Modified Chinese quince oligomeric proanthocyanidin protects deep-frying oil quality by inhibiting oxidation.

Chinese quince (Chaenomeles sinensis) fruit is an underutilized resource, rich in proanthocyanidins with antioxidant ability but poor lipid solubility. In this study, a novel modified oligomeric proanthocyanidin (MOPA) was prepared, which exhibited favorable lipid solubility (354.52 mg/100 g). It showed higher radical scavenging abilities than commercial antioxidant-BHA (butylated hydroxyanisole), both at 0.4-0.5 mg/mL. The addition of MOPA (0.04 %wt.) significantly increased the oxidative stability index of the soybean oil from 5.52 to 8.03 h, which was slightly lower than that of BHA (8.35 h). Analysis of the physicochemical properties and composition of oil during deep-frying showed that MOPA demonstrated significant antioxidant effects and effectively restricted the oil oxidation. This inhibition also delays the formation of heterocyclic amines (HAs) in fried food, thereby reducing the migration of HAs from food to deep-frying oil. Therefore, MOPA is a promising novel liposoluble antioxidant for protecting the quality of deep-frying oil.

Evaluation of Quality Properties of Brown Tigernut (Cyperus esculentus L.) Tubers from Six Major Growing Regions of China: A New Source of Vegetable Oil and Starch.

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.

Influence of the Essential Oil of Foeniculum vulgare Mill. on Sunflower Oil during the Deep-frying Process of Chinese Maye.

Sunflower oil (SFO) is faced with serious oxidation problems during the deep-frying of Chinese Maye, and the search for natural antioxidants has become a focus of scientific research due to the potential toxicity of synthetic antioxidants. In the present study, the Foeniculum vulgare Mill. essential oil (FVEO), tert-butylhydroquinone (TBHQ) were added to SFO for a 30 h deep frying experiment and the results showed that FVEO added to sunflower oil at 1 g/kg was similar to that of TBHQ-0.01 g/kg, and FVEO-1.5 g/kg would promote the oxidation of SFO. FVEO to sunflower oil also prominently restrained the decrease of the sensory properties of the fried product, Chinese Maye, including appearance, taste, flavor and overall acceptance by 24.2%, 20.2%, 46.1% and 56.0% (p < 0.01 or p < 0.05), respectively. The results indicated that FVEO could be used as a natural antioxidant to replace TBHQ in the deep-frying process of SFO, but further research is needed on the key antioxidant constituent of FVEO.

Composition and Antioxidant Ability of Extract from Different Flaxseed Cakes and Its Application in Flaxseed Oil.

In this research, extracts from five flaxseed cakes (hot-pressed cake (HPC), cold-pressed cake (CPC), n-hexane extracted cake (HEC), supercritical CO2 extracted cake (SCEC) and subcritical n-butane extracted cake (SBEC)) were analyzed for the contents of total phenolic, total flavonoid and antioxidant ability. At the same time, the antioxidant capacity of HPC extract and synthetic butylated hydroxyanisole (BHA) in the oxidative evolution of flaxseed oil was compared by accelerated storage experiment (8 days at 65°C). The results showed that compared with other flaxseed cake extract, the extract of HPC contained the highest content of total phenolic (78.01 mg GAE/g extract) and total flavonoid (2.73 mg RE/g extract), and showed the strongest antioxidant ability on DPPH, ABTS FRAP and total reducing power assay. We also found that different concentrations (800, 1000, 2000 ppm) of flaxseed cake extract could significantly slow down the oxidation of flaxseed oil during storage at 65°C, and the antioxidant effect strengthened with the increase of extract dosage. The antioxidant effect of the 2000 ppm extract was higher than that of 200 ppm BHA. The results indicated that flaxseed cake extract could effectively inhibit the oxidation of flaxseed oil and was a good substitute for synthetic antioxidants in oil industry.

Optimization and Kinetics Modeling of Microwave-Assisted Subcritical n-Butane Extraction of Tigernut Oil.

