Search results for "Fermentation"
showing 6 items of 746 documents
The effect of temperature on the biodegradation of different types of packaging materials under test conditions
2023
The development of civilization contributed to the exponential growth in the production of plastics. Policy of the, so-called, “European Green Deal” places particular emphasis on reducing the use of plastics through various mechanisms, including their reuse, recycling and, in particular, the development of new biodegradable and compostable plastics. In order to check if plastics are suitable for biodegradability and compostability they must undergo a series of tests in accordance with applicable standards. The biodegradation test procedures are very general and allow for the use of different temperatures of the biodegradation process in the test. The aim of the research was to evaluate the …
THE INFLUENCE OF THIAMINE IN THE FERMENTATION OF THE WINE YEASTS
2011
Due to the enzymatic equipment, the yeast cell produces alcoholic fermentation by the meaning of a zimazic complex which catalyzes in different stages the redox processes of the carbohydrates, which are able to ferment, ultimately leading to ethanol. The fermentation rate is an exponential function being influenced by the cells concentration in the development environment and the starter cultures of micro-organisms. Most of the yeast strains do ferment some substrates rich in hexosanes and oligoglucides: sucrose, maltose, raffinose, lactose and celobiose. The biomass quantity may be increased in various ways. An important aspect in the increasing of the multiplication rate of the yeast cell…
Evolutionary advantage conferred by an eukaryote-to-eukaryote gene transfer event in wine yeasts
2015
Although an increasing number of horizontal gene transfers have been reported in eukaryotes, experimental evidence for their adaptive value is lacking. Here, we report the recent transfer of a 158-kb genomic region between Torulaspora microellipsoides and Saccharomyces cerevisiae wine yeasts or closely related strains. This genomic region has undergone several rearrangements in S. cerevisiae strains, including gene loss and gene conversion between two tandemly duplicated FOT genes encoding oligopeptide transporters. We show that FOT genes confer a strong competitive advantage during grape must fermentation by increasing the number and diversity of oligopeptides that yeast can utilize as a s…
Regulation of hdc expression and HDC activity by enological factors in lactic acid bacteria.
2008
Aims: The aim of this work was to study the influence of enological factors on the histidine decarboxylase gene (hdc) expression and on histidine decarboxylase enzyme (HDC) activity in Lactobacillus hilgardii, Pediococcus parvulus and Oenococcus oeni. Methods and Results: Cell extracts and whole cells were used. Glucose, fructose, malic acid and citric acid diminished the hdc expression. Ethanol did not increase hdc expression or activity in cells, but increased HDC activity. Temperature and pH had effect on the activity of HDC but not on hdc expression. Tartaric acid and l-lactic acid, and sulphur dioxide (SO2) had no effect on enzyme synthesis and activity. Bacterial species differ in t…
Advances in Wine Fermentation
2021
Fermentation is a well-known natural process that has been used by humanity for thousands of years, with the fundamental purpose of making alcoholic beverages such as wine, and also other non-alcoholic products. From a strictly biochemical point of view, fermentation is a process of central metabolism in which an organism converts a carbohydrate, such as starch or sugar, into an alcohol or an acid. The fermentation process turns grape juice (must) into wine. This is a complex chemical reaction whereby the yeast interacts with the sugars (glucose and fructose) in the must to create ethanol and carbon dioxide. Fermentation processes to produce wines are traditionally carried out with Saccharo…
Microbial dynamics during green Sicilian table olive fermentations
2009
The production of green table olives is traditionally a spontaneous fermentation carried out by indigenous microflora. Variability of microbial raw material may result in changes in the qualitative aspects of final products (Silvestri et al., 2009). Table olives of five different green table olive cultivars (four Sicilian Brandofino, Castriciana, Nocellara del Belice and Passalunara and the Spanish Manzanilla) were produced according to a semi-industrial technology, in which lactic acid bacteria (LAB) role is partially replaced by lactic acid addiction. Transformation processes were studied by a combined strategy consisting of chemical, microbiological and sensory analyses. Yeasts harboured…