Food Antimicrobials Nanocarriers

Natural food antimicrobials are bioactive compounds that inhibit the growth of microorganisms involved in food spoilage or food-borne illness. However, stability issues result in degradation and loss of antimicrobial activity. Nanoencapsulation allows protection of antimicrobial food agents from unfavorable environmental conditions and incompatibilities. Encapsulation of food antimicrobials control delivery increasing the concentration of the antimicrobials in specific areas and the improvement of passive cellular absorption mechanisms resulted in higher antimicrobial activity. This paper reviews the present state of the art of the nanostructures used as food antimicrobial carriers including nanoemulsions, nanoliposomes, nanoparticles, and nanofibers

Characterization of Bacterial Communities in Mexican Artisanal Raw Milk “Bola de Ocosingo” Cheese by High-Throughput Sequencing

The dynamics of bacteria community of “Bola de Ocosingo” cheese, a Mexican artisanal raw milk cheese was investigated by high-throughput sequencing (454 pyrosequencing). Dairy samples (raw milk, curd, cheese at 50 and 110 days of ripening) were collected at dry (March-June) and rainy season (August-November) from three producers located in Chiapas, Mexico. In general, raw milk contained high bacterial diversity which was reduced throughout cheese manufacture. However, in two productions an important increase during cheese ripening was observed probably due to cross-contamination. Species such as Streptococcus thermophilus, Lactococcus lactis, Lactobacillus helveticus, L. delbrueckii and L. plantarum from which potential probiotic strains may be obtained, predominated during processing, varying its prevalence from one producer to another. Furthermore, low proportions of Escherichia coli/Shigella flexnerii were detected in almost all processes, however, could not be recovered by traditional methodology, indicating presence of non-cultivable cells. This work provides insights into bacteria communities of Bola de Ocosingo cheese for starter culture development, many of which are reported to provide health related benefits, and the usefulness of high-throughput sequencing to evidence cross-contamination during processing

Pursuing the Perfect Performer of Fermented Beverages: GMMs vs. Microbial Consortium

Fermented beverages are widely diverse around the world and their quality is largely based on the organoleptic characteristics developed by the metabolism of the microorganisms present during fermentation. In order to achieve controllable processes in fermented beverages along with organoleptic complexity, two divergent approaches have been followed in terms of inoculum development: (1) the inoculation of multiple microorganisms, intending to promote synergism and favor organoleptic complexity derived from the metabolic diversity, and (2) the genetic modification of a single strain with the intention that it performs multiple functions. In this chapter, we discuss these divergent approaches, their achievements and perspectives

Growth Kinetics for the Selection of Yeast Strains for Fermented Beverages

Criteria to select autochthonous yeast strains for their use in fermented beverages include their ability to dominate the media and to enhance desired sensorial characteristics and their inability to produce undesired compounds such as biogenic amines or off-odors. One of the key features in yeast selection is its Implantation, surpassing different stresses, and its fermentation performance, which requires setting up the process and monitoring it, involving important amount of resources. Methods to evaluate the tolerance of yeast strains are usually based in the qualitative measure of the growth of the microorganism in a medium containing the limiting compound after a specific time of incubation. However, studying strain growth through optical density measurements permits to estimate quantitative and comparable parameters providing an insight into the fitness of the cell to certain environment, lag phase duration, growth rate, and maximum population, among others. In the last decades, culture-independent methods have been used to evaluate the dynamic of microbial populations during fermentative process. In this chapter, a review of recent advances in the selection of fermentative yeasts as well as the utilization of kinetic evaluation and molecular strategies in conditions associated with fermented beverage for selecting yeast strains is presented

Mechanisms of resistance in postharvest fruit-pathogen interaction

The objective of this review was to bring together concepts related to studies aimed at elucidating defense mechanisms against disease-causing agents, mainly in postharvest. Like plants, fruits are exposed to attack by pathogens that cause rot during postharvest storage, resulting in considerable losses. To control these pathogens, synthetic chemicals are used; however, since they are toxic, genetic resistance is regarded as a viable alternative. Fruits can withstand pathogens by means of physical barriers (presence of thick cuticular or trichome layers) and chemical ones, or through induced defenses that are activated once the host detects the presence of the pathogen, triggering the oxidative burst during the early hours of interaction. This burst entails the generation of reactive oxygen species (ROS), such as superoxide (O2ˉ), hydroxyl radical (OHˉ) or hydrogen peroxide (H2O2), and the activation of genes involved in several metabolic pathways. The study of such mechanisms may allow detecting disease-resistant genetic materials, thus reducing the use of toxic products.Este trabajo ha sido financiado por el gobierno español a través del proyecto AGL2011-30519-C03-03 y por el Consejo Nacional de Ciencia y Tecnología de México a través de los Fondos FOMIX-QRO-2010-C01-145514

