pigments from natural resources. The efficiency of DES extraction for the anthocyanin and carotenoid can be enhanced by microwave-assisted extraction (MAE) and/or ultrasound-assisted extraction (UAE) techniques. Apart from the extraction efficiency, the toxicity and recovery of the pigments and their bioavailability are crucial for potential applications. A plethora of studies have explored the extraction efficiency, toxicity, and recovery of pigments from various natural plant-based matrices using DES. Nevertheless, a detailed review of the deep eutectic solvent extraction of natural pigments has not been reported to date. Additionally, the toxicity, safety, and bioavailability of the extracted pigments, and their potential applications are not thoroughly documented. Therefore, this review is designed to understand the aforementioned concepts in using DES for anthocyanin and carotenoid extraction.

Fibrillization of lentil proteins is impacted by the protein extraction conditions and co-extracted phenolics.

Legume proteins can be induced to form amyloid-like fibrils upon heating at low pH, with the exact conditions greatly impacting the fibril characteristics. The protein extraction method may also impact the resulting fibrils, although this effect has not been carefully examined. Here, the fibrillization of lentil protein prepared using various extraction methods and the corresponding fibril morphology were characterized. It was found that an acidic, rather than alkaline, protein extraction method was better suited for producing homogeneous, long, and straight fibrils from lentil proteins. During alkaline extraction, co-extracted phenolic compounds bound proteins through covalent and non-covalent interactions, contributing to the formation of heterogeneous, curly, and tangled fibrils. Recombination of isolated phenolics and proteins (from acidic extracts) at alkaline pH resulted in a distinct morphology, implicating a role for polyphenol oxidase also in modifying proteins during alkaline extraction. These results help disentangle the complex factors affecting legume protein fibrillization.

Ultrasonic-assisted extraction of grape seed procyanidins, preparation of liposomes, and evaluation of their antioxidant capacity.

The residue remaining after oil extraction from grape seed contain abundant procyanidins. An ultrasonic-assisted enzyme method was performed to achieve a high extraction efficiency of procyanidins when the optimal extraction conditions were 8 U/g of cellulase, ultrasound power of 200 W, ultrasonic temperature of 50 ℃, and ultrasonic reaction time of 40 min. The effects of free procyanidins on both radical scavenging activity and thermal stability at 40, 60, and 80 ℃ of the procyanidins-loaded liposomal systems prepared by the ultrasonic-assisted method were discussed. The presence of procyanidins at concentrations ranging from 0.02 to 0.10 mg/mL was observed to be effective at inhibiting lipid oxidation by 15.15 % to 69.70 % in a linoleic acid model system during reaction for 168 h, as measured using the ferric thiocyanate method. The procyanidins-loaded liposomal systems prepared by the ultrasonic-assisted method were characterized by measuring the mean particle size and encapsulation efficiency. Moreover, the holographic plots showed that the effect-response points of procyanidins combined with α-tocopherol in liposomes were lower than the addition line and 95 % confidence interval limits. At the same time, there were significant differences between the theoretical IC50add value and the experimental IC50mix value. The interaction index (γ) of all combinations was observed to be less than 1. These results indicated that there was a synergistic antioxidant effect between procyanidins combined with α-tocopherol, which will show promising prospects in practical applications. In addition, particle size differentiation and morphology agglomeration were observed at different time points of antioxidant activity determination (0, 48, 96 h).

Response surface methodology as a tool to optimize the extraction of bioactive compounds from plant sources.

Response surface methodology (RSM) is a widely used mathematical and statistical technique for modeling and optimizing the process for the extraction of bioactive compounds. This review explains the optimization approach through the use of experimental design and empirical models for response prediction and the utilization of the desirability function for multiple response optimization. This paper also reviews recent studies on the application of RSM to optimize bioactive compound extraction processes such as conventional solvent extraction, microwave-assisted extraction, supercritical fluid extraction, and ultrasound-assisted extraction. Finally, the challenges associated with the use of RSM and the efforts made to improve RSM in the extraction process are also highlighted. Overall, this review informs many aspects of RSM that are occasionally ignored or insufficiently discussed with regard to the optimization of bioactive compound extraction processes, and it summarizes significant applications where RSM proved suitable. © 2022 Society of Chemical Industry.

