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    ABSTRACT: Outbreaks of food-borne disease associated with the consumption of fresh and minimally processed fruits and vegetables have increased dramatically over the last few years. Traditional chemical sanitizers are unable to completely eradicate or kill the microorganisms on fresh produce. These conditions have stimulated research to alternative methods for increasing food safety. The use of protective cultures, particularly lactic acid bacteria (LAB), has been proposed for minimally processed products. However, the application of bioprotective cultures has been limited at the industrial level. From this perspective, the main aims of this study were to select LAB from minimally processed fruits and vegetables to be used as biocontrol agents and then to evaluate the effects of the selected strains, alone or in combination with natural antimicrobials (2-(E)-hexenal/hexanal, 2-(E)-hexenal/citral for apples and thyme for lamb's lettuce), on the shelf-life and safety characteristics of minimally processed apples and lamb's lettuce. The results indicated that applying the Lactobacillus plantarum strains CIT3 and V7B3 to apples and lettuce, respectively, increased both the safety and shelf-life. Moreover, combining the selected strains with natural antimicrobials produced a further increase in the shelf-life of these products without detrimental effects on the organoleptic qualities.
    Food Microbiology 05/2015; 47. · 3.37 Impact Factor
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    ABSTRACT: The use of pig rennet is very ancient and in Italy is only applied in the manufacture of Pecorino di Farindola cheese. In order to evaluate the key role of this rennet in the establishment of peculiar features of Pecorino di Farindola, cheeses made from raw ewes' milk using calf (A) and kid (B) rennets were compared to those produced with pig (C) rennet. The use of pig rennet for Pecorino di Farindola cheese making confers physico-chemical and proteolytic characteristics that differentiate it from cheeses produced with other coagulants. However, no microbiological differences were observed. Chesses made with pig and kid rennets were characterised by higher proteolysis after 7days of ripening. The content of isovaleric and propionic acids at the end of ripening was correlated with the presence of propionibacteria. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Food Chemistry 05/2015; 175:121-7. · 3.26 Impact Factor
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    ABSTRACT: In this study the thermal resistance of seven strains of staphylococci was studied. Three of them (two Staphylococcus epidermidis and one Staphylococcus lugdunensis) were isolated from pasteurized tofu, while one Staphylococcus aureus from fermented sausages. Also the corresponding type strains were tested. Their heat resistance was assessed at 80 °C also in relation to different growth conditions (high NaCl concentrations and low pH). Moreover, the effect of two terpenes (carvacrol and citral) on their survival during thermal treatment was assessed. All the strains were able to survive a 20 min thermal treatment and showed a similar behavior, i.e. an inactivation of about 6 log units in the first 2–4 min of treatment, followed by constant survivor counts (2–4 log CFU/ml). The pre-culture of staphylococci under stressing conditions (high NaCl concentration and low pH) increased the susceptibility to thermal treatment in three strains isolated from food matrices. The addition of carvacrol and citral during thermal treatment influenced the number of survived cells at the end of the treatment. This new insight in the thermal resistance of staphylococci needs to be better investigated, in order to study proper strategies to control their occurrence and behavior in real food systems.
    Food Control 04/2015; 50:605. · 2.82 Impact Factor
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    ABSTRACT: The antimicrobial activity of essential oils (EOs) from spices and medicinal plants or their constituents has gained increasing interest. However, studies on their use in combination with other antimicrobials or technologies are still scarce. In this paper, the survival of Salmonella enteritidis exposed to a combined effect of four EOs (from Xylopia aethiopica, Curcuma longa, Zanthoxylum leprieurii and Zanthoxylum xanthoxyloides) and mild heat treatments (55° and 60°C) were assessed. Salmonella enteritidis demonstrated a biphasic inactivation curve at 55°C in the absence of EOs, while in the presence of EOs the Weibull model was used. The combination of temperature and EOs reduced the treatment time needed to inactivate 7 log cfu/mL of S. enteritidis: this reduction ranged, with respect to the control, from 92.6% to 96.4% when the treatment was performed at 55°C, and from 20.5% to 27. 5% at 60°C. The efficiency of the interaction of the combination of EOs and mild thermal treatment is related to increased vapor pressure of EO constituents, which became more soluble in the membrane of stressed cells.
