Search results for " Fermentation"

Medium for Screening Leuconostoc oenos Strains Defective in Malolactic Fermentation

1989

A new sensitive medium was developed to screen and isolate mutagenic Leuconostoc oenos strains defective in malolactic fermentation. The essential components of the medium included fructose (22 mM), l -malic acid (74.6 mM), bromocresol green (as pH indicator), and cellulose powder. The wild-type colonies turned blue, but defective malolactic colonies gave an acid reaction and remained yellow-green.

Beneficial effects of Candida zemplinina in wine fermentation: lower alcohol level and higher glycerol content

2012

Influence of autochthonous microbiota on the sicilian wine producution

2014

Effects of temperature, pH and sugar concentration on the growth parameters of Saccharomyces cerevisiae, S. kudriavzevii and their interspecific hybr…

2008

The effects of temperature, pH and sugar concentration (50% glucose + 50% fructose) on the growth parameters of Saccharomyces cerevisiae T73, S. kudriavzevii IFO 1802T and the hybrid strain S. cerevisiae × S. kudriavzevii W27 were studied by means of response surface methodology based in a central composite circumscribed design. Lag phase could not be properly modelled in the wine model system, where yeasts started the fermentation in few hours after inoculation. In the case of the maximum specific growth rate (μ max), the temperature was the most important variable for three yeasts, although the effects of sugar concentration (in T73 and W27) and pH (W27 and 1802) were also significan…

Effect of the natural winemaking process applied at industrial level on the microbiological and chemical characteristics of wine.

2013

The composition of yeast and lactic acid bacteria (LAB) communities and the chemical evolution of the large-scale commercial vinification of Catarratto IGT Sicilia, carried out under the biological regime, was followed from grape harvest until bottling. Simultaneously to the maximum growth of yeasts, LAB counts reached high level of concentration (6-7 log CFU mL(-1)) during the first steps of the alcoholic fermentation. Yeast identification was determined applying different molecular methods. The highest species biodiversity was observed on grape and must samples taken soon after pressing. Saccharomyces cerevisiae was detected at dominant concentrations during the entire winemaking process.…

Current Developments in Industrial Fermentation Processes

2021

Mise en évidence d'une production de protéases exocellulaires par les levures au cours de la fermentation alcoolique du moût de raisin

1980

<p style="text-align: justify;">La durée d'activité très limitée dans le temps des protéases du raisin est confirmée en vinification en blanc, mais une nouvelle activité protéolytique peut être caractérisée à 37 °C et à pH 3,7 dans le moût au cours de la fermentation alcoolique.</p><p style="text-align: justify;">Cette activité doit être attribuée à des protéases exocellulaires libérées dans le milieu des levures. Parmi les souches essayées <em>S. bayanus</em> a une activité protéolytique plus importante que <em>S. cerevisiae</em>, ce qui se traduit par l'obtention de vins plus riches en azote soluble, donc plus stables du point de vue protéique et …

Biochemical aspects of stuck and sluggish fermentation in grape must

1998

Recently a number of studies have focused on the factors responsible for the occurrence of stuck and sluggish fermentations. Results from these studies indicate that together with nutritional deficiencies and inhibitory substances, technological practices could lead to such situations. This review explains, from a biochemical point of view, the influence of nutritional deficiencies, inhibitory substances and technological practices on yeast cell development and physiology and the fermentation process.

Modeling of continuous Ph-stat stirred tank reactor withLactococcus lactisssp.lactisbv.diacetylactisimmobilized in calcium alginate gel beads

1995

A dynamic diffusion-reaction-growth model is proposed for the study of lactic fermentation, the bioconversion of citric acid, and cell release in an immobilized cell reactor [pH-stat continuous stirred tank-reactor (CSTR)]. The model correctly simulates the onset of fermentation and colonization of the gel, followed by the steady state. External diffusion is nonlimiting and internal diffusion is limited by high cell densities at the periphery of the gel beads. Lactose-citrate cometabolism in the gel is related to the distribution of active included biomass within the gel and to gradients of substrates (lactose, citrate) and products (lactate, pH) in the beads. The utilization of lactose is …

A simple protocol for extraction and detection of pyrazines produced by fungi in solid state fermentation

1992

A protocol for the extraction and detection of pyrazines produced by fungi in Solid State Fermentation that gave good recovery of these compounds was devised together with specific techniques for detection by Gas Chromatography (GC). The protocol involved solid-liquid and liquid-liquid extractions, concentration of the extracts and GC analysis. Extraction yields were measured from a model system in which synthetic pyrazines were added. Extracts were analysed with a gas chromatograph equipped with a thermo-ionic detector to allow specific pyrazine detection.