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1.
Tocopherols (Toc), tocotrienols (T3), and γ‐oryzanol (GO), important lipid antioxidants in rice, are known to possess various pharmacological properties. In this study, our aim was to examine the effects of soaking conditions on the extractable contents of Toc, T3, and GO in cooked pigmented (PBR) and non‐pigmented brown rice (non‐PBR). The results showed that Toc, T3, and GO concentrations in non‐PBR peaked after soaking at 25 °C for 120 min, whereas soaking conditions showed minimal effects on these compounds in PBR. In non‐PBR, high Toc, T3, and GO levels were also noted in the treatments at higher soaking temperatures (45 and 55 °C) with a shorter soaking time (less than 60 min). The GO level in both cultivars was at least ten times greater than the total vitamin E content. Vitamin E analogues having concentrations greater than 10 mg/kg in PBR and non‐PBR were γ‐Toc and γ‐T3, and α‐Toc and γ‐T3, respectively. This study concludes that presoaking and cooking processes can improve the extractable contents of Toc, T3, and GO in cooked PBR and non‐PBR, and the extraction yield of these bioactive compounds was significantly different between cultivars.  相似文献   

2.
Corn steryl ferulates (CSF), oryzanol, a combination of equal amounts of CSF and oryzanol, and ferulic acid were added to refined, bleached, deodorized, soybean oil at a concentration of 8.1–8.4 μmol/g oil, which corresponded to 0.5% (w/w) for the steryl ferulates. The rate of polymerized triacylglycerol (PTAG) formation was determined in three replicate, two-day frying experiments using a miniature frying protocol with potato cubes. Oryzanol and ferulic acid slightly inhibited PTAG formation on the first day of frying. However, the two treatments were not significantly different from the SBO control on the second day of frying. CSF and the combination of CSF and oryzanol significantly inhibited PTAG formation on both days of frying, but the combination was slightly more effective on the second day of frying. Tocopherol degradation in SBO with added oryzanol or ferulic acid proceeded more rapidly compared to the control. However, CSF and the combination of CSF and oryzanol appeared to protect tocopherols from degradation. In addition, CSF was more stable to frying compared to oryzanol, but when CSF and oryzanol were combined, CSF protected oryzanol from degradation.  相似文献   

3.
The phase behavior of binary mixtures of γ‐oryzanol and β‐sitosterol and ternary mixtures of γ‐oryzanol and β‐sitosterol in sunflower oil was studied. Binary mixtures of γ‐oryzanol and β‐sitosterol show double‐eutectic behavior. Complex phase behavior with two intermediate mixed solid phases was derived from differential scanning calorimetry (DSC) and small‐angle X‐ray scattering (SAXS) data, in which a compound that consists of γ‐oryzanol and β‐sitosterol molecules at a specific ratio can be formed. SAXS shows that the organization of γ‐oryzanol and β‐sitosterol in the mixed phases is different from the structure of tubules in ternary systems. Ternary mixtures including sunflower oil do not show a sudden structural transition from the compound to a tubule, but a gradual transition occurs as γ‐oryzanol and β‐sitosterol are diluted in edible oil. The same behavior is observed when melting binary mixtures of γ‐oryzanol and β‐sitosterol at higher temperatures. This indicates the feasibility of having an organogelling agent in dynamic exchange between solid and liquid phase, which is an essential feature of triglyceride networks.  相似文献   

4.
Optimal defense theory (ODT) predicts that plant defenses will be allocated to plant organs and tissues in proportion to their relative fitness values and susceptibilities to attack. This study was designed to test ODT predictions on the myrosinase–glucosinolate defense system in Brassica juncea by examining the relationships between the fitness value of B. juncea cotyledons and the levels and effectiveness of cotyledon defenses. Specifically, we estimated fitness value of cotyledons during plant development by measuring plant growth and seed production after cotyledon damage or removal at successive seedling ages. Cotyledon removal within five days of emergence had a significant impact on growth and seed production, but cotyledon removal at later stages did not. Consistent with ODT, glucosinolate and myrosinase levels in cotyledons also declined with seedling age, as did relative defenses against a generalist herbivore, Spodoptera eridania, as estimated by bioassay. Declines in glucosinolates were as predicted by a passive, allometric dilution model based on cotyledon expansion. Declines in myrosinase activity were significantly more gradual than predicted by allometric dilution, suggesting active retention of myrosinase activity as young cotyledons expand.  相似文献   

