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Lignin from the Chinese quince (Chaenomeles sinensis) fruit offers a promising source of natural antioxidant for industrial applications. However, the utilization of Chinese quince fruit lignin is restricted by its inhomogeneous nature. Accordingly, Chinese quince fruit lignin was sequentially fractionated with organic solvents of increasing dissolving capacity to prepare homogeneous lignin fractions. The GPC (gel permeation chromatography) results showed that the molecular weights of lignin fractions increased from dichloromethane fraction to dioxane/water fraction. The five lignin fractions were also compared with respect to yield, carbohydrate content, thermal stability, inter-unit linkages, S/G ratios, and phenolic OH content. Among the five fractions, the ethyl acetate fraction showed a lower proportion of β-O-4′ linkages (48.4%), the highest thermal stability, the highest phenolic OH content (2.8 mmol/g), and the highest DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging index and reducing power. The high antioxidant performance of the ethyl acetate fraction implies that it can be used as a natural antioxidant. This study shows that sequential solvent fractionation of lignin can produce homogeneous fractions with enhanced antioxidant performance. In addition, it demonstrates that Chinese quince fruits are a potentially valuable natural resource.

Acetic acid at atmospheric pressure is an alternative solvent that can be used for high-efficiency separation of lignin. However, few studies reported the isolation of lignin using acetic acid at above atmospheric pressure. In this study, acetic acid solution at above atmospheric pressure was used to extract lignin from Chinese quince fruit. The influences of different extraction conditions on the lignin yields were firstly investigated. Among the five extraction parameters (extraction temperature/pressure, acetic acid concentration, extraction time, catalyst dosage, and solid/liquid ratio), catalyst dosage had the most important influence on lignin yields. Five acetic acid lignin (AAL80, AAL100, AAL120, AAL140, and AAL160) samples obtained at different extraction temperatures/pressures (80 °C–160 °C/0.03–0.35 MPa) were used to analyze the influence of extraction temperatures/pressures on their structural features. Comparing to lignins extracted with acetic acid at atmospheric pressure, lignins obtained by acetic acid extraction at above atmospheric pressures (AAL120, AAL140, and AAL160) had higher purity. The acetic acid could degrade lignin at temperatures above 120 °C. When extracted at 120 °C–160 °C, the depolymerization degree of lignins increased with rising temperatures. AAL160 with more condensed structures was the most thermally stable. As the extraction temperature rose, the proportion of β–5 linkages in lignins gradually increased, while the proportion of β–O–4 and β–β linkages decreased. AAL80 had the highest DPPH, while AAL120 showed the highest ferric reducing activity. The study clarifies the lignins isolated with acetic acid at above atmospheric pressure from Chinese quince fruits and contributes to their potential application.

Gelatinization and retrogradation characteristics of starches from tigernut (Cyperus esculentus) tuber before and after various oil extraction processes were studied in this investigation. The results indicated that starches isolated from tigernut tuber after the various oil extraction processes varied significantly in gelatinization and retrogradation properties. The starches isolated from the cakes of tigernut tuber after hot press extraction exhibited higher retrogradation tendency and relatively less shear-thinning than other starch samples. The results of FT-IR, XRD, and NMR analysis indicated that oil extraction had an unfavorable influence on starch retrogradation, which may be due to structural changes caused by oil extraction processes. In particular, oil extraction led to more efficient packing of double helices in the crystalline lamella of the starches during storage. Retrogradation of the starch gels also reduced the water holding capacities of the starches. The starch sample isolated from the cake after cold press extraction exhibited the highest water absorption capacity among the five samples for all storage times. This investigation provides valuable novel information for the industrial utilization of tigernut tuber starches isolated from meals and cakes after oil extraction.

The effects of extraction conditions on the yield of polysaccharides from the fruit of Chaenomeles sinensis (FCS) using a hot compressed water method were investigated. The results showed that an appropriately high temperature (150 °C) and a moderate extraction time (45 min) at a material to water ratio of 1 to 10 g/mL led to a high yield of alcohol precipitation polysaccharide (PA). The purified polysaccharides (CSP-1, CSP-2, and CSP-3) were successfully obtained using a DEAE-52 chromatographic column. Chemical analysis showed that CSP-2 and CSP-3 were homogenous and exhibited characteristics of esterified pectins, whereas CSP-2 mainly consisted of galacturonic acid (GalA), galactose (Gal), arabinose (Ara), rhamnose (Rha), and mannose (Man) with an average molecular weight of 59.1 kDa. Furthermore, CSP-1 possessed stronger antioxidant ability according to DPPH scavenging and reducing power compared with CSP-2 and CSP-3. However, it was weaker with respect to OH scavenging. The technical data presented in this study could help the industry make use of polysaccharides from FCS as a source of pectin for a range of pharmaceutical, culinary, and cosmetic products.

