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Electronic nose devices are becoming a practical tool for the identification of differences among food products badsed on their origin, intrinsic quality and process conditions. The difficulty in using such instruments is to obtain, from the sensors response patterns, suitable parameters to identify the differences among samples. In this work the electronic nose analyses, trymethilamine determination and panel test were performed on samples of three species of farmed fish []ecentrachus labrax, Sparatus aurata and Salmo salar]tored for 8 days both under ice and abuse temperature of 6°C. Data from electronic nose were analysed choosing a group of features, i.e. average of the last 5 points, maximum point, average of the whole points and average of the signal resposnse characterised by the highest variation. A polynomial regression was performed on the different features in order to identify the contribution of the sensors to the sample response patterns. The data from the best sensors were then used to create an optimum feature (mixed feature). A principal component analysis (PCA)was performed on the data of all the features and the degree of separation of the tridimensional scatterplots used as a selective tool. Based on the results obtained, the features "average of the last 5 points" and "mixed feature" gave a good discrimination of the samples, "mixed feature" being the best. The scatterplot from "mixed feature" data allowed the separation of the fish samples based on species, freshness and storage time. The evolution overtime of the scores of the PCA, accounting for the highest variation of the best two features, was correlated both with TMA content and the overall evaluation of the product given by panelists.

Aims To evaluate the antifungal activity of the volatile organic compounds (VOCs) produced by 75 different food-borne Bacillus species against Aspergillus niger, Aspergillus flavus, Aspergillus parasiticus, Aspergillus clavatus, Fusarium oxysporum f. sp. lactucae and Moniliophthora perniciosa and to determine the VOCs responsible for the inhibition. Methods and Results Bacillus strains inhibited fungal growth, although with different inhibition grades, with Bacillus subtilis, Bacillus amyloliquefaciens and Bacillus cereus strains as the best antifungal VOCs producers. While M. perniciosa DM4B and F. oxysporum f.sp. lactucae MA28 were the most sensitive fungi, A. parasiticus MG51 showed the greatest resistance to Bacillus VOCs exposure. Thirty-seven compounds were detected by SPME-GC-MS analysis, although similar patterns in volatile compounds were evidenced within the species, interspecific VOCs differences determined different effects on fungal growth. Multiple partial least regression (MPLRS) and antifungal activity of the individual VOCs revealed that only propanone, 1-butanol, 3-methyl-1-butanol, acetic acid, 2-methylpropanoic acid, carbon disulphide, 3-methylbutanoic acid and ethyl acetate were responsible for mycelia inhibition of M. perniciosa DM4B and F. oxysporum f.sp. lactucae MA28. Conclusions The antagonistic activity of the Bacillus VOCs was demonstrated, although it cannot easily be explained through the action of a single molecule, thus a holistic approach could be more appropriate to estimate the fungal growth inhibition. Significance and Impact of the Study VOCs produced by Bacillus from cooked food can be considered as promising antifungal compounds useful in the control of fungal plant pathogens. This study investigates for the first time the correlation between mycelia inhibition of M. perniciosa and F. oxysporum f. sp. lactucae and the VOCs emitted by the Bacillus species.

Gluten represents one of the principal by-products of the wheat starch industry. Peptides obtained by wheat hydrolysis can be used for specific functional and biological activities, albeit at relatively low yields. Although the Maillard reaction (glycation) is widely used to increase functionality of proteins, its main disadvantage is the production of undesirable compounds due to high processing temperature. In this research, functional and biologically active glycopeptides were obtained from gluten. Alcalase or Flavourzyme proteases were used to hydrolyse gluten protein, and the resulting peptides were conjugated with glucosamine by enzymatic glycosylation, using transglutaminase, or through glycation. Both reactions were performed at mild temperatures (25 or 37°C). The formation of glycopeptides depended mostly on the glycation process, as demonstrated by MALDI-TOF-MS. The bioactivities of the conjugated hydrolysates were compared to the native hydrolysates. Although a reduction in the anti-ACE activity was detected, improved DPPH scavenging activity and enhanced antimicrobial activity against Escherichia coli were observed in the glycated Alcalase-derived hydrolysates and in the glycated Flavourzyme-derived hydrolysates, respectively. This study showed that mild conditions are an alternate approach to the traditional Maillard process conducted at elevated temperatures in creating conjugated gluten hydrolysates with enhanced bioactivities. © 2014 Elsevier Ltd.

