Papers by Francesca Patrignani
Microorganisms, 2020
Sub-lethal high-pressure homogenization treatments applied to Lactobacillus paracasei A13 demonst... more Sub-lethal high-pressure homogenization treatments applied to Lactobacillus paracasei A13 demonstrated to be a useful strategy to enhance technological and functional properties without detrimental effects on the viability of this strain. Modification of membrane fatty acid composition is reported to be the main regulatory mechanisms adopted by probiotic lactobacilli to counteract high-pressure stress. This work is aimed to clarify and understand the relationship between the modification of membrane fatty acid composition and the expression of genes involved in fatty acid biosynthesis in Lactobacillus paracasei A13, before and after the application of different sub-lethal hyperbaric treatments. Our results showed that Lactobacillus paracasei A13 activated a series of reactions aimed to control and stabilize membrane fluidity in response to high-pressure homogenization treatments. In fact, the production of cyclic fatty acids was counterbalanced by the unsaturation and elongation of ...
Food Microbiology, 2003
... 1. The pH of BHI broth was adjusted with HCl 0.1N (Merck) and was measured with a pHmeter HI ... more ... 1. The pH of BHI broth was adjusted with HCl 0.1N (Merck) and was measured with a pHmeter HI 8520 (Hanna Instruments, Padova ... of 3 repetitions and 2 replicates) collected (expressed as %v/v) was modelled according to the Gompertz equation modified by [Zwietering et al ...
![Research paper thumbnail of Two 2[5H]-Furanones as Possible Signaling Molecules in Lactobacillus helveticus](https://attachments.academia-assets.com/35956613/thumbnails/1.jpg)
Applied and Environmental Microbiology, 2006
Two 2[5H]-furanones, in association with medium-chain fatty acids, were released in whey by Lacto... more Two 2[5H]-furanones, in association with medium-chain fatty acids, were released in whey by Lactobacillus helveticus exposed 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 of Lactobacillus helveticus to the supernatants, which can be regarded as conditioned media (CM), and to a commercial furanone, 5-ethyl-3hydroxy-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 by Lactobacillus 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 of Lactococcus lactis subsp. cremoris or to those identified in some cheeses with Lactobacillus helveticus as a starter culture.
Journal of Dairy Research, 2009
High pressure homogenization (HPH) is one of the most promising alternatives to traditional therm... more High pressure homogenization (HPH) is one of the most promising alternatives to traditional thermal treatment for food preservation and diversification. In order to evaluate its potential for the production of fermented milks carrying probiotic bacteria, four types of fermented milks were manufactured from HPH treated and heat treated (HT) milk with and without added probiotics. Microbiological, physicochemical and organoleptic analyses were carried out during the refrigerated period (35 d at 4 8C). HPH application to milk did not modify the viability of the probiotic cultures but did increase the cell loads of the starter cultures (ca. 1 log order) compared with traditional products. The coagula from HPH-milk was significantly more compacted (P <0 . 05) (higher firmness) than that obtained with HT-milk, and it had the highest values of consistency, cohesiveness and viscosity indexes compared with fermented milks produced without HPH treatment. All the samples received high sensory analysis scores for each descriptor considered. HPH treatment of milk can potentially diversify the market for probiotic fermented milks, especially in terms of texture parameters.
Fuel and Energy Abstracts, 2011
This work studied the variability in lipolytic activity in 35 strains of Yarrowia lipolytica inoc... more This work studied the variability in lipolytic activity in 35 strains of Yarrowia lipolytica inoculated in pork fat after 7 and 21 days of storage at 15 °C.The strains were able to generate three different hydrolysis profiles. In particular, the strains PO10, PO14, RO1, RO5, Y15, Y16A, Y20, B5, 7B, 7B3, 16B and 21C caused an increase with time in concentrations of C16:0, C18:0, C18:1, C18:1(Δ11) and C18:2 which were the predominant free fatty acids (FFAs). On the contrary, the strains PO1, PO19, PO23, RO22, Y12, B4, B74, GB, 5B, 5D, 27D and W29 showed an opposite trend, while the remaining ones induced no change.Because the released FFAs can be considered precursors for flavour development, the results suggest the potential use of some Y. lipolytica strains in sausage making to improve the overall aroma.