Cloud point extraction assisted spectrophotometric quantification of trace boron impurity in uranium-based nuclear fuels.

The separation of boron in nuclear fuels by cloud point extraction (CPE) has been a challenge due to high acidity of digested sample solutions. High acidity hampers the coacervation of micelles. As a result, the cloud point temperature increases and thus could cause the inevitable loss of boron as volatile species. Herein we have proposed a novel CPE-assisted colorimetric method for the quantification of traces of boron (B) in uranium-based fuels. A 1:1 mixture of 2-ethyl hexane-1,3-diol (EHD) and curcumin dispersed in Triton X-114 surfactant was used in the proposed CPE process. We had investigated several compounds to act as micelle surface modifiers. Among them, only bromine water (Br2) was found not only to lower the cloud point temperature (CPT, from 80 °C to 42 ± 2 °C) but also resulted in the quantitative recovery of boron (≥95%). The CPE of boron from uranium matrix in a 2.0 mol L-1 HCl medium was suitable for direct chemical quality assurance of routine uranium-based fuels. The molar extinction coefficient of the boron-EHD-curcumin complex was found to be 4.75 × 105 L mol-1 cm-1 (λmax at 458 nm) in N,N-dimethyl formamide medium. The linear dynamic range and detection limit of the proposed analytical procedure were calculated to be 10-150 ng mL-1 and 0.8 ng mL-1 respectively. The proposed analytical methodology was validated by analysis of three in-house working reference materials of uranium. Determination of traces of boron in two uranium dioxide and two metallic uranium samples were found to demonstrate the applicability of the method. The relative standard deviation of the proposed method was found to be of 3-5%.

Microwave-Assisted Extraction of Anticancer Flavonoid, 2',4'-Dihydroxy-6'-methoxy-3',5'-dimethyl Chalcone (DMC), Rich Extract from Syzygium nervosum Fruits.

2',4'-Dihydroxy-6'-methoxy-3',5'-dimethyl chalcone (DMC) is a biological flavonoid that is present in the fruits of Syzygium nervosum (Ma-Kiang in Thai). Microwave-assisted extraction (MAE), which utilizes microwave radiation to heat the extraction solvent quickly and effectively, was used to recover DMC-rich extract from Syzygium nervosum fruit. To determine the DMC content, a highly accurate and precise HPLC technique was developed. The influences of MAE conditions, including the solid-liquid ratio, microwave power, and microwave duration on the content of DMC, were sequentially employed by a single factor investigation and response surface methodology (RSM) exploratory design. The predicted quadratic models were fitted due to their highly significant (p < 0.0001) and excellent determination coefficient (R2 = 0.9944). The optimal conditions for producing DMC-rich extract were a ratio of sample to solvent of 1:35 g/mL, a microwave power of 350 W, and a microwave time of 38 min. Under the optimal MAE setting, the DMC content reached 1409 ± 24 µg/g dry sample, which was greater than that of the conventional heat reflux extraction (HRE) (1337 ± 37 µg/g dry sample) and maceration (1225 ± 81 µg/g dry sample). The DMC-rich extract obtained from MAE showed stronger anticancer activities against A549 (human lung cancer cells) and HepG2 (human liver cancer cells) than the individual DMC substance, which makes MAE an effective method for extracting essential phytochemicals from plants in the nature.

A Comprehensive Review on the Techniques for Extraction of Bioactive Compounds from Medicinal Cannabis.