Sesame processing facilities typically discard sesame seed hulls (SH) as waste or animal feed. However, these hulls are rich in cellulose and make them potentially valuable to the food industry. This study for the first time studied the effect of subcritical water (SW) and alkali (AT) pretreatment on extraction of purified cellulose from SH. The results indicated that the yield of SWCs (cellulose obtained by subcritical water pretreatment, 9.2–11.6%) was close to that of ATC (cellulose obtained by alkali pretreatment, 10.1%). Crystallinity of SWCs (68.7–75.8%) was significantly higher than ATC (60.9%). Subcritical water pretreatments interfered more significantly than alkali with the removal of non-cellulosic components according to Fourier transform infrared spectrometry and scanning electron microscope photographs. In addition, the diameter of the SWC was smaller than ATC, and the obtained SWC was comparable to ATC in terms of thermal stability. This study shows that subcritical water, as an environmentally friendly solvent, can be used to extract good quality cellulose from SH. In addition, subcritical water is more effective than alkali, suggesting it could be used more widely in the food industry for producing cellulose from other sources.

Complete utilization of tigernut tubers, including their use in oil production and use of the meal as a byproduct, is an important aspect in improving their industrial value. However, there are few studies on the use of starch isolated from tiger tuber meals and cakes remaining after oil extraction. In this investigation, starches were isolated from tigernut tubers before and after various oil extraction processes and their structural and functional properties were comparatively investigated. A typical C-type X-ray diffraction pattern was observed for all of the isolated starches. Noticeable decreases in relative crystallinity by XRD and solid state 13C NMR were observed for starches from the cakes of tigernut tubers remaining after oil extraction utilizing a mechanical expeller. The proportion of amorphous phase (PPA) in the starches isolated from meals and cakes was relatively low compared with that of starch isolated from raw tigernut tuber. The branch-chain length distribution of the starches isolated from meals and cakes exhibited a low average chain length of amylopectin. These changes reflect a disruption in the ordered structure of starch granules caused by the various oil extraction processes, which led to significant variability in their functional properties, including paste clarity, freeze-thaw characteristics, thermal transition temperatures, texture, solubility, and swelling power. This investigation provides important information for the complete utilization of tigernut tubers.

Enzyme-assisted extraction is a powerful technology for polysaccharides from plant materials. In the present investigation, the emulsifying properties of Chinese yam polysaccharides extracted by enzyme-assisted methods were determined and compared to the properties of polysaccharide fractions isolated by conventional hot water method. The structural properties of the various polysaccharide fractions were also investigated to understand their relationships with emulsifying properties. Results showed that the polysaccharide fractions extracted by papain hydrolysis exhibited relatively better emulsifying activities and stability. According to particle size distribution and gravitational phase separation experiments, PA12 exhibited the best emulsifying capacity and stability among the various polysaccharide fractions. All of the polysaccharide fractions differed from each other with respect to monosaccharide composition, free amino acid distribution, molecular weight, and flow behavior; these differences influenced the emulsifying properties of the polysaccharide fractions. The results obtained provide important information for choosing appropriate polysaccharide-based emulsifiers for food processing and other applications.

The aim of this investigation was to characterize oils extracted from pepper seed (Capsicum annuum L.) by subcritical propane at various stages of the extraction. During the extraction, the pepper seed oil (PSO) was sampled at five different times. The various oil fractions were named: PSO-1 (0–3 min), PSO-2 (4–6 min), PSO-3 (7–9 min), PSO-4 (10–12 min), and PSO-5 (13–15 min). Results showed that 97.2% of total oil content was extracted before PSO-4. There were no significant difference in fatty acid composition between the oil samples; however, results show that extraction time did significantly affect other chemical constituents (i.e., tocopherols, sterols, and volatile flavor compounds), and thermal stability. This investigation provides important information for the application of pepper seed and for further development of subcritical fluid extraction.