5.
Mixtures of γ-oryzanol and β-sitosterol are able to form transparent organogels in edible oils. Small-angle X-ray scattering was used to elucidate the microstructure of the building blocks of these organogels in sunflower oil. It was found that the plant sterol(ester)s form hollow tubes with a diameter of 7.2 ± 0.1 nm. Tubes prepared with γ-oryzanol-rich structurant show the least bundle aggregation, and can be supercooled during formation most easily. The tubes melt at elevated temperatures, in agreement with the loss of structuring capacity as observed in earlier experiments.  相似文献   

6.
The aim of this study was to determine the effect of avocado fruit maturity (as estimated by time of harvest during the season) on cold-pressed oil yield. ‘Hass’ avocado fruit at six different stages of on-tree maturity (harvested between September and April 2016/2017) were processed in a commercial cold-pressed oil extraction plant. After destoning and grinding, the fruit pulp was malaxed for 120 min. Avocado pulp samples were examined by light microscopy, electrical conductivity, and electrical impedance spectroscopy. More intact parenchyma cells were observed by microscopy in early-season fruit. The greatest cell disruption occurred after the grinding step as shown by electrical resistance values. The late-season fruit were found to have higher conductivity and lower electrical resistance values which indicated more cell disruption occurred during extraction. Cell walls extracted from fruit harvested later in the season showed a higher yield of the water-soluble polysaccharides and a lower yield of the trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CDTA)-soluble polysaccharides. The cold-pressed oil extraction yield (g oil/100 g fresh flesh) was found to increase with fruit maturity from 10.4 in the early season to 22.5 (g oil/100 g fresh flesh) in the late season. The extraction efficiency (cold-pressed extraction yield/total oil content) also increased from early season (77.2%) to late season (96.6%). In conclusion, the avocado flesh cellular structure ruptured more easily in late-season fruit suggesting of a contribution to more oil release and improved extraction yields.  相似文献   

7.
A high density olive orchard represents a new planting system that requires cultivars with low vegetative vigor, such as Arbequina and Arbosana varieties. Different cultivars provide different performances in such orchards. This research was performed in order to determine the behavior of the new olive variety Tosca 07® in a commercial, high density orchard. The quality of Tosca 07® olive oils in three different maturity degrees during two crops seasons by physico-chemical and nutritional characterization were compared with Arbequina olive oils obtained from trees grown under the same conditions. Tosca 07® is a very interesting olive variety for high density orchards. Because of its early ripening, it would be suitable for early harvesting, and this could be interesting for avoiding cold temperatures, frost, etc. Tosca 07® olive oils have also demonstrated a very suitable chemical composition in comparison with Arbequina olive oils, especially for their high content of antioxidant compounds (α-tocopherol and pigments) present within the oils.  相似文献   

8.
The effect of location of fruit in canopies of hedgerow olive trees (Olea europaea L., cv. ‘Arbequina’) on quality of virgin oil was tested by analyzing oils extracted from different height layers and faces of nine olive hedgerows (6 North–South oriented and 3 East–West). Although sensory attributes were not different, other oil quality parameters may be significantly modified by fruit position. Oils extracted from fruits harvested from higher layers exhibited significantly higher stability against oxidation, along with higher palmitic acid, linoleic acid and phenol contents, but lower oleic acid content. Oils extracted from fruits harvested from East and North facing hedgerows oriented North–South and East–West, respectively, exhibited higher oleic contents and lower saturated and polyunsaturated fatty acid contents. The mean phenol content of oils extracted from fruits from a North–South oriented hedgerow was significantly greater from one of the East–West oriented hedgerows. These findings may be relevant for the design of future olive hedgerows destined for olive oil production.  相似文献   

9.
《分离科学与技术》2012,47(10):1231-1249
Abstract

The membrane separation technologies of microfiltration, ultrafiltration, nanofiltration, and reverse osmosis are suitable for treating many dilute streams and effluents generated in mining and mineral processing. Membrane technologies are capable of treating these dilute streams in order to produce clean permeate water for recycle and a concentrate that can potentially be used for valuable metals recovery. Membrane technologies can be utilized alone, or in combination with other techniques as a polishing step, in these separation processes. A review of potential applications of membranes for the treatment of different process streams and effluents for water recycling and pollution control is given here. Although membranes may not be optimum in all applications, these technologies are recognized in the mining sector for the many potential advantages they can provide.

