Antioxidant Activity of Oat Malt Extracts in Accelerated Corn Oil Oxidation

Oat cultivar AC Vermont was malted to concentrate antioxidants, milled to fractionate only the endosperm portion and extracted with methanol to isolate the crude antioxidants. The oat malt antioxidant fraction was assessed as a natural antioxidant based upon enhancing the stability of corn oil against oxidation and compared to the synthetic antioxidant butylated hydroxytoluene (BHT). The induction time (time required for the formation of 10 meq hydroperoxide per kilogram corn oil thermally oxidized) was used to measure antioxidant activity of oat antioxidant or BHT. The protection factor achieved by crude oat malt antioxidant extract concentrate at 0.26% (2,600 μg/g) was comparable to BHT (75 μg/g). The antioxidant activity of the oat and barley malt extract concentrates was not significantly different. However, the extract concentrate of oat malt had 44% less color compared to that of barley malt at equal concentrations showing its potential as a natural food antioxidant.     

Antioxidant Activity of Added Phenolic Compounds in Freeze-Dried Microencapsulated Sunflower Oil

This study was aimed at evaluating the effectiveness of phenolic antioxidants with a similar structure but having a different polarity in dried microencapsulated sunflower oil. The antioxidants tested were, on one hand, α-tocopherol and its water soluble analogue, Trolox, and on the other, gallic acid and its ester derivatives, propyl gallate and dodecyl gallate. At a moderate temperature (40 °C), the samples were oxidized under accelerated conditions by using Cu(II) as an oxidation catalyst. The progress of oxidation was followed up over time in the free and encapsulated oil fractions. The peroxide value, the total content of polymers and, when appropriate, the content of α-tocopherol were determined. Quantitative analysis of the total fraction of the non-volatile oxidation products and their distribution in oligomers, dimers and monomers was applied to samples to obtain a complete evaluation of oxidation. Finally, as a complementary measure, the antioxidants were also assessed by direct application of the Rancimat test at 100 °C on the dried microencapsulated oil samples. Results showed that the antioxidants of lower polarity in each series, i.e. tocopherol and dodecyl gallate, were to a great extent the most protective antioxidants. The results obtained by the Rancimat test were consistent with those found during oxidation at moderate temperature. Furthermore, the addition of Cu(II) reduced proportionally the oxidative stability index of the dried microencapsulated samples.     

Oxidation and Colloidal Stability of Oil-in-Water Emulsion as Affected by Pigmented Rice Hull Extracts

Extracts from the hull of pigmented rice were prepared using a mixture of methanol–water (1:1, 2:1, and 3:1, v/v) for different extraction times (0–180 min). Total phenolic content (TPC) of the extracts increased with increasing concentration of methanol and extraction time (P < 0.05). A positive correlation between TPC and antioxidant activities, i.e., DPPH and ABTS radical scavenging activities and reducing power, was observed. The extracts prepared using methanol–water at the ratio of 3:1 for 180 min at 50 °C, referred as rice hull phenolic extract (RHPE), showed the highest TPC and free radical scavenging abilities and reducing power (P < 0.05). When the effects of RHPE on physicochemical stability of the emulsions stabilized by different emulsifiers, i.e., Tween 20 and bovine serum albumin (BSA), were examined, the collapse of emulsion was retarded when RHPE was applied in BSA‐based emulsions, whereas a negative effect was noticeable in Tween 20‐based counterpart. Lower oxidative degree was found for BSA stabilized emulsions, compared to Tween 20 containing system. RHPE (1–3 %) markedly improved the oxidative stability, particularly for BSA stabilized emulsions. Therefore, RHPE could be employed along with the selected protein to increase physicochemical stability of emulsion.     

Antioxidant Activity of Hybrid Grape Pomace Extracts Derived from Midwestern Grapes in Bulk Oil and Oil‐in‐Water Emulsions

Natural antioxidants to inhibit oxidation in edible oils are in high demand. Grape pomace is an abundant, inexpensive source of polyphenolic antioxidants, which are responsible for numerous health benefits. We examined pomace from eight varieties of Midwestern hybrid grapes for phenolic content and antioxidant activity. Ethanolic extracts produced from the pomace of each grape variety were added to two model systems, bulk soybean oil and oil‐in‐water emulsions, to determine antioxidant activity. Oxidation was monitored in each model system at a temperature appropriate to that particular system. While the extracts had relatively little effect in bulk oil, we observed dose‐dependent antioxidant effects of some extracts in oil‐in‐water emulsions. Oxidation in bulk oils was assessed via total polar compounds and polymerized triacylglycerols. Oxidation in emulsions was assessed by peroxide value, headspace oxygen measurements, gas chromatography of headspace volatiles, and fatty acid analysis. Pomace extracts derived from red grapes generally outperformed those from white grapes, with the Marechal Foch variety showing high antioxidant activity at intermediate concentrations. At higher concentrations, Marechal Foch, Corot Noir, Frontenac, and Norton extracts showed promising antioxidant activity. This is the first report on antioxidant activity in an oil and emulsion setting for many of these grape varieties.     

