Effects of α-Tocopherol, ß-Carotene and Epigallocatechin Gallate on the Oxidative Stability of Sunflower Oil.

Using sunflower oil as the oil matrix, the antioxidant effects and types of interactions of three natural components, α-tocopherol, ß-carotene and epigallocatechin gallate (EGCG), were investigated and the kinetic model of oxidation reaction was established. The results showed that the ability of the three antioxidants to scavenge DPPH radicals was ranked as EGCG > ß-carotene > α-tocopherol in the concentration range of 0~100 mg/kg. 15 samples were obtained by combining two of three natural components. When the concentration ratios of ß-carotene and EGCG were 1:20 and 1:7.5, α-tocopherol and EGCG were 1:13.3, 1:6, and 1:2, and α-tocopherol and ß-carotene were 1:0.2 and 1:0.05, the type of interaction was synergistic, while the rest of the samples showed antagonistic effects. The sample with a 1:13.3 concentration of α-tocopherol and EGCG showed the longest induction period, the lowest oxidation rate constant, the highest activation energy, the best oxidative stability, and the longest shelf life at different temperatures. This compounded natural antioxidant was the most favorable for the stability of sunflower oil. This provides some theoretical basis for the development and application of compounded natural antioxidants in vegetable oils.

Effects of different deodorization methods on the oxidation of sterol components in rice bran oil.

Rice bran oil contains a significant quantity of phytosterols that have various active functions and are natural active substances beneficial to humans. It is well known that deodorization during refining affects the quality of rice bran oil. However, changes in phytosterols fraction caused by stripping with nitrogen compared to water vapor remain unexplored. We measured phytosterols in rice bran oil after deodorization with nitrogen and water vapor. The variations in sitosterol fraction, which accounts for the highest percentage of phytosterols in rice bran oil, were analyzed by Gas chromatography (GC), Fourier transform infrared spectrometer (FTIR), and Nuclear magnetic resonance (NMR). Results showed that using nitrogen as the stripping gas was more suitable for deodorization. It promoted the formation of phytosterol esters, reduced the production of phytosterol oxidation products and improved the oil quality. This study provides a theoretical basis for improving the industrial production quality of rice bran oil.

Construction of hemp seed protein isolate-phosphatidylcholine stablized oleogel-in-water gel system and its effect on structural properties and oxidation stability.

Rice bran wax was added to hemp seed oil (HSO) to prepare oleogel, and hemp seed protein isolate (HPI)-phosphatidylcholine (PC) was used as the emulsifier to obtain an oleogel-in-water (Og/W) gel system. The effect of HPI concentration on the construction of gel system was studied. Microscopic observations found that the oil droplets were encapsulated by the emulsifier. X-ray diffraction and Fourier transform infrared spectroscopy analysis showed that the increase in HPI concentration promoted the interaction between PC and protein, but didn't affect the crystal structure of gel. Thermogravimetric analysis showed that when the HPI concentration was 8 %, the sample formed a dense gel network and had good thermal stability. At this time, the oil holding capacity of gel was 98.81 ± 0.08 %, and the gel hardness was 109.55 ± 1.74 g. After 30 days of storage, the retention rate of Δ9-THC reached 96.3 %, and the peroxide value was 4.98 mmol/kg.

Properties of OSA-modified starch and emulsion prepared with different materials: Glutinous rice starch, japonica rice starch, and indica rice starch.

Octenyl succinic acid (OSA)-modified starch was prepared using three kinds of rice starch with different amylose content: glutinous rice starch (GRS, 3.67 g/100 g), japonica rice starch (JRS, 17.61 g/100 g), and indica rice starch (IRS, 27.94 g/100 g). The degree of polymerization of OSA and the starch types was 0.0093, 0.0143, and 0.0159, respectively. In addition, holes and cracks were observed in the starch particles owing to esterification. The OSA modification introduced OS group and affected hydrogen bond, but exerted no effect on the crystal form (A-type). The contact angle and emulsifying index revealed that OSA-JRS exhibited the most promising emulsification effect compared to the other samples. Next, soybean oil was added into the OSA-JRS solution to prepare an oil-water emulsion. The results revealed that compared to natural JRS, OSA-JRS exhibited decreased D4,3 and a more uniform distribution. Additionally, its absolute potential value increased to 21.34 mV. Further, the dynamic interfacial tension and contact angle of the OSA-modified samples decreased, whereas the storage and loss moduli of the emulsion increased. The shear resistance, centrifugal force resistance, and storage stability of the OSA-modified emulsion significantly improved. The results demonstrated the potential of the OSA-modified JRS for preparing stable emulsions.

