Alginate-Based Emulsions and Hydrogels for Extending the Shelf Life of Banana Fruit.

Edible coatings are used to extend the shelf life of various fruit, including bananas (Musa from the Musaceae family). After harvest, bananas reach the ripening and subsequent senescence phase. During senescence, the quality of the fruit deteriorates as it takes on a brown color and the tissue becomes soft. To extend the shelf life of such a fruit, effective methods to delay ripening are required. In this study, an alginate-based emulsion, i.e., an oil-in-water emulsion of lemongrass essential oil in alginate, was used to combine the mechanical properties of hydrocolloids with the water barrier properties of the oil phase. The emulsion was sprayed onto the whole fruit with an airbrush, and calcium chloride was added to promote gelling of the alginate. Compared to the uncoated fruit, coated bananas remained uniform in appearance (peel color) for longer, showed less weight loss, had a delay in the formation of total soluble solids, and in the consumption of organic acids. The shelf life of the coated fruit was extended by up to 11 days, at least 5 days more than uncoated bananas. Overall, the proposed coating could be suitable for reducing the global amount of food waste.

A bicentric cohort study comparing umbilical cord and neonatal blood samples for chemistry tests at birth.

OBJECTIVES: To compare umbilical cord and neonatal blood for chemistry tests upon admission to the neonatal intensive care unit (NICU). METHODS: We designed a prospective, bicentric cohort study enrolling newborns (n = 71) with a planned admission to the NICU. Paired samples of umbilical cord and infant's blood were collected, analyzed, and compared. An intraclass correlation coefficient (ICC) was calculated for a repeatability analysis, and a Bland-Altman analysis was performed to assess the agreement between the 2 methods of sampling. The multivariable coefficient of determination (R2) was reported to quantify the degree of correlation between the methods of measurement. RESULTS: The degree of agreement between the 2 sampling methods for chemistry tests was fair to good for high-sensitivity C-reactive protein (ICC = 0.79 [95% CI, 0.67-0.87]), phosphorus (ICC = 0.83 [95% CI, 0.73-0.90]), and albumin (ICC = 0.76 [95% CI, 0.60-0.86]), while it was good to excellent for γ-glutamyl transpeptidase (ICC = 0.95 [95% CI, 0.88-0.98]) and procalcitonin (ICC = 0.90 [95% CI, 0.76-0.96]). CONCLUSIONS: Umbilical cord blood is a reliable replacement source for multiple chemistry tests at birth. This sampling method has the potential to minimize the risk of transfusion-requiring anemia in newborns and its associated complications. Further studies are warranted to assess the efficacy of this strategy in improving neonatal outcomes.

From the Intersection of Food-Borne Zoonoses and EU Green Policies to an In-Embryo One Health Financial Model.

The European Union (EU) adopts the One Health (OH) approach, based on the relationships between human, animal, and environmental health. OH concerns a multitude of aspects, some of which are discussed here. OH overlaps the European Green Deal plan and its relaunched Farm to Fork Strategy, which aims at spreading organic farms adopting the circular economy, in order to improve human health through both better environmental conditions and healthier food. Nevertheless, zoonoses cause sanitary cost in terms of infected farm personnel, lower productivity, and lower fertility of infected farm animals. In such scenarios, the decreased breeding yield and the lower income induce higher cost of farm products, meaning that the market price rises, becoming uncompetitive when compared to the prices of industrial products. Consequently, lower revenues can hinder the farm growth expected in the framework of the EU Green Deal. Since zoonosis control is a key element in aligning EU policies aimed at achieving the EU Green Deal goal of "ZERO environmental impact" by 2050, the authors suggest the inclusion of the parameter economic health in the OH approach, in order to individuate EU Member States (MSs) economically unable to conduct eradication programmes and to finance them. Economic health is here considered as a starting point of the new ethical and science-based One Health Financial Model that the authors suggest as an in-embryo model, in which specific rules should regulate public funds, private investments, and trading, which should exclusively concern public services and private enterprises complying with most of the OH parameters. In this way, economic losses due to collateral negative effects deriving from human activities can be progressively decreased, and the entire planet will benefit from the process. Despite the considerable efforts being carried out in the context of the OH approach, war causes tragic and devastating effects on the physical and mental health of human beings, on their lives, on pandemic and zoonotic threats, on animals, on plants and, last but not least, on the environment. War is incompatible with OH. Enormous efforts for peace are therefore urgently needed.

