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Chinese quince is one kind of crop that has edibility and historical medical applications. However, the high amount of lignin makes processing Chinese quince fruit difficult; on the other hand, this lignin represents a valuable resource if a way of using it in industrial applications could be found. In this study, the structural features and antioxidant activities of Brauns native lignin (BNL) isolated from Chinese quince fruit after oven drying (60 °C, 75 °C, and 90 °C), sun drying, freeze-drying, and subcritical dimethyl ether drying were assessed. The BNL samples had low molecular weights (Mw, 2604–5511 g/mol), high carbohydrate content (6.10–9.95 %), and high phenolic OH content (1.76–2.29 mmol/g). NMR spectra showed that the BNL is of the SGH-type with the relative content of p-hydroxyphenyl units ranging from 13 to 21 %. Oven drying (90 °C) reduced the carbohydrate content and increased the phenolic hydroxyl content. Freeze-drying reduced the relative content of β-O-4′ linkages and increased the H-unit content. In terms of antioxidant activities, all samples possessed high DPPH free radical scavenging capacity (IC50, 0.12−0.22 mg/mL) and strong reducing power. These results indicate that BNL extracted from Chinese quince fruit is a promising source of natural antioxidant and biomass material.

This article reports a study of the degradation of roasted sesame hulls cellulosic polysaccharides contribution to the Maillard and caramelization reaction. In the present study, cellulosic polysaccharides were extracted from sesame hulls before and after roasting at various temperatures (160, 180, 200, and 220 °C). The structural vari-ations of the cellulosic polysaccharides were elucidated by using the techniques: scanning electron microscope (SEM), high-performance anion-exchange chromatography, Fourier transform (FT-IR) spectrometer, carbon-13 nuclear magnetic resonance (CP/MAS 13C-NMR), and thermal gravimetric analysis. The pyrolysisgas chromatography-mass spectrometry (Py-GC/MS) characterized and verified the chemical composition obtained from the polysaccharide degradation during roasting. The sugar analysis results showed that galacturonic acid, xylose, and rhamnose were more easily degraded than arabinose, galactose, glucose, and mannose. The morphology of the cellulosic polysaccharides shows irregular dispersed globular fragments after roasting by SEM observation. FT-IR and CP/MAS 13C-NMR spectra indicated the crystalline structure and linkages of the cellulose did not break down in comparison to amorphous cellulose that partly degraded. Abundant acetic acid and 3-furaldehyde were among the polysaccharide degradation products identified by Py-GC/MS. These chemical compounds were likely the significant contributors to caramelization and the Maillard reaction in sesame seed roasting.

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.

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.

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.

Few investigations have been made to apply thermal analysis methods on solid residue analysis to understand biomass liquefaction mechanistic information. To investigate the mechanism of cornstalk liquefaction in water/ethanol mixtures, the solid residues remaining after the liquefaction process were characterized by thermogravimetric analysis (TGA) and analytical pyrolysis (Py-GC/MS). Pyrolysis temperature and liquefaction temperature have synergetic effects on the distributions and yields of various chemical groups during the pyrolysis process. The thermal stabilities of the solid residues remaining after the cornstalk liquefaction process increased with the increase of liquefaction temperature. Compared with raw cornstalk pyrolysis, the proportions of total phenol compounds from solid residue pyrolysis at 400 °C, 500 °C and 600 °C were reduced. The volatilized compounds identified by Py-GC/MS analysis of solid residues and cornstalks displayed significant variability in the peak area and composition distribution. These changes reflect different mechanistic information during the biomass liquefaction process. These results indicate that analytical pyrolysis of the solid residues remaining after biomass liquefaction in water/ethanol mixtures could provide new information about the mechanism of the liquefaction process.