The principal aim of this work was to compare Pecorino cheeses obtained from ewes' milk previously subjected to high pressure homogenization (HPH) at 100 MPa with those produced from raw and heat treated ewes' milk. The HPH milk treatment induced a significant increase of the cheese yield and caused a reduction of enterococci, lactococci and yeasts in the curds. Enterococci cell loads remained at lower levels in cheeses obtained from HPH milk over the ripening period. Analyses of free fatty acids, Sodium Dodecil Sulphate (SDS)-PAGE profiles, Gas Chromatography-Mass Spectrometry-Solid Phase Microextraction (GC-MS-SPME) measurements of volatile compounds and sensory traits evidenced that the pressure treatment can be regarded also as a useful tool to differentiate products obtained from the same raw material. In fact such a milk treatment induced a marked lipolysis, an early proteolysis, a relevant modification of the volatile molecule profiles and sensory properties of Pecorino cheese.

The effects of the interaction between Saccharomyces cerevisiae LBS and Lactobacillus sanfranciscensis LSCE1 and of their responses to acid, oxidative or osmotic stress on alcohol and aroma production were assessed. The exposure of S. cerevisiae LBS and L. sanfranciscensis LSCE1 cells to oxidative, acid or osmotic sub-lethal stress gave rise to a common or specific responses. γ-decalactone, 2(5H)-furanones and aldehydes were overproduced by LAB following oxidative stress. The acid stress induced both in yeasts and LAB, as well as in their co-cultures, a relevant accumulation of isovaleric and acetic acids and higher alcohols. A cross-exposure of yeasts and LAB to their preconditioned media, generated in S. cerevisiae a release of esters including esters of long-chain unsaturated fatty acids coming from membrane phospholipids. These esters were excreted also by yeasts following a pressure stress.

Two 2[5H]-furanones, in association with medium-chain fatty acids, were released in whey byLactobacillus helveticusexposed to oxidative and heat stresses. This species plays an important role in cheese technology, particularly for Swiss-type cheeses and Grana cheese. Moreover, it significantly contributes to cheese ripening by means of an early autolysis and the release of enzymes during processing. Experimental evidence of the involvement of the two 2[5H]-furanones, detected by a gas chromatography-mass spectrometry/solid-phase microextraction technique, in the autolysis phenomenon has been obtained. Zymograms performed by using renaturing sodium dodecyl sulfate-polyacrylamide gels were used to detect the bioactivity of the supernatants containing the two furanones on fresh cells of the same strain. In addition to bands corresponding to known autolysins, new autolysins were detected concomitant with the exposure ofLactobacillus helveticusto the supernatants, which can be regarded as conditioned media (CM), and to a commercial furanone, 5-ethyl-3-hydroxy-4-methyl-2[5H]-furanone (HEMFi), having spectral data similar to those of the newly described 2[5H]-furanones. Morphological changes were observed when fresh cells were exposed to CM containing the two 2[5H]-furanones and HEMFi. The two furanones produced byLactobacillus helveticus, which met a number of criteria to be included in cell-cell signaling molecules, have a presumptive molecular mass lower than those of already known 3[2H]-furanones having an autolytic activity and being produced by gram-negative bacteria. Moreover, they present a different chemical structure with respect to the furanones already identified as products ofLactococcus lactissubsp.cremorisor to those identified in some cheeses withLactobacillus helveticusas a starter culture.

The aim of this study was to identify and characterize the microorganism responsible for a case ofindustrial spoilage in a soft drink factory. About 500000 bottles of an orange-based soft drink were fermented bya Saccharomyces cerevisiae strain in spite of the addition of sodium benzoate. A similar soft drink, which differedmainly for its flavoring component, was not spoiled because of the antimicrobial activity of the orange essentialoil used in its production.Keywords : Saccharomyces cerevisiae , soft drinks, essential oil, stabilization, benzoic acid Introduction T he chemicophysical and compositive characteristics of ready-to-drink beverages make these products susceptible to spoil-age by specific microbial groups. In fact, their high C/N ratio andlow pH selectively allow the growth of acetic and lactic acid bacte-ria, molds, and yeasts (Battey and others 2002). These latter fungiare usually responsible for the degradation of carbonated softdrinks, in which the presence of CO