In Vitro Assessment of Bio-Functional Properties from Lactiplantibacillus plantarum Strains.

In recent years, alongside the conventional screening procedures for the evaluation of probiotics for human usage, the pharmaceutical and food industries have encouraged scientific research towards the selection of new probiotic bacterial strains with particular functional features. Therefore, this study intended to explore novel functional properties of five Lactiplantibacillus plantarum strains isolated from bee bread. Specifically, antioxidant, antimicrobial and ß-glucosidase activities, exopolysaccharides (EPS) production and the ability to synthesize γ-aminobutyric acid (GABA) were evaluated. The results demonstrated that the investigated L. plantarum strains were effective in inhibiting the growth of some human opportunistic pathogens in vitro (Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, Enterococcus faecalis and Staphylococcus aureus). Moreover, the evaluation of antioxidant and ß-glucosidase activity and of EPS and GABA production, revealed a different behavior among the strains, testifying how these properties are strongly strain-dependent. This suggests that a careful selection within a given species is important in order to identify appropriate strains for specific biotechnological applications. The results highlighted that the five strains of L. plantarum are promising candidates for application as dietary supplements in the human diet and as microbial cultures in specific food productions.

Fungi Occurrence in Ready-to-Eat Hazelnuts (Corylus avellana) From Different Boreal Hemisphere Areas.

The present study evaluated the fungal contamination of ready-to-eat dried hazelnuts considering for the first time the application of the same condition drying process of several hazelnut cultivars from different boreal hemisphere areas. Fifty lots of hazelnuts (Corylus avellana), belonging to eight cultivars from seven regions in four countries, were analyzed for fungal microbiota, describing both load levels and species diversity. For this purpose, a polyphasic approach consisting of morphological examination (optical and scanning electron microscope observation) and molecular characterization [PCR-DGGE analysis and sequence analyses of the internal transcribed spacer (ITS)] was performed. The results show that different fungal populations occur in dried hazelnuts regardless of their geographical area of production. Although some varieties appear to be relatively less susceptible, species related to Aspergillus, such as A. commune and A. ochraceus, Penicillium, including P. commune, P. solitum, and P. expansum, and Rhizopus, for instance, R. stolonifer and R. oryzae, have generally been found. A related character "hazelnut cultivar-fungi" was found for species related to the genera Trichoderma and Fusarium, including F. oxyxporum, F. solani, and F. falciforme. All 14 species found are known to host pathogenic strains. Therefore, their presence in a ready-to-eat product, such as dried hazelnuts, can pose a real danger to the consumer. Based on these considerations, the development of new protective strategies seems highly desirable. The species-level description of the contaminating fungal community acquired through this study is the starting point for the development of tailor-made protective biotechnologies.

Probiotic Potentiality from Versatile Lactiplantibacillus plantarum Strains as Resource to Enhance Freshwater Fish Health.

Dietary probiotic supplementation has the potential to enhance the health of fish and their disease resistance. In this study, some properties of ten Lactiplantibacillus plantarum strains have been evaluated, for their potential use as probiotics in freshwater fish diet. In particular, antimicrobial activity, antioxidant activity, the potentiality to survive the gastrointestinal transit and persist in the intestine, were evaluated in vitro. The experimental tests were carried out at 15 °C and 30 °C to determine the suitability of these lactic acid bacteria to be used as probiotics in the diet of fish grown at different temperatures. The results demonstrated that the evaluated Lp. plantarum strains, which often have significant differences among themselves, are characterized by important functional characteristics such as cell surface properties (auto-aggregation and hydrophobicity), ability to produce antioxidant substances, capacity to survive in the presence of 0.3% bile salts and acidic environment (2.5 pH), antagonistic activity against some fish opportunistic pathogens (A. salmonicida, Ps. aeruginosa, E. coli and C. freundii) and other unwanted bacteria present in fish products (S. aureus and L. innocua). The outcomes suggest that these Lp. plantarum strains may be candidates as probiotics in warm- and cold-water aquaculture.