Mechanism of the Inhibitory Effect of Hydroxytyrosol on Lipid Oxidation in Different Bulk Oil Systems

The autoxidation of purified triacylglycerols obtained from fish, canola, and olive oils in the presence of different concentrations of hydroxytyrosol at 60–100 °C was evaluated by different kinetic parameters including the stabilizing factor (F) as a measure of effectiveness, the oxidation rate ratio (ORR) as a measure strength, and the antioxidant activity (A) which combines the F and ORR parameters. The overall performance of hydroxytyrosol was attributed to the main reaction of chain termination () as competed with the main oxidation reaction of chain propagation () and, additionally, the antioxidative side reactions of chain propagation ( and ), and the pro‐oxidative side reaction of chain initiation () in some cases.     

利用受限空间装置从低浓度水包油乳状液中分离油相的研究(英文)

A miniature process for separating the oil phase from dilute oil/water emulsion is developed.This process applies a confined space apparatus,which is a thin flow channel made of two parallel plastic plates.The space between the two plates is rather narrow to improve the collisions between oil droplets and the plate surface.Oil droplets have an affinity for the plate surface and thus are captured,and then coalesce onto the surface.The droplet size distribution of the residual emulsion resulted from the separation process is remarkably changed.The oil layer on the plate weakens the further separation of oil droplets from the emulsion.Three types of plate materials,polypropylene(PP),polytetrafluoroethylene(PTFE) and nylon 66,were used.It is found that PP is the best in terms of the oil separation efficiency and nylon 66 is the poorest.The interaction between droplets in the emulsion and plate surface is indicated by the spreading coefficient of oil droplet on the plate in aqueous environment,and the influences of formed oil layer and plate material on the separation efficiency are discussed.     

Antioxidant Activity of Seaweed Extracts: In Vitro Assays,Evaluation in 5 % Fish Oil‐in‐Water Emulsions and Characterization

In this study the antioxidant activity of absolute ethanol, 50 % ethanol and water extracts of two species of seaweeds, namely Fucus serratus and Polysiphonia fucoides, were evaluated both in in vitro assays and in 5 % fish oil‐in‐water (o/w) emulsions. The 50 % ethanolic extracts of P. fucoides showed higher antioxidant activity both in in vitro assays and in 5 % oil‐in‐water emulsion in the presence or absence of iron. In spite of the higher phenolic content and very good antioxidant activity in some of the in vitro assays, the absolute ethanol extracts of both the species showed a pro‐oxidative tendency in 5 % fish oil‐in‐water emulsion in the presence or absence of iron. In order to investigate the reason for the higher antioxidant activity of 50 % ethanolic extracts of P. fucoides, these extracts were further fractionated into polyphenol‐rich, protein‐rich, polysaccharide‐rich and low‐molecular‐weight fractions. These fractions were tested both in in vitro and in 5 % oil‐in‐water emulsions. The results of the present study showed that the main effect was due to the phenolic compounds. In conclusion, the 50 % ethanolic extracts of P. fucoides can be a potential source of natural antioxidants as these extracts have antioxidant activities similar to those of synthetic antioxidants such as BHT.     

Temperature-Dependent Mechanism of Antioxidant Activity of o-Hydroxyl,o-Methoxy,and Alkyl Ester Derivatives of p-Hydroxybenzoic Acid in Fish Oil

The autoxidation of purified fish oil in the presence of different concentrations of o‐hydroxyl, o‐methoxy, and alkyl ester derivatives of p‐hydroxybenzoic at 35–55 °C was evaluated by different kinetic parameters including the stabilizing factor as a measure of effectiveness, the oxidation rate ratio as a measure of strength, and the antioxidant activity which combines the two parameters. Methyl gallate as the most reactive antioxidant participated only in the main reaction of chain termination (ROO· + InH ROOH + In·). Gallic acid, ethyl protocatechuate, protocatechuic acid, vanillic acid, and syringic acid, were able to protect fish oil against oxidation in terms of the extent of their participation in the pro‐oxidative side reactions of chain initiation (InH + ROOH In· + RO· + H₂O and InH + O₂ In· + HOO·) and the antioxidative side reactions of chain propagation (In· + ROO· In‐OOR and In· + In· products).     