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°C 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.

Separated from the Essential Oil of Coriandrum sativum L. Leaves, Carvacrol and Limonene Showed Antioxidant Effects in Sunflower Oil under Frying Conditions.

The frying process, a popular cooking technique, is widely used in the food industry around the world for the production of fried foods. Nevertheless, it is always accompanied by potential challenges including lipid peroxidation of vegetable oils. In this study, the influence of the coriander leaves essential oil (CLEO) on the oxidative stability of sunflower oil under frying conditions and the sensory attributes of fried food (Chinese Mahua) during the sensory evaluation were investigated. The results indicated that compared with the control, CLEO at 0.12 g/kg could obviously suppress the increases for the total polar compounds (TPC), thiobarbituric acid (TBA), color, conjugated dienes (CD), conjugated trienes (CT) and viscosity of sunflower oil, and prominently restrain the oxidization procedure of unsaturated fatty acid (UFA). Meanwhile, the decline in the sensory attributes for the Chinese Mahua was significantly inhibited. Furthermore, the study revealed the antioxidant effect of CLEO was mainly attributed to two compounds, carvacrol and limonene, which were separated by the bioassay-guided fractionation. Consequently, CLEO and the two compounds may be employed as potential natural antioxidants to improve the oxidation stability of sunflower oil under frying conditions.

Effects of Deodorization on the Formation of Processing Contaminants and Chemical Quality of Sunflower Oil.

Tocopherols and phytosterols are generally considered to be nutritionally beneficial, and 3-Monochloropropane-1,2-diol esters (3-MCPD esters), glycidyl esters (GEs) and trans fatty acids (TFAs) are generally considered to be harmful. The high temperature deodorization step is when these harmful 3-MCPD esters, GEs and TFAs are generated. Knowing how deodorization conditions affect levels of these substances is essential for designing refining processes that will produce nutritious, high quality edible oils. This study analyzed the changes of these components of sunflower oil at different temperatures (210, 230, 250 and 270°C) and times (60, 80, 100 and 120 min) during deodorization. Our research found that during the whole deodorization process (including undeodorized sunflower oil), the contents of 3-MCPD esters, GEs and TFAs all progressively increased, from 0.47 to 11.18 mg/kg, 0.24 to 18.42 mg/kg and 0.062% to 0.698%, respectively. However, the deodorization process significantly decreased the levels of tocopherols (from 535.94 to 240.26 mg/kg) and phytosterols (from 2803.58 to 1864.34 mg/kg). Meanwhile, the retention ratios of total tocopherols and total phytosterols also decreased from 96.29% to 44.83% and 92.29% to 66.50%, respectively.

Changes in key aroma-active compounds and sensory characteristics of sunflower oils induced by seed roasting.