Fuel and Energy Abstracts, 2011
The effects of selected variables, i.e. temperature, water activity and yeast inoculation level, ... more The effects of selected variables, i.e. temperature, water activity and yeast inoculation level, on the lipolytic pattern and volatile production by Yarrowia lipolytica Y16A (chosen on the basis of a previous screening) were assessed. The variables were varied according to a central composite design and the models obtained enabled evaluation and weighting of the effects of the independent variables on the free fatty acids (FFAs) and volatile profiles in pork fat based medium. The polynomial models showed the levels temperature, water activity of the pork fat based system and yeast strain inoculation were able to maximize the release of specific FFAs or molecules of sensory importance.
Journal of Dairy Science, 2007
The aim of this research was the evaluation of the effects of milkfat content, nonfat milk solids... more The aim of this research was the evaluation of the effects of milkfat content, nonfat milk solids content, and high-pressure homogenization on 1) fermentation rates of the probiotic strain Lactobacillus paracasei BFE 5264 inoculated in milk; 2) viability loss of this strain during refrigerated storage; and 3) texture parameters, volatile compounds, and sensorial properties of the coagula obtained. The data achieved suggested a very strong effect of the independent variables on the measured attributes of fermented milks. In fact, the coagulation times were significantly affected by pressure and added milkfat, and the rheological parameters of the fermented milk increased with the pressure applied to the milk for added nonfat milk solids concentrations lower than 3%. Moreover, the polynomial models and the relative response surfaces obtained permitted us to identify the levels of the 3 independent variables that minimized the viability loss of the probiotic strain used during refrigerated storage.
Journal of Dairy Research, 2006
The principal aim of this work was to compare Caciotta cheeses obtained from cow milk previously ... more 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.
Food Chemistry, 2007
... envelope. The main components of the proteolytic system of the LAB are the cell envelope asso... more ... envelope. The main components of the proteolytic system of the LAB are the cell envelope associated proteinases, although intracellular proteinases have been reported (Upadhyay, McSweeney, Magboul, &amp; Fox, 2004). Moreover ...
Dairy Science & Technology, 2010
The aim of this study was to characterize dairy Lactobacillus plantarum-group strains on the basi... more The aim of this study was to characterize dairy Lactobacillus plantarum-group strains on the basis of their phenotypic and genotypic profiles in order to increase the knowledge on the ecology and biodiversity within this wild Lactobacillus group. In addition, their in vitro potential probiotic properties were evaluated with a view to identifying potential interesting applications. Among the strains, both physiological and biochemical characteristics differed noticeably, indicating biodiverse phenotypic differences. Genotyping experiments using randomly amplified polymorphic DNA (RAPD)-PCR with primer M13 also showed a remarkable heterogeneity among the strains and allowed the strains to be grouped into the species L. plantarum and L. pentosus/L. paraplantarum. With regard to probiotic functional characteristics, the L. plantarum strains 31C and 143C and the L. plantarum strains 64FS and 61FS, isolated from Caciotta and Fiore Sardo cheeses, respectively, survived simulated gastrointestinal conditions and were considered to be acid and bile tolerant. The majority of the strains exhibited antagonistic activity towards Escherichia coli ATCC 43895 and L. sakei DSM 20017, but only one of these strains was found to produce a bacteriocin-like compound. The results of this study suggest the presence of both phenotypic and genotypic variation within the L. plantarum group isolated from the two different Italian cheeses. Further investigation and development as potential probiotic strains is required.
Food Control, 2007
The main objective of this paper was to evaluate the eYcacy, in terms of safety, shelf life exten... more The main objective of this paper was to evaluate the eYcacy, in terms of safety, shelf life extension and keeping quality of diVerent commercial ingredients, including nitrite/nitrate and spices, of fresh Italian Toscana traditional sausages. In particular, the role of spices, in the possible reduction or replacement of nitrate and nitrite, was investigated. The data evidenced the signiWcant role of the spices on the growth reduction of deliberately inoculated Listeria monocytogenes,. The Principal Component Analyses of the microbial metabolite and sausage Xavours suggested that the microbial activity was aVected more by spices than by nitrite and nitrate extent.
