Abstract Lactic acid bacteria have been studied for their ability to accumulate inorganic selenium, which is reduced to its elemental form or could be integrated into selenoproteins in the form of selenocysteine. This ability to produce bioavailable organic selenium for humans is an advantage that could be exploited in the production of functional foods. In this work, Enterococcus faecium ABMC-05 isolated from a traditional Mexican beverage (tepache) and with NCBI entry number OL413240 was used. Microorganism selenization was performed after the determination of minimal inhibitory concentration of Na2SeO3 (184 mg/L), which was calculated using the graphical method of Talmadge and Fitch. The selenium concentration of accumulated selenium was calculated by inductively coupled plasma optical emission spectroscopy (ICP-OES). The concentration of selenium at 48 h of fermentation was 39.92 mg/L, which represented 23.8% of selenium at medium. This value was consistent with those reported for other lactic acid bacteria. Finally, it was determined the selenocysteine presence in biomass recovery after fermentation using RP-HPLC technique. With these results it was confirmed the biogenic production of selenocysteine by Enterococcus faecium ABMC-05 using an inorganic source.

Abstract The importance of functional foods added with probiotics and prebiotics is directly related with the promotion of the health benefits of human. In this study the survival of the probiotic Lactobacillus rhamnosus GG in a semi-ripened cheese added with agave juice, was determined. Cheese ripening was carried out at 14 °C for 35 days. The pH changes were measured and the hydrolysis of the protein was evaluated through the analysis of free amino groups by the trinitrobenzenesulfonic acid (TNBS) method and SDS-PAGE polyacrylamide gel electrophoresis. At the end of the study, in the symbiotic cheese, the viability of the probotic was increased in two logarithmic cycles (from 6.73 to 8.72 log CFU). A more active proteolytic process was observed with the addition of agave juice, due to the high production of low molecular weight peptides and the concentration of free amino groups (8.63 mg/L). The pH did not have a significant difference between the control and the cheese studied. With the obtained results, it is seen that agave juice is an ingredient that can be added to semi ripening cheeses with the objective of improving the survival capacity of probiotic microorganisms, which are used as starters.

Abstract In food systems, lipid oxidation is one of the most important factors affecting food quality, nutrition, safety, color and consumer acceptance. The objective of this study was to determine the kinetic parameters of lipid oxidation and its influence in the shelf life of third generation (3G) snacks stored in three types of packaging (polyethylene, polypropylene + Kraft paper, and polyethylene + polypropylene) at 25 °C and 40 °C. The peroxide value was the quality parameter selected and monitored for a 60 day period using a spectrophotometric technique. Based on the Arrhenius equation and activated complex theory, reaction rate constants (k), activation energies (Ea), Q10 factors, activation enthalpies (∆H‡), and activation entropies (∆S‡ ) for oxidative stability in 3G snacks were calculated. Results showed that oxidation phenomena can occur in the 3G snacks and affect its shelf-life. Packaging C (polyethylene + polypropylene) was the most appropriate for the storage of this kind of product. Finally, the shelf life of the analyzed pellets was longer than one year at 25 °C and it may be extended with the appropriate mix of packaging materials.

ABSTRACT In the last decade, thrombosis has been one of the pathologies with high incidence creating great concern in Health Institutes all around the world. Considering this, the aim of this research was to determine the antithrombotic activity of peptides released during lactic fermentation. Reconstituted skim milk powder was fermented by Lactobacillus casei Shirota and Lactobacillus johnsonii LA1 isolated from commercial fermented milks. The hydrolysis degree and proteolytic profile were analyzed by trinitrobenzenesulfonic acid spectrophotometry method and by peptide polyacrylamide electrophoresis gel separation. The milk fermented by Lactobacillus casei Shirota exhibited a higher concentration of free amino groups than that fermented by Lactobacillus johnsonii LA1. Additionally, in both fermentation systems peptides with molecular weights lower than 1.4 kDa were observed. The highest inhibition of thrombin (31.67±2.35%) was observed in milk fermented by Lactobacillus johnsonii LA1 at 10 hours of fermentation. Finally, no relationship was found between the antithrombotic capacity and the proteolytic profile.