This study investigated the changes in aroma composition and perception of sunflower oils induced by seed roasting using sensory-oriented flavor analysis. Volatile compounds were extracted by solvent-assisted flavor evaporation and headspace solid-phase microextraction. Odorants were characterized by gas chromatography-olfactometry-mass spectrometry and aroma extract dilution analysis. The cold-pressed and roasted sunflower oils contained 13 and 50 odorants, respectively, with the flavor dilution factors between 1 and 256. Fifty-six odorants were newly identified in sunflower oils. Quantification of 26 important odorants by the external standard method revealed apparent changes induced by seed roasting in loss of terpenes, formation of Maillard reaction products, and the increase in lipid oxidation products. The most important odorants (odor active values, OAVs = 1-1857) in the cold-pressed sunflower oil included α-pinene (11,145 µg/kg), ß-pinene (4068 µg/kg), linalool (56 µg/kg), hexanal (541 µg/kg), octanal (125 µg/kg), α-phellandrene (36 µg/kg), and (E)-2-octenal (69 µg/kg), contributing to the raw sunflower seed, woody, green, earthy, and sweet aromas of the oil. The most important contributors (OAVs = 1-884) to the roasted, smoky, and burnt aromas of the roasted sunflower oil were 2- and 3-methylbutanal (6726 and 714 µg/kg), 2,6-dimethylpyrazine (2329 µg/kg), 2,5-dimethylpyrazine (12,228 µg/kg), 2,3-dimethylpyrazine (238 µg/kg), 2,3-pentanedione (1456 µg/kg), 2-pentylfuran (1332 µg/kg), 2,3-dimethyl-5-ethylpyrazine (213 µg/kg), and 1-pentanol (693 µg/kg). Aroma recombination of the key odorants in odorless sunflower oil adequately mimicked the general aroma profiles of sunflower oils. This study provides an important foundation for understanding the relationship between oil processing and aroma molecules of sunflower oils. PRACTICAL APPLICATION: The clear changes observed in the composition and concentrations of key aroma compounds explained the changes in sensory characteristics of sunflower seed oils induced by seed roasting on a molecular basis. Characterizing the key aroma-active composition of sunflower oil and investigating its relationship with oil processing could provide important practical applications for the sunflower oil industry in flavor regulation, quality control, product development, and process optimization.

Comparison of key aroma-active compounds between roasted and cold-pressed sesame oils.

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.

Pectic polysaccharides extracted from sesame seed hull: Physicochemical and functional properties.

The objective of the present investigation was to extract pectic polysaccharides from sesame seed hull and to determine their physicochemical and functional characteristics. The pectic polysaccharides in the seed hull were extracted with HCl and then collected at three ethanol concentrations of 30% (SSP30), 50% (SSP50), and 90% (SSP90). We found that SSP30 represented 75.6% of the total polysaccharides, and that it contained 76.39% galacturonic acid, with many HG domains and few short side chains in the RG-I domains. SSP30 exhibited the strongest hydroxyl radical scavenging activity among the three fractions, and was better able to stabilize the emulsions. Higher Mw pectic polysaccharides were firstly precipitated at lower ethanol concentrations, and the Mw of the precipitated pectic polysaccharides decreased with increasing ethanol concentration. These results provide important information on the structure and functional characteristics of sesame hull polysaccharides. This information can contribute to the future development of sesame hull polysaccharides for industrial purposes.

Structural changes of lignin-carbohydrate complexes (LCCs) from Chinese quince fruits during the sequential fractionation of pectic and hemicellulosic polysaccharides.

Chinese quince (Chaenomeles sinensis) fruits offer a potential source of pectin and hemicellulose. However, the existence of lignin-carbohydrate complexes (LCCs) can negatively impact the extraction of pectin and hemicellulose. In this work, LCCs were sequentially fractionated from Chinese quince during the removal of pectin and hemicellulose. The structures of LCCs were characterized by HPAEC, FT-IR, GPC, Py-GC/MS, TGA and 2D HSQC NMR. The results showed that the carbohydrate content and molecular weight of LCCs was found to be changed significantly after the removal of hemicellulose (KSH). The lignin in Björkman LCCs was found to be linked mainly to galactan and fructan, whereas the lignin LCC-AcOHs was found to be linked mainly to arabinan after the removal of KSH. The isolation of carbonate-soluble pectin (NSP) increased thermal stability of Björkman LCC fraction, however, the isolation of chelator-soluble pectin (CSP) increased the thermal stability of LCC-AcOHs. The S/G ratios of LCC-AcOHs increased and large amounts of S-type lignin released during sequential fractionation of pectin and hemicellulose. These results will be beneficial for understanding the mechanisms of pectin and hemicellulose isolation, thereby facilitating the potential application of Chinese quince as a valuable natural resource for food and other industries.

Structural Changes in Milled Wood Lignin (MWL) of Chinese Quince (Chaenomeles sinensis) Fruit Subjected to Subcritical Water Treatment.

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 °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 ß-O-4' ether bonds, ß-5' and ß-ß', 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.

