0000000000117204
AUTHOR
Giuseppe Blaiotta
PCR-DGGE fingerprints of microbial succession during a manufacture of traditional water buffalo mozzarella cheese.
D . E R C O L I N I , G . M A U R I E L L O , G . B L A I O T T A , G . M O S C H E T T I A N D S . C O P P O L A . 2003. Aims: To monitor the process and the starter effectiveness recording a series of fingerprints of the microbial diversity occurring at different steps of mozzarella cheese manufacture and to investigate the involvement of the natural starter to the achievement of the final product. Methods and Results: Samples of raw milk, natural whey culture (NWC) used as starter, curd after ripening and final product were collected during a mozzarella cheese manufacture. Total microbial DNA was directly extracted from the dairy samples as well as bulk colonies collected from the plates…
Study of green Sicilian table olive fermentations through microbiological, chemical and sensory analyses.
The production of five different green table olive cultivars was studied by a combined strategy consisting of chemical, microbiological and sensory analyses. Cultivable microflora of samples collected during processing was monitored by plate counts on seven synthetic culture media. In all samples Enterobacteriaceae, Pseudomonaceae, staphylococci, lactic acid bacteria and spore-forming bacteria were undetectable. Yeasts and moulds were countable from the day 42 (2 log CFU/ml) till the end of fermentation (6 log CFU/ml). The use of three different approaches for microorganism detection, including a culture-independent methodology, revealed the presence of barely three yeast species during the…
Evaluation of microbial diversity during the manufacture of Fior di Latte di Agerola, a traditional raw milk pasta-filata cheese of the Naples area
Microbial diversity of the raw milk for the production of Fior di Latte di Agerola and its changes during cheesemaking were studied. Viable counts showed that at the end of curd ripening, loads of lactic acid bacteria, both mesophilic and thermophilic rods and cocci, higher than those commonly evidenced in similar cheeses produced by using natural or commercial starters, were detected. Identification of 272 isolates, supported by molecular diagnostic aids, evidenced representative cultures of a high number of bacterial taxa of interest as participating in the process, although most of the isolates belonged to Lactococcus lactis and Lactobacillus helveticus species. RAPD-PCR and REA-PFGE bio…
Presence and characterisation of verotoxin producing E. coli in fresh Italian pork sausages, and preparation and use of an antibiotic-resistant strain for challenge studies
One hundred and twenty six samples of fresh pork sausages were analysed-for the presence of verocytotoxigenic Escherichia coli (VTEC). Selective enrichment followed by DNA extraction and PCR amplification of the stx1 and stx2 genes highlighted the occurrence of the above mentioned genes in 20 out of 126 samples screened. From the stx positive enriched cultures, isolation was performed on CT-SMAC agar plates after immuno-magnetic separation of E. coli O157. Fifty three non-sorbitol fermenting isolates were obtained and further characterised, along with the reference strain E. coli ATCC 35150(T). All the isolates were characterised by PCR assays, assessing the presence of stx1, stx2, rfbE(O15…
Heterotrophic microorganisms in deteriorated medieval wall paintings in southern Italian churches
The Campania region in southern Italy is noted for its large number of churches that harbour invaluable frescoes, dated from the beginnings of the 4th up to the 13th century. The wall paintings represent an integral part of the monuments, and their deterioration constitutes a potentially significant loss for the world's cultural heritage. Heterotrophic microorganisms such as bacteria and mould can grow on the surface of paintings that contain a wide range of organic and inorganic constituents, and provide different ecological. niches that are exploited by a large variety of microbial. species. We isolated and identified the heterotrophic microorganisms found in the biodegraded medieval wall…
Could halophilic archaea improve the traditional salted anchovies (Engraulis encrasicholus L.) safety and quality?
