Fausto Gardini

Correlation between volatile profiles of Italian fermented sausages and their size and starter culture

The aroma profiles of 10 traditional Italian fermented sausages were evaluated. The volatile organic compounds (VOCs) obtained by solid-phase microextraction and gas chromatograph-mass spectrometry were analysed using principal component analysis (PCA) and linear discriminant analysis (LDA). PCA allowed an acceptable separation but some sausage typologies were not well separated. On the other hand, the supervised approach of LDA allowed a clear grouping of the samples in relation to sausage size and starter culture. In spite of the extreme variability of the volatile profiles of the sausage typologies, this work showed the influence of diameter on VOC profile. The differences observed can be related to the effects that some fundamental physicochemical characteristics (such as water loss kinetics and oxygen availability) have on the results of ripening processes. Differences in VOC profiles were also observed due to the lactic acid bacteria used as starter cultures, with differences mainly attributable to compounds deriving from pyruvate metabolism.

Chitosan-cinnamon essential oil nano-formulation: Application as a novel additive for controlled release and shelf life extension of beef patties

In this study cinnamon essential oil-incorporated chitosan nanoparticles (CEO-CSNPs) were produced by an emulsion-gelation method. Size, zeta potential and polydispersity index of the formed nanoparticles were 235.6nm, 25.1mV and 0.33, respectively. In vitro release evaluation showed an initial burst effect, followed by a slow CEO release during 104h (at pH∼5). Different formulations of patties including control, samples containing free and encapsulated CEO and ascorbic acid were analyzed for physicochemical characteristics, microbial growth and sensorial attributes during 8days of storage at 4°C. Both free and encapsulated CEO decreased the microbial population of patties compared to the control (p<0.05) throughout the experiment. On the 8th day, the best formulations in TBARS test were AA-0.05 (0.05% of ascorbic acid) and 0.1-EN-CEO (0.1% of encapsulated CEO). During storage, the color parameters of the patties containing encapsulated CEO changed slightly whereas color and metmyoglobin content significantly decreased in samples containing free CEO and control. Free CEO had an unfavorable impact on color and odor but the incorporation of encapsulated CEO improved the consumer acceptability. The principle component analysis clearly distinguished 6 formulation groups based on physicochemical characteristics.

Physico-chemical and microbiological characterisation of Italian fermented sausages in relation to their size

BACKGROUNDnThe aim of this work was to study the physico-chemical and microbiological parameters of 10 Italian fermented sausages, produced industrially, in order to highlight the differences in relation to their size. The sausages were classified as small, medium and large and the data concerning every feature considered were analysed with some statistical explorative tools: ANOVA, principal component analysis (PCA) and linear discriminant analysis (LDA).nnnRESULTSnSignificant differences in relation to the sausage size were found regarding microbial populations (in particular, enterobacteria and staphylococci). The pH was higher in the small sausages, and consequently the presence of lactate and acetate was higher in the bigger one. Also the biogenic amine content (particularly tyramine, cadaverine and putrescine) was influenced by the size.nnnCONCLUSIONSnIn spite of the extreme variability of the sausage types at the end of ripening, this work showed that it was possible to find a strict relationship between sausages diameter and some essential physico-chemical parameters. Thus, the cross-sectional size of the product is an essential parameter, which can drive the biochemical processes during ripening, not only by affecting the kinetics of water losses, but also by influencing the microbiota enzymatic activity.

Characterisation of yeast microbiota, chemical and sensory properties of organic and biodynamic Sangiovese red wines

Wine quality is closely linked to the fermentation step, which is driven by the microbial ecology of grape and the use of selected microbial strains as well. The microbial species developing during fermentation determines the type and concentration of many substances, which contribute to the sensory properties of wine and its safety. In this view, the present work aims to characterise the yeast microbiota, chemical and sensory properties of Sangiovese red wines obtained from both biodynamic and organic agriculture. The natural yeast populations of grape musts and their evolution during spontaneous were monitored and investigated. In addition, the volatile composition, physico-chemical and safety features (ethyl-carbamate) and sensory properties of wines were evaluated. The results showed that the yeast population was mostly related to the grape management, i.e. organic or biodynamic, while the wine composition was mainly affected by the winemaking process, and then by the grape management.

Tween 80 and respiratory growth affect metabolite production and membrane fatty acids in Lactobacillus casei N87

To evaluate the effect of cultivation (anaerobiosis vs respiration) and Tween 80 supplementation on the production of metabolites and on the composition of membrane fatty acids (FAs) in Lactobacillus casei N87.

Growth, biogenic amine production and tyrDC transcription of Enterococcus faecalis in synthetic medium containing defined amino acid concentrations

The tyraminogenic potential of the strains Enterococcus faecalis EF37 and ATCC 29212 was investigated in a synthetic medium containing defined amounts of tyrosine and phenylalanine at different temperatures.

Contribution of Two Different Packaging Material to Microbial Contamination of Peaches: Implications in Their Microbiological Quality.