Proanthocyanidins (PAs) are polyphenols that are widely distributed in various parts of plants, e.g., fruits, vegetables, nuts, bark, and leaves. PAs can be divided into three classes based on their constitutive units and the linkages between them: procyanidins, prodelphinidins, and propelargonidins. Many studies have demonstrated broad biological activities of proanthocyanidins, including antioxidant, antibacterial, antiviral, anticarcinogenic, and anti-inflammatory activities. Due to their structural diversity and the related physicochemical properties, isolation, and structural analysis of proanthocyanidins are important for their application. New technologies developed during the past decade are currently used for the extraction and structural analysis of proanthocyanidins. In addition to traditional organic solvents, new solvents, such as supercritical and subcritical fluids, ionic liquids, and deep eutectic solvents are used to extract proanthocyanidins. Qualitative and quantitative analysis of proanthocyanidins is a particularly interesting area of research. Several novel analysis methods, such as ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), two-dimensional (2D) NMR, matrix-assisted laser desorption/ionization (MALDI), and Fourier transform ion cyclotron resonance mass spectrometry (FT–ICR–MS) are used for identifying proanthocyanidins. In this chapter, recent advances in the extraction, purification, and structural elucidation of proanthocyanidins are reviewed.

This was the first study to compare the key aroma-active compounds that contributed to the different aroma profiles between roasted and cold-pressed sesame oils. Aroma compounds were extracted by headspace solid-phase micro-extraction (HS-SPME) and simultaneous distillation extraction (SDE) and were analysed using gas chromatography–olfactometry-mass spectrometry (GC-O-MS) and aroma extract dilution analysis (AEDA). The numbers of aroma-active compounds with the flavour dilution (FD) factors between 1 and 2048 were 57 and 16 in the roasted and cold-pressed sesame oils, respectively. A total of 28 volatile compounds were identified as aroma-active compounds in sesame oils for the first time. Important aroma compounds (FD ≥ 8) were quantified by the external standard method, and their odour activity values (OAV) were calculated as the ratio of their concentrations to odour thresholds in oil. The numbers of key aroma-active compounds defined by OAVs ≥ 1 were 23 (OAVs = 1–385) and 8 (OAVs = 1–42), respectively, in the roasted and cold-pressed sesame oils. 2-Methoxy-4-vinylphenol (smoked, 1924 µg/kg, OAV = 385), 2-methoxyphenol (smoked, 1488 µg/kg, OAV = 114) and pyrazines (roasted and nutty, 578–22750 µg/kg, OAV = 1–67) were the most important aroma-active compounds in the roasted sesame oil, whereas hexanal (green and fruity, 3094 µg/kg, OAV = 42) was the most important aroma-active compound in the cold-pressed sesame oil, followed by (E,E)-2,4-decadienal (earthy, 4170 µg/kg, OAV = 31), dimethyl sulfone (sulphur-like, 406 µg/kg, OAV = 20) and octanal (green and fruity, 901 µg/kg, OAV = 16). This study provides valuable information for manufacturers to achieve precise flavour control of sesame oil products.

In the present study, ultrasound was used to remove the residual solvent from the fragrant oil of red pepper seed obtained by subcritical propane extraction. The physical and chemical characteristics, particularly the volatile flavor compounds present of the oil before and after ultrasound-assisted desolventizing were comprehensively analyzed to determine the effect of the desolventizing process on product quality. The results showed that the maximum loss of residual solvent was achieved at a temperature of 90 °C maintained for 70 min with ultrasound applied during the entire process. After this treatment only a small amount of solvent (2.3% based on the total residual solvent originally present) remained in the oil. Although it was hypothesized that ultrasound treatment could result in the loss of volatile components, the analytical results showed no obvious reduction in the components associated with the typical aroma of the oil. After ultrasonic treatment, the oil also had good oxidation stability and quality. Additionally, after ultrasonic desolventizing, the oil samples were more suitable for cooking because they could more effectively minimize oxidation. Thus, these results demonstrate that this new ultrasonic technique is an effective and efficient method for removing the solvent remaining in fragrant oil after subcritical propane extraction.