Extraction and Characterization of Flaxseed Oil Obtained with Subcritical n-Butane.

In this study, subcritical n-butane was adopted to extract oil from flaxseed. The extraction conditions i.e. extraction temperature, extraction time, and liquid-solid ratio were investigated and optimized by response surface methodology. The flaxseed oil obtained by subcritical n-butane were characterized and compared with those prepared by n-hexane and cold pressing. Results indicated that the optimal combination of parameters was 53.93℃, 56.82 min, and 19.98:1 mL/g. Subcritical n-butane had higher yield (28.75%) than n-hexane and cold pressing. GC analysis indicated that subcritical n-butane extraction had no obvious influence on the fatty acid composition. Nevertheless, the oil obtained by subcritical n-butane with higher contents of phytosterols (2.93 mg/g) and carotenoids (46.56 mg/kg), and presented a higher oxidation stability (9.27 h). Thus, it was suggested that subcritical n-butane extraction is a promising alternative to extract high quality flaxseed oil.

Characterization and Oxidative Stability of Cold-pressed Sesame Oil Microcapsules Prepared by Complex Coacervation.

Although cold-pressed sesame oil (CPSO) possesses high nutritional value, its application in the food industry is limited due to its poor oxidative stability. The aim of this study was to enhance the oxidative stability of CPSO by complex coacervation microcapsule technology with gelatin and gum Arabic as wall materials. The characterization of CPSO microcapsules were evaluated by a particle image analyzer, a laser particle size distribution analyzer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The encapsulation efficiency (EE) reached 90.25%. The average particle size of the microcapsules was approximately 117.1 µm and many oil droplets were encapsulated by complex coacervation to form a multinuclear spherical microcapsule. The FTIR study confirmed that the process of complex coacervation was formed between gelatin and gum Arabic by electrostatic interactions. The TGA study suggested that the microcapsules had good heat resistance. The fatty acid composition, the content of sesamin, sesamolin and vitamin E in CPSO were determined before and after microencapsulation. It showed that the microencapsulation process had almost no effect on the fatty acid composition, sesamin and sesamolin, only Vitamin E was slightly lost during the microencapsulation process. The accelerated storage test showed that microencapsulation significantly increased the oxidative stability of CPSO.

ß-carbolines norharman and harman in vegetable oils in China.

The beta-carbolines norharman and harman, two heterocyclic aromatic amines with potential mutagenicity, have been determined in vegetable oils. Identification and analysis were carried out by ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-MS/MS). In 88 samples analysed, the concentrations of norharman and harman were < LOD to 336.22 ng/g and < LOD to 505.14 ng/g, respectively. A high variability of norharman and harman levels among different oil types was observed. Sesame-, flaxseed-, sunflower seed-, peanut- and rapeseed oils were most contaminated. Both ß-carbolines were most likely formed during roasting of the oilseeds. Oil consumption, especially of oils obtained after roasting of the seeds, was a major dietary source of the ß-carbolines norharman and harman. Under existing oil risk factors, this investigation contributes to the unprecedented and essential information for dietary assessments associated with oil consumption.

Effects of various oil extraction methods on the gelatinization and retrogradation properties of starches isolated from tigernut (Cyperus esculentus) tuber meals.

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.

Ultrasound-assisted desolventizing of fragrant oil from red pepper seed by subcritical propane extraction.

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.

Improvement of the oxidative stability of cold-pressed sesame oil using products from the Maillard reaction of sesame enzymatically hydrolyzed protein and reducing sugars.

