Search results for "fermentation"
showing 10 items of 746 documents
Factors affecting the presence of ochratoxin A in wines.
2006
Ochratoxin A (OTA) are synthesized mainly by different species of Aspergillus and Penicillium being its human toxicological effects reflected in different countries due to the consumption of different foods and beverages such as red, white, rose, and special wines. This review presents an overview of the direct (meteorological conditions, grape cultivation, and wine-making techniques) and indirect (latitude, year of production, use of pesticides, presence of spoilage microorganisms, conditions of storage of the harvested grapes, type of maceration, and conditions of fermentation), factors affecting the presence of OTA in wines.
Changes in ochratoxin A and type B trichothecenes contained in wheat flour during dough fermentation and bread baking processes
2009
Ochratoxin A (OTA) and type B trichothecenes are mycotoxins that occur frequently in cereals and thus can be found in cereal by-products such as bread. The aim of this work was to study the variation of the levels of OTA, deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON) and nivalenol (NIV) during the bread-making process. This was done by using wheat flour spiked with different levels of toxins. Mycotoxin levels were controlled after fermentation of the dough with yeasts (Saccharomyces cerevisiae) and after further baking at different temperature-time combinations. Analysis of variance (ANOVA) of the results showed a significant reduction in OTA level (p < 0.05) during fermentation of …
Metabolic differences between a wild and a wine strain of Saccharomyces cerevisiae during fermentation unveiled by multi‐omic analysis
2021
Saccharomyces cerevisiae, a widespread yeast present both in the wild and in fermentative processes, like winemaking. During the colonization of these human‐associated fermentative environments, certain strains of S. cerevisiae acquired differential adaptive traits that enhanced their physiological properties to cope with the challenges imposed by these new ecological niches. The advent of omics technologies allowed unveiling some details of the molecular bases responsible for the peculiar traits of S. cerevisiae wine strains. However, the metabolic diversity within yeasts remained poorly explored, in particular that existing between wine and wild strains of S. cerevisiae. For this purpose,…
Optimum design and operation of primary sludge fermentation schemes for volatile fatty acids production.
2003
This paper presents a model-knowledge based algorithm for optimising the primary sludge fermentation process design and operation. This is a recently used method to obtain the volatile fatty acids (VFA), needed to improve biological nutrient removal processes, directly from the raw wastewater. The proposed algorithm consists in a heuristic reasoning algorithm based on the expert knowledge of the process. Only effluent VFA and the sludge blanket height (SBH) have to be set as design criteria, and the optimisation algorithm obtains the minimum return sludge and waste sludge flow rates which fulfil those design criteria. A pilot plant fed with municipal raw wastewater was operated in order to …
Technological properties of Oenococcus oeni strains isolated from typical southern Italian wines.
2010
Aims: To isolate indigenous Oenococcus oeni strains suitable as starters for malolactic fermentation (MLF), using a reliable polyphasic approach. Methods and Results: Oenococcus oeni strains were isolated from Nero di Troia wines undergoing spontaneous MLF. Samples were taken at the end of alcoholic fermentation and during MLF. Wine samples were diluted in a sterile physiological solution and plated on MRS and on modified FT80. Identification of O. oeni strains was performed by a polymerase chain reaction (PCR) experiment using strain-specific primers. Strains were further grouped using a multiplex RAPD-PCR analysis. Then, six strains were inoculated in two wine-like media with two differe…
Mutation of the oxaloacetate decarboxylase gene of Lactococcus lactis subsp. lactis impairs the growth during citrate metabolism
2007
; Aims: Citrate metabolism generates metabolic energy through the generation of a membrane potential and a pH gradient. The purpose of this work was to study the influence of oxaloacetate decarboxylase in citrate metabolism and intracellular pH maintenance in relation to acidic conditions. Methods and Results: A Lactococcus lactis oxaloacetate decarboxylase mutant [ILCitM (pFL3)] was constructed by double homologous recombination. During culture with citrate, and whatever the initial pH, the growth rate of the mutant was lower. In addition, the production of diacetyl and acetoin was altered in the mutant strain. However, our results indicated no relationship with a change in the maintenanc…
Amylase production in submerged culture using principal component analysis
1989
Abstract The aim of our work was to study the production of α-amylase and glucoamylase in submerged culture by a species of Aspergillus niger screened for its high amylase activity. Statistical analysis was not used to optimize fermentation conditions but it was employed in a new approach to describe the culture behaviour. Principal component analysis (PCA) was applied to describe the influence of three agitation speeds on the rate of amylases synthesis and on the evolution of other indirect growth factors. The results of this analysis showed that the oxygen transfer at various agitation speeds affected the levels of enzymes, their production rates and the CO 2 production rate (indirect mea…
Multispectral fluorescence sensitivity to acidic and polyphenolic changes in Chardonnay wines – The case study of malolactic fermentation
2022
International audience; In this study, stationary and time-resolvedfluorescence signatures, were statistically and chemometrically analyzed among three typologies of Chardonnay wines (A, B and C) with the objectives to evaluate their sensitivity to acidic and polyphenolic changes. For that purpose, a dataset was built using Excitation Emission Matrices of fluorescence (N = 103) decomposed by a Parallel Factor Analysis (PARAFAC), andfluorescence decays (N = 22), mathematically fitted, using the conventional exponential modeling and the phasor plot representation. Wine PARAFAC component C4 coupledwith its phasor plot g and s values enable the description of malolactic fermentation (MLF) occur…
Development of a Higee bioreactor (HBR) for production of polyhydroxyalkanoate: Hydrodynamics, gas–liquid mass transfer and fermentation studies
2010
Abstract This study addresses the hydrodynamics and mass transfer characterisation of a Higee bioreactor (HBR) for application to polyhydroxyalkanoate (PHA) production from Pseudomonas putida KT2442 fermentation. The motivation for this work is to address the potential oxygen transfer limitations which can severely impede the progress of this aerobic fermentation process and reduce PHA productivity in conventional bioreactors. It is shown that a maximum of 2.5 transfer units can be achieved in an oxygen-stripping operation where the presence of packing, higher rotor speeds, higher air flowrates and lower liquid flowrates all have a positive influence on the number of transfer units (NTU). W…
Application of HPP in food fermentation processes
2020
Abstract High pressure processing (HPP) is widely used in the food industry for nonthermal pasteurization of juices, ready-to-eat meals, dairy products, pet food, etc. The pasteurization effect is induced by damaging the membranes of microorganisms (leading to cell lysis) as well as by protein denaturation, thus interrupting cellular functions such as nutrient uptake, DNA replication, etc. Nevertheless, as a thermodynamic variable, pressure can also be used to enhance the fermentative processes if applied at sublethal levels (up to 50/60 MPa) to induce metabolic shifts in microorganisms, This allows accelerating the fermentative processes or even obtaining different compounds resulting from…