Journal of Food Science, 2008
ABSTRACT: The aim of this study was the evaluation of the effects of pure citral and citron esse... more ABSTRACT: The aim of this study was the evaluation of the effects of pure citral and citron essential oil on microbial spoilage and growth and survival of pathogenic microorganisms during storage. They were added in the syrup of industrial ready-to-eat fruit salads stored at 9 °C. Both citral (25 to 125 ppm) and citron essential oil (300, 600, 900 ppm) were able to prolong the microbial shelf life of the fruit-based salads. The essential oil gave excellent results, avoiding the undesirable effects attributable to the cytotoxicity of citral. Citron essential oil doubled the time needed for the wild microflora to reach concentrations able to produce a perceivable spoilage in condition of thermal abuse (9 °C). The same essential oil had reduced effects on the survival of Gram-negative species Salmonella Enteritidis and Escherichia coli, but showed a strong inhibition toward the Gram-positive pathogen Listeria monocytogenes.
Food Control, 2007
The eVects of high pressure homogenization treatment at 100 MPa (HPH), in comparison to diVerent ... more The eVects of high pressure homogenization treatment at 100 MPa (HPH), in comparison to diVerent heat treatments, 70°C for 30 s, 70°C for 5 min or 100°C for 5 min, on the activity of lysozyme and lactoferrin, were studied. The antimicrobial activities of lysozyme and lactoferrin were tested on Listeria monocytogenes inoculated in milk or cultural medium.
Dairy Science & Technology, 2011
The aim of this study was to characterize dairy Lactobacillus plantarum-group strains on the basi... more The aim of this study was to characterize dairy Lactobacillus plantarum-group strains on the basis of their phenotypic and genotypic profiles in order to increase the knowledge on the ecology and biodiversity within this wild Lactobacillus group. In addition, their in vitro potential probiotic properties were evaluated with a view to identifying potential interesting applications. Among the strains, both physiological and biochemical characteristics differed noticeably, indicating biodiverse phenotypic differences. Genotyping experiments using randomly amplified polymorphic DNA (RAPD)-PCR with primer M13 also showed a remarkable heterogeneity among the strains and allowed the strains to be grouped into the species L. plantarum and L. pentosus/L. paraplantarum. With regard to probiotic functional characteristics, the L. plantarum strains 31C and 143C and the L. plantarum strains 64FS and 61FS, isolated from Caciotta and Fiore Sardo cheeses, respectively, survived simulated gastrointestinal conditions and were considered to be acid and bile tolerant. The majority of the strains exhibited antagonistic activity towards Escherichia coli ATCC 43895 and L. sakei DSM 20017, but only one of these strains was found to produce a bacteriocin-like compound. The results of this study suggest the presence of both phenotypic and genotypic variation within the L. plantarum group isolated from the two different Italian cheeses. Further investigation and development as potential probiotic strains is required. 为了增加对野生型乳杆菌 (Lactobacillus) 菌群的生态学和生物多样性的了解, 本文利用表型和基因鉴定法研究了意大利干酪 (Italian cheese) 中植物乳杆菌 (Lactobacillus plantarum) 菌群的分布。 并通过体外实验探讨了这些菌株的潜在益生菌功能特性。 结果显示不同菌株的生理和生化特征完全不同。 以引物M13 进行RAPD-PCR实验, 发现不同菌株之间的RAPD图谱有显著差异, 可以归为干酪乳杆菌 (L. plantarum), 戊糖乳杆菌 (L. pentosus) 和副干酪乳杆菌 (L. paraplantarum)。 关于益生菌的功能特性, 源于Caciotta干酪中的菌株L. plantarum 31C 和 143C 及 Fiore Sardo 干酪中的 L. plantarum 64FS 和61FS 菌株都能在模拟肠道环境中存活, 意味着这些菌是耐酸和耐胆汁的。 干酪中大部分乳杆菌能抑制大肠杆菌ATCC 43895 和L. sakei DSM 20017的生长, 但只有一株菌能产生类细菌素的化合物。 结果显示表型和基因鉴定法均能得到两种不同意大利干酪中植物乳杆菌群的变化。 但是其中的潜在益生菌 特性则需要进一步研究。
Journal of Food Science, 2010
ABSTRACT: This experimental work was aimed to evaluate the effects of repeated high-pressure hom... more ABSTRACT: This experimental work was aimed to evaluate the effects of repeated high-pressure homogenization (HPH) treatments at 100 MPa on the inactivation and regrowth of Zygosaccharomyces bailii inoculated in apricot and carrot juices. Thus, the spoilage yeast was inoculated in both the juices at level of about 5 log CFU/g and the 2 systems were treated with a lab-scale Panda homogenizer for 8 passes at 100 MPa. Microbiological and chemico-physical analyses were performed immediately after the treatment and during the juice storage at room temperature. Microbial data highlighted that yeast inactivation increased with the number of passes applied. Eight passes at 100 MPa allowed yeast inactivation higher than 2.5 log CFU/mL regardless of the juice considered. On the contrary, the juice type affected the yeast fate (growth or