Characterization of the Volatile, Phenolic and Antioxidant Properties of Monovarietal Olive Oil Obtained from cv. Halhali

Volatile and phenolic compositions of olive oil obtained from the cv. Halhali were investigated in the present study. Fruits were harvested at the optimum maturity stage of ripeness and immediately processed with cold press. Simultaneous distillation/extraction (SDE) with dichloromethane was applied to the analysis of volatile compounds of olive oil. Sensory analysis showed that the aromatic extract obtained by SDE was representative of olive oil odour. In the olive oil, 40 and 44 volatile components were identified and quantified in 2010 and 2012 year, respectively. The total amount of volatile compounds was 18,007 and 19,178 μg kg^?1 for 2010 and 2012, respectively. Of these, 11 compounds in the 2010 and 12 in the 2012 harvest presented odour activity values (OAVs) greater than 1, with 1‐octen‐3‐ol, ethyl‐3‐methyl butanoate, (E)‐2‐heptenal and (E,Z)‐2,4‐decadienal being those with the highest OAVs in olive oil. The high‐performance liquid chromatographic method coupled with diode‐array detection was used to identify and quantify phenolic compounds of the olive oil. A total of 14 phenolic compounds in both years were identified and quantified in olive oil. The major phenolic compounds that were identified in both years were hydroxytyrosol, tyrosol, elenolic acid, luteolin, and apigenin. Antioxidant activity of olive oil was measured using the DPPH and ABTS methods.     

Role of Water and Selected Minor Components on Association Colloid Formation and Lipid Oxidation in Bulk Oil

This study investigated the influence of water content in combination with selected minor components including oleic acid, stigmasterol, α‐tocopherol, and Trolox on their association colloid formation as well as their impact on lipid oxidation in bulk corn oil. First, surface activity of each minor component was evaluated by determining the ability of these components to lower the interfacial tension between bulk oil and water. All components but α‐tocopherol were able to decrease interfacial tension of stripped oil. Second, the critical micelle concentration (CMC) of each minor component was determined in bulk oil with no water added and in the presence of 1000 ppm of water. In the bulk oil without extraneous water, we could not determine the CMC of minor components in the range of concentrations studied. However, in the presence of 1000 ppm of water, only stigmasterol could form association colloids at the CMC of 20 mmol/kg oil. Last, the effect of water content (400 and 1000 ppm) and minor components on lipid oxidation in bulk oil was studied by following the lipid hydroperoxides and hexanal formation during storage at 55 °C. Different water content did not significantly impact the lag time of lipid oxidation compared with the control. Interestingly, water caused prooxidant by decreasing the lag time of lipid hydroperoxides and hexanal formation in bulk oil containing oleic acid, stigmasterol, and Trolox compared with the control of each system. On the other hand, there was not significant impact of water on the antioxidant activity of α‐tocopherol, a lipid soluble antioxidant in bulk oil. This study highlights the impact of water content on the surface activity of minor components as well as on the oxidative stability in bulk oil.     

Antioxidant activity of sesame,rice bran and bene hull oils and their unsaponifiable matters

Chemical composition of sesame (SEO), rice bran (RBO) and bene hull (BHO) oils was determined. During oven test, peroxide value on day 8 (PV₈, meq/kg) and carbonyl value on day 6 (CV₆, µmol/g) were considered as measures of resistance to the formation of primary and secondary oxidation products, respectively. The SEO and BHO showed statistically the same PV₈ (381.4 and 359.8, respectively) and CV₆ (25.2 and 25.8, respectively), and their stabilizing effect was significantly better than that of the RBO (455.5 and 32.7, respectively). The unsaponifiable matters (USM) fraction of the BHO (443.7 and 26.8, respectively) had an antioxidative effect higher than those of the SEO (478.0 and 38.6, respectively) and RBO (482.4 and 37.4, respectively). There was a good correlation (R² = 0.972) between the PV₈ and CV₆ throughout oxidation period. On the basis of the oxidative stability index (OSI, h) of Rancimat test, the best carry‐through properties belonged to the SEO (6.92 h), followed by the RBO (6.12 h) and BHO (5.0 h), and also a similar order was observed for the USM fractions (5.89, 5.28 and 4.50 h, respectively). There was no correlation between the results of Rancimat and oven tests, showing that the powerful antioxidative agents under oven test conditions were lack of appropriate carry‐through properties. The highest significant reducing power (mmol/L) belonged to the SEO (258.1), followed by the RBO (218.7) and BHO (152.4), whereas the USM fraction of the SEO indicated the least significant quantity among the USM fractions (89.3 vs. 216.6 and 158.0 for the RBO and BHO, respectively).     

