Quality assessment of commercial paprikas

Several quality parameters of smoked, oven‐dried and sun‐dried paprikas were studied. Smoked paprikas showed the highest American Spice Trade Association (ASTA) units and pigment concentrations, whereas oven‐dried paprikas showed the best browning index and red/yellow pigment ratio, and sun‐dried paprikas had the highest redness for reflected colour. The colour stability results showed drastic overall colour change (ΔE) and decreased redness and ASTA units of the sun‐dried and oven‐dried paprikas after two and 5 days of UV exposure. Degradation of the smoked paprika colour parameters was progressive, and they showed less degradation even after 30 days. The evaluation of the antioxidant activity showed higher DPPH radical‐scavenging capacity in the smoked samples. The profiles of volatile phenolic compounds of the smoked samples are responsible for the differences in the antioxidant capacity. The great differences in colour stability and antioxidant activity make smoked paprika the best choice for use in the food industry.     

Singly ionized double-donor complex in vertically coupled quantum dots

ABSTRACT: The electronic states of a singly ionized on-axis double-donor complex (D2+) confined in two identical vertically coupled, axially symmetrical quantum dots in a threading magnetic field are calculated. The solutions of the Schrodinger equation are obtained by a variational separation of variables in the adiabatic limit. Numerical results are shown for bonding and antibonding lowest-lying artificial molecule states corresponding to different quantum dot morphologies, dimensions, separation between them, thicknesses of the wetting layers, and magnetic field strength.     

Automatic categorisation of comments in social news websites

The use of the social web has brought a series of changes in the way how content is created. In particular, social news sites link stories and the different users can comment them. In this paper, we propose a new method based on different features extracted from the text able to categorise the comments. To this end, we use a combination of statistical, syntactic and opinion features and machine-learning classifiers to classify a comment within three different categorisation types: the focus of the comment, the type of information contained in the comment and the controversy level of the comment. We validate our approach with data from ‘Menéame’, a popular Spanish social news site.     

Distributed resource allocation in cognitive radio networks with a game learning approach to improve aggregate system capacity

This paper presents a game theoretic solution for joint channel allocation and power control in cognitive radio networks analyzed under the physical interference model. The objective is to find a distributed solution that maximizes the network utility, defined with different criteria, with limited information. The problem is addressed through a non-cooperative game based on local information. Although the existence of a pure Nash Equilibrium cannot be assured for this game, simulation results show that it exists with high probability and with a performance similar to that of a potential game, where each player requires overall network information. The obtained results are compared with a centralized heuristic genetic algorithm to show the correctness of the proposals. From this point, utility functions for the local game are modified to restrict the transmitted power to drive the solution to a more cooperative approach. To overcome the convergence limitations of the local game, no-regret learning algorithms are used to perform the joint channel and power allocation. These algorithms provide stable mixed strategies in any scenario with even better global performance. This opens an interesting perspective to develop realistic protocols based on the modeled interactions and increases the adaptability to perform efficient opportunistic spectrum access.     

Evaluation of table olive by‐product as a source of natural antioxidants

The main by‐product from the table olive canning industry is the stone with some residual olive flesh. The purpose of this study was to evaluate the composition – phenolic compounds (hydroxytyrosol, tyrosol and oleuropein) and tocopherol – and the antioxidant activity in different fractions (flesh, stone and seed) from the table olive by‐product and the whole by‐product. The highest amounts of phenolic compounds (1710.0 ± 33.8 mg kg^?1) as well as the highest antioxidant activity (8226.9 ± 9.9 hydroxytyrosol equivalents mg kg^?1) were obtained in the seed. The highest amounts of hydroxytyrosol (854.8 ± 66.0 mg kg^?1) and tyrosol (423.6 ± 56.9 mg kg^?1) were found in the whole by‐product from the pepper stuffed olives, while the stone without seed had the maximum oleuropein content (750.2 ± 85.3 mg kg^?1). α‐Tocopherol values were between 79.8 ± 20.8 mg kg^?1 in the seed of the olive stone and 6.2 ± 1.2 mg kg^?1 in the whole by‐product from the anchovy‐stuffed olives. In light of the results obtained, it would seem possible to use table olive by‐product as a source of natural antioxidants in foods, cosmetics or pharmaceutical products, thus contributing to diminishing the environmental impact of table olive by‐product and to its revalorisation.     