death) over the storage at 25 °C. In fact, Z. bailii was able to attain the spoilage threshold (6 log CFU/mL) in apricot juice, although with growth kinetics dependent of the survivor levels after HPH treatment. In carrot juice this microorganism was unable to recover over the storage in the most severely treated samples. The HPH treatment had a significant effect on apricot juice pH and viscosity, while no significant effect was observed in carrot juice. The viscosity measurements showed that the application of one pass at 100 MPa resulted in the triplication of apricot viscosity index. No further significant viscosity increase (P > 0.05) was observed increasing the number of passes at 100 MPa.Practical Application: The results obtained in the present study and the proposed technology could be exploited by the industries of the beverage sector to increase the shelf life of these kinds of products. Moreover, from a technological point of view, the increase of viscosity, following the high-pressure homogenization treatment, represents a tool to expand the product gamma without the use of gelling additives or thermal treatments, which are detrimental for the sensorial and nutritional properties of this kind of products.
International Journal of Food Microbiology, 2006
The purpose of this research was the evaluation of technological features and of the ability of f... more The purpose of this research was the evaluation of technological features and of the ability of functional LAB strains with desirable sensory characteristics, to produce fermented milk. Eight strains of Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus paracasei and Lactococcus lactis, isolated from Maasai traditional fermented milk in Kenya and previously tested for their probiotic properties, were selected for this investigation. Technological features such as growth kinetics in fresh heat-treated whole milk medium and survival in the final product during storage at 4 -C, were studied. The strains Lb. acidophilus BFE 6059, Lb. paracasei BFE 5264 and Lc. lactis BFE 6049 showed the best potential and were thus selected for use as starter cultures in further trials with the objective to improve their technological performance and to optimise the sensory features of fermented milk obtained. The effects of fat ( F), non-fat milk solids (S) and fermentation temperature (T), modulated according to a Central Composite Design, on fermentation rates and viability losses during refrigerated storage of the chosen starters, and on product texture parameters, were studied. From the data analysis, it was possible to select optimum conditions for enhancing positive sensory traits of final products and for improving the survival of these potentially probiotic cultures. D
Journal of Dairy Science, 2008
High-pressure homogenization (HPH) is one of the most promising alternatives to traditional therm... more High-pressure homogenization (HPH) is one of the most promising alternatives to traditional thermal treatment of food preservation and diversification. Its effectiveness on the deactivation of pathogenic and spoilage microorganisms in model systems and real food is well documented. To evaluate the potential of milk treated by HPH for the production of Crescenza cheese with commercial probiotic lactobacilli added, 4 types of cheeses were made: HPH (from HPH-treated milk), P (from pasteurized milk), HPH-P (HPH-treated milk plus probiotics), and P-P (pasteurized milk plus probiotics) cheeses. A strain of Streptococcus thermophilus was used as starter culture for cheese production. Compositional, microbiological, physicochemical, and organoleptic analyses were carried out at 1, 5, 8, and 12 d of refrigerated storage (4°C). According to results obtained, no significant differences among the 4 cheese types were observed for gross composition (protein, fat, moisture) and pH. Differently, the HPH treatment of milk increased the cheese yield about 1% and positively affected the viability during the refrigerated storage of the probiotic bacteria. In fact, after 12 d of storage, the Lactobacillus paracasei A13 cell loads were 8 log cfu/ g, whereas Lactobacillus acidophilus H5 exhibited, in P-P cheese, a cell load decrease of about 1 log cfu/g with respect to the HPH-P cheese. The hyperbaric treatment had a significant positive effect on free fatty acids release and cheese proteolysis. Also, probiotic cultures affected proteolytic and lipolytic cheese patterns. No significant differences were found for the sensory descriptors salty and creamy among HPH and P cheeses as well as for acid, piquant, sweet, milky, salty, creamy, 500 and overall acceptance among HPH, HPH-P, and P-P Crescenza cheeses.
