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Tigernut has been recognized as a promising resource for edible oil and starch. However, the research on the quality characteristics of tigernut from different regions is lagging behind, which limits the application of tigernut in food industry. Tigernut tubers were obtained from six major growing regions in China, and the physicochemical properties of their main components, oil and starch, were characterized. Tigernut tubers from Baoshan contained the most oil (30.12%), which contained the most ß-carotene (130.4 µg/100 g oil) due to high average annual temperature. Gas chromatography analysis and fingerprint analysis results indicated that tigernut oil (TNO) consists of seven fatty acids, of which oleic acid is the major component. Changchun TNO contained the least total tocopherols (6.04 mg/100 g oil) due to low average annual temperature. Tigernut tubers from Chifeng (CF) contained the most starch (34.85%) due to the large diurnal temperature range. Xingtai starch contained the most amylose (28.4%). Shijiazhuang starch showed the highest crystallinity (19.5%). Anyang starch had the highest pasting temperature (76.0°C). CF starch demonstrated superior freeze-thaw stability (syneresis: 50%) due to low mean annual precipitation. The results could be further applied to support tigernut industries and relevant researchers that looks for geographical origin discrimination and improvements on tigernut quality, with unique physicochemical and technological properties. [ABSTRACT FROM AUTHOR]

In this study, tigernut oil was extracted from tigernut meal by subcritical n-butane extraction with the assistance of microwave pretreatment. Effects of microwave pulse duration, particle size of tigernut meal, and subcritical extraction variables (temperature, time, solid-liquid ratio, number of extraction cycles) on extraction efficiency were examined by single-factor experiments and Response Surface Methodology (RSM) modeling. The results indicate that microwaving (560 W, 6 min) significantly increased the subcritical extraction efficiency. The variation of extraction yield could be interpreted as a nonlinear function of extraction time, temperature and liquid-solid ratio. Changing the independent variables could affect the oil extraction efficiency. The subcritical extraction of tigernut oil with a liquid-solid ratio of 3.62 kg/(kg of tigernut meal) at a temperature of 52° for 32 min after three extraction cycles produced the most oil, and a maximum yield (24.736%) of tigernut oil was achieved. The ratio of unsaturated to saturated fatty acids (4.68 UFA/SFA), low acid value (3.30 mg KOH/g oil), low peroxide value (0.28 meq.kg-1), and preponderance of oleic acid indicate a high-quality oil. To describe the extraction kinetics, a modified Brunner's mathematical model was used. The model fit the experimental data well over the entire operating range, and the explanation coefficient exceeds 96%. Our results can be used to develop an optimized method for subcritical fluid extraction of tigernut oil and can move industry further toward implementing microwave-assisted subcritical extraction in oil processing. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This investigation was carried out to offer insight into the formation and antioxidant activity of Maillard reaction products (MRPs) derived from various sugar-amino acid model systems active in the roasting of sesame seeds. Reducing sugars (glucose, fructose, and xylose) and amino acids (serine, cystine, arginine, and lysine) present in sesame seeds were used to prepare the MRPs at various reaction times, and then the effect of reaction time on the MRPs derived from the various model systems was investigated. Within the first 15 min, the amounts of free amino groups decreased around 40% remaining amino groups of Lys-sugar model and around 75% remaining amino groups of Arg-sugar model. Results indicated that reducing sugar and free amino groups decreased obviously in Lys- and Arg-model systems. Based on correlation coefficient of antioxidant activities assessment and MRP formation in the Lys- and Arg-model systems above 0.978 and an extremely significant correlation in Pearson test exists, a conclusion could be made that these model systems are critical contributing factors in MRP formation during the roasting of sesame seeds. These findings offer insight into the formation and antioxidation of MRPs during the sesame seeds roasting. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The objective of this investigation was to elucidate the structural changes of the polysaccharides isolated by hydrothermal treatment of corn bran after twin-screw extrusion. The structures and antioxidant activities of the purified polysaccharides were investigated and compared by monosaccharide analysis, Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR). The results showed that the structures of the linkages and monosaccharide components of the purified polysaccharides were not affected strongly by the twin-screw extrusion pretreatment. However, the purified polysaccharides isolated from pretreated samples displayed significant differences in monosaccharide ratios, degree of branching/linearity, and molecular weight. These physical changes may be related to the decrease of antioxidant activities of the polysaccharides. The present investigation contributes to the knowledge of how pretreatment by twinscrew extrusion affects the chemistry of corn bran polysaccharides. Results can be applied to improve the efficiency of hydrothermal extraction of polysaccharides from corn bran. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 Xray 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Rice bran oil was extracted using hexane, as well as subcritical butane and propane. The quality of rice bran oils obtained using these three solvents was comparatively studied. The results showed that subcritical fluid extraction oil showed higher concentrations of health-conducive components (such as vitamin E, oryzanol, and phytosterol) compared with hexane-extracted oil. Extraction solvent had an important effect on the distribution of linoleic acid and oleic acid. The sterol compositions in rice bran oils were identified to be composed of ethyl iso-allocholate, campesterol, stigmasterol, sitosterols, and cyclolanosts. NMR data showed that butane-extracted oil had the highest triacylglycerols (TAGs) content and that subcritical propane-extracted oil had the highest wax content among the oils extracted with these three extraction solvents. The oils extracted by subcritical butane and propane showed higher oxidative stabilities. These results indicate that subcritical fluid extraction technology could be a useful method for producing high-quality rice bran oils and could become widely used in industrial applications. [ABSTRACT FROM AUTHOR]