Characterization of the rheological properties of Chinese quince seed gum (CQSG) is fundamental when using it in food production. In the present paper, the chemical compositions and the rheological properties of CQSG at different concentrations, types of salts, temperatures and pH values were characterized by using shear or dynamic rheological experiments. The results demonstrated that uronic acid content of CQSG (31.7%) was high and different concentration CQSG solutions presented Newtonian plateaus followed by shear thinning regions. The viscosities of the gum solutions decreased with the addition of any salt, with increase in temperature and at extreme pH values (3 and 11). The stress and frequency sweep tests demonstrated a unique result in that the crossover frequency shifted to a higher value when the CQSG solution concentration increased. It is the basis for CQSG product development and quality control for its potential applications.

This work focused on how roasting changed the chemical components of chili (Capsicum annuum L.) seeds and how it affected the stability of chili seed oils during storage. The oils from chili seeds before and after roasting treatments were stored at 63 °C for 30 days and then analyzed. Results showed that roasting changed the main sugars compositions and amino acid compositions (total content decreased from 15.9 to 7.4%), which confirmed that it could form brown pigments and volatile flavor compounds in pepper seeds after roasting. Compared with oil from unroasted seeds, oils from roasted seeds had greater oxidative stability and maintained greater antioxidant capacity during storage. These effects were possibly due to the synergistic of the neo-formed products by Maillard reaction, vitamin E, and other bioactive components. This investigation showed that roasting treatment could be considered as an appropriate method for extending the storage stability of chili seed oils. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s10068-019-00578-9) contains supplementary material, which is available to authorized users.

Subcritical water treatment has received considerable attention due to its cost effectiveness and environmentally friendly properties. In this investigation, Chinese quince fruits were submitted to subcritical water treatment (130, 150, and 170 &deg, C), and the influence of treatments on the structure of milled wood lignin (MWL) was evaluated. Structural properties of these lignin samples (UL, L130, L150, and L170) were investigated by high-performance anion exchange chromatography (HPAEC), FT-IR, gel permeation chromatography (GPC), TGA, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), 2D-Heteronculear Single Quantum Coherence (HSQC) -NMR, and 31P-NMR. The carbohydrate analysis showed that xylose in the samples increased significantly with higher temperature, and according to molecular weight and thermal analysis, the MWLs of the pretreated residues have higher thermal stability with increased molecular weight. The spectra of 2D-NMR and 31P-NMR demonstrated that the chemical linkages in the MWLs were mainly &beta, O-4&prime, ether bonds, &beta, 5&prime, and &beta, &beta, &prime, and the units were principally G- S- H- type with small amounts of ferulic acids, these results are consistent with the results of Py-GC/MS analysis. It is believed that understanding the structural changes in MWL caused by subcritical water treatment will contribute to understanding the mechanism of subcritical water extraction, which in turn will provide a theoretical basis for developing the technology of subcritical water extraction.

The lignin-carbohydrate complexes (LCCs) of the mesocarp (MS) and near the endocarp (NE) of Chinese quince (Chaenomeles sinensis) fruits were analyzed using three different methods of fractioning: milled wood lignin (MWL), LCC extracted from crude MWL with acetic acid (LCC-AcOH), and Bjorkman LCC. The MWL and LCC fractions were characterized by carbohydrate composition analysis, SEC, FT-IR, Py-GC/MS, thermal analysis and 2D HSQC NMR. Notably, large amounts of arabinose and galactose remained in the Björkman LCC fractions suggesting a chemical bond between the lignin and pectin. MWL and LCC-AcOH fractions showed better thermal stability than the Björkman LCC fractions. The structure of MS lignin was similar to that of NE lignin; however, fractions from the different fractionation methods revealed differences. The MWL fractions were rich in benzyl ether and γ-ester linkages, while the Björkman LCC fractions contained phenyl glycoside and γ-ester linkages, and the LCC-AcOH fractions contained phenyl glycoside and benzyl ether linkages. These findings are helpful in understanding the nature of lignin and LCC in Chinese quince fruits and provide a theoretical support for their potential application.