Effect of high-intensity ultrasonic treatment on the emulsion of hemp seed oil stabilized with hemp seed protein.

In this study, hemp seed oil (HSO) emulsions stabilized with hemp seed protein (HPI) were prepared and treated with high intensity ultrasonic (HIU). The effects of different treatment powers (0, 150, 300, 450, 600 W) on the properties, microstructure and stability of emulsions were investigated. HIU-treated emulsions showed improved emulsifying activity index and emulsifying stability index, reduced particle size, and increased absolute values of ζ-potential, with the extreme points of these indices occurring at a treatment power of 450 W. Here, the emulsion showed the best dispersion and the smallest particle size in fluorescence microscopy observation, with the highest adsorbed protein content (30.12%), and the highest tetrahydrocannabinol (THC) retention rate (87.64%). The best thermal and oxidative stability of the emulsions were obtained under HIU treatment with a power of 450 W. The D43 and the peroxide values (POV) values after 30 d storage were the smallest at 985.74 ± 64.89 nm and 4.6 µmol/L, respectively. Therefore, 450 W was optimal HIU power to effectively improve the properties of HPI-stabilized HSO emulsion and promote the application of HSO and its derivatives in food processing production.

Effect of ultrasound on the structural characteristics and oxidative stability of walnut oil oleogel coated with soy protein isolate-phosphatidylserine.

In this study, the three-dimensional network system formed by rice bran wax (RBW) was used as the internal structure, and the external structure formed by soybean protein isolate (SPI) and phosphatidylserine (PS) was added on the basis of the internal structure to prepare walnut oil oleogel (SPI-PS-WOG). Ultrasonic treatment was applied to the mixed solution to make SPI-PS-WOG, on the basis, the effects of ultrasonic treatment on SPI-PS-WOG were investigated. The results showed that both ß and ß' crystalline forms were present in all SPI-PS-WOG samples. When the ultrasonic power was 450 W, the first weight loss peak in the thermogravimetric (TGA) curve appeared at 326 °C, which was shifted to the right compared to the peak that occurred when the ultrasonic power was 0 W, indicating that the thermal stability of the SPI-PS-WOG was improved by the ultrasonic treatment. Moreover, when the ultrasonic power was 450 W, the oil holding capacity (OHC) reached 95.3 %, which was the best compared with other groups. Both confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) showed that the ultrasonic treatment of appropriate power succeeded in making the SPI-PS-WOG samples more evenly dispersed in the internal structure and denser in the external structure. In terms of oxidative stability, it was found that the peroxide value of SPI-PS-WOG remained at 9.8 mmol/kg oil for 50 days under 450 W ultrasonic power treatment, which was significantly improved compared with liquid walnut oil (WO). These results provide a new idea for the preparation of oleogels, and also lay a theoretical foundation for the application of ultrasonic treatment in oleogels.

Effect of high-intensity ultrasound on the physicochemical properties, microstructure, and stability of soy protein isolate-pectin emulsion.

In this study, an emulsion stabilized by soy protein isolate (SPI)-pectin (PC) complexes was prepared to investigate the effects of high-intensity ultrasound (HIU) treatment (150-600 W) on the physicochemical properties, microstructure, and stability of emulsions. The results found that the emulsion treated at 450 W showed the best emulsion stability index (ESI) (25.18 ± 1.24 min), the lowest particle size (559.82 ± 3.17 nm), the largest ζ-potential absolute value (16.39 ± 0.18 mV), and the highest adsorbed protein content (27.31%). Confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) revealed that the emulsion aggregation was significantly improved by ultrasound treatment, and the average roughness value (Rq) was the smallest (10.3 nm) at 450 W. Additionally, HIU treatment reduced the interfacial tension and apparent viscosity of the emulsion. Thermal stability was best when the emulsion was treated at 450 W, D43 was minimal (907.95 ± 31.72 nm), and emulsion separation also improved. Consequently, the creaming index (CI) was significantly decreased compared to the untreated sample, indicating that the storage stability of the emulsion was enhanced.