Probiotic Properties and Potentiality of Lactiplantibacillus plantarum Strains for the Biological Control of Chalkbrood Disease.

Ascosphaera apis is an entomopathogenic fungus that affects honeybees. In stressful conditions, this fungus (due not only to its presence, but also to the combination of other biotic and abiotic stressors) can cause chalkbrood disease. In recent years, there has been increasing attention paid towards the use of lactic acid bacteria (LAB) in the honeybees' diets to improve their health, productivity and ability to resist infections by pathogenic microorganisms. The screening of 22 strains of Lactiplantibacillus plantarum, isolated from the gastrointestinal tracts of honeybees and beebread, led to the selection of five strains possessing high antagonistic activity against A. apis. This study focused on the antifungal activity of these five strains against A. apis DSM 3116 and DSM 3117 using different matrices: cell lysate, broth culture, cell-free supernatant and cell pellet. In addition, some functional properties and the antioxidant activity of the five L. plantarum strains were evaluated. All five strains exhibited high antagonistic activity against A. apis, good surface cellular properties (extracellular polysaccharide (EPS) production and biofilm formation) and antioxidant activity. Although preliminary, these results are encouraging, and in future investigations, the effectiveness of these bacteria as probiotics in honeybee nutrition will be tested in vivo in the context of an eco-friendly strategy for the biological control of chalkbrood disease.

Inter- and Intra-Species Diversity of Lactic Acid Bacteria in Apis mellifera ligustica Colonies.

Lactic acid bacteria could positively affect the health of honey bees, including nutritional supplementation, immune system development and pathogen colonization resistance. Based on these considerations the present study evaluated predominant Lactic Acid Bacteria (LAB) species from beebread as well as from the social stomach and midgut of Apis mellifera ligustica honey bee foragers. In detail, for each compartment, the diversity in species and biotypes was ascertained through multiple culture-dependent approaches, consisting of Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE), 16S rRNA gene sequencing and Randomly Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR). The study of a lactic acid bacteria community, performed with PCR-DGGE and sequence analysis targeting the V1-V3 region of the 16S rRNA gene (rDNA), highlighted the presence of a few species, including Apilactobacillus kunkeei, Lactiplantibacillus plantarum, Fructobacillus fructosus, Levilactobacillus brevis and Lactobacillus delbrueckii subsp. lactis. Depending on the different compartments, diverse levels of biodiversity in species were found. Particularly, a very low inter-species biodiversity was detected in the midgut that was prevalently dominated by the presence of Apilactobacillus kunkeei. On the other hand, the beebread was characterized by a reasonable biodiversity showing the presence of five species and the predominance of Apilactobacillus kunkeei, Lactiplantibacillus plantarum and Fructobacillus fructosus. The RAPD-PCR analysis performed on the three predominant species allowed the differentiation into several biotypes for each species. Moreover, a relationship between biotypes and compartments has been detected and each biotype was able to express a specific biochemical profile. The biotypes that populated the social stomach and midgut were able to metabolize sugars considered toxic for bees while those isolated from beebread could contribute to release useful compounds with functional properties. Based on this knowledge, new biotechnological approaches could be developed to improve the health of honey bees and the quality of bee products.

Potential Application of Apilactobacillus kunkeei for Human Use: Evaluation of Probiotic and Functional Properties.