    Journal of Essential Oil Research 01/2015; 27(1). · 0.82 Impact Factor
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    ABSTRACT: Pandoro is a traditional Italian sweet-leavened baked product, usually consumed at Christmas. It is manufactured according to specific procedures and preparation starts from a sourdough called ‘‘madre’’ (mother sponge) continuously refreshed. This sourdough is the result of a complex microbial association including yeasts and lactic acid bacteria (LAB) and its use can improve sensory quality and shelf-life of the resulting products. The aim of this work was to evaluate the effect of the use of two different sourdoughs matured at different temperature (13 and 19 °C) on some metabolites, which can affect the organoleptic characteristics of Pandoro. Different samples, taken throughout the 19 h of process, were analysed for the determination of yeast and LAB counts, pH, aw, carbohydrates, organic acids content and volatile profile. The results showed that, at the end of fermentation process, the sourdough propagated at 19 °C reached lower pH values than that at 13 °C. This was probably due to higher LAB counts (1 log unit higher), resulting also in higher lactic acid concentration and faster sugars depletion. On the contrary, temperature of dough during maturation did not affected yeast concentrations. Different production processes strongly affected also the volatile profile, both of sourdough at the end of fermentation and of the final products.
    Lebensmittel-Wissenschaft und-Technologie 11/2014; 59(1):289–299. · 2.47 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate the competitive effects of three bacteriocin producing strains of Lactococcus lactis subsp. lactis against two aminobiogenic lactic acid bacteria, i.e. the tyramine producing strain Enterococcus faecalis EF37 and the histamine producing strain Streptococcus thermophilus PRI60, inoculated at different initial concentrations (from 2 to 6logcfu/ml). The results showed that the three L. lactis subsp. lactis strains were able to produce bacteriocins: in particular, L. lactis subsp. lactis VR84 and EG46 produced, respectively, nisin Z and lacticin 481, while for the strains CG27 the bacteriocin has not been yet identified, even if its peptidic nature has been demonstrated. The co-culture of E. faecalis EF37 in combination with lactococci significantly reduced the growth potential of this aminobiogenic strain, both in terms of growth rate and maximum cell concentration, depending on the initial inoculum level of E. faecalis. Tyramine accumulation was strongly reduced when E. faecalis EF37 was inoculated at 2logcfu/ml and, to a lesser extent, at 3logcfu/ml, as a result of a lower cell load of the aminobiogenic strain. All the lactococci were more efficient in inhibiting streptococci in comparison with E. faecalis EF37; in particular, L. lactis subsp. lactis VR84 induced the death of S. thermophilus PRI60 and allowed the detection of histamine traces only at higher streptococci inoculum levels (5-6logcfu/ml). The other two lactococcal strains did not show a lethal action against S. thermophilus PRI60, but were able to reduce its growth extent and histamine accumulation, even if L. lactis subsp. lactis EG46 was less effective when the initial streptococci concentration was 5 and 6logcfu/ml. This preliminary study has clarified some aspects regarding the ratio between bacteriocinogenic strains and aminobiogenic strains with respect to the possibility to accumulate BA and has also showed that different bacteriocins can have different effects on BA production on the same strain. This knowledge is essentially aimed to use bacteriocinogenic lactococci as a predictable strategy against aminobiogenic bacteria present in cheese or other fermented foods.
