Free Amino Acids in Pacu, Piaractus mesopotamicus, Eggs and Larvae

Free amino acids (FAA) are used principally as substrate in protein synthesis and the source of energy in aerobic catabolism. In marine fish, embryo and larvae FAA are used to maintain body fluid osmolality during fish early development. However, there is essentially no information about FAA concentrations in early ontogeny of freshwater neotropical species in comparison to marine fishes. Therefore, the aim of this study was to evaluate the FAA concentrations in pacu, Piaractus mesopotamicus, eggs and larvae. Broodstock fish were induced to spawn and ovulated females were stripped of their eggs and immediately sampled for analysis. Larvae were sampled right after hatching (HL) and after the completion of the yolk-sac absorption (YSA). The wet weight of the HL and YSA larvae amounted to 0.5±0.1mg and 1.1±0.3mg, respectively. HL larvae showed higher levels of most of the indispensable amino acids (IAA) in comparison to eggs and YSA larvae. Exceptions were observed with His and Trp that showed higher or similar levels, respectively, in YSA larvae. The FAA Orn, Tau, Glu, Gln, Gly, and Tyr increased concentrations in both larval stages while that of Tau was found in higher concentration in all analyzed stages. Also, the concentrations of Asn, Ala, Pro, Ser, and Asp were higher in HL larvae. Both larval stages displayed a rise in total free IAA/total free DAA (dispensable amino acids) ratio. The authors conclude that the highest level of FAA in HL pacu larvae is indicative of active proteolysis of yolk reserves and a probable catabolism regulation of some FAA through spare-effect. In addition, Tau is one of the major FAA occurring during pacu ontogeny and may be performing regulation on body fluid osmolality regulation. © Copyright by the World Aquaculture Society 2013.

Molecular and stable isotope composition of headspace and total hydrogencarbon gases of ODP Leg 104 sites

Molecular and isotope compositions of headspace and total (free + sorbed) hydrocarbon gases from drilled cores of the three ODP Leg 104 Sites 642, 643, and 644 of the Voring Plateau are used to characterize the origin and distribution of these gases in Holocene to Eocene sediments. Only minor amounts of methane were found in the headspace (0.1 to < 0.001 vol%). Although methane through propane are present in all of the total gas samples, different origins account for the concentration and composition variations found. Site 643 at the foot of the outer Voring Plateau represents a geological setting with poor hydrocarbon generating potential, (sediments with low TOC and maturity overlying oceanic basement). Correspondingly, the total gas concentrations are low, typical for background gases (yield C1 - 4 = 31 to 232 ppb, C1/C2+ = 0.6 to 4; delta13C(CH4) -22 per mil to -42 per mil) probably of a diagenetic origin. Holocene to Eocene sediments, which overlie volcanic units, were drilled on the outer Vdring Plateau, at Holes 642B and D. Similar to Site 643, these sediments possess a poor hydrocarbon generating potential. The total gas character (yield C1 - 4 = 20 to 410 ppb; C1/C2+ = 1.7 to 13.3; delta13C(CH4) ca. -23 per mil to -40 per mil) again indicates a diagenetic origin, perhaps with the addition of some biogenic gas. The higher geothermal gradient and the underlying volcanics do not appear to have any influence on the gas geochemistry. The free gas (Vacutainer TM) in the sediments at Site 644 are dominated by biogenic gas (C1/C2+ > 104; delta13C(CH4) -77 per mil). Indications, in the total gas, of hydrocarbons with a thermogenic signature (yield C1 - 4 = 121 to 769 ppb, C1/ C2+ = 3 to 8; delta13C(CH4) = -39 per mil to -71 per mil), could not be unequivocally confirmed as such. Alternatively, these gases may represent mixtures of diagenetic and biogenic gases.

Quantification of MgO surface excess on the SnO(2) nanoparticles and relationship with nanostability and growth

In this work, we experimentally showed that the spontaneous segregation of MgO as surface excess in MgO doped SnO(2) nanoparticles plays an important role in the system`s energetics and stability. Using Xray fluorescence in specially treated samples, we quantitatively determined the fraction of MgO forming surface excess when doping SnO(2) with several different concentrations and established a relationship between this amount and the surface energy of the nanoparticles using the Gibbs approach. We concluded that the amount of Mg ions on the surface was directly related to the nanoparticles total free energy, in a sense that the dopant will always spontaneously distribute itself to minimize it if enough diffusion is provided. Because we were dealing with nanosized particles, the effect of MgO on the surface was particularly important and has a direct effect on the equilibrium particle size (nanoparticle stability), such that the lower the surface energy is, the smaller the particle sizes are, evidencing and quantifying the thermodynamic basis of using additives to control SnO(2) nanoparticles stability. (C) 2010 Elsevier B.V. All rights reserved.

