QuEChERS Method for the Determination of 3‑Alkyl‑2‑Methoxypyrazines in Wines by Gas Chromatography-Mass Spectrometry

A new method for determining 3-isopropyl-2-methoxypyrazine, 3-sec-butyl-2-methoxypyrazine, and 3-isobutyl-2-methoxypyrazine in wines is presented. A modified quick, easy, cheap, effective, rugged, and safe method and gas chromatography-mass spectrometry (GC-MS) were used for sample preparation and compound determination, respectively. The analytes were extracted from wine (30 mL) with 1 mL toluene, in the presence of 12 g anhydrous MgSO₄ and 3 g NaCl. Cleanup of the toluene phase was performed by a miniaturized dispersive solid-phase extraction with a combination of anhydrous CaCl₂ (25 mg), anhydrous MgSO₄ (25 mg), and primary-secondary amine (10 mg), which was effective for minimizing co-extractives and matrix effects. GC-MS parameters were also tuned up to optimize limits of detection between 4.2 and 7.1 ng L^?1. The overall recoveries (trueness) of the method ranged between 71 and 87 % for the white and red wine samples, respectively, spiked at 40 and 100 ng L^?1, with relative standard deviations below 21 %. The method was applied for the determination of target methoxypyrazines in the samples of commercial wines from Argentina.     

Exploring the milk-clotting properties of a plant coagulant from the berries of S. elaeagnifolium var. Cavanilles

Solanum elaeagnifolium (trompillo or silverleaf nightshade) is an endemic plant from the northeast of Mexico and southwest of United States. This plant is considered as a weed with negative impact on agriculture and livestock production. Nevertheless, in some places of Chihuahua, Mexico, the berries of this plant have been used for decades in the manufacture of artisanal filata-type asadero cheese. The milk-clotting enzyme of S. elaeagnifolium has been scarcely studied; for this reason, the aim of this work was to explore some properties of this plant coagulant. Protein extracts (PEs) from ripe berries of S. elaeagnifolium were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and assessed for milk-clotting activity. In addition, milk gels and miniature fresh-type cheeses manufactured with the plant coagulant were analyzed for their texture properties. The PE from the berries of S. elaeagnifolium contained 8 proteins with molecular weights from 22 to 62 kDa. Some bands observed in the PE had similar molecular weights as reported for aspartic proteinases such as chymosin. The extracts from the berries of S. elaeagnifolium had lower milk-cloting activities than observed with rennin or chymosin, but this plant coagulant produced firm gels under acidic conditions. The mini-cheeses manufactured with this coagulant were softer than cheeses manufactured with rennin or chymosin. For this reason, the coagulant from the ripe berries of S. elaeagnifolium could be suitable not only for the manufacture of filata-type cheeses but also for the manufacture of soft cheeses such as cream cheese. PRACTICAL APPLICATION: Silverleaf nightshade (trompillo) is a plant that grows in northern Mexico and the southwestern United States. This plant is considered a weed with negative impact on agriculture and livestock production. However, the ripe berries of this plant have been used by ancient Pima Indians as a substitute of rennin in making cheese. In this work, it was observed that this plant coagulant had lower activity and produced softer cheeses than did rennin or chymosin. For this reason, the coagulant from berries of S. elaeagnifolium could be used for the manufacture of soft cheeses such as cream cheese.     

Regulation of prolactin secretion during the estrus in rats: possible role of glucocorticoids