Aim: Aim of this work was understanding the microbial transfer dynamics from packaging to packed peaches in relation to the packaging used. Method and Results: A challenge test was performed, inoculating Escherichia coli, Pseudomonas spp. and Saccharomyces cerevisiae on cardboards and RPC (Reusable Plastic Containers), and monitoring their cell loads on fruits according to a probabilistic model and a Response Surface Methodology (RSM) in relation to several independent variables (number of fruit lesions, fruit temperature storage and commercialization time). The data recorded on packed peaches for Pseudomonas and S. cerevisiae were modeled to fit the second order model to study the main, interactive and quadratic effects of the independent variables on the cell loads of target microorganisms as well as on the shelf-life of the fruits in relation to packaging material used. The data collected for E. coli were codified as presence (1) or absence (0) and modeled with a logistic regression analysis to assess the probability of E. coli transferring from packaging to fruits in relation to the adopted variables. The data showed a higher contamination frequency of the fruits packed in plastic than in cardboard. Increasing the storage temperature and the number of lesions, the probability of transferring of E. coli from packaging materials to fruits increased, independently on commercialization time or packaging used. For Pseudomonas, the contamination levels detected on fruits packaged in plastic were significantly higher compared to those found on fruits packed in cardboard, independently on the considered variables. The polynomial equations showed the S. cerevisiae cell loads of fruits stored in plastic was positively affected by the quadratic term of temperature. Conclusions: the use of cardboard, compared to plastic, can significantly reduce the potential of microbial transferring from packaging to fruits. The probabilistic and kinetic models used showed a higher microbiological qualities of peaches stored in cardboard boxes, independently on the independent variables considered. The best performances of cardboard, compared to plastic, was probably due to its capability to entrap microbial cells. Significance and Impact: cardboard reduces fruit contamination and increases their shelf-life with positive fallouts on fruit shelf-life and all the logistic and distribution chain.

Geochemistry and microbial diversity of cave waters in the gypsum karst aquifers of Emilia Romagna region, Italy

Fifty-seven control points of waters (sinking streams, rivers in caves, and resurgences) hosted in gypsum karst areas in Emilia Romagna region (N-Italy) were sampled in the framework of a Project LIFE+08NAT/IT/000369 Gypsum in the period 2010-2014. The microbiology and chemistry of these waters have been analyzed to evaluate the impact of human activities or natural factors, in the gypsum karst systems. Waters have been analyzed for major chemistry (Ca, Mg, Na, K, SO4, HCO3, Cl, NO3) and some minor constituents (F, Br, NH4 and PO4), measuring pH, electric conductivity (EC), total dissolved solids (TDS) and temperature (T) in situ. The same samples have been analyzed with traditional microbiology techniques focused on total microbial count and on fecal microbiota, as index of human and/or animal contamination, and molecular biology techniques (sequencing of 16S rRNA segment and PCR-DGGE), focused on the characterization of microbial populations in the different sampling sites and determination of their variations and/or changes during the five years of the project. As expected, waters tend to be increasingly mineralized from sinking streams to resurgences, with only local and temporarily high contents in nitrates and ammonium, often related to the presence of bat colonies. PCR-DGGE revealed ecological changes, in terms of microbial populations present in the bulk water samples, in different sampling sites within the same cave. Although the impact of fecal microorganisms only rarely exceeded 2 log UFC/ml, the results evidenced fluctuations of these microorganisms mainly correlated to the season and to the biological activity of bats.

Environmental Factors Affecting Escherichia coli Concentrations in Striped Venus Clam (Chamelea gallina L.) Harvested in the North Adriatic Sea

The aim of this work was to evaluate the microbiological quality of striped venus clams (Chamelea gallina L.) harvested in the north Adriatic Sea during an 8-year monitoring period. A total of 387 samples were analyzed to assess the presence of Escherichia coli. Environmental parameters (salinity, pH, dissolved oxygen, seawater temperature, and freshwater outflow) were collected to find out a possible relationship between the E. coli counts and environmental factors. The results evidenced that the microbiological quality of the clams was good, with only about 5% of the samples not complying with European and Italian regulations for this product, that is, with E. coli counts higher than 230 most probable number (MPN) per 100 g of flesh and intravalvar liquid. Statistical analyses revealed a relationship between microbial contamination and the season and water temperature, probably due to the difference in the filtering activity of the mollusks. However, the main factor affecting the E. coli concentration in the clams turned out to be the flow rate of Marecchia, the major river that reaches the sea in the area of harvesting. In fact, a model fitted to evaluate the probability of finding a higher E. coli count in relation to the environmental parameters evidenced that it was an increase of the level of the Marecchia led to a higher probability of elevated E. coli contamination. This result could be explained by the higher supply of both nutrients and coliforms (including E. coli) when the river is higher and by the anthropogenic characteristics of the lands crossed by the river.

Effect of thyme essential oil and Lactococcus lactis CBM21 on the microbiota composition and quality of minimally processed lamb’s lettuce

The main aim of this work was to evaluate, at pilot scale in an industrial environment, the effects of the biocontrol agent Lactococcus lactis CBM21 and thyme essential oil compared to chlorine, used in the washing step of fresh-cut lambs lettuce, on the microbiota and its changes in relation to the time of storage. The modification of the microbial population was studied through pyrosequencing in addition to the traditional plate counts. In addition, the volatile molecule and sensory profiles were evaluated during the storage. The results showed no significant differences in terms of total aerobic mesophilic cell loads in relation to the washing solution adopted. However, the pyrosequencing data permitted to identify the genera and species able to dominate the spoilage associations over storage in relation to the treatment applied. Also, the analyses of the volatile molecule profiles of the samples during storage allowed the identification of specific molecules as markers of the spoilage for each different treatment. The sensory analyses after 3 and 5 days of storage showed the preference of the panelists for samples washed with the combination thyme EO and the biocontrol agent. These samples were preferred for attributes such as flavor, acceptability and overall quality. These results highlighted the effect of the innovative washing solutions on the quality of lettuce through the shift of microbiota towards genera and species with lower potential in decreasing the sensory properties of the product.