Abstract Background: Metabolism produce free radicals, which damage cells and biomolecules, causing lipid peroxidation, aging process and chronic degenerative diseases. The genus Ganoderma has metabolites with antibacterial, anti-cancer, anti-tumor, anti-inflammatory and antioxidant activities. Objective: Compare antioxidant capacity and total polyphenols content of ethanolic and aqueous extracts (basidiomes and mycelium) of three species of Ganoderma from Hidalgo State. Methods: Antioxidant capacity was evaluated by the ABTS method and total polyphenols content by the Folin-Ciocalteu method. Statistical tests included variance analysis (ANOVA), Tukey test and generalized linear discriminant analysis (AFDG). Results and conclusions: Significant differences were observed between aqueous and ethanolic extracts, the highest activity happened in ethanolic extracts of G. brownii, G. applanatum (GaA-b) and G. curtisii (GcZ-b) and aqueous extracts of G. brownii, G.applanatum (GaA-m) and G. curtisii (GcA-m), the most active was G. brownii (GbT-m). The AFDG analysis explained 77.96% of the variance in first discriminant function by antioxidant capacity and phenols present in ethanolic extracts and 20.07% in second function correlating phenols of both extracts and antioxidants in aqueous extracts. These results show that antioxidant activity is determined by the presence of phenols, polysaccharides and sterols, varying according to the species, stage of development, extract and collection area.

Resumen Antecedentes: El metabolismo produce radicales que dañan células y biomoléculas, promoviendo peroxidación lipídica, envejecimiento y enfermedades crónico-degenerativas. El género Ganoderma posee metabolitos con actividad antioxidante, anticancerígena, antitumoral y antiinflamatoria. Objetivo: Comparar la capacidad antioxidante y el contenido de polifenoles de extractos etanólicos y acuosos (basidiomas, micelio) de tres especies de Ganoderma del estado de Hidalgo. Métodos: La capacidad antioxidante se evaluó con el método ABTS y los fenoles totales con el método Folin-Ciocalteu. Se analizó la varianza (ANOVA), pruebas de Tukey y análisis discriminante generalizado lineal (AFDG). Resultados y conclusiones: Existieron diferencias significativas entre extractos acuosos y etanólicos, la mayor actividad antioxidante ocurrió en extractos etanólicos de G. brownii, G. applanatum (GaA-b) y G. curtisii (GcZ-b), y en acuosos de G. brownii, G. applanatum (GaA-m) y G. curtisii (GcA-m); G. brownii (GbT-m) mostró mayor actividad. El análisis AFDG, determinó 77.96% de varianza en la primera función discriminante por capacidad antioxidante y polifenoles de extractos etanólicos, y 20.07% en la segunda por correlación de fenoles de ambos extractos y antioxidantes en acuosos. Los resultados indican que la actividad antioxidante se asocia a la presencia de fenoles, polisacáridos y esteroles, variando según la especie, etapa de desarrollo, extracto y lugar de colecta.

Milk is an important source of bioactive compounds. Many of these compounds are released during fermentation and refrigerated storage. The aim of this study was to determine the release of peptides by lactic acid bacteria in commercial fermented milk during refrigerated storage. The size and profile of peptides were analyzed by polyacrylamide gel electrophoresis and sizeexclusion HPLC. During electrophoresis, it was observed that the peptides were released from caseins, whereas β-lactoglobulin was the whey protein with the highest degradation. HPLC analysis confirmed the pattern of peptide formation observed in electrophoresis. Two fractions lower than 2 kDa with aromatic amino acids in their structure were separated. These results were consistent with those reported for structures of peptides with antihypertensive activity. Therefore, the presence of aromatic amino acids in the peptide fractions obtained increases the likelihood of finding peptides with such activity in refrigerated commercial fermented milk. In conclusion, during cold storage, peptides with different molecular weights are released and accumulated. This could be due to the action of proteinases and peptidases of the proteolytic system in lactic acid bacteria.

With the purpose of obtaining the main factors in the nitrite quantification by bleaching Roselle anthocyanins, an experimental design (2³) was carried out. The control factors were ultrasound, time and temperature at two levels (-, +). Results for sausages analysis were obtained by the colorimetric method of AOAC 973.31, and the proposed spectrophotometric method. Statistical analysis show that results do not differ significantly. A better linear calibration range is obtained using this new method. The main advantage is the reagents that are used are cheaper.