Antioxidant Activity and Kinetics Studies of Quercetin,Epicatechin and Naringenin in Bulk Methyl Linoleate

The objective of this work was to evaluate the antioxidant action of flavonoids with specific differences in chemical structure, namely, quercetin (Q), epicatechin (E) and naringenin (N), in bulk methyl linoleate (ML) under different oxidation conditions at 60 °C, in an oven and in a Rancimat apparatus. The oxidation kinetics were studied by direct and concomitant analysis of primary and secondary oxidation compounds. Addition of 200 mg/kg of E or Q to ML increased about tenfold the oxidative stability of ML. The protective effect was significantly higher for E, independent of the oxidation conditions used. However, N showed no effect. Results obtained were attributed to differences in structural features and polarity. Thus, the presence of the ortho-dihydroxy structure in the B ring and the 3-hydroxyl group in the C ring of E and Q seemed to be determinant and the comparatively higher polarity of E may have enhanced its antioxidant efficiency.     

纺丝油剂废水处理工艺研究

纺丝油剂废水是高浓度的O/W型乳状液,具有相当的稳定性。采用“破乳-反渗透”处理工艺得到了良好的实验结果。以自配的DEMUL-B1作为破乳剂,试验并分析了破乳剂的用量、水样的pH值、加热温度和加热时间等因素对破乳效果的影响。以OSMONICS公司的SE反渗透膜对破乳后的水样进一步处理。结果表明,经“破乳-反渗透”处理净化后的水质,其COD的去除率达到99.96%,含油量和浊度的去除率均为100%,达到了污水综合排放一级标准(GB8978-1996),可以直接排放或回用。     

静电强化乳液中油滴(纳米尺度)聚并过程(英文)

Oil droplets in nanometer scale which are dispersed in water cannot be separated easily.An attractive technique is carried out by electrical phenomena to demulsify oil in water emulsion.In this research,non-uniform electric field or dielectrophoresis(DEP) is applied to remove sunflower oil(which is dispersed in the water).Effects of temperature,time and voltage(using AC-electric field) were considered to get the highest DEP-force(Fdi) and the best results.The oil particles sizes with average of approximately 76 nm have been shown using a ZetaSizer Nano ZS,Model ZEN 1600(Malvern Instrument Ltd.).The maximum separation efficiency of 85% is obtained at the optimum temperature of 38 ℃ and voltage of 3000 V.     

比例法和对分法在农药水乳剂配方研制中的应用

以外观、分散性、乳液稳定性、离心稳定性作为实验指标,联合运用比例法与对分法快速研制水乳剂最佳配方。     

我国农药水乳剂的发展现状及稳定机理研究

介绍了农药水乳剂在我国的发展现状,并对水乳剂稳定体系稳定机理及其研究方法进行了综述。在我国,农药水乳剂在1993至2005年12年间共登记108个,至2007年4月处于登记有效期内的品种就达224个,发展速度较快。在水乳剂稳定体系形成机理研究方面已有相体积理论等多种理论,乳液稳定性研究方法则有电导法等多种方法。运用Zeta电位法、单滴法对40%三唑磷EW稳定体系形成机理研究表明,水乳剂体系稳定的关键因素为"乳化剂和物理稳定剂",另外,加工工艺与助剂种类均不同程度地影响水乳剂体系的稳定。     

Influence of Fat and Emulsifier Content on Volatile Release of Butter Aroma Used in Water Phase and Physical Attributes of Model Margarines