Cannabis is well-known for its numerous therapeutic activities, as demonstrated in pre-clinical and clinical studies primarily due to its bioactive compounds. The Cannabis industry is rapidly growing; therefore, product development and extraction methods have become crucial aspects of Cannabis research. The evaluation of the current extraction methods implemented in the Cannabis industry and scientific literature to produce consistent, reliable, and potent medicinal Cannabis extracts is prudent. Furthermore, these processes must be subjected to higher levels of scientific stringency, as Cannabis has been increasingly used for various ailments, and the Cannabis industry is receiving acceptance in different countries. We comprehensively analysed the current literature and drew a critical summary of the extraction methods implemented thus far to recover bioactive compounds from medicinal Cannabis. Moreover, this review outlines the major bioactive compounds in Cannabis, discusses critical factors affecting extraction yields, and proposes future considerations for the effective extraction of bioactive compounds from Cannabis. Overall, research on medicinal marijuana is limited, with most reports on the industrial hemp variety of Cannabis or pure isolates. We also propose the development of sustainable Cannabis extraction methods through the implementation of mathematical prediction models in future studies.

Development of Ultrasound-Assisted Extraction to Produce Skin-Whitening and Anti-Wrinkle Substances from Safflower Seed.

In this study, ultrasound-assisted extraction (UAE) was applied to extract bioactive substances with skin-whitening, anti-wrinkle, and antioxidant effects from safflower seeds, and the extraction conditions were optimized by a central composite design. The independent variables, including extraction time (5.0~55.0 min), extraction temperature (26.0~94.0 °C), and ethanol concentration (0.0~100%), were optimized to increase tyrosinase activity inhibitory (TAI), collagenase activity inhibitory (CAI), and radical scavenging activity (RSA), which are indicators of skin-whitening, anti-wrinkle, and antioxidant effects. An extraction time of 26.4 min, extraction temperature of 52.1 °C, and ethanol concentration of 50.7% were found to be optimum conditions of UAE, under which TAI, CAI, and RSA were 53.3%, 91.5%, and 27.7%, respectively. The extract produced by UAE was analyzed by LC-MS/MS, and maleic acid and levulinic acid were identified as the main substances. Therefore, UAE is evaluated as an effective process to extract skin-whitening, anti-wrinkle, and antioxidant substances from safflower seeds at lower temperatures and shorter extraction times compared to the conventional extraction methods. Overall, safflower seeds extract can be used as a material for value-added cosmetics, including maleic acid and levulinic acid, which have bioactive functions.

In Vivo Anti-Inflammatory Effect, Antioxidant Activity, and Polyphenolic Content of Extracts from Capsicum chinense By-Products.

By-products of Capsicum chinense Jacq., var Jaguar could be a source of bioactive compounds. Therefore, we evaluated the anti-inflammatory effect, antioxidant activity, and their relationship with the polyphenol content of extracts of habanero pepper by-products obtained from plants grown on black or red soils of Yucatán, Mexico. Moreover, the impact of the type of extraction on their activities was evaluated. The dry by-product extracts were obtained by maceration (ME), Soxhlet (SOX), and supercritical fluid extraction (SFE). Afterward, the in vivo anti-inflammatory effect (TPA-induced ear inflammation) and the in vitro antioxidant activity (ABTS) were evaluated. Finally, the polyphenolic content was quantified by Ultra-Performance Liquid Chromatography (UPLC), and its correlation with both bioactivities was analyzed. The results showed that the SFE extract of stems of plants grown on red soil yielded the highest anti-inflammatory effect (66.1 ± 3.1%), while the extracts obtained by ME and SOX had the highest antioxidant activity (2.80 ± 0.0052 mM Trolox equivalent) and polyphenol content (3280 ± 15.59 mg·100 g-1 dry basis), respectively. A negative correlation between the anti-inflammatory effect, the antioxidant activity, and the polyphenolic content was found. Overall, the present study proposed C. chinense by-products as a valuable source of compounds with anti-inflammatory effect and antioxidant activity.

Polarity Directed Appraisal of Pharmacological Potential and HPLC-DAD Based Phytochemical Profiling of Polygonum glabrum Willd.