A mixture of novel glycopeptides from glycosylation between cold water fish skin gelatin hydrolysates and glucosamine (GlcN) via transglutaminase (TGase), as well as glycation between fish gelatin hydrolysate and GlcN were identified by their pattern of molecular distribution using MALDI-TOF-MS. Glycated/ glycosylated hydrolysates showed superior bioactivity to their original hydrolysates. Alcalase-derived fish skin gelatin hydrolysate glycosylated with GlcN in the presence of TGase at 25 °C (FAT25) possessed antioxidant activity when tested in a linoleic acid oxidation system, when measured according to its 2,2- diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and when tested at the cellular level with human hepatocarcinoma (HepG2) cells as target cells. In addition, Alcalase-derived glycosylated hydrolysates showed specificity toward the inhibition of Escherichia coli (E. coli). The Flavourzyme-derived glycopeptides prepared at 37 °C (FFC37 and FFT37) showed better DPPH scavenging activity than their native hydrolysates. The glycated Flavourzyme-derived hydrolysates were found to act as potential antimicrobial agents when incubated with E. coli and Bacillus subtilis. © 2013 Elsevier Ltd. All rights reserved.

This research was conducted to determine the biogenic amine (BA) and ethyl carbamate (EC) concentrations in commercial Primitivo wine samples and the influence of the use of malolactic starter culture on concentrations of these potentially hazardous compounds in this wine. One hundred sixty bottles of wine from eight producers in the Apulia region of southern Italy were purchased at retail and analyzed. The most common BAs were histamine, 2-phenylethylamine, tyramine, cadaverine, putrescine, spermine, and spermidine. Putrescine (derived from ornithine) was the most abundant BA in all commercial Primitivo wines (5.41 to 9.51 mg/liter), 2-phenylethylamine was detected in only two commercial wines (at less than 2.12 mg/liter), and histamine was found at concentrations of 1.49 to 16.34 mg/liter. The concentration of EC in commercial Primitivo wine was 6.81 to 15.62 ppb, which is not considered dangerous for human health. Malolactic fermentation (MLF) affected the concentrations of BAs and EC differently. For EC, no significant differences were detected between samples of wine produced by spontaneous fermentation and wine that was inoculated malolactic starter. Mean EC concentrations were 12 and 14 ppb in two batches tested (always 18 ppb or less), regardless of whether the malolactic starter was added. Although present at trace levels in wine before the MLF, histamine accumulated during the MLF process, regardless of whether the malolactic starter was added. However, the increase in histamine was higher in wines without the malolactic starter. The concentrations of putrescine and cadaverine increased after MLF, especially in the wine that spontaneously fermented. The use of a selected malolactic starter resulted in reductions in BA concentrations in wine produced by this guided MLF compared with wine produced by spontaneous MLF.

Bacteria colonizing the human intestinal tract exhibit a high phylogenetic diversity that reflects their immense metabolic potentials. The catalytic activity of gut microbes has an important impact on gastrointestinal (GI) functions and host health. The microbial conversion of carbohydrates and other food components leads to the formation of a large number of compounds that affect the host metabolome and have beneficial or adverse effects on human health. Metabolomics is a metabolic-biology system approach focused on the metabolic responses understanding of living systems to physio-pathological stimuli by using multivariate statistical data on human body fluids obtained by different instrumental techniques. A metabolomic approach based on an analytical platform could be able to separate, detect, characterize and quantify a wide range of metabolites and its metabolic pathways. This approach has been recently applied to study the metabolic changes triggered in the gut microbiota by specific diet components and diet variations, specific diseases, probiotic and synbiotic food intake. This review describes the metabolomic data obtained by analyzing human fluids by using different techniques and particularly Gas Chromatography Mass Spectrometry Solid-phase Micro Extraction (GC-MS/SPME), Proton Nuclear Magnetic Resonance ((1)H-NMR) Spectroscopy and Fourier Transform Infrared (FTIR) Spectroscopy. This instrumental approach has a good potential in the identification and detection of specific food intake and diseases biomarkers.

Beef chops were stored at 4°C under different conditions: in air (A), modified-atmosphere packaging (MAP), vacuum packaging (V), or bacteriocin-activated antimicrobial packaging (AV). After 0 to 45 days of storage, analyses were performed to determine loads of spoilage microorganisms, microbial metabolites (by solid-phase microextraction [SPME]-gas chromatography [GC]-mass spectrometry [MS] and proton nuclear magnetic resonance [ 1 H NMR]), and microbial diversity (by PCR–denaturing gradient gel electrophoresis [DGGE] and pyrosequencing). The microbiological shelf life of meat increased with increasing selectivity of storage conditions. Culture-independent analysis by pyrosequencing of DNA extracted directly from meat showed that Brochothrix thermosphacta dominated during the early stages of storage in A and MAP, while Pseudomonas spp. took over during further storage in A. Many different bacteria, several of which are usually associated with soil rather than meat, were identified in V and AV; however, lactic acid bacteria (LAB) dominated during the late phases of storage, and Carnobacterium divergens was the most frequent microorganism in AV. Among the volatile metabolites, butanoic acid was associated with the growth of LAB under V and AV storage conditions, while acetoin was related to the other spoilage microbial groups and storage conditions. 1 H NMR analysis showed that storage in air was associated with decreases in lactate, glycogen, IMP, and ADP levels and with selective increases in levels of 3-methylindole, betaine, creatine, and other amino acids. The meat microbiota is significantly affected by storage conditions, and its changes during storage determine complex shifts in the metabolites produced, with a potential impact on meat quality.