  相似文献   

10.
11.
Shin  Kyong-Oh  Kim  Kunpyo  Jeon  Sanghun  Seo  Cho-Hee  Lee  Yong-Moon  Cho  Yunhi 《Lipids》2015,50(10):1051-1056
Ceramide 1 (Cer1), a Cer species with eicosasphingenine (d20:1) amide‐linked to two different ω‐hydroxy fatty acids (C30wh:0:C32wh:1), which are, in turn, ester‐linked to linoleic acid (LNA; 18:2n‐6), plays a critical role in maintaining the structural integrity of the epidermal barrier. Prompted by the recovery of a disrupted epidermal barrier with dietary borage oil [BO: 36.5 % LNA and 23.5 % γ‐linolenic acid (GLA; 18:3n‐6)], in essential fatty acid (EFA)‐deficient guinea pigs, we further investigated the effects of BO on the substitution of ester‐linked GLA for LNA in these two epidermal Cer1 species by LC–MS in positive and negative modes. Dietary supplementation of BO for 2 weeks in EFA‐deficient guinea pigs increased LNA ester‐linked to C32wh:1/d20:1 and C30wh:0/d20:1 of Cer1. Moreover, GLA ester‐linked to C32wh:1/d20:1, but not to C30wh:0/d20:1, of Cer1 was detected, which was further confirmed by the product ions of m/z 277.2 for ester‐linked GLA and m/z 802.3 for the deprotonated C32wh:1/d20:1. C20‐Metabolized fatty acids of LNA or GLA were not ester‐linked to these Cer1 species. Dietary BO induced GLA ester‐linked to C32wh:1/d20:1 of epidermal Cer1.  相似文献   

12.
Antisolvents increase the supersaturation in the crystallization process which can enhance the product yield. The effect of an antisolvent on the solubility of γ-DL-methionine (γ-DL-met) in aqueous solution was investigated. The solubility of γ-DL-met was measured with various binary solvent mixtures. It improved with higher temperature but decreased with increasing the antisolvent mass fraction. Acetone showed the highest efficiency to reduce the solubility. The solubilities were correlated with the van't Hoff-Jouyban-Acree model and the modified Apelblat-Jouyban-Acree model. Both models fitted to the experimental results with high accuracy. Enthalpy, entropy, and Gibbs free energy of dissolution were determined by van't Hoff analysis. The thermodynamic properties indicated that the dissolution process is endothermic and entropy-driven.  相似文献   

13.
Silanes are commonly used as coupling agents to enhance the adhesion between polymeric and inorganic materials. Once silane hydrolysis has taken place, the condensation of the silane on the substrate surface should follow. Optimum hydrolysis conditions will depend on the type of silane and the process conditions of the solution. The pH is particularly important as it has a significant effect on the hydrolysis process. This paper deals with the hydrolysis process of 1 vol% γ-methacryloxypropyltrimethoxysilane (MPS) in aqueous solution at different pHs (2, 4, 6, 8 and 10). Because the hydrolysis rate is a function of pH, hydrolysis times, ranging from 2 min to 48 h, were studied. Fourier transform infrared spectroscopy was used to evaluate the chemical modifications produced by changing the hydrolysis time. The disappearance of the infrared band due to the Si–O–C groups and the appearance of the bands due to the Si–OH bonds were studied. It was shown that longer times were necessary for complete hydrolysis, under almost neutral pH conditions. On the other hand, the Zn-electrocoated steel was silanized with MPS under an optimum pH and the hydrolysis time conditions and the resulting surfaces were analysed by Reflection–Absorption Infrared Reflectance Spectroscopy.  相似文献   

14.
15.
A comparative investigation of the induction of double-strand DNA breaks (DSBs) in the Chinese hamster V79 cells by γ-radiation at dose rates of 1, 10 and 400 mGy/min (doses ranged from 0.36 to 4.32 Gy) was performed. The acute radiation exposure at a dose rate of 400 mGy/min resulted in the linear dose-dependent increase of the γ-H2AX foci formation. The dose-response curve for the acute exposure was well described by a linear function y = 1.22 + 19.7x, where “y” is an average number of γ-H2AX foci per a cell and “x” is the absorbed dose (Gy). The dose rate reduction down to 10 mGy/min lead to a decreased number of γ-H2AX foci, as well as to a change of the dose-response relationship. Thus, the foci number up to 1.44 Gy increased and reached the “plateau” area between 1.44 and 4.32 Gy. There was only a slight increase of the γ-H2AX foci number (up to 7) in cells after the protracted exposure (up to 72 h) to ionizing radiation at a dose rate of 1 mGy/min. Similar effects of the varying dose rates were obtained when DNA damage was assessed using the comet assay. In general, our results show that the reduction of the radiation dose rate resulted in a significant decrease of DSBs per cell per an absorbed dose.  相似文献   