Intra- and extracellular osmotic regulation in the hololimnetic Caridea and Anomura: a phylogenetic perspective on the conquest of fresh water by the decapod Crustacea

We investigate extra- and intracellular osmoregulatory capability in two species of hololimnetic Caridea and Anomura: Macrobrachium brasiliense, a palaemonid shrimp, and Aegla franca, an aeglid anomuran, both restricted to continental waters. We also appraise the sharing of physiological characteristics by the hololimnetic Decapoda, and their origins and role in the conquest of fresh water. Both species survive salinity exposure well. While overall hyperosmoregulatory capability is weak in A. franca and moderate in M. brasiliense, both species strongly hyporegulate hemolymph [Cl(-)] but not osmolality. Muscle total free amino acids (FAA) increase slowly but markedly in response to the rapid rise in hemolymph osmolality consequent to hyperosmotic challenge: 3.5-fold in A. franca and 1.9-fold in M. brasiliense. Glycine, taurine, arginine, alanine and proline constitute a parts per thousand 85% of muscle FAA pools in fresh water; taurine, arginine, alanine each contribute a parts per thousand 22% in A. franca, while glycine predominates (70%) in M. brasiliense. These FAA also show the greatest increases on salinity challenge. Muscle FAA titers correlate strongly (R = 0.82) with hemolymph osmolalities across the main decapod sub/infraorders, revealing that marine species with high hemolymph osmolalities achieve isosmoticity of the intra- and extracellular fluids partly through elevated intracellular FAA concentrations; freshwater species show low hemolymph osmolalities and exhibit reduced intracellular FAA titers, consistent with isosmoticity at a far lower external osmolality. Given the decapod phylogeny adopted here and their multiple, independent invasions of fresh water, particularly by the Caridea and Anomura, our findings suggest that homoplastic strategies underlie osmotic and ionic homeostasis in the extant freshwater Decapoda.

Evolutionary transition to freshwater by ancestral marine palaemonids: evidence from osmoregulation in a tide pool shrimp

The transition from marine/brackish waters to freshwater habitats constitutes a severe osmotic and ionic challenge, and successful invasion has demanded the selection of morphological, physiological, biochemical and behavioral adaptations. We evaluated short-term (1 to 12 h exposure) and long-term (5 d acclimation), anisosmotic extracellular (osmolality, [Na(+), Cl(-)]) and long-term isosmotic intracellular osmoregulatory capability in Palaemon northropi, a neotropical intertidal shrimp. F northropi survives well and osmo- and ionoregulates strongly during short- and long-term exposure to 5-45 parts per thousand salinity, consistent with its rocky tide pool habitat subject to cyclic salinity fluctuations, Muscle total free amino acid (FAA) concentrations decreased by 63% in shrimp acclimated to 5%. salinity, revealing a role in hypoosmotic cell volume regulation; this decrease is mainly a consequence of diminished glycine, arginine and proline. Total FAA contributed 31% to muscle intracellular osmolality at 20 parts per thousand, an isosmotic salinity, and decreased to 13% after acclimation to 5 parts per thousand. Gill and nerve tissue FAA concentrations remained unaltered. These tissue-specific responses reflect efficient anisosmotic and anisoionic extracellular regulatory mechanisms, and reveal the dependence of muscle tissue on intracellular osmotic effectors. FAA concentration is higher in P. northropi than in diadromous and hololimnetic palaemonids, confirming muscle FAA concentration as a good parameter to evaluate the degree of adaptation to dilute media. The osmoregulatory capability of P. northropi may reflect the potential physiological capacity of ancestral marine palaemonids to penetrate into dilute media, and reveals the importance of evaluating osmoregulatory processes in endeavors to comprehend the invasion of dilute media by ancestral marine crustaceans.

