Microbial Diversity and Safety in Fermented Beverages

For thousands of years, humans have exploited the natural process of fermentation of various foods to preserve them, and to enjoy the changes in the sensory characteristics that could be produced. Recently, the world of fermented beverages has gone through a rapid transformation linked to deep changes in consumer preferences, consumption habits, climate, new regulations and entry of emerging countries, accompanied by safety concerns and an important reduction in economic resources available to people. As with all food handling and preparation, we need to be sure the fermented food produced is safe. Fermentation is a complex biological process where microbial diversity takes place and the environment created inside of the fermented food provides the conditions to reduce the risk of pathogenic bacteria growth, thus providing safe food. In addition, food manufacturers fermenting food carefully control their processing and must comply with the National Food Standards Codes. Although these products have a generally good food safety record, sometimes inadequate manufacturing practices or the presence of acidophilic pathogens could compromise food safety. In fact, fermented beverages may adversely become contaminated with pathogens or microbial toxins and thereby transform into vehicles that can transmit diseases to the consumers. Moreover, many microorganisms can deteriorate the physical-chemical and sensory properties as well as the flavor of the final products. In this editorial, we present an overview of a review and six original research papers published in the Special Issue “Fermentation Process and Microbial Safety of Beverages” of the Beverages journal

Efecto de los parámetros agronómico del viñedo sobre la biodiversidad de levaduras asociadas a la uva

Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada. Fecha de lectura: 22-07-201

Bacteriophages as an Up-and-Coming Alternative to the Use of Sulfur Dioxide in Winemaking

Certain acetic and lactic acid bacteria are major causes of quality defects in musts and wines, giving rise to defects such as a "vinegary," "sharp, like nail polish-remover" taste or preventing alcoholic and/or malolactic fermentation. Sulfur dioxide is the major tool currently used in the control of these bacteria in wine. The aim of this work was to isolate bacteriophages from musts and wine of different grape varieties that were able to eliminate lactic and acetic acid bacteria spoilages at the laboratory scale. Musts obtained from grape-berries of Vitis vinifera cv. Chardonnay and Moscatel and a red wine made with V. vinifera cv. Tintilla de Rota were used to isolate bacteriophages. Bacteriophages were obtained from each of the musts and the wine and belonged to the order Caudovirals and the family Tectivirals. They were isolated by classical virology methods and identified by electron microscopy. The host bacteria used in the study were lactic acid bacteria of the species Lactobacillus hilgardii, Lactobacillus plantarum, and Oenococcus oeni and the acetic bacteria Acetobacter aceti. A comparative study was performed by adding phage titrations and SO2 to musts and wines, which had been previously inoculated with bacteria, to study the effectiveness of bacteriophages against bacteria. The comparative study showed that some bacteriophages were as effective as sulfur dioxide at low concentration

Co-Existence of Inoculated Yeast and Lactic Acid Bacteria and Their Impact on the Aroma Profile and Sensory Traits of Tempranillo Red Wine

This study investigates the effects of simultaneous inoculation of a selected Saccharomyces cerevisiae yeast strain with two different commercial strains of wine bacteria Oenococcus oeni at the beginning of the alcoholic fermentation on the kinetics of malolactic fermentation (MLF), wine chemical composition, and organoleptic characteristics in comparison with spontaneous MLF in Tempranillo grape must from Castilla-La Mancha (Spain). Evolution of MLF was assessed by the periodic analysis of L-malic acid through the enzymatic method, and most common physiochemical parameters and sensory traits were evaluated using a standardized sensory analysis. The samples were analyzed by GC/MS in SCAN mode using a Trace GC gas chromatograph and a DSQII quadrupole mass analyzer. Co-inoculation reduced the overall fermentation time by up to 2 weeks leading to a lower increase in volatile acidity. The fermentation-derived wine volatiles profile was distinct between the co-inoculated wines and spontaneous MLF and was influenced by the selected wine bacteria used in co-inoculation. Co-inoculation allows MLF to develop under reductive conditions and results in wines with very few lactic and buttery flavors, which is related to the impact of specific compounds like 2,3-butanedione. This compound has been also confirmed as being dependent on the wine bacteria use

