Whey protein isolate and inulin-glycosylated conjugate affect the physicochemical properties and oxidative stability of pomegranate seed oil emulsion.

Glycosylated protein was obtained by the reaction of whey protein isolate(WPI) with inulin of different polymerization degrees and was used to stabilize a pomegranate seed oil emulsion. The physicochemical and antioxidative properties of the emulsions were assessed, and the impacts of accelerated oxidation on pomegranate seed oil were examined. The interfacial tension of WPI and short-chain inulin (SCI)-glycosylated conjugate (WPI-SCI) gradually decreased with increasing glycosylation reaction time. Emulsions stabilized by WPI-SCI (72 h) were the most stable, with a thick interfacial film on the surface of the droplets. After accelerated oxidation for 72 h, WPI-SCI inhibited the oxidation of oil in the emulsion. GC-IMS results showed that the production of harmful volatile components in oil was inhibited, and the peroxide strength was less than 30 mmol/kg oil. This study contributes to understanding of stable storage of lipids.

Natural antioxidants enhance the oxidation stability of blended oils enriched in unsaturated fatty acids.

BACKGROUND: Rancidity causes unpleasant tastes and smells, and the degradation of fatty acids and natural antioxidants, so that an oil is unfit to be consumed. Natural antioxidants, including tocopherols, polyphenols (sesamol, canolol, ferulic acid, caffeic acid, etc.), ß-carotene, squalene and phytosterols, contribute to delay the oxidation of vegetable oils. However, studies on the combination of natural antioxidants to lengthen the shelf life of unsaturated fatty acid-rich blended oil have not been reported. RESULTS: All of the composite antioxidants had the potential to significantly improve the oxidation stability of blended oil. Blended oil G with 0.05 g kg-1 ß-carotene, 0.25 g kg-1 sesamol and 0.25 g kg-1 caffeic acid showed the best anti-autooxidation. It is also effective in improving the oxidative stability of vegetable oils containing various fatty acids. The oxidation stability index of the blended oil containing the optimum composition of natural antioxidants was 2.17-fold longer than that of the control sample. After the end of accelerated oxidation, the oil's peroxide value, p-anisidine value and total oxidation value were 6.59 times, 12.26 times and 6.65 times lower than those of the control sample, respectively. CONCLUSION: (1) The combination of natural antioxidants ß-carotene (0.05 g kg-1 ), sesamol (0.25 g kg-1 ) and caffeic acid (0.25 g kg-1 ) enhances the oxidative stability of unsaturated fatty acid-rich blended oils. (2) ß-Carotene is the main antioxidant in the early stages of oxidation. (3) Sesamol and caffeic acid are the main antioxidants in the middle and late stages of oxidation. © 2023 Society of Chemical Industry.

Effects of Endogenous Anti-Oxidative Components from Different Vegetable Oils on Their Oxidative Stability.

The effects of endogenous anti-oxidative components of ten common edible vegetable oils (palm olein, corn oil, rapeseed oil, soybean oil, perilla seed oil, high oleic sunflower oil, peanut oil, camellia oil, linseed oil, and sesame oil) on oxidation were explored in this research. The oxidation processes and patterns of the oils were investigated with the Schaal oven test using fatty acids and the oxidative stability index, acid value, peroxide value, p-anisidine value, total oxidation value, and content of major endogenous anti-oxidative components as indicators. The major endogenous anti-oxidative components in vegetable oils were tocopherols, sterols, polyphenols, and squalene, among which α-tocopherol, ß-sitosterol, and polyphenols showed good anti-oxidative activity. However, squalene and polyphenols were relatively low and showed limited anti-oxidative effects. Moreover, the oxidative stability index of edible vegetable oils oxidized at high temperature (120 °C) was positively correlated with the content of saturated fatty acids (r = 0.659) and negatively correlated with the content of polyunsaturated fatty acids (r = -0.634) and calculated oxidizability (r = -0.696). When oxidized at a low temperature (62 °C), oxidative stability was influenced by a combination of fatty acid composition as well as endogenous anti-oxidative components. An improved TOPSIS based on Mahalanobis distance was used to evaluate the oxidative stability of different types of vegetable oils. Moreover, the oxidative stability of corn oil was better than the other vegetable oils, while perilla seed oil was very weak.