Apilactobacillus kunkeei is an insect symbiont with documented beneficial effects on the health of honeybees. It belongs to fructophilic lactic acid bacteria (FLAB), a subgroup of lactic acid bacteria (LAB) notably recognized for their safe status. This fact, together with its recurrent isolation from hive products that are traditionally part of the human diet, suggests its possible safe use as human probiotic. Our data concerning three strains of A. kunkeei isolated from bee bread and honeybee gut highlighted several interesting features, such as the presence of beneficial enzymes (ß-glucosidase, ß-galactosidase and leucine arylamidase), the low antibiotic resistance, the ability to inhibit P. aeruginosa and, for one tested strain, E. faecalis, and an excellent viability in presence of high sugar concentrations, especially for one strain tested in sugar syrup stored at 4 °C for 30 d. This datum is particularly stimulating, since it demonstrates that selected strains of A. kunkeei can be used for the probiotication of fruit preparations, which are often used in the diet of hospitalized and immunocompromised patients. Finally, we tested for the first time the survival of strains belonging to the species A. kunkeei during simulated gastrointestinal transit, detecting a similar if not a better performance than that showed by Lacticaseibacillus rhamnosus GG, used as probiotic control in each trial.

Antimicrobial Activity against Paenibacillus larvae and Functional Properties of Lactiplantibacillus plantarum Strains: Potential Benefits for Honeybee Health.

Paenibacillus larvae is the causative agent of American foulbrood (AFB), a severe bacterial disease that affects larvae of honeybees. The present study evaluated, in vitro, antimicrobial activity of sixty-one Lactiplantibacillus plantarum strains, against P. larvae ATCC 9545. Five strains (P8, P25, P86, P95 and P100) that showed the greatest antagonism against P. larvae ATCC 9545were selected for further physiological and biochemical characterizations. In  particular, the hydrophobicity, auto-aggregation, exopolysaccharides production, osmotic tolerance, enzymatic activity and carbohydrate assimilation patterns were evaluated. The five L. plantarum selected strains showed suitable physical and biochemical properties for their use as probiotics in the honeybee diet. The selection and availability of new selected bacteria with good functional characteristics and with antagonistic activity against P. larvae opens up interesting perspectives for new biocontrol strategies of diseases such as AFB.

Low-Fat and High-Quality Fermented Sausages.

The present study, considering for the first time microbiological concerns due to the use of lemon albedo as a fat replacer, aimed at the selection of an anti-Listeria strain to be used as protective culture in low-fat southern Italian fermented sausages. In fact, these kinds of products require appropriate bio-protective strategies to avoid risks due to Listeria monocytogenes. Sixty-seven Lactiplantibacillus plantarum strains isolated from diverse sources were screened for their antimicrobial activity and their interaction with starter strains (Latilactobacillus sakei 152 and Staphylococcus xylosus MVS9). Lactiplantibacillus plantarum Lpls100, highlighting both listericidal activity and the ability to promote Staphylococcus xylosus MVS9 growth, was used as a protective strain in low-fat fermented sausages prepared with lemon albedo as a fat replacer. The effect of the albedo and the protective strain on the fermentation process and the final quality was ascertained. Results highlighted that the use of the albedo did not affect the growth of starter strains and enhanced some quality features, such as fatty acid profiles and certain sensory attributes. However, the albedo also produced a slow decrease in water activity, compromising the microbial quality. The anti-Listeria strain, enhancing coagulase negative cocci growth and exerting antimicrobial activity, avoided the inconveniences caused by the use of the albedo. Moreover, the anti-Listeria effectiveness was assessed through a challenge test using a Listeria cocktail. The study revealed that Lactiplantibacillus plantarum Lpls100, regardless of the presence of the albedo, assures a prompt inhibition of Listeria spp. Therefore, its use could be an important contribution to the quality of low-fat fermented sausages.

Effect of Biofilm Formation by Lactobacillus plantarum on the Malolactic Fermentation in Model Wine.

Biofilm life-style of Lactobacillus plantarum (L. plantarum) strains was evaluated in vitro as a new and suitable biotechnological strategy to assure L-malic acid conversion in wine stress conditions. Sixty-eight L. plantarum strains isolated from diverse sources were assessed for their ability to form biofilm in acid (pH 3.5 or 3.2) or in ethanol (12% or 14%) stress conditions. The effect of incubation times (24 and 72 h) on the biofilm formation was evaluated. The study highlighted that, regardless of isolation source and stress conditions, the ability to form biofilm was strain-dependent. Specifically, two clusters, formed by high and low biofilm producer strains, were identified. Among high producer strains, L. plantarum Lpls22 was chosen as the highest producer strain and cultivated in planktonic form or in biofilm using oak supports. Model wines at 12% of ethanol and pH 3.5 or 3.2 were used to assess planktonic and biofilm cells survival and to evaluate the effect of biofilm on L-malic acid conversion. For cells in planktonic form, a strong survival decay was detected. In contrast, cells in biofilm life-style showed high resistance, assuring a prompt and complete L-malic acid conversion.