    International Journal of Food Microbiology 08/2014; 190C:14-23. · 3.16 Impact Factor
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    ABSTRACT: First aim of this research was to characterize oregano (Origanum vulgare) essential oil and the characterization of its minimum inhibitory concentration against the pathogenic species, Listeria monocytogenes and Escherichia coli. Moreover, the oregano essential oil antimicrobial activity was tested against these pathogenic species, inoculated onto wood and stainless steel surface. The GC/MS profile of oregano essential oil revealed the presence of 34 compounds, principally terpinolene, carvacrol and p-cymene accounting for about 70% of the total area of the identified molecules. Oregano essential oil showed higher antimicrobial activity against L. monocytogenes in comparison with E. coli. In fact, the L. monocytogenes minimum inhibitory concentration ranged between 125 and 200 mg/L while those for E. coli ranged between 250 and 350 mg/L. Regarding the decontamination efficacy, the washing of the two surfaces with oregano fastened the viability decrease of both the inoculated microorganisms over time. This phenomenon was more pronounced for wood as compared to steel. The data obtained suggests the great potential of this essential oil to be employed, as alternative to traditional chemicals, and as sanitizing strategy for surfaces.
    African journal of microbiology research 07/2014; 8:2746-2753. · 0.54 Impact Factor
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    ABSTRACT: Salami are typical European dry fermented sausages manufactured mainly with pork meats. Water loss is a crucial aspect of industrial ripening process because it is responsible for the lowering of water activity, which determines limitations to successive conservation. This paper describes two parametric numerical models developed to study the moisture diffusion physics, during ripening and storage in package. Mass transfer equations inside the sausage volume were numerically solved using a finite element technique. A first model describes diffusion phenomena occurring inside the salami and the exchange phenomena involving the surface of the product and the industrial environment, while a second one describes also the evaporation and condensation phenomena occurring between the salami surface and the atmosphere inside the packaging. The models were experimentally validated showing a good agreement with observed data. The numerical models allowed to study the water transfer inside of dry fermented sausages with a detail unreachable by any experimental technique. In addition the models could be used to find the best conditions for ripening, packaging and distribution.
    Journal of Food Engineering 07/2014; 132:14–20. · 2.58 Impact Factor
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    ABSTRACT: Salama da sugo is a fermented sausage from Ferrara tradition (Italy, Emilia-Romagna region), subjected to a long ripening period (4-6 months) and characterized by a high content of wine and spices in the mixture. It can be consumed after cooking and it is served with its sugo, i.e. the liquid extracted by cooking process. The aim of this work is the setting up of a method for the sensory profile of Salama da sugo, whereas it has been requested to the European Commission the Protected Geographical Indication (PGI).
    Journal of the Science of Food and Agriculture 06/2014; · 1.88 Impact Factor
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    ABSTRACT: a b s t r a c t Minimally processed fruit are susceptible to microbial proliferation and to a fast loss of sensory quality. In this experimental work, in order to increase shelf-life and quality parameters (texture and colour) maintenance of sliced apples (Malus communis, var. Golden delicious), the use of natural antimicrobials was proposed as alternative to the traditional sanitization methods. Citron EO, hexanal, 2-(E)-hexenal, citral and carvacrol, alone or in combination, were employed. As control, apples washed only with 0.5% of ascorbic and 1% of citric acid were used. The apples were dipped with traditional or natural antimicrobial solutions according to a defined protocol. After the treatment, apples were packaged in active modified atmosphere (7% O 2 and 0% CO 2) , into medium permeability bags. The products were stored at 6 C and, immediately after washing and during storage, the yeast cell loads were monitored until the spoilage threshold (6 log CFU/g). In addition, the volatile profiles, electronic nose analyses, colour and texture analyses were monitored during the storage. In all the samples the spoilage yeast threshold was not attained within the 35 days of storage independently on the substance or mixture of substances sup-plemented. Samples treated with the combinations citral/2-(E)-hexenal and hexanal/2-(E)-hexenal showed a good retention of colour parameter during storage. Among investigated samples, hexanal/2-(E)-hexenal treatment promoted the best retention of firmness throughout 35 days of storage. These results evidence the potentiality of dipping treatment based on these natural antimicrobials to strongly prolong the shelf-life of fresh-cut apples.