In the current study, batch culture fermentations on fecal samples of 3 healthy individuals were performed to assess the effect of the addition of prebiotics (FOS), probiotics (Bifidobacterium longum Bar33 and Lactobacillus helveticus Bar13) and synbiotics (B. longum Bar33 þ L. helveticus Bar13 þ FOS) on the fecal metabolic profiles. A total of 84 different metabolites belonging to the families of sulfur compounds, nitrogen compounds, aldehydes, ketones, esters, alcohols, phenols, organic acids, and hydrocarbons were detected by GC-MS/SPME analysis. The highest number of metabolites varied in concentration in the models with added FOS and synbiotics, where several metabolic signatures were found in common. The increase of butyrate represented the greatest variation registered after the addition of FOS alone. Following the B. longum Bar33 addition, 2-methyl butyrate underwent the most evident variation. In the batch fermentation with added L. helveticus Bar13, the decrease of pyridine and butandiene was observed together with the increase of 2-methyl-5-ethyl-pyrazine, 2-butanone and butyrate. The modification of the fecal metabolic profiles induced by the simultaneous addition of B. longum Bar33 and L. helveticus Bar13 was very similar to that observed after the supplementation with L. helveticus Bar13, regarding mainly the decrease of pyridine and the increase of butyrate.

The aim of this work was to evaluate the suitability of four strains of Saccharomyces cerevisiae endowed with in vitro β-glucosidase activity to improve the Sangiovese wine aroma profiles. In particular the effects of the strains on fermentation kinetics, wine sugar and acid concentrations, volatile molecule profiles and colour parameters were evaluated. Moreover their effects on anthocyanins, anthocyanidins and poliphenols were evaluated. These four strains of S. cerevisiae were tested in comparison with one commercial strain and with a spontaneous fermentation in the presence and in the absence of paraffin oil. The results showed that the four wild strains had high fermentation rates and an efficient conversion of grape sugars to alcohol. However, each strain imparted specific features to the wine. AS11 and AS15 gave rise to wine having low volatile acidity values associated to high levels of linalool and nerolidol. They provoked decrease of anthocyanins accompanied by the increase of some anthocyanidins. S. cerevisiae BV12 and BV14 showed the best performances producing wines with the lowest residual sugar contents and volatile acidity values, high levels of nerolidol and citronellol without detrimental effects on wine colour.

Our objective was to investigate the effect of fertilization (mineral vs. organic) and ripening stage (pre-climacteric vs. climacteric) on the emission of volatile organic compounds (VOCs) and antioxidant activity of nectarine [Prunus persica, Batsch var. nectarina (Ait) Maxim.]. The trial was carried out in 2007 in an experimental orchard of cv. Stark RedGold grafted to GF677 peach x almond hybrid planted in 2001. The trees were subjected to mineral (N, 120 kg ha -1 year -1 ) or organic (compost, 10 t DW ha -1 year -1 ) fertilization from plantation, with treatments applied 40 days after full bloom at 60% of the annual rate and in September at 40%. A fruit sample was collected every day from 22 July to 3 August. The difference in the absorbance index (I AD ) of each fruit at each sampling date was measured by visible/near infrared spectroscopy (VIS/NIRs). Fruits were sorted into two groups corresponding to two ripening stages: pre-climacteric (l AD >0.9 and flesh firmness > 50N) and climacteric (I AD