Margarines are water‐in‐oil (W/O) emulsion‐type products produced with butter aroma. The aim of this study is to investigate the volatile release of the butter aroma compounds used in the water phase of model margarine and sensory properties influenced by the change of fat and emulsifier. A headspace/solid phase microextraction/gas chromatography/mass spectrometry (HS/SPME/GC/MS) system is used for the identification of the volatile compounds. It is determined that high fat content in model margarine samples results in an increase in the release of both 2,3‐butandione and butanoic acid. On the other hand, an increase in fat content reduces the release of butanoic acid ethyl ester and vanillin. In addition, an increase in the emulsifier content of the model margarines results in a decrease in butanoic acid ethyl ester release. The model margarines with 80% fat content have the highest hardness and storage modulus (G′) values. The perception of butter aroma and taste are more intense in high‐fat margarine samples, while fruity aroma and taste, vanilla aroma, and taste perception are higher in low‐fat margarine samples. However, emulsifier content does not affect the sensory properties of the model margarines. Practical Applications: Decreasing high fat content food intake has become increasingly popular among consumers. Thus, in order to meet consumer demands, manufacturers have begun to reduce the fat content of the foods they produce. However, the flavor properties of a product can change as a consequence of fat content reduction. In order to produce a product in accordance with the properties demanded by the consumer, the change in the flavor of that product should be foreseen depending on the change in fat content. This study aimed to determine the volatile compound release and sensory properties of margarine samples due to fat and emulsifier changes. The findings of this study are a guide for the production of low‐fat products.     

Antioxidant Activity and Total Polyphenols Content of Camellia Oil Extracted by Optimized Supercritical Carbon Dioxide

In this study, Camellia oil is co-extracted from Camellia oleifera seeds and green tea scraps by supercritical carbon dioxide (SC-CO₂), which is optimized on the extraction yield, ABTS-scavenging activity, and total polyphenols content (TPC) of oil by single-factor experiments combined with response surface methodology (RSM). The extraction temperature, pressure, dynamic time, carbon dioxide (CO₂) flow rate, and seed mass ratio were investigated with single-factor experiments. The results indicated the optimum CO₂ flow rate and dynamic extraction time were 15 L hour⁻¹ and 60 min (i.e., 2.382 kg CO₂/100 g sample). Furthermore, the complicated effects of extraction temperature (40–50 °C), pressure (20–30 MPa), and seed mass ratio (0.25–0.75) were optimized by RSM based on the Box–Behnken design (BBD). The models with high R-squared values were obtained and used to predict the optimum operating conditions of the process. Under the optimum operating conditions (i.e., temperature of 46 °C, pressure of 30 MPa, and seed mass ratio of 0.35), the extraction yield, ABTS-scavenging activity, and TPC of oil were 14.43 ± 0.17 g/100 g sample, 73.70 ± 0.34%, and 2.18 ± 0.05 mg GAE/g oil, which were in good agreement with the predicted values. In addition, the experiments indicated that the Camellia oil obtained was rich in polyphenols, resulting in better oxidation stability and antioxidant activity than the original oil.     

Oxidation of Methyl Linoleate in Oil-in-Water Micro- and Nanoemulsion Systems

Oxidation of methyl linoleate in O/W emulsions having droplets of median diameters ranging from 17 nm to 8.0 μm was carried out at 40°C. The oxidation process was analyzed on the basis of a kinetic equation of the autocatalytic type. The induction period was found to be shorter and the oxidation rate constant lower for emulsions with smaller oil droplets. The stoichiometry between methyl linoleate and oxygen was observed to be independent of both the size of oil droplet and the type of the surfactant and was found to be unity during the early stage of the oxidation. However, more oxgen was consumed in the oxidation of the methyl linoleate in the later half of the oxidation process.     

Surfactant Concentration,Antioxidants, and Chelators Influencing Oxidative Stability of Water‐in‐Walnut Oil Emulsions

Effects of surfactant concentration, antioxidants with different polarities, and chelator type on the oxidative stability of water‐in‐stripped walnut oil (W/O) emulsions stabilized by polyglycerol polyricinoleate (PGPR) were evaluated. The formation of primary oxidation products (lipid hydroperoxides) and secondary oxidation products (hexanal) decreased with increasing PGPR concentrations (0.3–1.0 wt% of emulsions). Excess surfactant might solubilize lipid hydroperoxides out of the oil–water interface, resulting in the decreased lipid oxidation rates in W/O emulsions. At concentrations of 10–1000 μM, the polar Trolox demonstrated concentration‐dependent antioxidant activity according to both hydroperoxide and hexanal formation. The antioxidant efficiency of the non‐polar α‐tocopherol was slightly reduced at the higher range of 500–1000 μM based on hydroperoxide formation. Both ethylenediaminetetraacetic acid (EDTA) and deferoxamine (DFO) at concentrations of 5–100 μM reduced the rates of lipid oxidation at varying degrees, indicating that endogenous transition metals may promote lipid oxidation in W/O emulsions. EDTA was a stronger inhibitor of lipid oxidation than DFO. These results suggest that the oxidative stability of W/O emulsions could be improved by the appropriate choice of surfactant concentration, antioxidants, and chelators.