    Food Control 06/2014; 46:403-411. · 2.82 Impact Factor
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    ABSTRACT: The aim of this work was to characterize the essential oil (EO) of Eryngium foetidum (EfEO) and assess its activity toward Listeria monocytogenes in broth and during thermal inactivation of the pathogen in pineapple juice. In this respect, EfEO was chemically characterized, and its antilisteria potential in broth as a function of pH, cell load, and EfEO concentration was assessed through a central composite design. Furthermore, the inactivation kinetics of L. monocytogenes in the juice were assessed by combining EfEO and low pasteurization temperatures. A total of 81 compounds were identified from EfEO. The reduction of pH and cell load increased EO activity. The use of only 15 ppm of EfEO during pasteurization of pineapple juice at 60°C reduced the time required for a 4-log reduction in L. monocytogenes CFU/ml by 74.9% (i.e., from 8.5 to 2.1 min) compared with treatment without EfEO. It could be concluded that EfEO activity toward L. monocytogenes increases with the reduction of pH and that it can be used at sublethal concentrations in combination with low temperatures in pineapple juice pasteurization. This study demonstrates that EO-assisted pasteurization is a promising strategy for the reduction of thermal impact during juice production. EfEO is easily available and compatible with many juices and is thus promising for industrial application.
    Journal of food protection 03/2014; 77(3):435-43. · 1.80 Impact Factor
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    ABSTRACT: Nine Leuconostoc mesenteroides phages were isolated during blue cheese manufacture yielding faulty products with reduced eye formation. Their morphologies, restriction profiles, host ranges and long-term survival rates (25°C, 8°C, -20°C and -80°C) were analysed. Based on restriction analysis, six of them were further examined regarding resistance to physical (heat and high pressure homogenization, HPH) and chemical treatments (ethanol, sodium hypochlorite, peracetic acid, biocides A, C, E and F). According to their morphology, L. mesenteroides phages studied in the present work belonged to the Caudovirales order and Siphoviridae family. Six distinct restriction patterns were obtained with EcoRV, HindIII, ClaI and XhoI enzymes, revealing interesting phage diversity in the dairy environment. No significant reductions in phage counts were observed after ten months of storage at -20°C and -80°C, while slightly and moderate decrease in phage numbers were noticed at 8°C and 25°C, respectively. The phages subjected to heat treatments generally showed high resistance at 63°C and moderate resistance at 72°C. However, 80°C for 30min and 90°C for 2min led to complete inactivation of viral particles. In general, the best ethanol concentration tested was 75%, as complete inactivation for most Leuconostoc phages within 30min of incubation was achieved. Peracetic acid, and biocides A, C, E and F were highly effective when used at the same or at a moderately lower concentration as recommended by the producer. Usually, moderate or high concentrations (600-1600ppm) of sodium hypochlorite were necessary to completely inactivate phage particles. Leuconostoc phages were partially inactivated by HPH treatments as remaining viral particles were found even after 8 passes at 100MPa. This is the first report of L. mesenteroides phages isolated from an Argentinean dairy cheese plant. The results of this work could be useful for establishing the most effective physical and chemical treatments for inactivating phages in industrial plants and laboratory environments.
    International journal of food microbiology 02/2014; 177C:81-88. · 3.01 Impact Factor
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    ABSTRACT: The antimicrobial effects of 2 terpenes (citral and linalool) on a Saccharomyces cerevisiae strain isolated from spoiled soft drink have been evaluated, alone or in combination, in relation to pH and aw using in vitro assays. The obtained data were fitted with the logit model to find the growth/no growth boundary regions of the 2 terpenes, focusing the attention on the type of interaction exerted by citral and linalool. In particular, the results showed an increase of citral antimicrobial effect in growth media characterized by low aw value, as well as a higher linalool antimicrobial effect in media at low pH. Moreover, the interactive effects of the 2 terpenes were exploited. The results obtained with the model were validated in an independent experiment. The knowledge of the interactions of essential oil molecules with enhanced antimicrobial activity, in relation to some of the most important chemicophysical variables, can have important industrial applications, since these substances are able to assure the desired antimicrobial effect without negatively modifying the product flavor profile.