Antagonistic Activity against Ascosphaera apis and Functional Properties of Lactobacillus kunkeei Strains.

: Lactic acid bacteria (LAB) are an important group of honeybee gut microbiota. These bacteria are involved in food digestion, stimulate the immune system, and may antagonize undesirable microorganisms in the gastrointestinal tract. Lactobacillus kunkeei is a fructophilic lactic acid bacterium (FLAB) most frequently found in the gastrointestinal tracts of honeybees. Ascosphaera apis is an important pathogenic fungus of honeybee larvae; it can colonize the intestine, especially in conditions of nutritional or environmental stress that cause microbial dysbiosis. In this work, some functional properties of nine selected L. kunkeei strains were evaluated. The study focused on the antifungal activity of these strains against A. apis DSM 3116, using different matrices: cell lysate, broth culture, cell-free supernatant, and cell pellet. The cell lysate showed the highest antifungal activity. Moreover, the strains were shown to possess good cell-surface properties (hydrophobicity, auto-aggregation, and biofilm production) and a good resistance to high sugar concentrations. These L. kunkeei strains were demonstrated to be functional for use in "probiotic syrup", useful to restore the symbiotic communities of the intestine in case of dysbiosis and to exert a prophylactic action against A. apis.

Inoculum Strategies and Performances of Malolactic Starter Lactobacillus plantarum M10: Impact on Chemical and Sensorial Characteristics of Fiano Wine.

Malolactic fermentation (MLF) is a biological process that, in addition to deacidifying, also improves biological stability and changes the chemical and sensorial characteristics of wines. However, multiple biotic and abiotic factors, present in must and wine, make the onset and completion of MLF by indigenous malolactic bacteria or added commercial starters difficult. This work illustrates the metabolic and fermentative dynamics in winemaking Fiano wine, using a commercial starter of Saccharomyces cerevisiae and the selected strain Lactobacillus plantarum M10. In particular, an inoculum of malolactic starter was assessed at the beginning of alcoholic fermentation (early co-inoculum), at half alcoholic fermentation (late co-inoculum), and post alcoholic fermentation (sequential inoculum). The malolactic starter, before its use, was pre-adapted in sub-optimal growth conditions (pH 5.0). In sequential inoculum of the Lb. plantarum M10, even in a wine with high acidity, has confirmed its good technological and enzymatic characteristics, completing the MLF and enriching the wine with desirable volatile compounds.

Preliminary Evaluation of the Safety and Probiotic Potential of Akkermansia muciniphila DSM 22959 in Comparison with Lactobacillus rhamnosus GG.

In this study, for the first time, we examined some of the physico-chemical properties of the cell surface of Akkermansiamuciniphila DSM 22959, comparing it with those of Lactobacillusrhamnosus GG-one of the most extensively studied probiotic microorganisms. In particular, hydrophobicity, auto-aggregation, co-aggregation, and biofilm formation were investigated. In addition, antibiotic susceptibility, co-culture, and antimicrobial activity of the two strains were compared. Hydrophobicity was evaluated using xylene and toluene, showing that A. muciniphila DSM 22959 possessed moderate hydrophobicity. A. muciniphila showed a faster and higher auto-aggregation ability than Lb. rhamnosus GG, but a lower aptitude in biofilm formation. In the co-aggregation test, the best performance was obtained by Lb. rhamnosus GG. Regarding the susceptibility to antibiotics, the differences between the two strains were remarkable, with A. muciniphila DSM 22959 showing resistance to half of the antibiotic tested. Interesting results were also obtained with regard to the stimulating effect of Lb. rhamnosus GG on the growth of A. muciniphila when co-cultured.