Biorefinería de residuos lignocelulósicos procedentes de la actividad agrícola del olivo y del trigo

Motivación: La principal razón que da origen a este Proyecto es poder aprovechar íntegramente una serie de residuos lignocelulósicos generados en la agricultura y muy abundantes en Andalucía, como son la paja de trigo y las podas de olivo. Este tipo de residuos son estudiados como fuentes alternativas de materia lignocelulósica en la industria papelera. A día de hoy, los procesos de producción de pastas celulósicas están en fase de optimización y los residuos lignocelulósicos líquidos (licores negros) que se generan son susceptibles de ser usados para diferentes propósitos, entre ellos la producción de bioetanol usando los microorganismos adecuados. Con el Proyecto se pretende trabajar en el desarrollo de estos aspectos y de esta manera obtener productos de valor a partir de residuos.Métodos: La paja de trigo fue proporcionada por Cooperativas agrícolas de Écija (Sevilla) y las podas de olivo por Cooperativas de Motril (Granada). La caracterización de las propiedades físico-químicas de la pasta celulósica y de la hoja de papel obtenida se llevaron a cabo mediante métodos normalizados (TAPPI, UNE). El licor negro generado en el proceso de obtención de la pasta se acondiciona para que Saccharomyces cerevisiae CECT 1170 pueda llevar a cabo la fermentación alcohólica a 30ºC, a un pH de 5,5 y con una agitación de 150 rpm. La determinación del grado alcohólico se realizó a partir del método propuesto por Crowell y Ough (1979).Resultados y conclusiones: Los resultados de las propiedades físico-químicas de las pastas y el papel son similares a las obtenidas con otro tipo de residuos que son fuente alternativa en la industria papelera. El rendimiento en la producción de bioetanol a partir de los licores negros no fue elevado con el uso de la cepa S. cerevisiae CECT 1170. Se requiere incrementar la conversión de todos los tipos de monosacáridos presentes y para ello, puede ser conveniente la utilización simultánea de este tipo de cepa con otros microorganismos

Culturable Yeasts as Biofertilizers and Biopesticides for a Sustainable Agriculture: A Comprehensive Review

The extensive use of synthetic fertilizers and pesticides has negative consequences in terms of soil microbial biodiversity and environmental contamination. Faced with this growing concern, a proposed alternative agricultural method is the use of microorganisms as biofertilizers. Many works have been focused on bacteria, but the limited literature on yeasts and their potential ability to safely promote plant growth is gaining particular attention in recent years. Thus, the objective of this review is to highlight the application of yeasts as biological agents in different sectors of sustainable agricultural practices through direct or indirect mechanisms of action. Direct mechanisms include the ability of yeasts to provide soluble nutrients to plants, produce organic acids and phytohormones (indole-3-acetic acid). Indirect mechanisms involve the ability for yeasts to act as biocontrol agents through their high antifungal activity and lower insecticidal and herbicidal activity, and as soil bioremediating agents. They also act as protective agents against extreme environmental factors by activating defense mechanisms. It is evident that all the aspects that yeasts offer could be useful in the creation of quality biofertilizers and biopesticides. Hence, extensive research on yeasts could be promising and potentially provide an environmentally friendly solution to the increased crop production that will be required with a growing populatio

Alcoholes no vínicos para la mejora del desarrollo del velo de flor y de las características sensoriales de los vinos Finos de la D.O. Jerez-Xérèz-Sherry

Abstract The wines produced in the Jerez-Xérès-Sherry Designation of Origin fall within the category of Fortified Wines, according to Regulation 1308/2013 of the European Parliament, which stipulates that they must be exclusively fortified with wine alcohol, with an acquired alcoholic strength between 95.0% and 96.0%. However, there are other alternative alcohols whose behavior is unknown but could be equally effective in the development of biological aging, with an impact on the final product quality and lower economic costs. This study examines the effect of using malt alcohols, grape pomace, agave, sugarcane, and cereal alcohols, as well as wine alcohols obtained through different distillation methods and at varying alcohol concentrations, for fortifying wines subjected to biological aging. The development of the "flor" yeast veil will be evaluated under each aging condition and isolated and characterized using molecular techniques. Additionally, the base wine fortified with the different alcohols will be monitored and analyzed both physicochemically and organoleptically