In Situ Current-Accelerated Phase Cycling with Metallic and Semiconducting Switching in Copper Nanobelts at Room Temperature.

Here, a current-accelerated phase cycling by an in situ current-induced oxidation process was demonstrated to reversibly switch the local metallic Cu and semiconducting Cu2O phases of patterned polycrystalline copper nanobelts. Once the Cu nanobelts were applied by a direct-current bias of ∼0.5 to 1 V in air with opposite polarities, the resistance between several hundred ohms and more than MΩ can be manipulated. In practice, the thickness of 60 nm with a moderate grain size inhibiting both electromigration and permanent oxidation is the optimized condition for reversible switching when the oxygen supply is sufficient. More than 40% of the copper localized beneath the positively biased electrode was oxidized assisted by the Joule heating, blocking the current flow. On the contrary, the reduction reaction of Cu2O was activated by the thermally assisted electromigration of Cu atoms penetrating the interlayer at the reverse bias. Finally, based on a high on/off ratio, the fast switching and the scalable production, reusable feasibility based on copper nanobelts such as the memristor array was demonstrated.

Comparison of Three Accelerated Oxidation Tests Applied to Red Wines with Different Chemical Composition.

BACKGROUND: Three accelerated oxidation tests were proposed to simulate red wine oxidation thus providing information useful to correctly manage moderate oxygen exposure of wine during aging in regard to phenolic composition and wine color. Since the results of the tests have never been compared on wines with different initial composition, the aim of this study was to find a suitable method to simulate oxidation of any still red wine. METHODS: Aglianico, Barbera, Gaglioppo, Magliocco, and Nerello wines were treated with (1) three cycles of air saturation, (2) the addition of hydrogen peroxide, and (3) the addition of acetaldehyde. Changes in chromatic characteristics and phenolic composition were determined by spectrophotometric and HPLC methods. RESULTS: Important differences in the behavior of the different wines were detected: the highest formation of polymeric pigments was observed in Barbera and Aglianico wines. In contrast, Gaglioppo and Magliocco wines showed a lower variability before and after the oxidation probably due to the lower anthocyanin/tannin ratio. Among the accelerated oxidation tests applied, no significant differences in color parameters and phenolic composition were detected in samples treated with the addition of H2O2 and the air saturation method. CONCLUSION: The study demonstrated that H2O2 addition is a successful tool to predict the evolution of different phenolic compounds during the air saturation treatment of wines.

Partial replacement of pork fat by Echium oil in reduced sodium bologna sausages: technological, nutritional and stability implications.

BACKGROUND: The present research aimed to evaluate the nutritional, technological, microstructural and sensory characteristics of bologna sausages made with pork fat replaced with Echium oil. Three different treatments were processed, all of them with approximately 35% less sodium than a regular bologna-type sausage: Control (only pork backfat addition) and T25 and T50 (replacement of 25 and 50% of the added animal fat with Echium oil respectively). RESULTS: Proximate composition, texture profile analysis, fatty acid profile and microstructure were evaluated to characterize the products. In refrigerated storage, the following characteristics were assessed: thiobarbituric acid-reactive substances (TBARS) index, objective color, pH value, microbiological counts and sensory acceptance. Both samples with Echium oil (T25 and T50) showed a healthier lipid profile, with high omega-3 content, mainly from α-linolenic and stearidonic fatty acids, consequently presenting better (P ≤ 0.05) values of nutritional indices than the Control. However, the replacement of 50% animal fat with Echium oil negatively affected (P ≤ 0.05) most of the technological characteristics and the sensory acceptance of bolognas. In contrast, the treatment with 25% replacement did not show significant differences in most of the evaluated parameters compared with the Control sample. CONCLUSION: Thus the replacement of 25% of pork backfat with Echium oil in bologna sausages can be recommended, representing a good balance between nutritional gains and sensory impairment. © 2019 Society of Chemical Industry.