Fresh-cut aromatic herbs: Nutritional quality stability during shelf-life

Fresh-cut vegetables are a successful convenient healthy food. Nowadays, the presence of new varieties of minimally processed vegetables in the market is common in response to the consumers demand for new flavours and high quality products. Within the most recent fresh-cut products are the aromatic herbs. In this work, the objective was to evaluate the nutritional quality and stability of four fresh-cut aromatic herbs. Several physicochemical quality characteristics (colour, pH, total soluble solids, and total titratable acidity) were monitored in fresh-cut chives, coriander, spearmint and parsley leaves, stored under refrigeration (3 ± 1 ºC) during 10 days. Their nutritional composition was determined, including mineral composition (phosphorous, potassium, sodium, calcium, magnesium, iron, zinc, manganese and copper) and fat- and water-soluble vitamin contents. Total soluble phenolics, flavonoids and the antioxidant capacity were determined by spectrophotometric methods. The aromatic herbs kept their fresh appearance during the storage, maintaining their colour throughout shelf-life. Their macronutrient composition and mineral content were stable during storage. Coriander had the highest mineral and fatsoluble vitamin content, while spearmint showed the best scores in the phenolic, flavonoid and antioxidant capacity assays. Vitamins and antioxidant capacity showed some variation during storage, with a differential behaviour of each compound according to the sample.

Variation of the physicochemical and morphological characteristics of solvent casted poly(vinylidene fluoride) along its binary phase diagram with dimethylformamide

Poly(vinylidene fluoride), PVDF, films and membranes were prepared by solvent casting from dimethylformamide, DMF, by systematically varying polymer/solvent ratio and solvent evaporation temperature. The effect of the processing conditions on the morphology, degree of porosity, mechanical and thermal properties and crystalline phase of the polymer were evaluated. The obtained microstructure is explained by the Flory-Huggins theory. For the binary system, the porous membrane formation is attributed to a spinodal decomposition of the liquid-liquid phase separation. The morphological features were simulated through the correlation between the Gibbs total free energy and the Flory-Huggins theory. This correlation allowed the calculation of the PVDF/DMF phase diagram and the evolution of the microstructure in different regions of the phase diagram. Varying preparation conditions allow tailoring polymer 2 microstructure while maintaining a high degree of crystallinity and a large β crystalline phase content. Further, the membranes show adequate mechanical properties for applications in filtration or battery separator membranes.

Optimisation of antiretroviral therapy : pharmacokinetic and pharmacogenetic approaches