Food antimicrobials nanocarriers

Natural food antimicrobials are bioactive compounds that inhibit the growth of microorganisms involved in food spoilage or food-borne illness. However, stability issues result in degradation and loss of antimicrobial activity. Nanoencapsulation allows protection of antimicrobial food agents from unfavorable environmental conditions and incompatibilities. Encapsulation of food antimicrobials control delivery increasing the concentration of the antimicrobials in specific areas and the improvement of passive cellular absorption mechanisms resulted in higher antimicrobial activity. This paper reviews the present state of the art of the nanostructures used as food antimicrobial carriers including nanoemulsions, nanoliposomes, nanoparticles, and nanofibers

Mechanisms of resistance in postharvest fruit-pathogen interaction

El objetivo de esta revisión fue conjuntar conceptos relacionados con estudios dirigidos a elucidar los mecanismos de defensa contra agentes causantes de enfermedades, principalmente en poscosecha. Al igual que las plantas, los frutos se encuentran expuestos al ataque por patógenos que producen podredumbres durante su almacenamiento en poscosecha, causando considerables pérdidas. Para el control de dichos patógenos, se emplean productos químicos de síntesis que son tóxicos, y la resistencia genética se considera una alternativa viable. Los frutos pueden tolerar a los patógenos mediante barreras físicas (presencia de capas gruesas de cutícula o de tricomas) y químicas, o bien, a través de defensas inducidas que se activan una vez que el huésped detecta la presencia del patógeno, desencadenando la explosión oxidativa durante las primeras horas de la interacción. Esta explosión conlleva la generación de especies reactivas de oxígeno (ROS) como el superóxido (O2ˉ), el radical hidroxilo (OHˉ) o el peróxido de hidrógeno (H2O2), y la activación de genes involucrados en diversas rutas metabólicas. El estudio de tales mecanismos puede permitir detectar materiales genéticos resistentes a enfermedades, reduciendo así el uso de productos tóxicos

Enological potential of native non-Saccharomyces yeasts from vineyards established in Queretaro, Mexico

A ctualmente el estado de Querétaro es un importante productor de vinos en México; sin embargo, éstos difícilmente se comercializan debido a su falta de calidad y tipicidad, factores en que las levaduras vínicas juegan un papel esencial. Las Saccharomyes son responsables de la producción de etanol y las no- Saccharomyes (n S ) pueden aportar metabolitos que mejoren la calidad, por lo que su uso en inóculos mixtos es de gran interés. En este estudio, levaduras aisladas de la fermentación espontánea de mostos de uva de tres viñedos queretanos se diferenciaron como n S en medio-lisina. Se evaluó su actividad β- glucosidasa, su tolerancia a SO 2 (30 mg·L -1 ) y a etanol (6 %). Aquellas sobresalientes se probaron en microvinificaciones mixtas con Saccharomyces cerevisiae (K1-V1116) y se identificaron mediante el análisis del gen 26S. De 197 cepas aisladas, 146 resultaron n S ; 90 presentaron actividad β glucosidasa y ocho (NB1, NA4, NB27, NB31, NB39, NR77, NR90, NB108) se seleccionaron con base en los ensayos de tolerancia, identificándose como pertenecientes al género Hanseniaspora . Las n S no interfirieron en la actividad fermentativa de K1-V1116; ya que no se encontraron diferencias en las variables evaluadas entre los vinos elaborados con cultivos mixtos y el control (K1-V1116). Se obtuvieron valores de pH, acidez total, acidez volátil y alcohol, considerados de calidad aceptable para vinos secos. La cepa NB39 destacó en su producción de glicerol obteniendo el mayor valor (7.45 g · L -1 ). Se concluye que en la región existen cepas de levaduras n S con potencial enológico para ser utilizadas a nivel comercial