This study aimed at investigating the fecal microbiotas of children with celiac disease (CD) before (U-CD) and after (T-CD) they were fed a gluten-free diet and of healthy children (HC). Brothers or sisters of T-CD were enrolled as HC. Each group consisted of seven children. PCR-denaturing gradient gel electrophoresis (DGGE) analysis with V3 universal primers revealed a unique profile for each fecal sample. PCR-DGGE analysis with group- or genus-specific 16S rRNA gene primers showed that the Lactobacillus community of U-CD changed significantly, while the diversity of the Lactobacillus community of T-CD was quite comparable to that of HC. Compared to HC, the ratio of cultivable lactic acid bacteria and Bifidobacterium to Bacteroides and enterobacteria was lower in T-CD and even lower in U-CD. The percentages of strains identified as lactobacilli differed as follows: HC (ca. 38%) > T-CD (ca. 17%) > U-CD (ca. 10%). Lactobacillus brevis , Lactobacillus rossiae , and Lactobacillus pentosus were identified only in fecal samples from T-CD and HC. Lactobacillus fermentum , Lactobacillus delbrueckii subsp. bulgaricus , and Lactobacillus gasseri were identified only in several fecal samples from HC. Compared to HC, the composition of Bifidobacterium species of T-CD varied, and it varied even more for U-CD. Forty-seven volatile organic compounds (VOCs) belonging to different chemical classes were identified using gas-chromatography mass spectrometry-solid-phase microextraction analysis. The median concentrations varied markedly for HC, T-CD, and U-CD. Overall, the r 2 values for VOC data for brothers and sisters were equal to or lower than those for unrelated HC and T-CD. This study shows the effect of CD pathology on the fecal microbiotas of children.

The composition of four essential oils (EOs) extracted by hydrodistillation from plants of common use in Cameroon (Curcuma longa, Xylopia aethiopica, Zanthoxylum leprieurii L., Zanthoxylum xanthoxyloides) was assessed by gas chromatography-mass. Their bactericidal and bacteriostatic activity was tested in vitro against three food borne pathogenic bacteria: Listeria monocytogenes, Salmonella enteritidis and Staphylococcus aureus. The bacteriostatic activities of this EOs on food borne bacteria were assessed in vitro through optical density measurements. The minimal bactericidal concentrations (MBC) were determined in broth combined with a spot plating method. Z. xanthoxyloides and Z. leprieurii showed a similar composition, with a prevalence of oxygenated monoterpenes (about 58%). The EO of Z. xanthoxyloides was the most effective against the microorganisms tested. Its higher concentration of geraniol could be linked to this higher activity. In almost all cases, the MBC was higher than the maximum concentration tested (3000 ppm). Notwithstanding their low bactericidal effect, the EOs studied showed interesting inhibiting activities against the tested food borne pathogens. S. enteritidis was the most resistant to the bacteriostatic effect of the four EOs. The knowledge of the antimicrobial potential of local plant EOs used in developing countries could help in their choice and their use to improve food safety and shelf-life.

Europe and particularly its Mediterranean regions have a long and rich dairy heritage. At the same time, the dairy industry is nowadays an incubator of innovations particularly regarding fresh cheeses, yoghurts and milk desserts. However, the traditional dairy products are anchored to rigid protocols that limit the introduction of technological innovations. More than ten years of experimental evidences showed the great potentialities of a novel technology - the high pressure homogenization (HPH) within 80 and 180 MPa - in the generation of product innovations and improvement of the quality and safety also of traditional dairy products. The HPH pre-treatment of the starter cultures used to produce cheeses or probiotic fermented milks is one of the most promising applications of this technique. The stress-induced activation of specific metabolic activities in some Lactobacillus species starter cultures resulted in relevant changes in fermentation dynamics and final products having different texture and richer flavour patterns. Moreover, a precocious release of intracellular and cell wall located proteolytic enzymes accelerated casein breakdown during the subsequent cheese-making phases. The HPH treatment of milk before starter inoculum strongly reduced spoilage and pathogenic species viability also due to an enhancement of the activity of naturally occurring enzymes such as lactoperoxidase and lysozyme, suggesting the use of this cold technique as an alternative to heat treatment also for traditional products. In particular, long ripened cheeses from HPH-treated milk were characterized by a relevant reduction of the accumulation of biogenic amines. Moreover, dairy products obtained from HPH-treated milk were characterized by an accelerated ripening, with a faster lipolysis and proteolysis resulting in a higher production of volatile molecules that improved the scores attributed to the products during sensorial evaluation. The ability of HPH to induce conformational changes of milk proteins results in texture and microstructure changes of dairy products with respect to those from heat treated milk and can be regarded as a useful tool to differentiate probiotic fermented milks and expand the range of innovative products able to satisfy the heterogeneous consumer demand