Se realizó un diseño experimental (2³) con la finalidad de obtener los principales factores en la cuantificación de nitrito por degradación de antocianinas de la flor de jamaica. Los factores de control fueron ultrasonido, tiempo y temperatura a dos niveles (-, +). Los resultados para el análisis de embutidos fueron obtenidos por el método colorimétrico de AOAC 973.31 y el método espectrofotométrico propuesto. El análisis estadístico muestra que los resultados no difieren significativamente. Utilizando el nuevo método se obtiene un mejor intervalo de calibración lineal. La principal ventaja es que los reactivos que se utilizan son más baratos.

A simple and fast method was developed to identify anthocyanins in red grapes, plums and capulins by MALDI-ToF MS. Three different matrices were used: α-CHCA (α-cyano-4-hydroxycinnamic acid), THA (2’,4’,6’-trihydroxyacetophenone) and DHBA (2,5-dihydroxybenzoic acid). Post-Source Decay (PSD) fragment detection allowed studying the structure of compounds detected. Deprotonated anthocyanin species were assigned in capulin ([Cyanidin-3-glucosidedeprotonated]K+ and [Cyanidin-3-rutinoside-deprotonated]K+), dueto these compounds also can be ionized in form of potassium adducts combined with a deprotonation.

Se desarrolló un método simple y rápido para identificar antocianinas en uvas rojas, ciruelas y capulines por MALDI-ToF MS. Se utilizaron tres matrices diferentes: α-CHCA (ácido α-ciano-4-hidroxicinámico), THA (2’,4’,6’-trihidroxiacetofenona) y DHBA (ácido 2,5-dihidroxibenzoico. La detección del fragmento por Decaimiento Post-Fuente (PSD) permitió el estudió de los compuestos detectados. En el capulín se asignaron especies desprotonadas de antocianinas ([3glucósido-de cianidina desprotonada]K+ y [3-rutinósido de cianidina desprotonada]K+) ya que estos compuestos también pueden ionizarse en forma de aductos de potasio combinados con una desprotonación.

The characterization of the ground waters that supply the general distributor of water of Zimapán city, State of Hidalgo, Mexico and the distributor itself, is carried out in this work. Eleven sampling points have been selected in which 28 physical-chemical parameters of the collected water have been determined during 10 samplings distributed along one year (March of 1999-March of 2000). In general these waters present normal physical-chemical properties and are classified as bicarbonated-calcic and bicarbonated-mixed waters, with low levels of sulfates, chlorides, sodium and potassium; with very high concentrations of As up to 550 µg· l-1, exceeding in more than 10 times the norm NOM-127-SSA1-1994 for drinking water (Secretaria de Salud, 1996). The study of temporal variation showed significant seasonal variations with an increase in the concentrations of the total elements during the months of February and March (season of scarce rains) and a decrease in the months of April to July (season of rains), this is probably due to dilution effects caused by pluvial precipitation, which is infiltrated to the phreatic mantle. In addition, the supply wells and the points of sampling of the general distributor were correlated by means of a multi-varied analysis of physical-chemical properties.

En este trabajo se llevó a cabo la caracterización de las aguas subterráneas que abastecen al distribuidor general de agua de la ciudad de Zimapán Hidalgo, México y del propio distribuidor. Para ello se seleccionaron 11 puntos de muestreo en los que se determinaron 28 parámetros fisico-químicos de las aguas colectadas durante 10 muestreos distribuidos a lo largo de un año (marzo de 1999-marzo de 2000). De forma general, estas aguas presentaron propiedades fisicoquímicas normales clasificadas como aguas bicarbonatadas-cálcicas y bicarbonatadas-mixtas con bajos niveles de sulfatos, cloruros, sodio y potasio; pero presentaron concentraciones de As muy elevadas de hasta 550 µg· l-1, superando en más de 10 veces la norma NOM-127-SSA1-1994 para aguas potables (Secretaria de Salud, 1996). En el estudio de variación temporal se observaron cambios significativos de carácter estacional con incremento en las concentraciones de los elementos totales durante los meses de febrero y marzo (temporada de escasas lluvias) y una disminución de los mismos durante el período abril a julio (temporadas de lluvias), ésto último probablemente debido a efectos de la dilución causada por la precipitación pluvial que se infiltra al manto freático, además, se han correlacionado los pozos de suministro y los puntos de muestreo del distribuidor general mediante un análisis multivariado de las propiedades fisicoquímicas.