Les progrès de la thérapie antirétrovirale ont transformé l'infection par le VIH d'une condition inévitablement fatale à une maladie chronique. En dépit de ce succès, l'échec thérapeutique et la toxicité médicamenteuse restent fréquents. Une réponse inadéquate au traitement est clairement multifactorielle et une individualisation de la posologie des médicaments qui se baserait sur les facteurs démographiques et génétiques des patients et sur les taux sanguins totaux, libres et/ou cellulaires des médicaments pourrait améliorer à la fois l'efficacité et la tolérance de la thérapie, cette dernière étant certainement un enjeu majeur pour un traitement qui se prend à vie.L'objectif global de cette thèse était de mieux comprendre les facteurs pharmacocinétiques (PK) et pharmacogénétiques (PG) influençant l'exposition aux médicaments antirétroviraux (ARVs) nous offrant ainsi une base rationnelle pour l'optimisation du traitement antiviral et pour l'ajustement posologique des médicaments chez les patients VIH-positifs. Une thérapie antirétrovirale adaptée au patient est susceptible d'augmenter la probabilité d'efficacité et de tolérance à ce traitement, permettant ainsi une meilleure compliance à long terme, et réduisant le risque d'émergence de résistance et d'échec thérapeutique.A cet effet, des méthodes de quantification des concentrations plasmatiques totales, libres et cellulaires des ARVs ainsi que de certains de leurs métabolites ont été développées et validées en utilisant la chromatographie liquide coupée à la spectrométrie de masse en tandem. Ces méthodes ont été appliquées pour la surveillance des taux d'ARVs dans diverses populations de patients HIV-positifs. Une étude clinique a été initiée dans le cadre de l'étude VIH Suisse de cohorte mère-enfant afin de déterminer si la grossesse influence la cinétique des ARVs. Les concentrations totales et libres du lopînavir, de l'atazanavir et de la névirapine ont été déterminées chez les femmes enceintes suivies pendant leur grossesse, et celles-ci ont été trouvées non influencées de manière cliniquement significative par la grossesse. Un ajustement posologique de ces ARVs n'est donc pas nécessaire chez les femmes enceintes. Lors d'une petite étude chez des patients HIV- positifs expérimentés, la corrélation entre l'exposition cellulaire et plasmatique des nouveaux ARVs, notamment le raltégravir, a été déterminée. Une bonne corrélation a été obtenue entre taux plasmatiques et cellulaires de raltégravir, suggérant que la surveillance des taux totaux est un substitut satisfaisant. Cependant, une importante variabilité inter¬patient a été observée dans les ratios d'accumulation cellulaire du raltégravir, ce qui devrait encourager des investigations supplémentaires chez les patients en échec sous ce traitement. L'efficacité du suivi thérapeutique des médicaments (TDM) pour l'adaptation des taux d'efavirenz chez des patients avec des concentrations au-dessus de la cible thérapeutique recommandée a été évaluée lors d'une étude prospective. L'adaptation des doses d'efavirenz basée sur le TDM s'est montrée efficace et sûre, soutenant l'utilisation du TDM chez les patients avec concentrations hors cible thérapeutique. L'impact des polymorphismes génétiques des cytochromes P450 (CYP) 2B6, 2A6 et 3A4/5 sur la pharmacocinétique de l'efavirenz et de ces métabolites a été étudié : un modèle de PK de population intégrant les covariats génétiques et démographiques a été construit. Les variations génétiques fonctionnelles dans les voies de métabolisation principales (CYP2B6) et accessoires {CYP2A6et 3A4/S) de l'efavirenz ont un impact sur sa disposition, et peuvent mener à des expositions extrêmes au médicament. Un? ajustement des doses guidé par le TDM est donc recommandé chez ces patients, en accord avec les polymorphismes génétiques.Ainsi, nous avons démonté qu'en utilisant une approche globale tenant compte à la fois des facteurs PK et PG influençant l'exposition aux ARVs chez les patients infectés, il est possible, si nécessaire, d'individualiser la thérapie antirétrovirale dans des situations diverses. L'optimisation du traitement antirétroviral contribue vraisemblablement à une meilleure efficacité thérapeutique à iong terme tout en réduisant la survenue d'effets indésirables.Résumé grand publicOptimisation de la thérapie antirétrovirale: approches pharmacocinétiques et pharmacogénétiquesLes progrès effectués dans le traitement de l'infection par le virus de llmmunodéficienoe humaine acquise (VIH) ont permis de transformer une affection mortelle en une maladie chronique traitable avec des médicaments de plus en plus efficaces. Malgré ce succès, un certain nombre de patients ne répondent pas de façon optimale à leur traitement etyou souffrent d'effets indésirables médicamenteux entraînant de fréquentes modifications dans leur thérapie. Il a été possible de mettre en évidence que l'efficacité d'un traitement antirétroviral est dans la plupart des cas corrélée aux concentrations de médicaments mesurées dans le sang des patients. Cependant, le virus se réplique dans la cellule, et seule la fraction des médicaments non liée aux protéines du plasma sanguin peut entrer dans la cellule et exercer l'activité antirétrovirale au niveau cellulaire. Il existe par ailleurs une importante variabilité des concentrations sanguines de médicament chez des patients prenant pourtant la même dose de médicament. Cette variabilité peut être due à des facteurs démographiques et/ou génétiques susceptibles d'influencer la réponse au traitement antirétroviral.Cette thèse a eu pour objectif de mieux comprendre les facteurs pharmacologiques et génétiques influençant l'efficacité et ta toxicité des médicaments antirétroviraux, dans le but d'individualiser la thérapie antivirale et d'améliorer le suivi des patients HIV-positifs.A cet effet, des méthodes de dosage très sensibles ont été développées