Corn hulls were abundant and inexpensive byproducts of the corn dry or wet milling processes, but most of them were discarded as agro-wastes. The aim of this study was to extract the dietary fiber by hot-compressed water (HCW) from defatted corn hull and to determine the chemical properties. Results showed that temperature and time played critical roles in extraction efficiency; the maximal yield of dietary fiber A (DFA) extracted by HCW reached 33.0% at 150°C for 60 min. The yield of dietary fiber B (DFB) increased from 2.0% to 56.9% as the temperature increased from 110 to 180°C, while the yield of solid residue (SR) decreased from 88.7% to 27.7%. Fourier transform infrared spectroscopy (FT-IR) results demonstrated that C-H, O-H, C=O, COO- occurred in the DFA, SR and DFB. The dietary fiber polysaccharides consisted of arabinose, galactose, glucose, xylose and uronic acid.

In this study, three pretreatment processes were evaluated for their effects on the structural features and antioxidant activities of lignins extracted by the acetosolv process from the fruit of Chinese quince. The three pretreatments included dephenolization, sugar removal, and multiple processes (a combination of both dephenolization and sugar removal). The results showed that after sugar removal pretreatment, the carbohydrate content, the molecular weight and S/G value of the lignin fractions decreased. However, after dephenolization pretreatment, the carbohydrate content and the molecular weight of the lignin fractions increased. After sugar removal and dephenolization, there were increases in the temperatures corresponding to the maximal rate of decomposition (DTGmax) in all lignin fractions. The radical scavenging index of lignin after sugar removal pretreatment was higher compared to other pretreatments and no treatment. The results of these tests showed that sugar removal, as a pretreatment, enhanced lignin extraction, yielding pure and highly functional lignins. Additionally, dephenolization or multiple process were beneficial to the acquisition of macromolecular lignins. All the results provided references for the biorefinery of biomass rich in polyphenol and sugar compounds.

Chinese quince seed gum (CQSG) extracted under water-, alkali- and acid- conditions at 25, 50, and 80 °C, were evaluated in terms of yield, monosaccharide composition, molecular distribution, thermal gravimetry, emulsifying stability, rheological properties, and free radical scavenging ability. The results showed that the yield of CQSG increased to 3.9% after water extraction at 80 °C. Alkali and acid treatments promoted the conversion of neutral sugars to the uronic acid branch. Regardless of the extraction temperature, the xylose chain was the main component (35%–40%); however, a reduction was observed as the extraction temperature increased to 80 °C. All CQSG solutions extracted under these isolation conditions exhibited non-Newtonian rheological behavior. Compared to water-extracted samples, the alkali-extracted samples showed the worst thermal stability, while the acid-treated samples showed the worst emulsifying stability. This study provides theoretical support for the potential application of CQSG polysaccharides in the food and pharmaceutical industries.

Making full use of sunflower seeds, including oil and the polysaccharides extracted from the meals which oil has been extracted, is one way to enhance their industrial value. Such meals contain abundant polysaccharides; however, the application of polysaccharides isolated from sunflower remaining meals after oil extraction has not been investigated. In this study, polysaccharides were isolated by alkali from sunflower meals after different oil extraction processes, and their structural properties and antioxidant activities were compared. The results indicated that these polysaccharides displayed significant variability in monosaccharide composition and molecular weight. Differences in structural properties could result in differences in functional antioxidant properties. The polysaccharide (SPHE-1) obtained from the meals after traditional hexane extraction exhibited the best antioxidant activities, including DPPH free radical-scavenging assay and hydroxyl radical scavenging activity among all the polysaccharide fractions. The research provides valuable information for making efficient use of sunflower seeds in the food industry.

Roasting pretreatment enhances the commercial qualities of tigernut oil. Oil extraction leaves behind meal, which is a potential source of starch. For industry to use this starch, its physicochemical characteristics of starch in meals after oil extraction with different roasting temperatures must be known, but have not been reported. In this investigation, the physicochemical properties of starches extracted from tigernut tubers before and after roasting at four different temperatures were investigated. Roasting increased the number of double helices and the ratios of A chains while decreasing crystallinity. There were differences in starch structure among samples roasted at different temperatures, which induced functional differences. The increase in A chains led to a decrease of peak viscosity, and improvement in freeze-thaw stability; the destruction of molecular interactions caused a decrease in pasting temperature; damage to the crystalline structure caused the decrease in gelatinization enthalpy and transition temperatures. As for differences in rheological properties, the interference of non-starch components and molecular interactions appear to be major factors. This study provides scientific information for the complete utilization of tigernut tubers.