A new family of putative signaling molecules having a 2(5H)-furanone configuration has been described in Lactobacillus helveticus, L. plantarum, L. paraplantarum, L. sanfranciscensis, Enterococcus faecalis and Salmonella enterica. The release of these molecules was cell density dependant and was enhanced by oxidative, acid and heat stresses. The cell exposure to conditioned media containing 2(5H)-furanones triggered morphological changes and autolysin production in L. helveticus and E. faecalis. Experimental evidences of the involvement of these furanones in the intra- and inter-specific communication have been obtained. The principal aim of this work was the identification of the precursors of these molecules and their biosynthetic mechanism on the basis of the hypothesis that the endogenous conversion of cell unsaturated fatty acids and the enzymatic routes giving rise to the family of the oxylipins are involved in their biosynthesis. Lactobacillus helveticus, L. sanfranciscensis, Enterococcus faecalis and Salmonella enterica were grown in presence of labeled unsaturated fatty acids in order to trace their integration in the membrane phospholipids and their metabolic fate by using GC-Mass spectrometer and the single ion monitoring technique also associated with solid phase microextraction. Compounds derived from the oxidative metabolism of polyunsaturated fatty acids were detected with GC-Mass spectrometry. Intra- and inter-specific activity was evaluated by detecting the production of autolysins with renaturating SDS–Page electrophoresis as well as by quantifying violacein produced by Chromobacterium violaceum 30191 which was used as indicator organism for quorum sensing bioassay. The analysis of the distribution of the labelled carbon of the supplemented unsaturated fatty acids into the various cell components and in the released metabolites allowed the formulation of a biosynthesis hypothesis.

In lactobacilli stress conditions can elicit overproduction of specific compounds or a metabolic shift, which may result in flavour improvement or off-flavour generation depending on the type of food. In particular in food-systems the organoleptic perception of isovaleric acid (IVA) depends on its concentration and interactions with other metabolites. IVA is a key intermediate in the branched-chain-fatty-acids biosynthesis and its role as signalling molecule in bacteria has been proven. The mechanism for IVA production/overproduction by Lactobacillus sanfranciscensis under acid stress conditions was investigated upon exposure to pH3.6 in the presence of maltose or fructose and precursors of IVA. The metabolites released were analysed by GC-MS/SPME and HPLC. For the gene-expression analyses RT- PCR was used. The results obtained demonstrated that the availability of the precursors is not limiting for IVA overproduction. IVA accumulation (>100 folds than the control) was associated with acid stress. In the samples at pH3.6 the concentration of IVA was particularly elevated in the presence of fructose. The maximal IVA production was obtained at pH3.6 with fructose combined with citrate, or leucine, or a-ketoglutarate. The gene-expression analyses were calculated for gluAT, bcAT, idh, which are involved in the IVA pathway, in respect to the control. The results revealed that, in the presence of maltose, leucine or glutamate, gluAT was overexpressed. Moreover gluAT and idh were overexpressed in the presence of fructose and citrate, or a-ketoglutarate, respectively. Interesting relationships between flavour compounds from branched-chain-amino-acid and fatty-acids biosynthesis were observed during analysis of the metabolic fate of deuterate-leucine. The control of the metabolic mechanisms and the effects of acid stress on overproduction of flavour compounds represent an important tool to optimise fermented-food production.

The capacity of human Lactobacilli and Bifidobacteria to produce metabolites under conditions that may prevail in the human intestine has been studied in vitro. However the effect of systematic probiotics consumption on human metabolic phenotype has not been investigated in feces. This paper shows the potential for the use of 1H-Nuclear Magnetic Resonance (1H-NMR) spectroscopy for studying the changes of the metabolic profiles of human fecal slurries. Feces of 16 subjects characterized by natural different level of Lactobacilli and Bifidobacteria before and after 1 month of supplementation with a symbiotic food based on Lactobacillus acidophilus, Bifidobacterium longum and fructooligosaccharides have been analyzed with 1H NMR. Multivariate statistical approach has been applied to the data obtained and particularly Canonical Discriminant Analysis of Principal Coordinates (CAP). More than 150 molecules belonging to the short chain fatty acids, organic acids, esters, alcohols and amino acids were detected and quantified in the samples considered. The number and the extent of these molecules in fecal slurries were strongly affected by the symbiotic food consumption and gave rise to characteristic metabolic signature. In particular, the short chain fatty acids concentrations significantly increased while the amino acids contents decreased. The comparison of the data indicated that the intake of the symbiotic food taken into consideration alters the metabolism of hosts in a measure dependent on the natural initial level of Lactobacilli and Bifidobacteria in the host fecal slurries. 1H NMR profiles combined with CAP allowed a separation of fecal slurries of the subjects considered on the basis of the thirty days supplementation or not with symbiotic food. The analytical system and the multivariate statistical approach used demonstrate the potential of metabolic profiling of the gut microbial activity related to dietary supplementation of probiotics.