Monitoring of Oxidation Process of Human Milk Lipid Substitutes by Molecular Fluorescence Spectroscopy / 分析化学

The fatty acid contents in soybean oil, corn oil, coconut oil, sunflower seed oil and fish oil were detected by gas chromatography. According to the characteristics of fatty acids of raw oil and the relevant regulations of GB 10765-2010,the formula of 6 kinds of human milk lipid substitutes was designed by Matlab software and Excel linear programming. At the same time, the Schaal oven accelerated oxidation method was used to study the oxidation process of 6 formulations using synchronous fluorescence technique combined with traditional chemical reagents (oxidation index:peroxide value,value of fennel and total oxidation value). By statistical analysis of data, the statistical relationship between fluorescence intensity and oxidation index was explored. The results showed that the main fatty acids of coconut oil were lauric acid and myristic acid,and its saturated fatty acid content was the highest 93.75% ±0.06%;while all the other oils were mainly composed of palmitic acid,linoleic acid and other components,wherein the fish oil had the highest content of unsaturated fatty acid. With the increase of oxidation time,the fluorescence intensity decreased gradually and the oxidation index value increased continuously. The correlation analysis and regression analysis results showed that the change of oxidation index and the fluorescence intensity of 6 samples had negative correlation, and the fluorescence intensity and the peroxide value and total oxidation value was quadratic linear correlation, and anisidine value as a linear correlation had strong correlation.

Aplicação de planejamento fatorial na oxidação de óleos contendo diferentes tipos de ácidos graxos ômega 3 / The use of factorial design to evaluate the oxidation of oils containing differents types of omega 3 fatty acids

Óleos contendo alta proporção de ácidos graxos ômega-3 (n-3 FA) têm sido aplicados na formulação de alimentos ou comercializados como suplementos, com a finalidade de reduzir o risco cardiovascular, principalmente devido aos seus efeitos hipotriglicêmicos e anti-inflamatórios. No entanto, a susceptibilidade à oxidação dos n-3 FA é elevada, levando à formação de vários produtos secundários, incluindo alguns tóxicos e potencialmente aterogênicos. Por esta razão, compostos naturais com propriedades antioxidantes têm sido investigados com o objetivo de melhorar a estabilidade oxidativa dos óleos com alta proporção de n-3 FA. Neste estudo, avaliou-se a capacidade antioxidante de dois compostos naturais (ácido sinápico e hidrato de rutina) utilizando-se um modelo acelerado para oxidar os óleos. Foram combinados cinco indutores (Temperatura; Ferro- Fe2+; 2,2'-Azobis dicloridrato de 2-amidinopropano - AAPH; ascorbil palmitato - AP e 2,2'-azobis -2,4-dimetilvaleronitrilo - AMVN) em um delineamento fatorial (25-1) com ½ fração de "resolução V" para acelerar a oxidação de três óleos (linhaça, Echium e peixe) contendo diferentes fontes de n-3 FA: ácido α-linolênico (ALA), ácido estearidônico (SDA) e ácido eicosapentaenóico (EPA) + ácido docosahexaenóico (DHA), respectivamente. Não houve diferença entre os marcadores de oxidação (LOOH e TBARS) estimados pelos modelos e os valores observados experimentalmente. Os indutores AMVN e Fe2+ foram os principais fatores responsáveis pelo aumento da concentração de TBARS. Os valores dos marcadores oxidativos obtidos 48 h após a indução foram semelhantes ou superiores àqueles observados nas amostras oxidadas a 60°C por 15 dias, sendo ambos maiores que os valores observados nas amostras de óleo frescas. Entre os compostos voláteis formados pela oxidação de diferentes fontes de n-3 FA, (E, E) 2,4 -heptadienal, (E, E) 2,4-decadienal, decanal, undecanal e (E) -2-undecenal foram identificados em todas as amostras, podendo ser utilizados como marcadores oxidativos mais específicos. Utilizando o modelo de oxidação acelerada, o hidrato de rutina melhorou a estabilidade oxidativa do óleo de peixe, provavelmente devido à presença de grupos catecol em sua estrutura química. Este estudo contribuiu para que ensaios mais rápidos fossem realizados na avaliação do efeito antioxidante de novas moléculas aplicadas em óleos funcionais comestíveis