pour permettre la quantification des médicaments antirétroviraux dans le sang et les cellules. Ces méthodes analytiques ont été appliquées dans le cadre de diverses études cliniques réalisées avec des patients. Une des études cliniques a recherché s'il y avait un impact des changements physiologiques liés à la grossesse sur les concentrations des médicaments antirétroviraux. Nous avons ainsi pu démontrer que la grossesse n'influençait pas de façon cliniquement significative le devenir des médicaments antirétroviraux chez les femmes enceintes HIV- positives. La posologie de médicaments ne devrait donc pas être modifiée dans cette population de patientes. Par ailleurs, d'autres études ont portés sur les variations génétiques des patients influençant l'activité enzymatique des protéines impliquées dans le métabolisme des médicaments antirétroviraux. Nous avons également étudié l'utilité d'une surveillance des concentrations de médicament (suivi thérapeutique) dans le sang des patients pour l'individualisation des traitements antiviraux. Il a été possible de mettre en évidence des relations significatives entre l'exposition aux médicaments antirétroviraux et l'existence chez les patients de certaines variations génétiques. Nos analyses ont également permis d'étudier les relations entre les concentrations dans le sang des patients et les taux mesurés dans les cellules où le virus HIV se réplique. De plus, la mesure des taux sanguins de médicaments antirétroviraux et leur interprétation a permis d'ajuster la posologie de médicaments chez les patients de façon efficace et sûre.Ainsi, la complémentarité des connaissances pharmacologiques, génétiques et virales s'inscrit dans l'optique d'une stratégie globale de prise en charge du patient et vise à l'individualisation de la thérapie antirétrovirale en fonction des caractéristiques propres de chaque individu. Cette approche contribue ainsi à l'optimisation du traitement antirétroviral dans la perspective d'un succès du traitement à long terme tout en réduisant la probabilité des effets indésirables rencontrés. - The improvement in antirétroviral therapy has transformed HIV infection from an inevitably fatal condition to a chronic, manageable disease. However, treatment failure and drug toxicity are frequent. Inadequate response to treatment is clearly multifactorial and, therefore, dosage individualisation based on demographic factors, genetic markers and measurement of total, free and/or cellular drug level may increase both drug efficacy and tolerability. Drug tolerability is certainly a major issue for a treatment that must be taken indefinitely.The global objective of this thesis aimed at increasing our current understanding of pharmacokinetic (PK) and pharmacogenetic (PG) factors influencing the exposition to antirétroviral drugs (ARVs) in HIV-positive patients. In turn, this should provide us with a rational basis for antiviral treatment optimisation and drug dosage adjustment in HIV- positive patients. Patient's tailored antirétroviral regimen is likely to enhance treatment effectiveness and tolerability, enabling a better compliance over time, and hence reducing the probability of emergence of viral resistance and treatment failure.To that endeavour, analytical methods for the measurement of total plasma, free and cellular concentrations of ARVs and some of their metabolites have been developed and validated using liquid chromatography coupled with tandem mass spectrometry. These assays have been applied for the monitoring of ARVs levels in various populations of HIV- positive patients. A clinical study has been initiated within the frame of the Mother and Child Swiss HIV Cohort Study to determine whether pregnancy influences the exposition to ARVs. Free and total plasma concentrations of lopinavir, atazanavir and nevirapine have been determined in pregnant women followed during the course of pregnancy, and were found not influenced to a clinically significant extent by pregnancy. Dosage adjustment for these drugs is therefore not required in pregnant women. In a study in treatment- experienced HIV-positive patients, the correlation between cellular and total plasma exposure to new antirétroviral drugs, notably the HIV integrase inhibitor raltegravir, has been determined. A good correlation was obtained between total and cellular levels of raltegravir, suggesting that monitoring of total levels are a satisfactory. However, significant inter-patient variability was observed in raltegravir cell accumulation which should prompt further investigations in patients failing under an integrase inhibitor-based regimen. The effectiveness of therapeutic drug monitoring (TDM) to guide efavirenz dose reduction in patients having concentrations above the recommended therapeutic range was evaluated in a prospective study. TDM-guided dosage adjustment of efavirenz was found feasible and safe, supporting the use of TDM in patients with efavirenz concentrations above therapeutic target. The impact of genetic polymorphisms of cytochromes P450 (CYP) 2B6, 2A6 and 3A4/5 on the PK of efavirenz and its metabolites was studied: a population PK model was built integrating both genetic and demographic covariates. Functional genetic variations in main (CYP2B6) and accessory (2A6, 3A4/5) metabolic pathways of efavirenz have an impact on efavirenz disposition, and may lead to extreme drug exposures. Dosage adjustment guided by TDM is thus required in those patients, according to the pharmacogenetic polymorphism.Thus, we have demonstrated, using a comprehensive approach taking into account both PK and PG factors influencing ARVs exposure in HIV-infected patients, the feasibility of individualising antirétroviral therapy in various situations. Antiviral treatment optimisation is likely to increase long-term treatment success while reducing the occurrence of adverse drug reactions.

