258 research outputs found
New trends in technology and identity of traditional dairy and fermented meat production processes
Interest in ecofood tourism is strictly related to the consumption
of products associated with the geographical area visited.
Local products are often requested by consumers living far
from the production zones (e.g. in bistro restaurants that reproduce
the atmosphere of typicality). This phenomenon, if on the
one hand guaranteeing the continued popularity of certain
traditional foods, highlights the inherent dangers that certain
types of food pose. They could spread the risks to a much
wider area that they might typically inhabit. The higher the demand
for certain products, the more variations of the production
processes of the traditional products there will be. This is
particularly evident for fermented products that do not have
trademark protection which allows products made with
different technologies and/or raw materials to use the same
designation. This paper reports the strengths and the weaknesses
of traditional fermented food products, examining the
concept of typicality, and evidencing the risks associated
with consumption
Identification of predominant lactic acid bacteria and yeasts of Turkish sourdoughs and selection of starter cultures for liquid sourdough production using different flours and dough yields
Eight samples of mature sourdough were collected from fi ve provinces of Turkey. Lactic acid bacteria and yeasts were isolated and identifi ed
and used in different combinations to produce liquid sourdoughs. Microbiological and physicochemical characteristics of the experimental sourdoughs
made with different fl our types and dough yields were studied. The main lactic acid bacteria species identifi ed were Lactobacillus (L.) sanfranciscensis,
Pediococcus pentosaceus, L. plantarum, L. namurencis, L. rossiae, Leuconostoc mesenteroides and L. zymae. L. spicheri, L. paralimentarius, L. mindensis,
L. farciminis, L. acetotolerans, L. casei, Enterococcus faecium and Enterococcus durans were also found in sourdoughs at subdominant levels. Among
yeasts, mainly Saccharomyces cerevisiae, but also Pichia guiliermondii and Torulaspora delbrueckii were the predominant species of yeasts identifi ed
in sourdoughs.
Lactic acid bacteria and yeasts of liquid sourdoughs after fermentation were in the range of 9.61–9.89 log cfu/g and 6.55–7.36 log cfu/g, respectively.
Various chemical parameters such as pH, total titratable acidity, lactic and acetic acids, ethanol and sugars were determined for liquid sourdoughs.
Acidifi cation and metabolite contents of these products were different, depending on the starter culture, fl our type and dough yield. Total titratable
acidity was more pronounced in the sourdoughs produced with whole wheat fl our (14.08 mL NaOH) and rye fl our (13.56 mL NaOH), dough yield 250
(13.93 mL NaOH) and control sample (13.12 mL NaOH) which were produced without inoculum
Investigation of the hygienic safety of aromatic plants cultivated in soil contaminated with Listeria monocytogenes
The present work was undertaken to investigate the survival of Listeria monocytogenes ATCC 19114T in
soil during the whole crop cycle of rocket (Eruca sativa Mill.) and basil (Ocimum basilicum L.), to monitor
its transfer to the leaves, and to evaluate its viability at harvest. To this purpose, the soil was NePeK
fertilized and four trials, obtained with different combinations of soil treatment, listerial inoculums
and seed planting, were followed for each aromatic plant. Soil was weekly investigated for total microbial
counts and L. monocytogenes evolution. At the starting time, un-inoculated autoclaved soil showed
a limited microbial load (103 CFU g dw 1), while un-inoculated non-autoclaved soil contained approximately
108 CFU g dw 1 microorganisms. Listerial persistence in inoculated soil was evaluated by plate
counts and confirmed by randomly amplified polymorphic DNA (RAPD) analysis. Trials with nonautoclaved
un-inoculated soil, used as control productions, contained about 104 CFU g dw 1 of
presumptive Listeria spp., from the beginning till the end of the experimentation, which lasted six weeks.