Oils containing a high proportion of omega-3 fatty acids (n-3 FA) have been used in the formulation of foods or sold as supplements, aiming to reduce cardio-vascular risks, mainly due to their hypotriglycemic and anti-inflammatory effects. However, n-3 FA are highey susceptible to oxidation, leading to the formation of several products, including some toxic and potentially atherogenic. For this reason, natural products with antioxidant properties have been investigated to improve the oxidative stability of oils with a high proportion of n-3 FA. This study evaluated the antioxidant capacity of two natural compounds (sinapic acid and rutin hydrate), using an accelerated model to oxidize the oils. Five inducers were combined (Temperature, Iron-Fe2+, 2,2'-Azobis (2-amidinopropane) dihydrochloride-AAPH, Ascorbyl palmitate-AP and 2,2'-azobis-2,4-dimethylvaleronitrile-AMVN) in a factorial design (25-1) ½ fraction of "resolution V" to accelerate the oxidation of three oils (flaxseed, Echium and fish) containing different sources of n-3 FA: α-linolenic acid (ALA), stearidonic acid (SDA) and eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), respectively. There was no difference between the oxidation markers (LOOH and TBARS) estimated by the regression models and the values experimentally observed. The inducers AMVN and Fe2+ were the main factors responsible for the increase of TBARS concentration. The values of the oxidation markers obtained 48h after the induction were similar to or higher than those obtained when the samples were oxidized at 60°C for 15 days, both being more elevated than the values observed in the fresh oils. Among the volatile compounds formed by the oxidation of different sources of n-3 FA, (E, E) 2,4-heptadienal, (E, E) 2,4-decadienal, decanal, undecanal and (E)-2-undecenal were identified in all samples, and could be used as more specific oxidation markers. Using the accelerated model, rutin hydrate improved the oxidative stability of fish oil, probably due to the presence of catechol groups in its chemical structure. This study showed that faster anays could be performed to evaluate the antioxidant effect of new molecules applied on edible functional oils

A new test for plant bioaccessibility in sulphidic wastes and soils: A case study from the Wheal Maid historic tailings repository in Cornwall, UK.

Currently, bioaccessibility testing at contaminated sites is dominated by techniques designed to assess oral bioaccessibility to humans. Determining the plant bioaccessibility of toxic trace elements is also important. In mining landscapes, sulphides are an important source of potentially toxic elements. Simple tests to evaluate readily leachable metals and metalloids exist but do not extract elements temporarily constrained within the sulphide fraction. Sequential extractions describe the association of trace elements with different geochemical fractions but are time consuming, costly and provide excessive detail. This paper proposes a new test for plant bioaccessibility in sulphidic mine wastes and soils that uses hydrogen peroxide to simulate environmental oxidation. The bioaccessible fraction determined is operationally defined and does not predict actual plant uptake. The test targets a) the portion of an element that is currently available in the pore water for uptake by plant roots and also b) the fraction that is temporarily constrained in sulphide minerals but may become available upon oxidation of the substrate. A case study was conducted at a historic mine waste repository site in Cornwall, U.K. where near total As concentrations were extremely elevated and Cd, Cu, Pb, Sb and Zn were also high. Our test determined that bioaccessible concentrations of As, Cd, Cu and Zn and to a lesser extent Sb and Pb were highest in samples of pyritic grey tailings. This is attributed to sulphide mineral oxidation and, particularly for Cd and Zn, the dissolution of soluble secondary minerals. High As concentrations in the marbled tailings were not bioaccessible. Results from the case study show that this new test provides useful information on the future bioaccessibility of contaminants, allowing for classification of mineralised sulphidic waste materials which otherwise cannot be obtained using established geochemical and mineralogical techniques. Furthermore, the test is rapid, repeatable and cost effective.