Boron adsorption in soils from the State of São Paulo, Brazil

Boron adsorption was studied in five representative soils (Rhodic Hapludox, Arenic Paleudalf and three Typic Hapludox) from the State of São Paulo, Brazil. Adsorption was higher in the clayey Oxisols, followed by the Alfisol and the coarser Oxisols. Calcium carbonate promoted an increase in the amount of adsorbed boron in all soils, with the most pronounced effect in the coarser-textured Oxisols. High correlation coefficients were found between adsorbed boron and clay and amorphous aluminum oxide contents and specific surface area (r = 0.79, 0.76 and 0.73, respectively, p < 0.01). Clay content, free aluminum oxide, and hot CaCl2 (0.01 mol L-1)-extracted boron explained 93% of the variation of adsorbed boron. Langmuir and Freundlich isotherms fitted well to the adsorbed data, and highest values for maximum boron adsorption were found in clayey soils, which were significantly correlated with contents of total, free and amorphous iron and aluminum oxides, as well with the physical attributes. Ninety four percent of the variation in the maximum adsorption could be related to the free iron content.

Determination of Alkalinity and dissociation constants of high salinity waters: use of F5BC titration function

Measurements of parameters expressed in terms of carbonic species such as Alkalinity and Acidity of saline waters do not analyze the influence of external parameters to the titration such as Total free and associated Carbonic Species Concentration, activity coefficient, ion pairing formation and Residual Liquid Junction Potential in pH measurements. This paper shows the development of F5BC titration function based on the titrations developed by Gran (1952) for the carbonate system of natural waters. For practical use, samples of saline waters from Pocinhos reservoir in Paraiba were submitted to titration and linear regression analysis. Results showed that F5BC involves F1x and F2x Gran functions determination, respectively, for Alkalinity and Acidity calculations without knowing "a priori" the endpoint of the titration. F5BC also allows the determination of the First and Second Apparent Dissociation Constant of the carbonate system of saline and high ionic strength waters.

Influence of wheat straw and rhizosphere on seed germination, early seedling growth and bio-chemical attributes of Trianthema portulacastrum

Decomposing wheat (Triticum aestivum) straw and rhizosphere-infested soil were evaluated for their suppressive activity against horse purslane (Trianthema portulacastrum), a noxious summer weed in Pakistan. Two separate pot studies were carried out. Wheat straw was incorporated at 4, 6 and 8 g kg-1 soil five days before the sowing of horse purslane. Pots without straw incorporation were maintained as control. In a second study, soil was taken from 15 and 30 cm depths from a previously cropped wheat field immediately after its harvest and was used as growing medium. Soil from an intentionally uncropped area of the same field was used as control. Suppressive activity was measured in terms of germination dynamics, seedling growth, and biochemical attributes such as chlorophyll contents, total soluble phenolics, soluble protein and antioxidant enzymes. Germination, seedling growth, chlorophyll contents and soluble protein of horse purslane were all negatively influenced. Higher phenolics and enhanced activities of antioxidant enzymes were noticed in response to wheat residues incorporation and its rhizosphere soil. Both studies established that the phytotoxic influence of wheat straw and wheat-infested rhizosphere soil on horse purslane can further be exploited for horse purslane management as a sustainable approach.

Modifications in the chemical compounds and sensorial attributes of Engraulis anchoita fillet during marinating process

Marinated fish are fish products preserved by the combined action of salt and organic acids. The objective of this work was to analyze the variations in the chemical compounds of anchovy fillets that give them sensorial characteristics during the marinating process of Engraulis anchoita. The protein content decreased slightly and the TVB-N level decreased significantly in both the brining and marinating stages. In the marinating stage an increase in the total free aminoacids was observed. The NBV level in the brining and marinating solutions increased during these stages due to the solubilization of the non-protein nitrogenous compounds and the degradation of some protein compounds.The decrease of the contents of protein and TVB-N, and the increase of the acidity and the free aminoacids content during the marinating process give the marinated fillets the characteristic texture and aroma.