Isolation of bacteriophages from must and wine for the elimination of contaminating bacteria as an alternative to the use of sulfurous

Acetic and some lactic acid bacteria are the main reason for the loss of quality of musts and wines, giving rise to defects such as "vinegary", "chopped" or preventing alcoholic and / or malolactic fermentation. The solution to this problem consists in the application of authorized bactericidal agents, such as sulfurous. The aim of this work is to isolate bacteriophages from musts and wines of different grape varieties, able to eliminate lactic and acetic acid bacteria spoilages. Musts obtained from grape-berries of Vitis vinifera cv. Chardonnay and Moscatel and a red wine made with the Tintilla de Rota variety were used to isolate bacteriophages. It were isolated by classical virology methods and identified by electron microscopy. Host bacteria used in the study were the lactic acid bacteria of the species Lactobacillus hilgardii, L. plantarum and Oenococcus oeni and the acetic bacteria Acetobacter aceti. A comparative study was performed on musts and wines, previously inoculated with bacteria, by phage titration and SO2 addition to study the effectiveness of bacteriophages against bacteria. Bacteriophages were obtained from all musts and wine, belonging to the order of Caudovirals and Tectivirals. The comparative study showed that a cocktail of bacteriophages at low concentration is as effective as sulfur

Improving an Industrial Sherry Base Wine by Yeast Enhancement Strategies

There is growing interest in yeast selection for industrial fermentation applications since it is a factor that protects a wine's identity. Although it is strenuous evaluating the oenological characteristics of yeasts in selection processes, in many cases the most riveting yeasts produce some undesirable organoleptic characteristics in wine. The aim of the present work is to improve an industrial yeast strain by reducing its hydrogen sulfide (H2S) production. To accomplish this, two different improvement approaches were used on said yeast: hybridization by mass mating and adaptive laboratory evolution, both performed through spore generation and conjugation, thus increasing genetic variability. Three evolved variants with lower H2S production were obtained and used as starters to carry out fermentation at an industrial level. Wine quality was analyzed by its principal oenological parameters and volatile aroma compounds, which were both corroborated by sensory evaluations. Significant differences between the produced wines have been obtained and a substantial improvement in aromatic quality has been achieved. Both hybrids were the most different to the control due to terpenes and esters production, while the evolved strain was very similar to the parental strain. Not only have organoleptic defects been reduced at an industrial level, more floral and fruitier wines have been produced.This research was funded by the Centre for the Development of Industrial Technology (CDTI) (grant number IDI-20141202) and the European Regional Development Fund (ERDF) (grant number FEDER-UCA18-106947)

Non-Saccharomyces Are Also Forming the Veil of Flor in Sherry Wines

Biological ageing is an essential process for obtaining some distinctive Sherry wines, such as Fino and Manzanilla. It occurs after the fermentation of the grape must due to the appearance of a biofilm on the surface of the wine called "veil of flor". Yeasts belonging to the Saccharomyces cerevisiae species mainly comprise such biofilm. Although other species have also been found, these have been traditionally considered spoilage. Indeed, it has even been hypothesised that they may not be able to form biofilm on their own under such conditions. In the present work, four different non-Saccharomyces yeasts isolated from barrels in the Jerez area under biological ageing have been characterised through their physiological abilities, including extracellular enzymatic and biofilm-forming capabilities. Results showed not only a surprising ethanol tolerance, above 15.5% in all cases, but also a significant degree of extracellular enzyme production, highlighting the urease and proteolytic activities found in Pichia manshurica, as well as lipolytic activity in Pichia kudriavzevii, Pichia membranifaciens and Wicherhamomyces anomalus. As a conclusion, these non-Saccharomyces could be very interesting in the oenological field, beyond improving the organoleptic characteristics as well as technological features in these wines