Effect of α-tocopherol on oxidative stability of oil during spray drying and storage of dried emulsions.

Lipophilic compounds such as polyunsaturated fatty acids (PUFAs) and antioxidants can be encapsulated by spray drying in order to protect and prolong their functionalities and get new handling properties. The aim of this work was to study the effect of both the spray drying stage and storage (60°C - 50% RH) on the oxidation of lipophilic compounds encapsulated in spray dried oil-in-water emulsions (10% w/w oil in dry matter) using maltodextrin as matrix and Tween® 20 as emulsifier. Emulsions were prepared with oil containing or not containing α-tocopherol (482ppm in oil) in order to also demonstrate the influence of the antioxidant. Results showed that there is a beginning of oxidation during spray drying, evidenced by a slight increase of markers of rancidity, i.e. conjugated dienes and volatile organic compounds. During storage, the oxidative degradation of PUFAs and α-tocopherol started quickly under the conditions of aging. This was shown to be due to the negative effect of the process and to the porosity of the solid matrix to oxygen, associated with the hollow structure of the particles. An inhibitory action of maltodextrin on α-tocopherol was also hypothesized, but it has to be confirmed.

Effect of the phytochemicals curcumin, cinnamaldehyde, thymol and carvacrol on the oxidative stability of corn and palm oils at frying temperatures.

Several active components naturally available in plants are strongly considered as good antioxidants to retard the lipid oxidation. Response surface methodology was used to investigate the effects of frying temperature (150-180 °C) and concentration of four plant-based active components (60-350 mg/kg oil); curcumin, cinnamaldehyde, thymol and carvacrol on oxidative stability of corn and palm oils. According to induction time values, the stability of oils drastically decreased with increasing temperature. Curcumin and cinnamaldehyde showed no significant effect (p > 0.05) on both oils. Carvacrol significantly increased induction times of corn and palm oils, but thymol was effective in palm oil only (p < 0.05). An actual frying experiment was carried out with only corn oil to confirm efficiency of carvacrol. The free fatty acid (%), peroxide value (meq/kg), para-anisidine, and total polar component values (%) of the fresh oil were 0.080, 2.55, 2.85, and 7.5, respectively. These values changed to 0.144, 1.47, 12.01, 10.0, respectively for the control oil; 0.138, 2.27, 11.49, 10.0 for BHT-added oil; 0.132, 1.42, 5.66, 9.5 for carvacrol-added oil after 30 frying cycles. Therefore, carvacrol could be considered as a good alternative to BHT for preservation of oils at frying temperatures.

Antioxidative properties of Pandanus amaryllifolius leaf extracts in accelerated oxidation and deep frying studies.

The potential uses of Pandanus amaryllifolius leaf extract as a natural antioxidant were evaluated in refined, bleached and deodorized (RBD) palm olein, using accelerated oxidation and deep frying studies at 180°C from 0 to 40h. The extracts (optimum concentration 0.2%) significantly retarded oil oxidation and deterioration (P<0.05), comparably to 0.02% BHT in tests such as peroxide value, anisidine value, iodine value, free fatty acid, oxidative stability index (OSI), polar and polymer compound contents. In sensory evaluation studies, different batches of French fries were not significantly different (P<0.05) from one another for oiliness, crispiness, taste and overall acceptability when the same oil was used for up to the 40th hour of frying. P. amaryllifolius leaf extract, which had a polyphenol content of 102mg/g, exhibited an excellent heat-stable antioxidant property and may be a good natural alternative to existing synthetic antioxidants in the food industry.