Fungi are important spoilage agents of several foods causing great economic losses worldwide. Moreover, some moulds can produce toxic metabolites that may be mutagenic and therefore constitute a public health concern, whereas the growth of spoilage fungi results in organoleptic and chemical changes leading to the consumer rejection. Spoilage fungi are commonly controlled by synthetic chemicals; however, consumers demand for food without preservatives and associate healthy and safe foods with free or minimally processed products. As a consequence, attention has been increasingly focused on exploiting alternative methods to protect feed and food from fungal contamination such as natural antifungal molecules or biological control. The aim of this work was to evaluate the ability of some natural compounds belonging to different chemical families to affect the growth and spore germination as well as mycotoxin production of Aspergillus spp. and Penicillium spp.. Thirty compounds including furanones, oxylipins, unsaturated and saturated fatty acids, aldehydes and essential oils were screened on desiccated coconut agar at different concentrations, in the presence or absence of light and at different incubation temperatures. Moreover, mycotoxin production was confirmed and quantified by HPLC-fluorimeter detection analysis. The results evidenced that most of the substances were more active when moulds were grown in the absence of light. In particular, hexanal, bisabolol and alfa-angelica lactone induced both a delay in spore germination and a reduction of mycotoxin production in such conditions. On the contrary, 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone was found to be the most effective molecule controlling aflatoxinogenic strains in all the experimental conditions taken into consideration.

The aim was to study the effects of Debaryomyces hansenii and Yarrowia lipolytica strains, used with lactic acid starter cultures (Lactobacillus plantarum), in the manufacture of dried fermented sausages in order to understand their effects on volatile profile, biogenic amine content and sensory properties. The experimental data showed that every yeast strain produced a specific profile of volatile metabolic products. The yeasts also gave sausages with distinctive sensory properties. The degree of mincing also influenced these properties, but none of these factors had significant influence upon the accumulation of biogenic amines.

The principal aim of this work was to compare Caciotta cheeses obtained from cow milk previously subjected to high pressure homogenisation (HPH) at 100 MPa with those produced from raw (R) or heat-treated (P) cow milk. HPH had both direct and indirect effects on cheese characteristics and their evolution during ripening. In particular, HPH treatment of milk induced a significant increase of the cheese yield; moreover, it affected the microbial ecology of both curd and cheese. Compared with the thermal treatment, the HPH treatment resulted in a decrease of about one log cfu/g of yeast and lactobacilli cell loads of the curd. The initial milk treatment also affected the evolution over time and the levels attained at the end of ripening of all the microbial groups studied. In fact, lactobacilli, microstaphylococci and yeast cell loads remained at lower levels in the cheeses obtained from HPH milk with respect to the other cheese types over the whole ripening period. Moreover, HPH of milk induced marked and extensive lipolysis. Cheeses from HPH milk showed the presence of high amounts of free fatty acids immediately after brining. The electrophoretic patterns of the different cheese types showed that Caciotta made from HPH-treated milk was characterized by a more extensive and faster proteolysis as well as a significant modification of its volatile molecule profile. The results obtained and the sensory analysis indicated that HPH treatment of milk was able to differentiate Caciotta cheese or to modify its ripening patterns.

Sono riportati in letteratura molti lavori riguardanti la presenza di ceppi di S. cerevisiae in formaggi freschi e semi-stagionati. Pochi sono invece gli studi riguardanti le fermentazioni e le cinetiche di crescita. Lo scopo di questo lavoro è stato quello di studiare l’interazione tra Saccharomyces cerevisiae e Streptococcus thermophylus e/o Lactobacillus delbrueckii subsp. bulgaricus, inoculati in co-cultura, utilizzando siero come mezzo di sviluppo, seguendo la dinamica di produzione di CO2 e la cinetica di sviluppo. Il confronto tra le dinamiche di crescita del lievito e dei batteri lattici, inoculati da soli o insieme hanno evidenziato che la crescita di S.cerevisiae è stimolata dalla presenza di Str. thermophylus and Lb. delbrueckii subsp. bulgaricus.