Effect of high intensity ultrasound on the structure and solubility of soy protein isolate-pectin complex.

In this study, a soy protein isolate (SPI)-pectin (PC) complex was prepared, and the effects of different high intensity ultrasound (HIU) powers on the structure and solubility of the complex were studied. Fourier transform infrared (FTIR) spectroscopy analysis exhibited that with increasing HIU power, the α-helix content of the SPI in the complex was significantly reduced, and the random coil content increased; however, an opposite trend appeared after higher power treatments. Fluorescence spectra showed that HIU treatment increased the fluorescence intensity of the complex, and the surface hydrophobicity was increased. The trend of the protein structure studied by Raman spectroscopy was similar to that of FTIR and fluorescence spectroscopy. When the HIU treatment was performed for 15 min and at 450 W power, the particle size of the complex was 451.85 ± 2.17 nm, and the solubility was 89.04 ± 0.19 %, indicating that the HIU treatment caused the spatial conformation of the protein to loosen and improved the functional properties of the complex. Confocal laser scanning microscopy (CLSM) revealed that the complex after HIU treatment exhibited improved dispersibility in water and smaller particle size. Gel electrophoresis results indicated that HIU treatment did not affect the protein subunits of the complex. Therefore, the selection of a suitable HIU treatment power can effectively improve the structural properties and solubility of SPI in the complex, and promote the application of the SPI-PC complex in food processing and industries.

A photoelectrochemical biosensor based on SnO2 nanoparticles for phosphatidylcholine detection in soybean oil.

A photoelectrochemical (PEC) biosensor based on SnO2 nanoparticles (SnO2 NPs) was developed and applied for phosphatidylcholine (PC) detection in soybean oil. SnO2 NPs were grown on an indium tin oxide (ITO) electrode, polythionine (PTh) was electropolymerized on the surface of ITO/SnO2 NPs, and choline oxidase (ChOx) was immobilized to prepare the ITO/SnO2 NPs/PTh/ChOx electrode. The developed PEC biosensor can detect PC under visible light irradiation. The experimental conditions for PC detection were as follows: 1.8 mg mL-1 ChOx concentration, 0.5 V bias voltage, 18 mW cm-2 light intensity, and pH 6. The PEC biosensor had a detection limit of 0.005 mM (S/N = 3) and a detection range from 0.03 mM to 4 mM. This PEC biosensor based on SnO2 NPs was applied to detect PC in soybean oil. The recovery rate tested by the standard addition method was 95.2-107.4%. These findings were consistent with the results obtained by high-performance liquid chromatography (HPLC). Therefore, the proposed PEC biosensor based on SnO2 NPs has excellent reproducibility, stability, and great potential applications in the PEC analysis of PC in soybean oil.

Preparation of Conjugated Linoleic Acid by Ultrasound-assisted Nanonickel Catalyst Isomerization of Sunflower Oil.

A homemade nanonickel catalyst was made by the ultrasonic liquid-phase reduction method, characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, and applied to the isomerization reaction of high linoleic acid sunflower oil. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and particle size analysis showed that the homemade nickel particles were spherical, uniformly dispersed, less agglomerated, 20 to 75 nm in size, and nanoscale nickel powder. Compared with commercially available Raney nickel, the homemade nanonickel powder has a larger specific surface area, smaller pore size and higher catalytic activity. The X-ray diffraction spectrum of the homemade nanonickel powder had distinct diffraction peaks at its characteristic peaks which indicated that the powder was pure nickel. The nanometal nickel particles are fully dispersed in high oleic sunflower oil under the action of ultrasound. The results showed that it could effectively reduce the activation reaction time of nanonickel, and the conversion rate of conjugated linoleic acid could reach 86.24%. The process of activating the catalyst is omitted, the number of times of repeated uses of the nanonickel catalyst is increased, and the environmental pollution of the production is avoided. To obtain sunflower oil rich in CLA, it also provides a new idea for the preparation of conjugated linoleic acid.