Sequential inoculum of Hanseniaspora guilliermondii and Saccharomyces cerevisiae for winemaking Campanino on an industrial scale.

In this study, the effect of sequential inoculation with non-Saccharomyces (Hanseniaspora guilliermondii) and Saccharomyces cerevisiae yeast on the distinctive characteristics of the Campanino white wine was investigated. For this purpose, three independent winemaking experiments were carried out on an industrial scale (batches A, B and C). In detail, the first one was carried out using the sequential inoculation technique while the other two, using a S. cerevisiae single-strain starter or no inoculation representing the control batches. Microbiological and chemical parameters and sensorial profiles of the wines were defined. Interestingly, the results showed that when sequential cultures (H. guilliermondii in a sequential mixture with S. cerevisiae) were used, a better wine aroma and quality was observed. More specifically, the wine obtained by sequential inoculation showed lower acetic acid values and enhanced volatile profiles than the wine from the control batches. Finally, sensorial analysis confirmed that the sequential cultures led to an improvement in wine flavour. Therefore, results suggest that the sequential inoculation using non-Saccharomyces and Saccharomyces yeast represents a biotechnological practice that can improve the quality features of traditional white wine. It has been shown for the first time that on an industrial scale H. guilliermondii could be used in sequential inoculum with S. cerevisiae in making white Campanino wine.

Detection of Antilisterial Activity of 3-Phenyllactic Acid Using Listeria innocua as a Model.

The 3-Phenyllactic acid (PLA) produced by various lactic acid bacteria (LAB) possesses a broad spectrum of antimicrobial activity. In this study, the effect of PLA against Listeria innocua was studied with the aim to obtain additional information about its mechanism of action. The effect of pH on the antilisterial activity of PLA was investigated and a pH-dependent behavior, typical of weak acid, was detected. The antilisterial effect of PLA was firstly compared to that produced by lactic acid (LA) and than to that expressed by phenolic acids (gallic, caffeic, and ferulic acids) evaluating minimum inhibitory concentration (MIC), MBC, and survival kinetic parameters. PLA showed MIC values and death kinetic parameters significantly different from those exhibited by LA and by tested phenolic acids. In particular, the MIC value observed for PLA vs L. innocua resulted lower than that of the other preservative compounds studied herein, and consistent with the quantity generally produced by LAB. Moreover, the effect of PLA and phenolic acids on bacterial surface charge and loss of cellular content resulted different. The overall results highlighted strong differences in the antilisterial mechanism of action among PLA and other compounds such as LA and phenols. Specifically, it is possible to hypothesize that the antilisterial mechanism of action due to PLA is associated with the affinity to cell surface, which contributes to the cellular damage.

Antimicrobial activity of gallic acid against food-related Pseudomonas strains and its use as biocontrol tool to improve the shelf life of fresh black truffles.

Refrigeration alone or in combination with other technologies represents the main tool used in the last decades to preserve the freshness of black truffles. This is principally due to the delicateness and vulnerability of this edible hypogeous fungus, so that other invasive preservation practices cannot be adopted. However, the proliferation of some microbial species during the cold storage still represents an unsolved problem. Pseudomonads are among the main spoiler bacteria responsible for the deterioration of refrigerated black truffles. Their growth ability at low temperatures requires the use of additional hurdles to prolong the shelf-life of truffles without altering their major features. The use of natural compounds may represent an alternative system for the biocontrol of this kind of product. Specifically, gallic acid (GA) is a phenolic acid naturally present in different foods, whose effectiveness was in vitro demonstrated against Pseudomonas spp. In our study, we reported the antimicrobial activity expressed by GA not only in vitro, using as target bacteria Pseudomonas putida DSMZ 291T, P. fluorescens DSMZ 50090T, P. fragi DSMZ 3456T and Pseudomonas spp. P30-4, previously isolated from black truffles, but also in situ on fresh black truffles stored at 4°C for 28days. Our results showed Minimum Inhibitory Concentrations (MIC) of 2.5mg/mL GA for all tested strains, except for P. fluorescens DSMZ 50090T, having a MIC corresponding to 5mg/mL GA. The Minimum Bactericidal Concentration (MBC) was 10mg/mL for all strains. The analysis of kinetic parameters showed that the survival declined passing from 2.5 to 10mg/mL GA concentrations, with P. fluorescens confirmed to be the most resistant strain. Moreover, images obtained from Scanning Electron Microscopy revealed that Pseudomonas cells were strongly injured by the treatment with GA at 2.5mg/mL concentration, displaying visible pores on the cellular surfaces, absence of flagella and lysis with loss of cytoplasmic material. The storage test performed on fresh black truffles confirmed in situ the GA antimicrobial activity observed in vitro, with a drastic reduction not only of Pseudomonas spp., but also of the other assessed microbial groups, including Enterobacteriaceae and Eumycetes. Finally, sensory analysis established the absence of off-flavours and the preservation of positive features in black truffles treated with 2.5mg/mL GA and stored for 28 d at 4°C. The results obtained in this study suggest that GA is a potential biocontrol tool to decontaminate and preserve fresh black truffles during refrigerated storage.