Polysaccharides were extracted from jujube fruit using an efficient, optimized subcritical water extraction process. A maximum crude polysaccharide yield of 7.9% was obtained at an extraction temperature of 140 °C and a time of 60 min. The crude polysaccharides extracted under these conditions were purified. Three polysaccharide fractions, ZP1, ZP2 and ZP3, were obtained and their structures were investigated. The three fractions were mainly composed of arabinose, galactose, glucose, mannose, rhamnose, and galacturonic acid. ZP3 was further investigated using methylation and NMR spectroscopy, and ZP3 comprised a main chain of (1 → 4)-α-D-GalAp, (1 → 2,4)-α-L-Rhap, with a (1 → 4,6)-α-D-Galp branch. Assays of antioxidant activity showed that ZP3 exhibited a remarkable DPPH capacity and moderate hydroxyl radical scavenging ability, suggesting that it has potential applications as a natural antioxidant in foods and pharmaceuticals.

Lignocellulosic biomass, such as corn bran, has limited accessibility to solvents during thermal-chemical processes. However, a pretreatment can help to change the characteristics of the raw material and improve the yield of the polysaccharides. A twin-screw extrusion pretreatment was developed to enhance the polysaccharide yield and decrease the optimum temperature and time during the hydrothermal treatment of corn bran. The effects of temperature and time on the polysaccharide yield were investigated during the hydrothermal treatment with pretreated and unpretreated corn bran. All samples were comparatively analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis to investigate the changes in the chemical and physical characteristics. The results showed that the twin-screw extrusion pretreatment changed the main physical structure and thermochemical behavior of corn bran, which confirmed that it could enhance the polysaccharide yield and decrease the optimum treatment temperature and reduce the process duration. The pretreatment and the hydrothermal treatment temperature also had a synergetic effect on extraction yield and the composition of polysaccharide fractions of corn bran compared to the unpretreated sample. This study contributes to the knowledge improvement of corn bran pretreatments, which can be used for the efficient production of polysaccharides.

Chinese quince seed (CQS) is an underutilized oil source and a potential source of unsaturated fatty acids and α-tocopherol-rich oil. Subcritical fluid (SCF) extraction is executed at lower pressures and temperatures than the pressures and temperatures used in supercritical fluid extraction. However, no studies on the SCF extraction of CQS oil are reported. Therefore, the objective of this study was to evaluate the use of SCF for the extraction of CQS oil and to compare the use of SCF with the classical Soxhlet (CS) and supercritical CO₂ (SC-CO₂) extraction methods. Response surface methodology (RSM) was used to investigate the extraction conditions: temperature (45-65 °C), time (30-50 min), and solvent/solid ratio (5-15 mL/g). The optimization results showed that the highest yield (27.78%) was obtained at 56.18 °C, 40.20 min, and 12.57 mL/g. The oil extracted by SCF had a higher unsaturated fatty acid content (86.37%-86.75%), higher α-tocopherol content (576.0-847.6 mg/kg), lower acid value (3.97 mg/g), and lower peroxide value (0.02 meq O₂/kg) than extractions using CS and SC-CO2 methods. The SCF-defatted meal of oilseed exhibited the highest nitrogen solubility index (49.64%) and protein dispersibility index (50.80%), demonstrating that SCF extraction was a promising and efficient technique as an alternative to CS and SC-CO2 methods, as very mild operating conditions and an eco-friendly solvent can be used in the process with maximum preservation of the quality of the meal.

In this study, the subcritical butane extraction process of fenugreek seed oil was optimized using response surface methodology with a Box-Behnken design. The optimum conditions for extracted oil from fenugreek seed was as follows: extraction temperature of 43.24 °C , extraction time of 32.80 min, and particle size of 0.26 mm. No significant differences were found between the experimental and predicted values. The physical and chemical properties of the oil showed that the oil could be used as edible oil. Fatty acid composition of oils obtained by subcritical butane under the optimum conditions and by accelerated solvent extraction showed negligible difference. The oils were rich in linoleic acid (42.71%-42.80%), linolenic acid (26.03%-26.15%), and oleic acid (14.24%-14.40%). The results revealed that the proposed method was feasible, and this essay shows the way to exploit fenugreek seeds by subcritical butane extraction under the scope of edible oils.