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 investigation, a variety of innovative pH-sensitive polymers consisting of Chinese quince seed gum (CQSG) and poly (N,N-diethylacryl amide-co-methacrylic acid) were synthesized via free radical polymerization for controlled drug delivery. The resultant hydrogel polymers were characterized by scanning electron microscopy and X-ray diffraction, analyzed by Fourier-transform infrared spectroscopy, and confirmed with thermogravimetry. Results suggested the hydrogel polymers were composed of CQSG chains physically entangled in poly (N,N-diethylacryl amide-co-methacrylic acid) networks. Swelling properties of these hydrogels were strongly affected by the contents of CQSG and crosslinkers. The drug delivery applications of the hydrogels were evaluated using bovine serum albumin (BSA) as a model drug in vitro release. It was determined that BSA release from the hydrogels was pH-sensitive under simulated gastrointestinal conditions. All of these attributes imply that the new proposed CQSG/poly (N,N-diethylacryl amide-co-methacrylic acid) hydrogel polymers can be used as a good medium for oral delivery of proteinaceous drugs.

Two-step isolation of hemicelluloses from Chinese quince fruit was carried out in this investigation. At the first treatment stage, hydrothermal treatment was developed to enhance the xylose amount in the solid residue remaining after pectin extraction. Second, the alkali-extractable hemicelluloses were isolated from the solid residue obtained from hydrothermal treatment and were successively sub-fractionated by precipitation at graded ethanol concentrations of 30%, 50%, 70% and 90%. The structural properties of the isolated hemicelluloses from raw fruits and fruits treated with the hydrothermal process were characterized by sugar analysis, FT-IR, molecular weights, thermo-gravimetric analysis, morphological analysis, and NMR. Results showed that the xylose amount in the solid residue increased from 58.2% to 62.2% when the hydrothermal treatment temperature was increased from 120 °C to 150 °C. Arabinose and mannose were found to be hydrolyzed by hydrothermal treatment, while the crystalline cellulose and lignin were not affected. Compared with the raw Chinese quince, the treatment had an important effect on the sugar composition distributions and average molecular weights of hemicelluloses obtained at various ethanol concentrations. Structural characterization revealed that the isolated hemicellulosic sub-fractions precipitated at a final ethanol concentration of 30% had a backbone of d -xylose residues with a β-(1 → 4)-linkage. This work reveals a novel hemicelluloses isolation route from Chinese quince fruit, which was important in the development of biomass refining industry. This work reveals a novel hemicelluloses isolation route from Chinese quince fruit, which was important in the development of biomass refining industry.

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.

Sesame is an industrial crop widely planted in China. Sesame capsules and stalks are by-products of sesame oil production. The production of these byproducts is large, but their utilization rate is low. As lignocellulosic biomass, sesame stalks and capsules contain plentiful amounts of lignin. In this study, the ethanol organosolv method was used to isolate lignin from black sesame capsules (BSL-1) and stalks (BSL-2), and white sesame capsules (WSL-1) and stalks (WSL-2). In order to promote full utilization of these lignins, their structural features and chemical composition were investigated and are here reported for the first time; antioxidant capacities were also analyzed. Among the four lignin fractions, the yield of BSL-1 was highest (53.94%). Capsules (47.04%-53.94%) consistently yielded more lignin than stalks (40.23%–40.90%). The predominant monosaccharides associated with BSL-1, WSL-1, and WSL-2 (i.e., all except BSL-2) were glucose. BSL-2 showed the highest thermal stability with the highest molecular weight. A similar composition ratio of linkages (β-O-4', β-β', and β-5') was observed in BSL-1 and WSL-1, and in BSL-2 and WSL-2. All the lignins belong to the GSH type and had S/G ratio values (2.36–3.05) greater than 2.0. Antioxidant studies showed that BSL-1 had the highest DPPH scavenging activity (RSI = 3.31), WSL-2 had the highest ABTS scavenging activity (RSI = 16.31), and WSL-1 had the highest reducing power values. The current study advances understanding of the structural differences of organosolv lignin from sesame capsules and stalks and should promote their future applications.