Effect of ultrasound on the preparation of soy protein isolate-maltodextrin embedded hemp seed oil microcapsules and the establishment of oxidation kinetics models.

In this study, microcapsules were prepared by spray drying and embedding hemp seed oil (HSO) with soy protein isolate (SPI) and maltodextrin (MD) as wall materials. The effect of ultrasonic power on the microstructure and characteristics of the composite emulsion and microcapsules was studied. Studies have shown that ultrasonic power has a significant impact on the stability of composite emulsions. The particle size of the composite emulsion after 450 W ultrasonic treatment was significantly lower than the particle size of the emulsion without the ultrasonic treatment. Through fluorescence microscopy observation, HSO was found to be successfully embedded in the wall materials to form an oil/water (O/W) composite emulsion. The spray-dried microcapsules showed a smooth spherical structure through scanning electron microscopy (SEM), and the particle size was 10.7 µm at 450 W. Fourier transform infrared (FTIR) spectroscopy analysis found that ultrasonic treatment would increase the degree of covalent bonding of the SPI-MD complex to a certain extent, thereby improving the stability and embedding effect of the microcapsules. Finally, oxidation kinetics models of HSO and HSO microcapsules were constructed and verified. The zero-order model of HSO microcapsules was found to have a higher degree of fit; after verification, the model can better reflect the quality changes of HSO microcapsules during storage.

Soybean Oil Treatment Using the Dissolving Curve Equation of Hydrogen.

The solubility of hydrogen in n-hexane was determined using a homemade reactor. The solubility of hydrogen in soybean oil was established using the Peng-Robinson (PR) equation of state and the van der Waals mixing rule. The curve equation established a linear relationship between the solubility of hydrogen in oil and the number of moles of hydrogen in the reactor. Under the optimal temperature and catalyst, the relationship between the hydrogen consumption of the hydrogenation of oil and fat and the TFAs formed in the oil was determined. When the reaction pressure exceeded 3.0 MPa, the hydrogenation of oil was consumed. The amount of hydrogen, the rate of hydrogenation, and the change in the TFAs all stabilized. Therefore, the pressure of the general hydrogenation reaction should not exceed 3.0 MPa. This result provides a quick and simple method for controlling TFAs in oils and fats for industrial applications.

Catalytic Transfer Hydrogenation of Low-erucic-acid Rapeseed Oil over a Ni-Ag0.15/SBA15 Catalyst.

The kinetics of catalytic transfer hydrogenation (CTH) of low-erucic-acid rapeseed oil using ammonium formate as a hydrogen donor over a Ni-Ag0.15/SBA15 catalyst were studied. Then, a kinetic model for the hydrogenation of low-erucic-acid rapeseed oil was established, and it was found that the reaction rate constants of hydrogenations of 9c-18:1 and 12c-18:1 oleic acid were 0.1262 and 0.0148, and the catalytic selectivity of linoleic acid was 2.04. For the catalyst loading of 0.23%, the hydrogenation temperature was 80°C, the ammonium formate concentration was 0.32 mol/50 mL, and the low-erucic-acid rapeseed oil was hydrogenated in 90 min; it was also found that the iodine value of low-erucic-acid rapeseed oil was 80 g I2/100 g, the oleic acid content was 65%, and the trans fatty acids (TFAs) content was only 6.7%. Therefore, CTH may be widely used in the modification of oils and fats.

Enzyme-assisted Aqueous Extraction of Oil from Rice Germ and its Physicochemical Properties and Antioxidant Activity.

Enzyme-assisted aqueous extraction of rice germ oil (RGO) was performed in this study. The physicochemical properties, fatty acid composition, bioactive substances and antioxidant activity of RGO were analyzed. An enzyme composed of alcalase and cellulase (1:1, w/w) was found to be the most effective in the extraction yield of oil. The optimal oil yield of 22.27% was achieved under the conditions of an enzyme concentration of 2% (w/w), incubation time of 5 h, incubation temperature of 50°C, water to seed ratio of 5:1, and pH 6.0. The predominant fatty acids of RGO were oleic acid (39.60%), linoleic acid (34.20%) and palmitic acid (20.10%). The total saturated fatty acid (SFA), monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) composition of RGO were 22.50%, 39.60% and 36.00%, respectively. RGO yielded a high content of γ-oryzanol (530 mg/100 g oil), tocotrienol (62.96 mg/100 g oil), tocopherol (23.24 mg/100 g oil) and a significant amount of phytosterol (372.14 mg/100 g oil). It exhibited notable antioxidant activities with IC50 values of 32.37 and 41.13 mg/mL, according to the DPPH radical scavenging assay and ß-carotene/linoleic acid bleaching test, respectively.

