The active forms of Au and Pt in CeO2-based catalysts for the water–gas shift (WGS) reaction are an issue that remains unclear, although it has been widely studied. On one hand, ionic species might ...be responsible for weakening the Ce–O bonds, thus increasing the oxygen mobility and WGS activity. On the other hand, the close contact of Au or Pt atoms with CeO2 oxygen vacancies at the metal–CeO2 interface might provide the active sites for an efficient reaction. In this work, using in situ X-ray absorption spectroscopy, we demonstrate that both Au and Pt remain unoxidized during the reaction. Remarkable differences involving the dynamics established by both species under WGS atmospheres were recognized. For the prereduced Pt catalyst, the increase of the conversion coincided with a restructuration of the Pt atoms into cuboctahedrical metallic particles without significant variations on the overall particle size. Contrary to the relatively static behavior of Pt0, Au0 nanoparticles exhibited a sequence of particle splitting and agglomeration while maintaining a zero oxidation state despite not being located in a metallic environment during the process. High WGS activity was obtained when Au atoms were surrounded by oxygen. The fact that Au preserves its unoxidized state indicates that the chemical interaction between Au and oxygen must be necessarily electrostatic and that such an electrostatic interaction is fundamental for a top performance in the WGS process.
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Walnut (Juglans regia L.) is the most widespread tree nut in the world. There is a great diversity of genotypes differing in forestry, productivity, physical and chemical nut traits. Some of them ...have been evaluated as promising and may serve as germplasm sources for breeding. The nutritional importance of the nut is related to the seed (kernel). It is a nutrient-dense food mainly owing to its oil content (up to 740 g kg⁻¹ in some commercial varieties), which can be extracted easily by screw pressing and consumed without refining. Walnut oil composition is dominated largely by unsaturated fatty acids (mainly linoleic together with lesser amounts of oleic and linolenic acids). Minor components of walnut oil include tocopherols, phospholipids, sphingolipids, sterols, hydrocarbons and volatile compounds. Phenolic compounds, present at high levels in the seed coat but poorly extracted with the oil, have been extensively characterised and found to possess strong antioxidant properties. The oil extraction residue is rich in proteins (unusually high in arginine, glutamic and aspartic acids) and has been employed in the formulation of various functional food products. This review describes current scientific knowledge concerning walnut genetic resources and composition as well as by-product obtainment and characteristics. Copyright
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The oil yield, fatty acid composition and the physicochemical and quality characteristics of chia crude seed oils obtained by pressing and solvent extraction were determined. The extraction methods ...assayed influenced significantly the oil yield, obtaining about 30% more oil by solvent than by pressing. The main fatty acids ranked in the following order of abundance: α-linolenic acid (α Ln)
>
linoleic acid (L)
>
oleic acid (O)
≈
palmitic acid (P)
>
stearic acid (S) for both extraction systems. The
n-3/
n-6 FA ratio of chia oils ranged from 3.18 to 4.18, being markedly higher than that reported for other vegetable oils. The main triacylglycerols were: αLnαLnαLn
>
αLnαLnL
>
αLnLL
>
αLnαLnP
>
αLnLO
∼
αLnLP, which represent about 87–95% of the total content of these compounds. The quality and composition of some minor constituents of chia seed oils were influenced by the extraction process. Oils presented a moderate content of bioactive components, such as tocopherols, polyphenols, carotenoids and phospholipids; the high unsaturation level determined their low oxidative stability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The chia seed (Salvia hispanica L.) is globally popular and valued for its nutritional and health attributes. Chia oil is mainly composed of triglycerides, in which polyunsaturated fatty acids ...(PUFAs, linoleic and α-linolenic acids) are found in high amounts. Although it seems evident that such fatty acid composition is favorable from a nutritional point of view, a higher content of linoleic and linolenic acids results in poorer oxidative stability and shorter shelf life of the oil. The aim of this study was to evaluate the combined effects of the storage condition (300 days under fluorescent light - 800 Lux - or in the dark, both at room temperature) with the addition of natural antioxidants (rosemary extract, RE; tocopherol, TOC; ascorbyl palmitate, AP). In the dark, the combined addition of AP and TOC significantly reduced lipid oxidation and improved oil shelf life. Moreover, this combination maintained an acceptable quality of at least up to 300 storage days. Results from this work highlight the influence of illumination condition on chia oil oxidative stability, suggesting that this oil should be stored in containers with light-barrier properties, and probably added to the antioxidants examined in the current study.
•Chia oil is susceptible to oxidation and should be protected during storage.•Natural antioxidants could be effective to prevent chia oil oxidation.•The effect of combination of PA and TOC was greater to that achieved with TBHQ.
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Summary
The present work studied the effect of the incorporation of encapsulated chia seed oil on the cooking quality of dry pasta. Pasta morphology and oil distribution in the samples were studied. ...No significant variations were determined in cooking parameters as optimal cooking time, cooking loss and texture of cooked pasta with the incorporation of the encapsulated oil, but significant differences were determined in uncooked pasta texture and variables that describe water interaction, such as water absorption and swelling index. In addition, the incorporation of microencapsulated oil avoided oxidative deterioration, showing a protective effect and preventing the formation of hydroperoxide radicals in pasta preparation, storage and cooking procedures (compared with free oil‐containing pasta), resulting in a safer product. Storage at modified atmosphere exerts an additional protective effect on oil, enhancing the effect of the microcapsules. Microencapsulation proved to be an effective technology that preserves oil quality in ω‐3 rich pasta.
The incorporation of microencapsulated chia seed oil did not modify pasta cooking quality and textural properties of cooked pasta. Microencapsulation technology preserves chia oil oxidative stability during pasta preparation, storage and cooking for consumptionThe incorporation of microencapsulated chia seed oil did not modify pasta cooking quality and textural properties of cooked pasta. Microencapsulation technology preserves chia oil oxidative stability during pasta preparation, storage and cooking for consumption.