BACKGROUND: In recent years, cold-pressed oils have become more and more popular with consumers. However, their oxidative stability is low. Improving the oxidative stability of cold-pressed oils will increase their shelf life. Maillard reaction products (MRPs) have been shown to promote the oxidative stability of lipids. In this study, products from the Maillard reaction of reducing sugars and sesame enzymatically hydrolyzed protein (SEHP) were added to cold-pressed sesame oils to improve their oxidative stability. RESULTS: Three types of MRPs from reducing sugars (xylose, fructose, and glucose) and SEHP were prepared. Xylose-SEHP MRPs prepared under optimum conditions had the highest antioxidant activities among the three. The optimum conditions for xylose-SEHP were as follows: reaction temperature, 130 °C; reaction time, 180 min; pH, 6.5; and sugar/protein ratio, 10:1. The addition of xylose-SEHP MRPs at a level of 20 g kg-1 could significantly improve the oxidative stability of cold-pressed sesame oil. Besides, the addition of MRPs reduced the loss of tocopherol. The interaction of MRPs with endogenous antioxidants in the sesame oil (sesamol and tocopherol) was proved by comparison with lard. There was a synergistic increase in antioxidant activity for the combination of MRPs and sesamol and the combination of MRPs and tocopherol. CONCLUSIONS: The results provide evidence that adding certain MRPs can improve the oxidative stability of cold-pressed sesame oil. © 2019 Society of Chemical Industry.

Structure, rheological, thermal and antioxidant properties of cell wall polysaccharides from Chinese quince fruits.

To investigate the composition and structural characteristics of cell wall polysaccharides, three pectic fractions and two hemicellulose fractions, namely water-soluble pectin (WSP), chelator-soluble pectin (CSP), sodium carbonate-soluble pectin (NSP), 1 mol/L KOH soluble hemicellulose (KSH-1) and 4 mol/L KOH soluble hemicellulose (KSH-2), were isolated from Chinese quince fruits. The five fractions exhibited structural and compositional variation. The results showed NSP was the predominant cell wall polysaccharide fraction in the fruit. All pectic fractions had a low degree of esterification (31.7-42.4%). WSP fraction had the highest thermal stability among the five fractions. The polysaccharide chain lengths ranged from 19.4 nm to 121.4 nm. CSP had the highest molecular weight, giving it also the highest solution viscosity. NMR spectra revealed that NSP was composed of RG-I and galacturonic acid main chains, KSH-1 was composed of 1,4-ß-D-Xylp backbone attached to 1,5-α-L-Araf units. Among the five fractions, CSP has the highest DPPH radical scavenging activity while KSH-1 has the highest reducing power. This study can contribute to the applications of Chinese quince fruit polysaccharides in food and pharmaceutical industries.

Amano Lipase PS-catalyzed Hydrolysis of Pine Nut Oil for the Fatty Acids Production Using Deep Eutectic Solvent as Co-solvent.

Free fatty acids (FFAs) are the important material used in food, personal care, emulsifiers, adhesives and surfactants. In order to enhance the preparation of FFAs, the effects of reaction variables, optimization, thermodynamic property for the Amano lipase PS catalyzed hydrolysis of pine nut oil (PNO) using deep eutectic solvents (DESs) as co-solvents were studied. The results showed that FFAs could be successfully prepared from pine nut oil through Amano lipase PS catalyzed hydrolysis using Choline chloride:Urea (ChCl:U, 1:2, mol/mol) as co-solvent. Under the optimal conditions (reaction temperature 46°C, water amount 38%, DES addition 43%, lipase dosage 7.6%, reaction time 13 h), the maximum content of FFAs in the products and degree of hydrolysis (DH) of oil were up to 89.1 ± 1.9% and 92.7 ± 2.2%, respectively. The effects of reaction variables on the hydrolysis increased in the order of DES addition < reaction temperature < reaction time < lipase dosage < water amount. The thermodynamics (Arrhenius equation) for the triglycerides hydrolysis was V = 4289.39·exp(-22942.09/RT) with the activation energy (Ea) of 22.94 kJ/mol. The Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were 81.50 ± 2.64 kJ/mol, 20.18 ± 0.12 kJ/mol and -184.59 ± 0.36 J/mol/K, respectively. The lipase in the aqueous DES could be directly re-used for 3 times.