Advanced analysis technologies cannot be applicable to structural characterization of solid residue from biomass hydrothermal liquefaction due to its insoluble characteristics in organic solution. In this investigation, the milled solid residue fractions were isolated from the solid residues producing during cypress hydrothermal liquefaction at 220, 260, and 300 °C. Their fractions structural characteristics were comparatively investigated by advanced analysis technologies such as liquid state Nuclear Magnetic Resonance. Dichloroethane/ethanol insoluble fractions were firstly found during the liquefaction process at 260–300 °C and results showed that the fractions were the intermediate component of biomass carbonization and mainly produced from the re-polymerization reactions of lignin during hydrothermal liquefaction process. The presence of crosslinking reactions between carbon-carbon which lead to the formation of a highly crosslinked structure resulting in the formation of milled solid residue fractions, which made the fractions be not insoluble in dichloroethane/ethanol and have high thermal stable and molecular weight. Ether structures scission, de-methylation reactions, re-polymerization between carbon-carbon, and fragmentation of large molecular fractions have been occurred in lignin during hydrothermal liquefaction process. The result showed that characterization of milled solid residue fractions provided some new information of the mechanisms of biomass hydrothermal liquefaction.

In the present study, three polysaccharide fractions, QSMP-1, QSMP-2, and QSMP-3, were isolated and purified from the seed meal of Chinese quince. These fractions' structures were investigated by high performance anion exchange chromatography (HPAEC), gel permeation chromatography (GPC), Fourier transform infrared (FT-IR), and nuclear magnetic resonance (NMR), and their antioxidant activities were assessed. The results showed that QSMP-1 is a novel polysaccharide with a backbone mainly composed of →4)-Glcp-(1→, →6)-Glcp-(1→, →6)-Galp-(1→, →2, 3, 4)-Xylp-(1→. The side chains consist of →4)-Arap-(1→, →3, 4)-Arap-(1→, →2)-Galp-(1→, →4)-Manp-(1→, →3)-Galp-(1→, and →3, 6)-Glcp-(1→ with the non-reducing terminals Glcp and Galp. QSMP-1 exhibited effective antioxidant activities by ferrous ion chelation and superoxide anion-scavenging in a dose-dependent manner. These investigations of the polysaccharides from the seed meal of Chinese quince provide a scientific basis for the use of the by-products of quince seed oil processing, particularly as an ingredient in functional foods and medicines.

The stability of Chinese quince seed gum (CQSG) in oil-in-water (O/W) emulsions was investigated in terms of three factors: gum concentration, pH, and NaCl concentration. The surface interfacial tension of the gum under different conditions and the particle size, zeta potential, microstructure, and emulsion stability index of the prepared emulsion were characterized. The results revealed that all three factors influenced the CQSG emulsions. The CQSG can not only minimize gravity creaming effects but also increase the spatial repulsion between emulsion droplets. CQSG demonstrated an ability to reduce the surface and interfacial tension. The stability index of the emulsion showed that the stability of the emulsion increased with increasing CQSG concentration, and the addition of NaCl was not conducive to the stability of the emulsion. Both acidic and alkaline environments weakened the emulsification stability of the CQSG. CQSG exhibited the same excellent emulsifying stability as flaxseed gum when stored in a hot oven at 60 °C for 30 days. The results obtained indicate that CQSG is a suitable emulsifier for the food industry and thus could contribute to the development of Chinese quince seed, which is an important waste material in the processing of Chinese quince.