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The main aim of the study was to develop a vegetable oil (VO) microencapsulation process using a spray drying technique with the aid of the response surface methodology (RSM). The specific objectives ...were to evaluate the operating condition effect on VO powder qualities and analyze the microstructure and rancidity on VO microcapsules obtained under set conditions that lead to high solid yields. Maltodextrin and hydroxypropylmethylcellulose were used as wall materials. The influence of spray drying process variables over solid yield (SY), moisture content (MC), surface oil (SO) and encapsulation efficiency (EE) was studied. All experiments led to high values of EE, while SY and MC were significantly affected by modifying spray drier conditions, allowing the enhancement of SY when the optimization process was applied. The optimized VO microcapsules presented an external surface with a continuous wall and no apparent pores; with low moisture content, high VO content retained into microcapsules and low peroxide value.
The main aim of the study was to develop a vegetable oil (VO) microencapsulation process using a spray drying technique with the aid of the response surface methodology (RSM) and to evaluate the influence of operating conditions on VO powder qualities. Display omitted
•The response surface methodology was used to optimize the microencapsulation process.•Solid yield was improved by the changes on the process variables.•Optimized sunflower oil microcapsules presented high encapsulation efficiency.•The optimized process preserves the sunflower oil chemical quality.
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Chia oil represents the vegetable source with the highest content of omega-3 fatty acids. However, the incorporation of polyunsaturated fatty acids into food is limited due to their susceptibility ...toward oxidation. This investigation aimed to study the microencapsulation of chia oil (CO), using gallic acid (GA) crosslinked-soy protein isolate (SPI) as a wall material and its effect on its oxidative stability.
Microcapsules presented a moisture content, water activity, and encapsulation efficiency of around 2.95-4.51% (w.b.); 0.17 and 59.76-71.65%, respectively. Rancimat tests showed that with higher GA content, the induction period increased up to 27.9 h. The storage test demonstrated that the microencapsulated oil with crosslinked wall material has lower values of hydroperoxides and higher induction times concerning the non-crosslinked oil. Finally, the fatty acid profile at this storage time indicated that microcapsules with GA did not have significant changes. In vitro digestion exhibited a reduction in the percentage of bioavailable oil for crosslinked microcapsules, but with no variations in its chemical quality, and an increase in the total polyphenols amount and antioxidant activity.
The results obtained demonstrated that the microencapsulation of chia oil using SPI cross-linked with GA as wall material exerted a very important protective effect since a synergistic effect could be described between the microencapsulation effect and the antioxidant power of GA. This article is protected by copyright. All rights reserved.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A study of the microencapsulation process of omega-3 rich oil extracted from chia (Salvia hispanica L.) seeds was carried out, which included a comparative analysis of the microcapsules obtained by ...the spray- and freeze-drying methods using isolated soy proteins and maltodextrin as wall materials at different proportions. Color characterization of the obtained powders was performed and revealed a darker and yellower appearance of the freeze-dried samples compared with the spray-dried ones. Moisture content was measured for each sample and all presented values around 3.5%. The SEM micrographs revealed that spray-dried microcapsules can occur individually or may form clusters or aggregates, with the particles exhibiting a size range varying from 4 to 10μm. Encapsulation efficiency was measured, with no significant differences found between drying methods or on varying the proportion of wall components (all samples presented values of approximately 60%). The oxidative stability of microencapsulated oils under accelerated oxidative conditions revealed protection factors 2-fold higher for all samples. In addition, microencapsulated oil stored under 25°C revealed lower hydroperoxide values than those of unencapsulated oil throughout the whole storage test. Finally, oil encapsulated in SPI microcapsules also showed lower HPV values than that of the acceptable limit for virgin and cold-pressed vegetable oils (15meq.O2/kg oil) during the storage test, while unencapsulated oil attained the acceptable limit in 62days. This result represents an increase in the time of the oil shelf life of between 30 and 48%.
Display omitted
•A study of the microencapsulation process of omega-3 rich oil was developed.•Microcapsules presented a spherical morphology without pores and fissures.•RE and EE were not altered with the variation of wall components and drying method.•Protected oil showed lower hydroperoxide values than bulk oil in the storage test.•Chia oil powders stored for 90days presented IP values below the codex limits.
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The objective of this study was to evaluate the oil extraction process from walnut seeds by pressing followed by extraction with supercritical CO
2. In pressing experiments, a factorial arrangement ...was conducted in order to study the combined effects of seed moisture content (2.5%, 4.5% and 7.5%) and pressing temperature (25, 50 and 70
°C) on oil recovery and quality parameters. For all conditions tested, the oil quality compared well with that of cold-pressed walnut oil. Oil recovery increased significantly as moisture content raised. Highest oil recovery (89.3%) was obtained at 7.5% moisture content and 50
°C temperature. The cake resulting from pressing at these conditions was extracted with CO
2 in a high pressure pilot plant with single stage separation and solvent recycle. The effects of two different pressures (200 and 400
bar) and temperatures (50 and 70
°C) with regard to oil yield and quality, and time required for extraction were analyzed. At each condition, the extraction rate changed with the mass of solvent and extraction time. At first, the mass of oil extracted was determined by the oil solubility in CO
2 and a linear relationship was observed, where the slope results in the solubility of oil in CO
2 at the experiment conditions. After that, the extraction rate was governed by solubility and diffusion, and continuously decreased with time. The colour changed along the extraction from a whitish clear product to a yellow one. Tocopherol and carotenoid contents were significantly higher than those obtained by pressing. Extraction conditions did not affect significantly the fatty acid composition.
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