Inhibition of colon adenocarcinoma cell proliferation by flavonols is linked to a G2/M cell cycle block and reduction in cyclin D1 expression

The moderate consumption of red wine has been proposed to reduce the incidence of colorectal cancer. Its anti-cancer action my in part be mediated by the actions of polyphenols on colon cancer epithelial cells. We show that a red wine phenolic (50 μg/ml) extract devoid of anthocyanins (removed to reflect polyphenol bioavailability to the large intestine) and the major red wine flavonols quercetin, myricetin, laricitrin and syringetin (50 μM) are capable of inhibiting the proliferation of colorectal epithelial adenocarcinoma cells. This anti-proliferative activity was partly mediated by the direct cytotoxic actions of flavonols and also their ability to cause a significant cell cycle blockage in G2/M. The anti-proliferative effects induced by flavonols were preceded, in most cases, by a strong and significant reduction of cyclooxygenase-2 (COX-2) and cyclin D1 expression. These results indicate that the observed inverse correlation between colon cancer and a moderate red wine intake may be partly mediated by the actions of red wine flavonols on the growth of cancer cells.     

Rotational molding of polyethylene composites based on agave fibers

In this study, agave fiber/linear medium density polyethylene composites were manufactured by rotational molding. A laboratory scale biaxial machine was used, where the internal air temperature during the processing cycle was measured. Two sizes of agave fibers (50 and 100 mesh) were used separately and mixed together (50/50) at concentrations varying between 0 and 15 wt%. The initial mixtures were obtained by dry blending, rotomolded under different operation conditions (oven temperature, processing cycle time, and rotational speeds), and the final pieces were compared. For each process condition, a complete morphological analysis was performed to relate with mechanical properties in terms of tensile, impact, and flexural strength. The results show that there is an optimum fiber concentration around 10%, and blending fiber sizes gave better tensile properties than using each size alone. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Endogenous Proteases in Pacific Whiting (Merluccius productus) Muscle as A Processing Aid in Functional Fish Protein Hydrolysate Production

A fish protein hydrolysate (FPH) from Pacific whiting (Merluccius productus) muscle was produced by autolysis of a minced homogenate (8% protein) at pH 7.0 and 60°C, where maximum endogenous proteolytic activity was detected. FPH production was controlled by the pH stat method, yielding a 4.43% degree of hydrolysis after 1 h of autolysis. Upon autolytic processing, 28.9 ± 0.7% of the total protein was found in the soluble fraction. FPH was 100% soluble at pH 7.0 and 10.0 and was less soluble at pH 4 (82.5%, P ≤ 0.05). FPH showed better emulsifying properties than sodium caseinate (SCA) at pH 4.0 (P ≤ 0.05), but had a lower foaming capacity (P ≤ 0.05) than bovine albumin (BSA) at all evaluated pHs. FPH foaming capacity was not affected by pH, however, foam stability was equal or better than that of BSA, especially at pH 4.0 (P ≤ 0.05). These results suggest the possibility of producing FPH with similar or better functional properties than those of functional ingredients, such as SCA and BSA. Furthermore, the data presented support our hypothesis that the high proteolytic activity in Pacific whiting could be used as an advantage in fish protein hydrolysate production or as a processing aid where protein hydrolysis is required.     

Effect of extra virgin olive oil on glycaemia in healthy young subjects

In this approach we studied the glycaemia levels in 20 healthy young volunteers (26 ± 2 years), before and after a 30‐day intake of 50 mL of extra virgin olive oil (EVOO). We selected an oil rich in phenolic compounds (523 mg/L) with a high content of secoiridoidic derivatives (over 94.5%). The findings from our study reveal a significant decrease of glycaemia from 89.6 ± 6.8 to 82.7 ± 10.3 mg/dL (p<0.05), related to a long term daily intake of the study EVOO, as the only added fat. A significant increment of the HDL cholesterol, from 68.7 ± 11.5 to 75.2 ± 4.9 mg/dL, was also highlighted. Total cholesterol, LDL, VLDL, triglycerides, and blood pressure did not show significant variation after the 30‐day consumption of this EVOO. So far, few articles have described the influence of EVOO consumption, on plasma glucose levels in humans. This effect is observed in a group of healthy young humans. Moreover, we confirm that the level of free hydroxytyrosol (OH‐Tyr) in plasma increased up to fourfold (p<0.05) after the 30‐day intake of this EVOO. In addition, the excretion in urine of the main metabolite of OH‐Tyr, homovanillic acid (HVA), significantly increased.