The trials artificially contaminated with approximately 109 CFU g dw 1 of L. monocytogenes showed
a decrease of the initial inoculums, which was more rapid, reaching lower levels at harvest, for the trials
with non-autoclaved soil (4.95 and 4.81 log CFU g dw 1 for basil and rocket, respectively) than those
with autoclaved soil (5.28 and 5.24 log CFU g dw 1 for basil and rocket, respectively). At harvest, plants
and soil samples were also analysed by denaturing gradient gel electrophoresis (DGGE). The last analysis
showed the presence of L. monocytogenes in soil, but not on the leaves of plants of all inoculated trials
The influence of addition of Borago officinalis with antibacterial activity on the sensory quality of fresh pasta
Borage (Borago officinalis L.) is a herbaceous plant of the Boraginaceae family cultivated throughout the world for several purposes, including food preparations, mainly beverages and salads. Some Italian recipes use borage as a food ingredient, in particular as condiment for pasta. The aqueous extract (AE) from borage leaves can act as biopreservative in foods due to its inhibition towards the main foodborne pathogen bacteria. Fresh pasta, due to the high content of water, is a food product with a limited shelf life. In order to test the suitability of borage to produce fresh pasta with a prolonged shelf life, borage AE was used in dried form as a raw material for the production of tagliatelle pasta. Pasta produced with fresh borage was used as green tagliatelle control, while pasta produced without borage was used as white tagliatelle control. The colour of the three tagliatelle pasta types was different. A sensory panel was used to test the appreciation of these products prepared following three recipes with Sicilian ingredients. Both pastas produced with borage were preferred to control pasta with any preparation based on cheese, meat or fish as principal flavour ingredient. The present study demonstrated the suitability of borage AE as natural preservative for fresh pasta production
Rapid differentiation and in situ detection of 16 sourdough Lactobacillus species by multiplex PCR
A two-step multiplex PCR-based method was designed for the rapid detection of 16 species of lactobacilli known to be commonly present in sourdough. The first step of multiplex PCR was developed with a mixture of group-specific primers, while the second step included three multiplex PCR assays with a mixture of species-specific primers. Primers were derived from sequences that specify the 16S rRNA, the 16S-23S rRNA intergenic spacer region, and part of the 23S rRNA gene. The primer pairs designed were shown to exclusively amplify the targeted rrn operon fragment of the corresponding species. Due to the reliability of simultaneously identifying Lactobacillus plantarum, Lactobacillus pentosus, and Lactobacillus paraplantarum, a previously described multiplex PCR method employing recA gene-derived primers was included in the multiplex PCR system. The combination of a newly developed, quick bacterial DNA extraction method from sourdough and this multiplex PCR assay allows the rapid in situ detection of several sourdough-associated lactobacilli, including the recently described species Lactobacillus rossii, and thus represents a very useful alternative to culture-based methodologies
Yeast ecology of vineyards within Marsala wine area (western Sicily) in two consecutive vintages and selection of autochthonous Saccharomyces cerevisiae strains
In this work, the yeast ecology associated with the spontaneous fermentation of Grillo cultivar grapes from 10
vineyards was analyzed from grape harvest till complete consumption of must sugars. The microbiological investigation
started with the plate count onto two culture media to distinguish total yeasts (TY) and presumptive Saccharomyces (PS).
Yeasts were randomly isolated and identified by a combined genotypic approach consisting of restriction fragment
length polymorphism (RFLP) of 5.8S rRNA gene and 26S rRNA and sequencing of D1/D2 domain of the 26S rRNA gene,
which resulted in the recognition of 14 species belonging to 10 genera. The distribution of the yeasts within the vineyards
showed some differences in species composition and concentration levels among 2008 and 2009 vintages. Due to
the enological relevance, all Saccharomyces cerevisiae isolates were differentiated applying two genotypic tools (interdelta
analysis and microsatellite multiplex PCR of polymorphic microsatellite loci) that recognized 51 strains. Based on
the low production of H2S, acetic acid and foam, ethanol resistance, growth in presence of high concentrations of
potassium metabisulphite (KMBS) and CuSO4 and at low temperatures, 14 strains were selected and used as starter to
ferment grape must at 13 C and 17 C in presence of 100 mg/L of KMBS. Three strains (CS160, CS165 and CS182) showed
optimal technological aptitudes
Filamentous Fungi transported by birds during migration across the mediterranean Sea.