Hemicellulosic fractions were extracted from soybean hull with various concentrations of NaOH at 50 °C for 5 h. The chemical compositions and physicochemical properties were determined by high performance anion exchange chromatography (HPAEC), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analyzer (TGA), and 13C and 2D nuclear magnetic resonance (NMR) analysis. The crystallinity of soybean hulls treated and untreated by alkali liquid was examined by X-ray diffraction (XRD). The sugar analysis results indicated that all of the hemicellulosic preparations were heteropolysaccharides containing arabinose, galactose, glucose, xylose, and mannose. According to the spectral analysis, hemicelluloses from soybean hull were assumed to be L-arabino-4-O-methyl-D-glucurono-D-xylan. Xylose was the predominant monosaccharide in the hemicellulose fraction 1 (H1), and it ranged between 40.1% and 48.8% of the total neutral sugars. It was found that hemicellulose fraction 3 (H3) had the highest thermal stability and H1 had the lowest thermal stability. The crystallinity index (CrI) was found to be about 20.8%, 14.3%, 10.9%, and 4.7% for soybean hulls, untreated and treated with 1.5, 2.0, and 2.5 M NaOH, respectively. [ABSTRACT FROM AUTHOR]

Four bio-oils obtained from the hydrothermal liquefaction (at 280 °C for 0 min) of untreated and pretreated cypresses were subjected to several types of chemical analyses to compare their structural features and chemical constituents. Pretreatments were carried out with alkali at 90 °C for 0.5, 1, and 2 h. The bio-oils were further divided into water-soluble oil, diethyl ether-soluble oil, and diethyl ether-insoluble oil fractions. Alkaline pretreatment had a significant effect on the contents of different components in the bio-oils. The diethyl ether-insoluble oil fraction was made up of intermediate-sized macromolecular fragments of lignin decomposed during the hydrothermal liquefaction process. The G6 resonance, β-5, β-β', and β-O-4' peaks (which were present in the spectra of milled-wood lignin) almost disappeared from the spectra of the diethyl ether-insoluble oil fractions obtained via hydrothermal liquefaction of pretreated and untreated cypresses. At the same time, the intensities of the peaks corresponding to methoxy groups, G2, and G5 resonances were reduced. Long-duration alkaline pretreatment created a strong, highly water-soluble oil fraction with a wide molecular weight distribution. [ABSTRACT FROM AUTHOR]

The mechanism of hydrothermal liquefaction of cypress was investigated by examining the effects of temperature and retention time on the characteristics of the solid residues remaining after liquefaction. The solid residues were divided into acid-soluble and acid-insoluble residues. Results showed the polymerization reactions also mainly occurred at low temperatures. The reactive fragments transformed into acid-insoluble solid residue in the form of carbon and oxygen through polymerization reactions. The process of cellulose degradation consists of two steps: an initial hydrolysis of the more solvent- accessible amorphous region and a later hydrolytic attack on the crystalline portion. Hemicelluloses were decomposed into small compounds during the initial stage of the cypress liquefaction process, and then these compounds may rearrange through polymerization to form acid-insoluble solid residues above 240 °C. The higher heating value of the solid residues obtained from liquefaction at 260-300 °C was 23.4-26.3 MJ/kg, indicating that they were suitable for combustion as a solid fuel. [ABSTRACT FROM AUTHOR]

Liquefaction of cornstalk in sub-critical solution of ethanol without and with catalysts (K2CO3, Na2CO3 and ZnCl2) was performed in a stainless o steel reactor (1 L) at temperatures of 200 to 300°C. The cornstalk and the products of decomposition were divided into five lumps (gas, organic dissolved, heavy oil, volatile organic compounds, and residue). The effects of reaction temperature and the catalyst amount on the five lump yields were studied. The bio-oils produced with and without catalysts were characterized by GC/MS. Results showed that an increment in the temperature and the addition of catalysts had a synergetic effect on the lumps yield as compared to the non-catalytic experiments, and different catalytic procedures had an important effect on the lump yields and compounds of the bio-oils. The addition of the catalyst enhanced the gas yield and the total conversion rate. A high temperature, lower amount of Na2CO3, moderate amount of K2CO3, and a high amount of ZnCl2 were propitious to enhance the heavy oil. The formation of volatile organic compounds with the presence of ZnCl2 and K2CO3 was less than that in non-catalytic experiments at the higher temperatures. However, a higher conversion temperature had a negative impact on the bio-oils yield from liquefaction of cornstalk with and without catalysts. [ABSTRACT FROM AUTHOR]