16.
The effects of sodium bisulfite on the electrophoresis profile; turbidity; and thermal, surface, and adhesive properties of soy β-conglycinin protein were studied. Sodium bisulfite dissociated high-molecular-weight aggregates in the protein, and the aggregate percentage decreased with increasing sodium bisulfite concentration. Denaturation temperature of sodium-bisulfite-treated β-conglycinin increased as sodium bisulfite increased. However, at high sodium bisulfite concentration (i.e. 36 g/L), denaturation enthalpy decreased significantly. Sodium bisulfite caused changes in the β-conglycinin secondary structure and promoted ionization of lysine residues as indicated by FT-IR results. A sudden drop in turbidity at pH 4.8 was observed at the same salt level. The contact angle of β-conglycinin on cherry wood reached its minimum at 6 g/L sodium bisulfite and 24 g/L on glass. Water resistance of β-conglycinin was improved but not significantly by 6 g/L sodium bisulfite at pH 9.5. An obvious increase in adhesion strength of the protein occurred at 3 and 6 g/L sodium bisulfite at pH 4.8. A high sodium bisulfite concentration at 36 g/L sharply reduced the adhesive performance of β-conglycinin.  相似文献   

17.
l-carnitine is a fine chemical with pharmaceutical, nutritional and animal food applications. Thus, the product purification forms an essential part of the production process. Consequently, process optimization of biotransformation and downstream processing should be done in an integral way. There are several options for the process design of the biotransformation, e.g. chemostat with cell recycling, one-stage or multistage, fed-batch. Blackman kinetics for the product formation of the biotransformation of γ-butyrobetaine into l-carnitine provided adequate modelling of the bioprocess in order to define the optimal process design with respect to productivity, downstream processing and cost. With respect to these criteria, the fed-batch biotransformation of γ-butyrobetaine into l-carnitine appeared to be superior over several modes of operation of the continuous process with cell recycling. A lower productivity of the fed-batch process was compensated by a disproportionally cheaper downstream processing or a lower investment cost.Furthermore, process integration considerations determined the choice of raw materials for the biotransformation, such as carbon and nitrogen sources, resulting in optimized or even a reduced number of unit operations of the downstream processing.  相似文献   

18.
19.
The evolution of process engineering is reviewed and it’s ability to cope with the problems encountered by chemical and related industries is appraised. It appears that the necessary progress should come via a pluridisciplinary and multiscale approach, that will allow us to satisfy both the market requirements for specific end-use properties as well as the environmental and social constraints. In this context, an increasingly important contribution will be required from basic disciplines such as physics, physical chemistry and mathematics, mechanics and ecotoxicology.  相似文献   

20.
Antioxidant properties of 5 to 500 μg/g levels of α-and γ-tocopherols, in the oxidation of rapeseed oil triacylglycerols (RO TAG), were studied at 40°C in the dark. Each tocopherol alone and in a mixture was studied for its stability in oxidizing RO TAG. Also the effects of tocopherols on the formation of primary and secondary oxidation products of RO TAG were investigated. Both tocopherols significantly retarded the oxidation of RO TAG. At low levels (≤50 μg/g), α-tocopherol was more stable and was a more effective antioxidant than γ-tocopherol. At higher α-tocopherol levels (>100 μg/g), there was a relative increase in hydroperoxide formation parallel to consumption of α-tocopherol, which was not found with γ-tocopherol. Therefore, γ-tocopherol was a more effective antioxidant than α-tocopherol at levels above 100 μg/g. As long as there were tocopherols present, the hydroperoxides were quite stable and no volatile aldehydes were formed. In a mixture, α-tocopherol protected γ-tocopherol from being oxidized at the addition levels of 5+5 and 10+10 μg/g but no synergism between the tocopherols was found. α-Tocopherol was less stable in the 500+500 μg/g mixture than when added alone to the RO TAG. No prooxidant activity of either tocopherol or their mixture was found.  相似文献   

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