Effect of huitlacoche (Ustilago maydis DC Corda) paste addition on functional, chemical and textural properties of tortilla chips

AbstractThis study analyzed the addition of huitlacoche paste (HP) in baked tortilla chips (TC), evaluating its effects on functional, physicochemical and structural changes during processing. Two blue corn grains were nixtamalized, stone milled, air dried and milled to obtain flour; commercial blue corn flour (TM1) and commercial TC (TM2) were used as controls. Additions of 0, 3, 6 and 9% of HP were formulated; masas were prepared at 55% moisture content (MC), precooked and baked in an industrial machine. TC crispiness was influenced by grain characteristics and percentage of HP. Huitlacoche paste addition caused an increase in total dietary fiber (from 5.27 to 14.54%), total soluble phenolics content (from 17.52 to 37.60 mg GAE/100 g) and antioxidant capacity (from 6.74 to 7.98 μmol TE/g) in TC. Results suggest that tortilla chips added with huitlacoche can be an alternative to prepare this traditional edible fungus and produce healthier snacks, not fried and enriched with bioactive compounds.

Acute salinity stress alters the haemolymph metabolic profile of Penaeus monodon and reduces immunocompetence to white spot syndrome virus infection

Influence of acute salinity stress on the immunological and physiological response of Penaeus monodon to white spot syndrome virus (WSSV) infection was analysed. P. monodon maintained at 15‰ were subjected to acute salinity changes to 0‰ and 35‰ in 7 h and then challenged orally with WSSV. Immune variables viz., total haemocyte count, phenol oxidase activity (PO), nitroblue tetrazolium salt (NBT) reduction, alkaline phosphatase activity (ALP), acid phosphatase activity (ACP) and metabolic variables viz., total protein, total carbohydrates, total free amino acids (TFAA), total lipids, glucose and cholesterol were determined soon after salinity change and on post challenge days 2 (PCD2) and 5 (PCD5). Acute salinity change induced an increase in metabolic variables in shrimps at 35‰ except TFAA. Immune variables reduced significantly (Pb0.05) in shrimps subjected to salinity stress with the exception of ALP and PO at 35‰ and the reduction was found to be more at 0‰. Better performance of metabolic and immune variables in general could be observed in shrimps maintained at 15‰ that showed significantly higher post challenge survival following infection compared to those under salinity stress. Stress was found to be higher in shrimps subjected to salinity change to lower level (0‰) than to higher level (35‰) as being evidenced by the better immune response and survival at 35‰. THC (Pb0.001), ALP (Pb0.01) and PO (Pb0.05) that together explained a greater percentage of variability in survival rate, could be proposed as the most potential health indicators in shrimp haemolymph. It can be concluded from the study that acute salinity stress induces alterations in the haemolymph metabolic and immune variables of P. monodon affecting the immunocompetence and increasing susceptibility to WSSV, particularly at low salinity stress conditions

Reducing acrylamide precursors in raw materials derived from wheat and potato

A review of agronomic and genetic approaches as strategies for the mitigation of acrylamide risk in wheat and potato is presented. Acrylamide is formed through the Maillard reaction during high-temperature cooking, such as frying, roasting, or baking, and the main precursors are free asparagine and reducing sugars. In wheat flour, acrylamide formation is determined by asparagine levels and asparagine accumulation increases dramatically in response to sulfur deprivation and, to a much lesser extent, with nitrogen feeding. In potatoes, in which sugar concentrations are much lower, the relationships between acrylamide and its precursors are more complex. Much attention has been focused on reducing the levels of sugars in potatoes as a means of reducing acrylamide risk. However, the level of asparagine as a proportion of the total free amino acid pool has been shown to be a key parameter, indicating that when sugar levels are limiting, competition between asparagine and the other amino acids for participation in the Maillard reaction determines acrylamide formation. Genetic approaches to reducing acrylamide risk include the identification of cultivars; and other germplasm in which free asparagine and/or sugar levels are low and the manipulation of genes involved in sugar and amino acid metabolism and signaling. These approaches are made more difficult by genotype/ environment interactions that can result in a genotype being "good" in one environment but "poor" in another. Another important consideration is the effect that any change could have on flavor in the cooked product. Nevertheless, as both wheat and potato are regarded as of relatively high acrylamide risk compared with, for example, maize and rice, it is essential that changes are achieved that mitigate the problem.