    Journal of Food Science 02/2014; · 1.78 Impact Factor
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    ABSTRACT: Nine Leuconostoc mesenteroides phages were isolated during blue cheese manufacture yielding faulty products with reduced eye formation. Their morphologies, restriction profiles, host ranges and long-term survival rates (25 °C, 8 °C, − 20 °C and − 80 °C) were analysed. Based on restriction analysis, six of them were further examined regarding resistance to physical (heat and high pressure homogenization, HPH) and chemical treatments (ethanol, sodium hypochlorite, peracetic acid, biocides A, C, E and F). According to their morphology, L. mesenteroides phages studied in the present work belonged to the Caudovirales order and Siphoviridae family. Six distinct restriction patterns were obtained with EcoRV, HindIII, ClaI and XhoI enzymes, revealing interesting phage diversity in the dairy environment. No significant reductions in phage counts were observed after ten months of storage at –20 °C and − 80 °C, while slightly and moderate decrease in phage numbers were noticed at 8 °C and 25 °C, respectively. The phages subjected to heat treatments generally showed high resistance at 63 °C and moderate resistance at 72 °C. However, 80 °C for 30 min and 90 °C for 2 min led to complete inactivation of viral particles. In general, the best ethanol concentration tested was 75%, as complete inactivation for most Leuconostoc phages within 30 min of incubation was achieved. Peracetic acid, and biocides A, C, E and F were highly effective when used at the same or at a moderately lower concentration as recommended by the producer. Usually, moderate or high concentrations (600–1600 ppm) of sodium hypochlorite were necessary to completely inactivate phage particles. Leuconostoc phages were partially inactivated by HPH treatments as remaining viral particles were found even after 8 passes at 100 MPa. This is the first report of L. mesenteroides phages isolated from an Argentinean dairy cheese plant. The results of this work could be useful for establishing the most effective physical and chemical treatments for inactivating phages in industrial plants and laboratory environments.
    International Journal of Food Microbiology. 01/2014; 177:81–88.
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    ABSTRACT: Cultures of Escherichia coli 555 were grown at four levels of carvacrol (0-2mM) and the E. coli endo-metabolome was extracted and measured by (1)H NMR spectroscopy. The results show that glucose concentration is going up with concentration of carvacrol and so do formate until the highest concentration is reached, from which point it suddenly decreases. This is interpreted as if the bacteria are increasingly unable to further metabolize glucose and as if the bacteria increasingly shifts with higher levels of carvacrol toward sugar fermentation as carbon source, until the level of carvacrol reaches a level (2.00mM), where the E. coli must give up. Additionally, the multivariate Principal Component Analysis suggests that the adaptation occurring at sub-lethal doses of carvacrol is different from that occurring at higher doses.
    Food Chemistry 12/2013; 141(4):4367-74. · 3.26 Impact Factor
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    ABSTRACT: The aim was to evaluate the effect of wine addition during manufacturing of dry fermented sausages, in terms of safety aspects (biogenic amine accumulation), aroma profile and sensory characteristics. Three batches of salami were produced: without wine addition and with 7.5% or 15% (v/w) of white wine. The fermented sausages showed characteristics that can increase product diversification. Some of the sensory features (i.e. increased salty perception) can represent an important strategy because of the trend to reduce salt intake for health reasons. The presence of wine immediately reduced the pH and is a source of ethanol, which can have an inhibitory effect against undesirable microflora. The microbiological results observed regarding Enterobacteriaceae and enterococci were encouraging. The addition of wine did not negatively affect the ripening time or increase the presence of biogenic amines. The samples containing wine showed reduced concentrations of putrescine.