The potential for the transport and diffusion of
some pathogenic microorganisms by migratory birds is of
concern. Migratory birds may be involved in the dispersal of
microorganisms and may play a role of mechanical and
biological vectors. The efficiency of dispersal of pathogenic
microorganisms depends on a wide range of biotic and
abiotic factors that influence the survival or disappearance
of a given agent in a geographical area. In the present study,
349 migratory birds were captured in four sites (Mazara del
Vallo, Lampedusa, Ustica and Linosa), representing the
main stop-over points during spring and autumnal migration,
and analyzed for the presence of filamentous fungi. A
total of 2,337 filamentous fungi were isolated from 216
birds and identified by a combined phenotypic-genotypic
approach to species level. Twelve species were identified in
the study, with Cladosporium cladosporioides, Alternaria
alternata, and Aspergillus niger as the most abundant. The
transport of these fungal species isolated in this study is of
considerable importance because some of these species can
create dangers to human health
Design and implementation of a smart system to control aromatic herb dehydration process
Drying is a process aimed at reducing the water content in plant materials below a limit
where the activity of microbes and decomposing enzymes deteriorate the quality of medicinal and
aromatic plants. Today, the interest of consumers towards medicinal and aromatic herbs has registered
a growing trend. This study aims at designing a low-cost real-time monitoring and control system for
the drying process of aromatic herbs and evaluating drying ecacy on the microbial community
associated with the studied herbs. Hot-air drying tests of sage and laurel leaves were carried out
in a dryer desiccator cabinet at 40
C and 25% relative humidity using three biomass densities
(3, 4 and 5 kg/m
2
). The prototype of the smart system is based on an Arduino Mega 2560 board,
to which nine Siemens 7MH5102-1PD00 load cells and a DHT22 temperature and humidity sensor
were added. The data acquired by the sensors were transmitted through Wi-Fi to a ThingSpeak
account in order to monitor the drying process in real time. The variation in the moisture content of
the product and the drying rate were obtained. The system provided a valid support decision during
the drying process, allowing for the precise monitoring of the evolution of the biomass moisture
loss and drying rate for laurel and sage. The three dierent biomass densities employed did not
provide significant dierences in the drying process for sage. Statistically significant dierences
among the three tests were found for laurel in the final part of the process. The microbial loads of the
aromatic herbs after drying were influenced by the dierent leaf structures of the species; in particular,
with laurel leaves, microbial survival increased with increasing biomass density. Finally, with the
drying method adopted, the two species under consideration showed a dierent microbial stability
and, consequently, had a dierent shelf life, longer for sage than laurel, as also confirmed by water
activity (aw) values
Lactococcal 949 group phages recognize a carbohydrate receptor on the host cell surface
Lactococcal bacteriophages represent one of the leading causes of dairy fermentation failure and product inconsistencies. A new member of the lactococcal 949 phage group, named WRP3, was isolated from cheese whey from a Sicilian factory in 2011. The genome sequence of this phage was determined, and it constitutes the largest lactococcal phage genome currently known, at 130,008 bp. Detailed bioinformatic analysis of the genomic region encoding the presumed initiator complex and baseplate of WRP3 has aided in the functional assignment of several open reading frames (ORFs), particularly that for the receptor binding protein required for host recognition. Furthermore, we demonstrate that the 949 phages target cell wall phospho-polysaccharides as their receptors, accounting for the specificity of the interactions of these phages with their lactococcal hosts. Such information may ultimately aid in the identification of strains/strain blends that do not present the necessary saccharidic target for infection by these problematic phages
Effect of the natural winemaking process applied at industrial level on the microbiological and chemical characteristics of wine.
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 maximumgrowth of yeasts, LAB counts reached high level of concentration
(6e7 log CFU mLL1) 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. LAB
cultures were grouped and identified by a combined phenotypic and genotypic approach. Leuconostoc mesenteroides,
Lactobacillus hilgardii and Lactobacillus plantarum species were identified; the last was the main LAB recognized during
vinification. The winemaking process was also chemically monitored. The alcoholic content was approximately 12.67%
(v vL1) at bottling; pH, volatile acidity and total acidity showed a moderate increase during vinification. Tartaric, citric
and malic acids decreased until bottling, while lactic acid showed a rapid increase at the end of maceration and bottling.
Trans-caffeil tartaric acid was the most abundant phenolic compound and volatile organic compounds (VOC) were
mainly represented by isoamylic alcohol, isobutanol, ethyl acetate and octanoic acid
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