Aims: The positive influence of two selected extremely halophilic archaea strains in the production of salted anchovies (Engraulis encrasicolus, L., 1758) was highlighted. Methods and Results: Anchovies produced with salt artificially contaminated with halophiles exhibited lower loads of staphylococci, Enterobacteriaceae and lactic acid bacteria, and a reduced content of histamine as well as an improved organoleptic acceptance. Conclusions: The findings of this survey are expected to enhance the safety of salted anchovies, with regard to the histamine formation during ripening, and to improve the sensory attributes of this product. Significance and Impact of the Study: This study repres…
Microbial dynamics during green Sicilian table olive fermentations
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…
Evoluzione della popolazione blastomicetica durante la produzione di olive da tavola di differenti cultivar siciliane monitorata attraverso l’analisi dell’ITS rDNA.
La popolazione blastomicetica di olive verdi da tavola, prodotte a partire da 4 diverse cultivar siciliane (Brandofino, Castriciana, Nocellara del Belice, Passulunara) e da una spagnola (Manzanilla), è stata monitorata durante l’intero processo di fermentazione. La tecnologia produttiva poteva definirsi di tipo semi-industriale, giacché il ruolo della microflora lattica era parzialmente sostituito dall’aggiunta di acido lattico e la fermentazione naturale avveniva in salamoia all’8% di NaCl. La popolazione di lieviti all’avvio del processo fermentativo è risultata, indipendentemente dalla cultivar di appartenenza, nell’ordine di 2.0 log UFC g-1. Viceversa nel prodotto al consumo le conte ha…
Could halophilic archaea improve the traditional salted anchovies (Engraulis encrasicholus L) manufacture?
Although initial interest on extremely halophilic archaea turned to their involvement in the spoilage of salted meat and fish products, studies on the occurrence of such microorganisms in food ecosystems have rarely been performed. During salted anchovies production, a traditional process used by Mediterranean fishermen to obtain a tender product with a specific pleasant aroma and taste, extremely halophilic archaea belonging to the Halobacteriaceae family are often isolated. In order to elucidate the influence of halobacteria in salting and curing of this product, an experimental manufacturing was performed according to a traditional procedure. Salt to be employed was artificially inoculat…
Application of whey of Mozzarella di Bufala Campana fermented by lactic acid bacteria as a bread biopreservative agent
A total of nine isolated lactic acid bacteria (LAB) from tomato and sourdough with antifungal activity were employed to revaluate the whey of Mozzarella di Bufala through the fermentation process for 72 h at 37 °C. Then, the fermented whey (BWF) was characterised and used as biopreservative in bread formulation. L. plantarum TR7 and L. plantarum TR2 strains showed average lactic acid concentration in BWF of 13.8 g L 1. Also, the bread volatile organic compounds (VOC) analysis showed an increase in hexanal, benzeneacetaldehyde, benzaldehyde and pyrazine tetramethyl when using BWF as ingredient. Moreover, the DPPH-inhibitory activity of bread with BWF extract also reflected a 33% rise in comp…
Use of selected autochthonous lactic acid bacteria for Spanish-style table olive fermentation
The present work presents a successful attempt to achieve an enhanced and more predictable fermentation process in Spanish-style green olive technology by selection and use of autochthonous starter cultures. During the first phase of this work, two Spanish-like fermentations of green table olives of cultivar (cv) “Nocellara del Belice”, coming from irrigated and not irrigated fields, were monitored, in order to highlight the best agricultural conditions for drupe production and to isolate lactic acid bacteria strains with relevant technological properties. Among 88 identified isolates, one Lactobacillus pentosus strain showed remarkable biochemical features and high acidification rate in sy…
Technological and molecular diversity of Lactobacillus plantarum strains isolated from naturally fermented sourdoughs.
Thirty Lactobacillus (L.) plantarum strains, isolated from sourdough, were identified by biochemical tests as well as 16S rDNA sequencing and differentiated on the basis of technological properties, such as amylase, protease, phytase and antirope activities. These properties were shown to be widely differing among the strains, indicating a significant technological diversity. Genetic differentiation was achieved by restriction endonuclease analysis-pulsed field gel electrophoresis (REA-PFGE) that allowed the L. plantarum strains to be divided into 10 different genomic groups. Moreover, 32 different starters were employed in dough making experiments; each starter consisted of a single strain…