The present study was designed to evaluate polarity-dependent extraction efficiency and pharmacological profiling of Polygonum glabrum Willd. Crude extracts of leaves, roots, stems, and seeds, prepared from solvents of varying polarities, were subjected to phytochemical, antioxidant, antibacterial, antifungal, antidiabetic, and cytotoxicity assays. Maximum extraction yield (20.0% w/w) was observed in the case of an acetone:methanol (AC:M) root extract. Distilled water:methanol (W:M) leaves extract showed maximum phenolic contents. Maximum flavonoid content and free radical scavenging potential were found in methanolic (M) seed extract. HPLC-DAD quantification displayed the manifestation of substantial quantities of quercetin, rutin, gallic acid, quercetin, catechin, and kaempferol in various extracts. The highest ascorbic acid equivalent total antioxidant capacity and reducing power potential was found in distilled water roots and W:M leaf extracts, respectively. Chloroform (C) seeds extract produced a maximum zone of inhibition against Salmonella typhimurium. Promising protein kinase inhibition and antifungal activity against Mucor sp. were demonstrated by C leaf extract. AC:M leaves extract exhibited significant cytotoxic capability against brine shrimp larvae and α-amylase inhibition. Present results suggest that the nature of pharmacological responses depends upon the polarity of extraction solvents and parts of the plant used. P. glabrum can be considered as a potential candidate for the isolation of bioactive compounds with profound therapeutic importance.

Response Surface Methodology (RSM)-Based Optimization of Ultrasound-Assisted Extraction of Sennoside A, Sennoside B, Aloe-Emodin, Emodin, and Chrysophanol from Senna alexandrina (Aerial Parts): HPLC-UV and Antioxidant Analysis.

In this study, ultrasound-assisted extraction conditions were optimized to maximize the yields of sennoside A, sennoside B, aloe-emodin, emodin, and chrysophanol from S. alexandrina (aerial parts). The three UAE factors, extraction temperature (S1), extraction time (S2), and liquid to solid ratio (S3), were optimized using response surface methodology (RSM). A Box-Behnken design was used for experimental design and phytoconstituent analysis was performed using high-performance liquid chromatography-UV. The optimal extraction conditions were found to be a 64.2 °C extraction temperature, 52.1 min extraction time, and 25.2 mL/g liquid to solid ratio. The experimental values of sennoside A, sennoside B, aloe-emodin, emodin, and chrysophanol (2.237, 12.792, 2.457, 0.261, and 1.529%, respectively) agreed with those predicted (2.152, 12.031, 2.331, 0.214, and 1.411%, respectively) by RSM models, thus demonstrating the appropriateness of the model used and the accomplishment of RSM in optimizing the extraction conditions. Excellent antioxidant properties were exhibited by S. alexandrina methanol extract obtained using the optimized extraction conditions with a DPPH assay (IC50 = 59.7 ± 1.93, µg/mL) and ABTS method (47.2 ± 1.40, µg/mL) compared to standard ascorbic acid.

Comparison of water- and alkali-extracted polysaccharides from Fuzhuan brick tea and their immunomodulatory effects in vitro and in vivo.

In the present study, the purpose is to compare the effect of water extraction and alkali-assisted extraction on the structural characteristics and immunomodulatory activity of polysaccharides from Fuzhuan brick tea (FBTPs). The results indicated that water-extracted FBTPs (W-FBTPs) and alkali-extracted FBTPs (A-FBTPs) had similar molecular weights but different monosaccharide compositions, of which A-FBTPs had a higher yield and uronic acid groups corresponding to galacturonic acid (GalA). Moreover, A-FBTPs had stronger ability to promote phagocytic capacity, acid phosphatase activity and nitric oxide (NO) secretion in macrophages in vitro. In the in vivo study, A-FBTPs exhibited a promising effect to adjust the immune imbalance by enhancing the body features, antioxidant activities, immune response and intestinal mucosal barrier in cytoxan (CTX)-induced immunosuppressive mice. Besides, A-FBTP supplementation effectively improved CTX-induced gut microbiota dysbiosis, including promoting the abundance of beneficial bacteria (e.g., Lactobacillus) and short chain fatty acid (SCFA)-producing bacteria (e.g., Lachnospiraceae, Prevotellaceae and Ruminococcaceae), along with reducing the growth of potentially pathogenic microbes (e.g., Desulfovibrionaceae and Helicobacter). These findings suggested that alkaline extraction might be a promising way to obtain high-quality acidic polysaccharides from Fuzhuan brick tea (FBT), and A-FBTPs could be developed as novel potential prebiotics and immunomodulators for further application in food formulations.