    Meat Science 12/2013; 96(3):1395-1402. · 2.23 Impact Factor
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    ABSTRACT: The aim of this work was to assess if a sub-lethal high pressure homogenization (HPH) treatment could modulate in vitro functional and biological properties of probiotic bacteria. Lactobacillus paracasei A13, Lactobacillus acidophilus 08 and Dru, Lactobacillus delbrueckii subsp. lactis 200 and bile-resistant derivatives L. acidophilus Dru+ and L. delbrueckii subsp. lactis 200+ were suspended in phosphate buffered saline solution and treated at 50 MPa. Data obtained showed that HPH can modulate hydrophobicity and auto-aggregation without modification of viability and decarboxylase activity. Resistance to simulated gastric conditions resulted strain-dependent. High resistance was observed for treated L. paracasei A13, L. acidophilus Dru and 08 and L. delbrueckii subsp. lactis 200. The HPH-treatment reduced the resistance to simulated stomach duodenum-passage of L. acidophilus Dru while increased it for L. paracasei A13.Strain viability and resistance to simulated gastric conditions were evaluated treating at 50 MPa cells suspended in acidified buttermilk (pH 4.6) and stored at 4 °C for 30 days. The highest cell viability loss, after 30 d of refrigerated storage, was observed for L. acidophilus Dru, independently of the application of HPH. However, after 30 days of storage, the resistance of L. paracasei A13 to simulated gastric digestion significantly increased in HPH treated cells.
    Lebensmittel-Wissenschaft und-Technologie 10/2013; · 2.47 Impact Factor
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    ABSTRACT: This research investigated the potential of multi-pass homogenization treatment for the inactivation of Salmonella enterica serovar Enteritidis inoculated at different levels in liquid whole egg (LWE) comparing the efficacy of this treatment with a traditional thermal one performed at 65 °C. Moreover, the effects of high pressure treatment (HPH) on structural and functional properties such as viscosity, microstructure and foaming abilities of LWE were investigated. The data obtained suggested that the multi-pass high pressure treatment at 100 MPa of S. enterica serovar Enteritidis inoculated in LWE at 7 and 4 log CFU/ml resulted in a first order inactivation kinetic, while the thermal inactivation curves of S. enterica serovar Enteritidis inoculated at 8 and 4 log CFU/ml presented a non-linear behaviour, with a marked tail after 3 min of treatment at 65 °C. Additionally, HPH treatment caused an increase in foaming capacity of LWE, with respect to the untreated samples, passing from values of 26% of the control to 50% of pressure treated samples.
    Food Microbiology 10/2013; 36(1):63-9. · 3.37 Impact Factor
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    ABSTRACT: High Pressure of Homogenization (HPH) has been proposed to be applied directly to lactic acid bacteria cells at sub-lethal levels in order to enhance some functional properties. Since the principal target of HPH are the cell surface envelope structures, the aim of this work was to study the effect of a HPH, applied at 50 MPa, on cell membrane stress responses of already-known functional strains, isolated from Argentinean products. Specifically, the membrane fatty acid composition of cells before and after the sub-lethal treatment was investigated and the results showed that plasma membranes, their level of unsaturation and their composition are involved in response mechanisms adopted by microbial cells when subjected to a sub-lethal HPH stress. In fact, the data obtained demonstrated that the treatment was able to modify the fatty acid profile of the different strains, although an uniform response was not observed. Further studies are necessary both to elucidate the role of each fatty acid in the cell response mechanisms and to clarify the changes in membrane compositions induced by HPH treatment also in relation to the applicative potential of this technique. This article is protected by copyright. All rights reserved.
    Letters in Applied Microbiology 09/2013; · 1.63 Impact Factor
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    ABSTRACT: Salama da sugo is a fermented sausage from Ferrara tradition, subjected to a long ripening period (4–6 months). It can be consumed after cooking, served with its sugo, i.e. the liquid extracted by cooking process. Besides to pork meat and fat, also NaCl, curing salts, sugar, spices and almost 15% of red wine are added. The aim of this research was the microbial and aromatic profile characterization of Salama da sugo during ripening. The product was sampled in order to study chemico-physical parameters, microbial population composition (Enterobacteriaceae, lactobacilli, enterococci, micrococci and staphylococci, including coagulase positive, fungi, total mesophilic bacteria), biogenic amine content and aromatic profile. The results showed that this traditional product was characterized by a complex aroma.Moreover, the biogenic amine concentration was low (less than 200 mg/kg for tyramine, about 50 mg/kg for cadaverine and putrescine while histamine was below the detection limit).
    Food Control 08/2013; 32(2):638–643. · 2.82 Impact Factor

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