Evolution of free amino acids during ripening of Caciocavallo cheeses made with different milks.

The evolution of free amino acids (FAA) in Caciocavallo cheeses, made with cow milk (CC) and cow milk mixed with ewe (CE) and goat (CG) milk, was studied throughout ripening. In all Caciocavallo cheeses produced, the total free amino acid (TFAA) content increased during ripening. In general, the highest TFAA content was found in cow cheeses, and the lowest in CG cheeses, whereas CE cheeses ranged over an intermediate level. In all the analyzed samples, during ripening, the content of the individual FAA increased with the exception of arginine. Tyrosine and histidine were found only in CE samples from the middle to the end of ripening. The major FAA found throughout the whole ripening period, in all types of cheese, were leucine, phenylalanine, lysine, valine, asparagine, γ-aminobutyric acid, and ornithine. The TFAA and several AA showed significant differences in ripening time, whereas tyrosine and histidine showed significant differences in kinds of milk.

Pre-cultivation with Selected Prebiotics Enhances the Survival and the Stress Response of Lactobacillus rhamnosus Strains in Simulated Gastrointestinal Transit.

In our study, we dwelled upon combinations of lactobacilli/prebiotics, considering four different strains belonging to the Lactobacillus rhamnosus species, including Lactobacillus rhamnosus GG (LGG), and different prebiotics often found in commercial synbiotic products, such as inulin, lactulose and polyols mannitol and sorbitol. In the first step of the research, the survival, the growth kinetic parameters and the protein expression of Lb. rhamnosus strains cultivated in presence of the different prebiotics as a unique carbon source were evaluated. In the second step, the influence of pre-cultivation in medium added of metabolizable prebiotics on the strains survival to simulated gastrointestinal (GI) transit, assayed without prebiotics addition, was estimated. Our results showed that the presence in the medium of certain low fermented prebiotics, specific for each strain, represents a stress factor that significantly affects the growth of Lb. rhamnosus strains, inducing the up-regulation of several proteins. In detail, all added prebiotics used as unique carbon source caused a growth retard compared with glucose, as testified by increased values of the lag phase and decreased values of the µmax. Mannitol evidenced intermediate µmax values between those registered with glucose and those detected with the other assayed prebiotics. Moreover, the cultivation with prebiotics induced the over expression of 7 protein bands. Interestingly, we found a correlation between the up-regulation of two specific stress proteins, called P4 (ATP-binding subunit Clpx) and P7 (GrpE), and the death kinetic parameters (resistance and cells viability) registered during the simulated GI transit of strains pre-cultivated with specific, low fermented prebiotics. Specifically, the highest resistance and gastric-vitality scores were highlighted for the strain AT195 when pre-cultivated in presence of sorbitol. Conversely, the lowest values were found in the case of DSM20021 pre-cultivated with mannitol. Among the up-regulated stress proteins, P7 resulted involved in the response to the starvation. Finally, it is possible to conclude that the pre-cultivation with certain prebiotics as a unique carbon source represents a strain-specific, sub-lethal stress able to enhance the resistance of Lb. rhamnosus strains and consequently their viability under simulated GI transit.