Clove Essential Oil (Syzygium aromaticum L. Myrtaceae): Extraction, Chemical Composition, Food Applications, and Essential Bioactivity for Human Health.

Clove (Syzygium aromaticum L. Myrtaceae) is an aromatic plant widely cultivated in tropical and subtropical countries, rich in volatile compounds and antioxidants such as eugenol, ß-caryophyllene, and α-humulene. Clove essential oil has received considerable interest due to its wide application in the perfume, cosmetic, health, medical, flavoring, and food industries. Clove essential oil has biological activity relevant to human health, including antimicrobial, antioxidant, and insecticidal activity. The impacts of the extraction method (hydrodistillation, steam distillation, ultrasound-assisted extraction, microwave-assisted extraction, cold pressing, and supercritical fluid extraction) on the concentration of the main volatile compounds in clove essential oil and organic clove extracts are shown. Eugenol is the major compound, accounting for at least 50%. The remaining 10-40% consists of eugenyl acetate, ß-caryophyllene, and α-humulene. The main biological activities reported are summarized. Furthermore, the main applications in clove essential oil in the food industry are presented. This review presents new biological applications beneficial for human health, such as anti-inflammatory, analgesic, anesthetic, antinociceptive, and anticancer activity. This review aims to describe the effects of different methods of extracting clove essential oil on its chemical composition and food applications and the biological activities of interest to human health.

Bioactive Compounds of Opuntia spp. Acid Fruits: Micro and Nano-Emulsified Extracts and Applications in Nutraceutical Foods.

The acid fruit of the "xoconostle" cactus belongs to the genus Opuntia family of cacti. It is used as a functional food for its bioactive compounds. Several studies reported that xoconostle fruits have a high amount of ascorbic acid, betalains, phenols, tannins, and flavonoids. These compounds confer antioxidant, antibacterial, anti-inflammatory, and hepatoprotective gastroprotective activity. Xoconostle fruit extracts were tested by in vitro assays where the digestion conditions were simulated to measure their stability. At the same time, the extracts were protected by encapsulation (microencapsulation, multiple emulsions, and nanoemulsions). Applications of encapsulated extracts were probed in various food matrices (edible films, meat products, dairy, and fruit coatings). The xoconostle is a natural source of nutraceutical compounds, and the use of this fruit in the new food could help improve consumers' health.

Flash extraction of the active constituents and its antitumor activity from rehmanniae radix, achyranthes bidentatae radix, dioscoreae rhizoma and chrysanthemi flos.

In this study, we applied the Flash extraction (FE) for the first time to the extraction of active ingredients of Sidahuaiyao (including Rehmanniae Radix, Achyranthes Bidentatae Radix, Dioscoreae Rhizoma, and Chrysanthemi Flos), and the content of active ingredients (catalpinoside, ecdysterone, chlorogenic acid and diosgenin) was determined by HPLC, and compared with Soxhlet extraction (SE) and ultrasonic extraction (UE). The results show that under the same solvent ratio, FE is used to extract the largest amount of different active ingredients. Compared with SE and UE, the extraction amount increases by 20.8% -92%. It is demonstrated for the first time that using FE to extract the active ingredients from Sidahuaiyao produced the highest extraction efficiency. In addition, we evaluated the anticancer activities of the main components. Three cancer cells and one normal cells were used to detect the anti-proliferative activity by MTT assay. The results showed that diosgenin had the strongest inhibitory effect on MCF-7 cells with IC50 value of 19.28±0.36µM. In short, we optimized the extraction process of Sidahuaiyao, and evaluated the anti-cancer activity of the main components, which provided a scientific theoretical basis for the application of Sidahuaiyao.