Meat Science, 2007
The aim was to study the effects of Debaryomyces hansenii and Yarrowia lipolytica strains, used w... more 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.
Applied and Environmental Microbiology, 2007
The combined effects of a mild heat treatment (55°C) and the presence of three aroma compounds [c... more The combined effects of a mild heat treatment (55°C) and the presence of three aroma compounds [citron essential oil, citral, and (E)-2-hexenal] on the spoilage of noncarbonated beverages inoculated with different amounts of a Saccharomyces cerevisiae strain were evaluated. The results, expressed as growth/no growth, were elaborated using a logistic regression in order to assess the probability of beverage spoilage as a function of thermal treatment length, concentration of flavoring agents, and yeast inoculum. The logit models obtained for the three substances were extremely precise. The thermal treatment alone, even if prolonged for 20 min, was not able to prevent yeast growth. However, the presence of increasing concentrations of aroma compounds improved the stability of the products. The inhibiting effect of the compounds was enhanced by a prolonged thermal treatment. In fact, it influenced the vapor pressure of the molecules, which can easily interact within microbial membranes when they are in gaseous form. (E)-2-Hexenal showed a threshold level, related to initial inoculum and thermal treatment length, over which yeast growth was rapidly inhibited. Concentrations over 100 ppm of citral and thermal treatment longer than 16 min allowed a 90% probability of stability for bottles inoculated with 10 5 CFU/bottle. Citron gave the most interesting responses: beverages with 500 ppm of essential oil needed only 3 min of treatment to prevent yeast growth. In this framework, the logistic regression proved to be an important tool to study alternative hurdle strategies for the stabilization of noncarbonated beverages.
International Journal of Food Microbiology, 2008
In recent years, the interest in the possible use of natural alternatives to food additives to pr... more In recent years, the interest in the possible use of natural alternatives to food additives to prevent bacterial and fungal growth has notably increased. Plants and plant products can represent a source of natural alternatives to improve the shelf-life and the safety of food. Some of these compounds, i.e. hexanal, hexanol, 2-(E)-hexenal and 3-(Z)-hexenol, produced throughout the lipoxygenase pathway have important roles in plant defence with a protective action towards microbial proliferation in wounded areas. Otherwise, hexanal and 2-(E)-hexenal have evidenced a marked antimicrobial activity against food spoilage and pathogenic microbial species both in model and real systems. The precise mechanisms of action of all these antimicrobial compounds are not yet clear. Because the usage of these compounds as antimicrobials in foods has to be supported by the comprehension of mechanisms of action of these compounds, the overall purpose of this work was to study the modifications of the cell membrane and volatile compounds of Listeria monocytogenes, Staphylococcus aureus, Salmonella enteritidis and Escherichia coli during the growth in the presence of sub-lethal doses of these two aldehydes. The results obtained evidenced that the tested molecules induced noticeable modifications of the composition of cell membrane and the volatile compounds produced during the growth. Although specific differences in relation to the species considered were identified, 2-(E)-hexenal and hexanal induced a marked increase of some membrane associated fatty acids, both linear and branched fatty acids as well as unsaturated fatty acids, and released free fatty acids.
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Papers by Francesca Patrignani