In this study, we investigated the influence of Chinese quince seed gum (CQSG) on the functional and rheological features of tigernut tuber starch using a rapid visco-analyzer (RVA), differential scanning calorimetry (DSC), scanning electron microscopy, and rheometry. The addition of CQSG markedly increased the pasting temperature, peak, breakdown, final viscosities, and the setback value. The freeze-thaw stability of the gum/starch blends significantly (p

The application of cold-pressed sesame oil (CSO) in the food industry is limited by its weak oxidative stability. The objective was to improve the oxidative stability of CSO by using different solid acid catalysts (SACs) with heat. The effects of SACs on the physicochemical properties, lignan content, oxidative stability and antioxidant capacity of oil samples were investigated. The different oil samples were: CSO without catalyst or heat (L); CSO without catalyst but with heat (CK); and CSO treated with four different SACs, namely hydrogen beta zeolite (Hβ), citric acid (CA), CA loaded on Hβ (CA/Hβ), 12-tungstophosphoric acid (PA) and PA loaded on Hβ (PA/Hβ). In the oil samples treated with SACs, the content of sesamin and sesamolin decreased significantly, and the content of asarinin and sesamol increased accordingly. The oxidative stability and antioxidant capacity of the oil samples Hβ, CA/Hβ and PA/Hβ were significantly enhanced (P

The polysaccharides of soy hulls were extracted by hot-compressed water at temperatures of 110 from 180°C and various treatment times (10-150min) in a batch system. It was determined that a moderate temperature and short time are suitable for the preparation of polysaccharides. The structure of xylan and the inter- and intra-chain hydrogen bonding of cellulose fibrils in the soy hulls were not significantly broken down. The polysaccharides obtained were primarily composed of α-L-arabinofuranosyl units, 4-O-methyl-glucuronic acid units and α-D-galactose units attached with substituted units. A sugar analysis indicated that arabinose was the major component, constituting 35.6-46.9% of the polysaccharide products extracted at 130°C, 140°C, and 150°C. This investigation contributes to the knowledge of the polysaccharides of soy by-products, which can reduce the environmental impact of waste from the food industries.

Lignin is an increasingly valuable raw material for industrial, pharmaceutical and the food industries; natural antioxidants are also being used more and more widely. The Chinese quince fruits have an abundance of lignins with antioxidant properties; however, the lignins cannot be isolated by the methods conventionally used on other sources (e.g., wood, straw). In this investigation, multi-enzymatic hydrolytic pretreatments were used to isolate lignins from Chinese quince fruit, and the structures of these multi-enzyme mixture lignin (EML) fractions were then analyzed and compared with conventional cellulolytic enzyme lignin (CEL). EML fractions are structurally similar to CEL fractions except for an increased S/G ratio, greater number of β-O-4 linkages, higher average molecular weight and decreased thermal stability. The EML-2 fraction in particular seemed most representative of the lignins isolated, and it exhibited the highest antioxidant activity in comparison with CEL and other EML fractions.

Chinese quince (Chaenomeles sinensis) is used in food and pharmaceutical products, but it is seldom eaten as a raw fruit due to its astringent, woody flesh. The structural characterization of lignin fractions from Chinese quince was very important to investigate the structure-activity relationships of lignin. In this investigation, to characterize the structure of lignin in Chinese quince fruits, the milled wood lignin sample was isolated from the fruits (FMWL) and the chemical structure of FMWL was investigated by sugar analysis, FT-IR, GPC, pyrolysis-GC/MS analysis, UV spectra analysis, thermogravimetric analysis (TGA), and advanced NMR spectroscopic techniques. In addition, the lignin fraction from the stalk of Chinese quince (SMWL) was also prepared for comparison to obtained more information of lignin structure in the fruits. The results showed that the two lignin fractions isolated from fruit and stalk of Chinese quince exhibited different structural features. The two MWL samples were mainly composed of β-O-4 ether bonds, β-5 and β-β′ carbon-carbon linkages in the lignin structural units. Compared to the SMWL, the FMWL fraction had the higher S/G ratio and more carbohydrates linkages. The predominant carbohydrates associated with FMWL and SMWL fractions were glucans-type hemicelluloses and xylan-type hemicelluloses, respectively. Understanding the structure of lignin could give insight into the properties of the lignin and enable the food processing industry to separate lignin more efficiently.

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.