Characterization of lignin extracted from Acanthopanax senticosus residue using different methods on UV-resistant behavior.

Acanthopanax senticosus has been used to extract active products. However, abundant Acanthopanax senticosus residues (ASR), which contain plenty of lignin are discarded after extraction. An appropriate extraction method should be chosen to obtain the lignin with such desirable properties. Thus, this study investigated the effect of alkali, milled wood, deep eutectic solvent and ethanol methods on the lignin. Lignin obtained from different extraction methods were characterized, yields, chemical structure, thermal behavior, molecular weight and phenolic content were evaluated. The results show that the process of lignin acquisition has a great influence on the properties of lignin. Moreover, the multifarious functional groups exist in lignin macromolecules, such as phenolic, ether groups and other chromophores, conferred good UV resistance to lignin. Among them, the lignin from alkali method has the most phenolic-OH groups and smallest molecular weight result in a good UV-resistant, the SPF value achieves 2.39 at 1% AL content, the alkali method was the best way to make sunscreen blended with cream take various factors into consideration. This study used lignin as a bioactive ingredient to provide UV-resistant property to sunscreen formulations. Furthermore, lignin extracted from Acanthopanax senticosus residue provides a new application for the treatment of herb residue waste.

Bioactive Compounds from Ephedra fragilis: Extraction Optimization, Chemical Characterization, Antioxidant and AntiGlycation Activities.

Response surface methodology (RSM) with a Box-Behnken design (BBD) was used to optimize the extraction of bioactive compounds from Ephedra fragilis. The results suggested that extraction with 61.93% ethanol at 44.43 °C for 15.84 h was the best solution for this combination of variables. The crude ethanol extract (CEE) obtained under optimum extraction conditions was sequentially fractionated with solvents of increasing polarity. The content of total phenolic (TP) and total flavonoid (TF) as well as the antioxidant and antiglycation activities were measured. The phytochemical fingerprint profile of the fraction with the highest activity was characterized by using RP-HPLC. The ethyl acetate fraction (EAF) had the highest TP and TF contents and exhibited the most potent antioxidant and antiglycation activities. The Pearson correlation analysis results showed that TP and TF contents were highly significantly correlated with the antioxidant and antiglycation activities. Totally, six compounds were identified in the EAF of E. fragilis, including four phenolic acids and two flavonoids. Additionally, molecular docking analysis also showed the possible connection between identified bioactive compounds and their mechanisms of action. Our results suggest new evidence on the antioxidant and antiglycation activities of E. fragilis bioactive compounds that may be applied in the treatment and prevention of aging and glycation-associated complications.

Enzymatic extraction of pectic oligosaccharides from finger citron (Citrus medica L. var. sarcodactylis Swingle) pomace with antioxidant potential.

Finger citron pomace is a cheap and renewable by-product of the citrus processing industry, representing up to 60% of the fruit biomass. In this study, a pectinase-based and ultrasonic-assisted method was firstly used to extract pectic oligosaccharides (POS) from finger citron pomace. Using the orthogonal experiment design (OED), the maximum conversion rate of up to 64.5% from pomace to POS was obtained under the extraction conditions of 0.25 mg mL-1 pectinase and 50 mg mL-1 pectin at 45 °C and pH 4.5 for 2 h. The extracted POS was then fractionated and purified to homogeneous oligosaccharides (FCPOS-1) with a molecular weight of 2.15 kDa, and the analyses of monosaccharide composition, FTIR, NMR and ESI-MS indicated that FCPOS-1 consisted of GalA and a small amount of mannose, galactose and arabinose. Multiple antioxidant activity assays in vitro revealed that FCPOS-1 possessed remarkable antioxidant properties, especially scavenging activity against DPPH radicals up to 94.07%. FCPOS-1 has the potential to be an effective natural antioxidant for applications in the food and pharmaceutical industries.