Different methods able to differenziate between traditional and industrial Balsamic Vinegar of Modena (TBVM and BVM respectively) have been proposed. Most of the techniques have been developed specifically for TBVM. On the contrary BVM is characterized by a significant variability and its quality is usually defined by its compositive and sensory analysis. The aim of this work was to evaluate the potentiality of combined instrumental methods to assess the safety and quality of BVMs. 55 samples of commercial BVM and 9 experimental ones were analyzed with ATR-FTIR spectroscopy, gascromatography-mass spectrometry/solid phase microextraction (GC-MS/SPME), electronic nose and HPLC (with DAD and RI detectors). The multivariate statistical analysis of all the instrumental data enabled the discrimination and classification of the different samples on the basis of quality parameters. The data obtained evidenced the influence of raw materials and processing parameters on the safety and quality of final products. The results suggest new criteria for BVMs characterization and consequently for their differentiation according to their quality.

The aim of this research was to assess the antimicrobial activity of nine different industrial essences used in a soft drink factory in relation to their composition, as well as to verify the role of vapor pressure on their bioactivity. The essences were tested against a Saccharomyces cerevisiae strain isolated from spoiled soft drinks. The tests were carried out by adding the essences directly to a liquid medium or into the headspace of closed systems inoculated with the yeast. The headspace composition was evaluated through a solid phase microextraction-gas chromatography technique. The use of a mass spectrometer allowed the identification of the peaks detected. The microbial growth was indirectly monitored by measuring the metabolic CO2 released by the yeast. The results obtained indicated that the most effective essences were characterized by the highest concentration of some terpenes, such as citral, beta-pinene, and p-cymene. Moreover, all of the essences were more bioactive when added directly to the liquid medium.

The antimicrobial activity of various fatty acids or monoglycerides is well known and it has been exploited mainly for medical purposes to control infection caused by Chlamydia trachomatis, Neisseria gonorrheae and Candida albicans. However, studies concerning their mechanisms of action towards microbial cells are lacking. In this work the influence of some monoglycerides on the viability and heat resistance of Listeria monocytogenes was investigated. In particular, the deactivation curves of three stains of Listeria monocytogenes, characterised by a different stress resistance, were obtained in model system with added different monoglycerides, i.e. monolaurin, monomyristin, monolinolein and monolinolenin (0, 5, 15, 50 and 300 ppm). Moreover, the combined effect of thermal treatments and exposition to monoglycerides on cellular structure has been evaluated by means of Scanning Electron Microscopy (SEM). The results obtained evidenced that all the monoglycerides tested have an immediate and intense activity towards outer cell membranes generating superficial damages. This resulted in a viability loss ranging between 1 and 3.5 Log CFU/ml following a 10 min-exposure. This effect was strengthened when the temperature was lowered from 25°C down to 2°C. All the molecules tested also strongly influenced the deactivation dynamics of the three strains of Listeria monocytogenes subjected to heat treatments at 70°C: in fact their addition to the system resulted in a sharper slope of the survival curves regardless of the strain tested. The highest antimicrobial efficacy was detected for monolinolenin and monolinolein that caused a 6 and 5 Log CFU/ml reduction, respectively, following a 20-second treatment when employed at the lowest concentration (15 ppm). The antimicrobial activity of these compounds could be attributed to their affinity and “emulsifying” action towards cellular membranes, particularly at the high temperature adopted for the thermal treatments. In fact, SEM micrographs of cells exposed to the monoglycerides during heat treatments evidenced severe surface damages and loss of cellular turgor that could also result in the discharge of cytoplasmic content.

The principal aim of this work was to compare cheeses obtained from cow milk previously subjected to high pressure homogenization (HPH) at 1000 bar with those produced from raw and heat treated milk. The HPH treatment had both direct and indirect effects on cheese characteristics and their evolution during ripening. The direct effects were principally linked to the quali-quantitative modification of the microbial population, microstrucutre and water binding capacity of proteins. The indirect effects involved principally the activities of the microbial population and of the naturally occurring enzymes. The gas-chromatographic analyses of the free fatty acids, the SDS-Page profiles as well as the GC-SPME measurements of volatile compounds released during ripening evidenced that dynamic pressure can be regarded also as an useful tool to differentiate and positively characterise products obtained from the same raw material. The results obtained indicated that the activation of proteolytic and lipolytic activities in cheeses obtained from pressurised milk could be be linked to an enhancement of endogenous enzymatic activities, a shift of microbial population or to a different exposure of the proteins and lipids to enzymatic activity.