Ni-Ag Bimetallic Magnetic Catalyst Improves the Performance of the Catalytic Transfer Hydrogenated Soybean Oil.

The role of Ni-Ag bimetallic magnetic catalysts in the catalytic transfer of hydrogenated soybean oil was studied. First, a Ni-Ag0.15/PVP-DB-171/SiO2/Fe3O4 magnetic catalyst with a magnetic saturation value of 10.431 emu / g was prepared. It was found that the addition of the metal Ag promoter enhanced the dispersion of Ni on the PVP-DB-171/SiO2/Fe3O4 support. The conditions of the catalytic transfer hydrogenation (CTH) (temperature 80°C, catalyst loading 0.23%, donor concentration 0.32 mol /50 mL H2O, and time 90 min) showed the effects of the bimetallic catalysts on the soybean oil hydrogenation process. The hydrogenated soybean oil linolenic acid, linoleic acid and oleic acid reaction rate constants were 4.95×10-2, 8.6×10-3 and 7.54×10-4, respectively. The selectivity of linolenic acid and linoleic acid is as high as 5.75 and 11.4, respectively; the iodine value (IV) of soybean oil after hydrogenation is 102 g I2/100g and the trans fatty acids(TFAs) content is only 1.7%. The use efficiency of the catalyst decreased to 60% after 8 cycles. Catalytic transfer hydrogenation has important research significance and application prospects for the preparation of low-trans hydrogenated oils and fats. This method also provides a theoretical basis for the development of the oil hydrogenation industry.

Study on the Electrochemical Hydrogenation of Soybean Oil under H2 Conditions.

The solubility of H2 in electrolytes, H2 reaction consumption and the conductivity of electrolytes under different pressures in an electrochemical hydrogenation reactor were studied. It was found that with an increase in H2 pressure, H2 was electrolyzed at the anode, accompanied by the generation of H+. The solubility of H2 in the electrolytes and the conductivity of the electrolytes also increased. At first, the reaction consumption increased, followed by a tendency to be stable at 3 MPa. Therefore, the electrochemical hydrogenation of soybean oil was carried out at a H2 pressure of 3 MPa. When the current was 120 mA, the temperature was 50°C, the agitation speed was 300 rpm, and the time was 7.5 h, the IV of hydrogenated soybean oil was 99.6 g I2/100 g oil, and the TFA content of the oil was 4.3%.

Preparation of Margarine Stock Rich in Naturally Bioactive Components by Enzymatic Interesterification.

Fully hydrogenated expanded press soybean oil (FHEPSO) rich in naturally bioactive components was prepared using Palladium on Carbon (Pd/C) catalyst. Interesterified fat was prepared from binary blends of FHEPSO and cold press corn oil (CPCO) with FHEPSO/CPCO mass ratios of 50:50, 40:60 and 30:70. Lipozyme RM IM (6 wt% of total substrate) was used in a supercritical CO2 system to catalyze the transesterification. The fatty acid compositions had no significant changes in the fats before and after interesterification, and trans-fatty acid (TFA) was not detected. The fatty acid compositions within triacylglycerol (TAG) were rearranged, and the amounts of trisaturated and triunsaturated TAG decreased, whereas that of mixed TAG increased as a result of interesterification. The enzymatic interesterified fats (EIEF) had a lower solid fat content (SFC), broader melting and plasticity ranges compared to the noninteresterified blend (NIB). According to X-ray diffraction (XRD), the predominant crystal form had changed from ß to ß'. EIEF contained 0.33-0.51 g/100 g phospholipids, 88.6-105.6 mg/100 g total tocopherols, and 916-1053 mg/100 g total phytosterols, which could confer health benefits. The results indicated that EIEF may have a potential use in trans-free margarine stock preparation.