Mifepristone (MIF) administration to cycling rats at proestrus induces hypersecretion of prolactin (PRL) at the following estrus. We aimed to assess whether this effect is due to the antiprogesterone or antiglucocorticoid action of MIF and to help underscore the nature of the circulating hormone(s) regulating PRL secretion at estrus. Female cycling rats in proestrus were treated with vehicle; the progesterone (Pg) and glucocorticoid receptor antagonists, MIF (5?mg/kg) or ORG-33628 (5?mg/kg); the glucocorticoid agonist dexamethasone (DEX; 27?mg/kg)±MIF; or the inhibitor of steroid synthesis aminoglutethimide (AG; 150?mg/kg)±MIF. The animals' blood was sampled the same day at 1800?h and at 1800?h of the following day to assess for circulating PRL and Pg levels. To distinguish antiglucocorticoid from antiprogesterone effects of MIF, we administered a highly specific neutralizing antibody against Pg. None of the antagonists modified serum PRL values at proestrus but increased PRL levels at estrus. DEX decreased the secretion of PRL at proestrus, yet the effect was entirely blocked by MIF. Furthermore, DEX decreased PRL at estrus in a MIF-reversible manner, suggesting that adrenal corticoids during proestrous may regulate PRL secretion at estrus. AG increased PRL secretion at estrus, whereas its association with MIF produced an even higher response. PRL concentration at estrus was not modified by the antiprogesterone antibody, suggesting that the effect of MIF is a consequence of its antiglucocorticoid effect and not due to its antiprogesterone properties. In conclusion, PRL secretion in the afternoon of the estrus is most likely regulated by glucocorticoids through an inhibitory action.     

Study of the antioxidant properties of extracts obtained from nopal cactus (Opuntia ficus-indica) cladodes after convective drying

BACKGROUND: The process of convective drying was evaluated in terms of the bioactive compounds contained in nopal samples before and after dehydration. Total polyphenol, flavonoid, flavonol, carotene and ascorbic acid contents were determined in undehydrated and dehydrated samples. Two drying temperatures (45 and 65 °C) and two air flow rates (3 and 5 m s^?1) were evaluated. The rheology of samples under the best drying conditions was also studied, since it provides important information regarding processing (mixing, flow processing) as well as the sensory attributes (texture) of rehydrated samples. RESULTS: Non‐Newtonian shear‐thinning behaviour was observed for samples dried at 45 °C, while samples dried at 65 °C showed shear‐thickening behaviour, possibly caused by thermal chain scission of high‐molecular‐weight components. CONCLUSION: The best conditions for bioactive compound preservation were a drying temperature of 45 °C and an air flow rate of 3 m s^?1, resulting in 40.97 g phenols, 23.41 g flavonoids, 0.543 g β‐carotene and 0.2815 g ascorbic acid kg^?1 sample as shown in table 3. Copyright © 2011 Society of Chemical Industry     

Multiscale proper generalized decomposition based on the partition of unity

Solutions of partial differential equations could exhibit a multiscale behavior. Standard discretization techniques are constraints to mesh up to the finest scale to predict accurately the response of the system. The proposed methodology is based on the standard proper generalized decomposition rationale; thus, the PDE is transformed into a nonlinear system that iterates between microscale and macroscale states, where the time coordinate could be viewed as a 2D time, representing the microtime and macrotime scales. The macroscale effects are taken into account because of an FEM-based macrodiscretization, whereas the microscale effects are handled with unidimensional parent spaces that are replicated throughout the domain. The proposed methodology can be seen as an alternative route to circumvent prohibitive meshes arising from the necessity of capturing fine-scale behaviors.     

A Non-Invasive Technique for Online Defect Detection on Steel Strip Surfaces

During the production of steel strips, a large amount of surface defects can be generated, due to harsh environmental conditions. A high number of surface defects can lead to rejection by the customer, which represents significant economic losses to the production plant. Thus, it is very important to detect the presence and type of the defects generated during the production of each steel strip. Using this information, it is possible to determine whether a strip is suitable for sale, and it may also be useful to determine the origin of defects and, if possible, prevent them from being generated in subsequent strips. To perform these tasks, non-invasive inspection techniques are usually used, carried out automatically by artificial vision systems. Although the inspection conducted by humans is more accurate, they become fatigued quickly, or may even be unable to carry out the inspection correctly when the forward speed of the strip is high. In this paper, a new detection technique is proposed, based on the division of an image into a set of overlapping areas. The optimum values for the configuration parameters of the detection technique are automatically determined using a genetic algorithm. After the detection phase, all the defects are classified using a neural network. A very satisfactory success rate has been achieved in both detection and classification phases.