1,721,036 research outputs found
Functional and morphological investigation on Lactobacillus plantarum subs plantarum grown in the presence of prebiotics.
No full textSince many decades, food and health companies showed an increasing interest in using probiotics ad dietary adjusts. To produce the desired benefits, probiotics should persist in the product as viable cells during its shelf life. Probiotics are food components capable to resist host digestion and absorption, and are fermented by microbiota, which can stimulate the growth and/or activity of specific positive bacteria, generating also the production of specific useful short chain fatty acids.
The growth and viability of a probiotic strain of Lactobacillus plantarum subs. plantarum during a simulated gastrointestinal transit were evaluated, when strains were grown using inulin or pectin as carbon source, compared to glucose used as control. The in vitro coaggregation of the strain with E.coli as well as the potential morphological changes (by SEM) were also investigated. Pectin and inulin, in contrast induced a greeter cell stress resistance against gastrointestinal juices (Delta log 10=1.5 and 2.4 colony forming units/ml. respectively) conversely to glucose /delta log 10=4.0). The presence of the two prebiotics positively affected the capability of the strain to co-aggregate E.coli: inulin and pectin at the same way increased such property, with an increase of about 20% respect to the initial value of co-aggregation observed using glucose as energy source. SEM analysis did non show any morphological difference
Biochemical, antioxidant properties and antimicrobial activity of different onion varieties in the Mediterranean area
No full textOnion (Allium cepa L.) is a very important vegetable crop cultivated worldwide. The bulb is a major source of phytochemicals useful for human health and rich in sulphur compounds responsible for their typical odour and flavour. In this study, we investigated the volatile compounds and biochemical properties besides the antimicrobial activity of onion Montoro and Alife varieties, and of two ecotypes of Vatolla variety (spinning top and tapered shape), cropped in the southern Mediterranean area (Italy). For all investigated onions, the organosulphur compounds, mainly di- and trisulfides, are the most abundant compounds. Alife variety showed higher polyphenols amount (8.2 GAE mg/g dw) with respect to the lowest one (3.9 GAE mg/dw g) in spinning top Vatolla, as well as an higher antioxidant activity (42.37 μmol TE/g dw) about two-fold higher than those detected in the other varieties. All the onions showed low pungency level, confirming their popular classification as a sweet onion. The total content of soluble sugars ranged from 461 to 624 mg/g dw; malic acid was the major organic acid in Alife and Montoro varieties instead for both Vatolla ecotypes citric acid was the most abundant ones. The biochemical characterization highlighted the three onion varieties as a good source of bioactive compounds. The antimicrobial activity of the onion extracts pointed out an effective action against three Gram-positive species (B. cereus, L. innocua, S. aureus) and P. aeruginosa; consequently, they could represent a new source of natural antimicrobial agents
Essential Oils and Antifungal Activity
No full textSince ancient times, folk medicine and agro-food science have benefitted from the use of plant derivatives, such as essential oils, to combat different diseases, as well as to preserve food. In Nature, essential oils play a fundamental role in protecting the plant from biotic and abiotic attacks to which it may be subjected. Many researchers have analyzed in detail the modes of action of essential oils and most of their components. The purpose of this brief review is to describe the properties of essential oils, principally as antifungal agents, and their role in blocking cell communication mechanisms, fungal biofilm formation, and mycotoxin production
Chemical Characterization and Antibiofilm Activities of Bulbs and Leaves of Two Aglione (Allium ampeloprasum var. holmense Asch. et Graebn.) Landraces Grown in Southern Italy
Full text linkThe present study was carried out to determine some biochemical characteristics, in particular the total polyphenol content and the free radical scavenging activity, of the extracts recovered from bulbs and aerial parts (these last often considered as by-products) of two landraces of A. ampeloprasum var. holmense cultivated in Southern Italy. For the first time, the capacity of the extracts of these landraces to inhibit the formation of biofilm of different Gram-negative and Gram-positive bacteria and to affect the metabolism of the cells present within the bacterial biofilm was evaluated. All extracts exhibited an amount of total polyphenols not lower than 2.86 mg/g of dried product and revealed a noteworthy antioxidant activity, with EC50 values not exceeding 4.95 mg. In both cases, the aerial parts extracts were more effective than the bulb extracts, which also showed a minor amount of total polyphenols. The extracts inhibited mainly the adhesive capability of Pseudomonas aeruginosa and Staphylococcus aureus, by 95.78% and 85.01%, respectively. The extracts demonstrated to inhibit also the metabolism of the bacterial cells reaching levels up to 90%. Finally, as assessed by the assays performed on the 24-h preformed biofilms, all the extracts were also capable to cause a reduction in bacterial biomass and to affect their metabolis
Lactic Acid Bacteria Biota and Aroma Profile of Italian Traditional Sourdoughs From the Irpinian Area in Italy
Full text linkThis study identified the lactic acid bacteria (LAB) biota and the volatilome profile of 28 typical sourdoughs of Irpinia—a large area of the Campania region of Southern Italy where numerous breads are produced, even today, following the ancient procedures of sourdough fermentation and for which information on the microbiological and sensory profile is lacking in literature. For this purpose, microbial quality, LAB biodiversity, chemical, and technological characteristics, as well as aroma profile by solid-phase microextraction technique (SPME)–gas chromatography/mass spectrometry (GC/MS) of Irpinian sourdoughs were investigated. The dominant LAB microbiota was examined by both culture-dependent and culture-independent methods Polymerase Chain Reaction/Denaturing Gradient Gel Electrophoresis (PCR-DGGE). Results showed a high biodiversity in LAB community whereas the most frequent lactobacilli species recognized were Lactobacillus plantarum (ca. 22% of total LAB isolates), Lactobacillus sanfranciscensis (11%), Lactobacillus paralimentarius (8%), and Lactobacillus rossiae (6.5%), whereas LAB cocci could be mainly referred to Pediococcus pentosaceus (9.5% of total LAB isolates), Leuconostoc spp. (7.8%), and Weissella cibaria (7.7%).
Sourdoughs were characterized by the dominance of one or two LAB species, thus proving that the environment influences the selection and the establishment of few key LAB species and that no specific correlation can be traced between microbial composition and geographical origin of the samples. Furthermore, although sourdoughs were characterized by different qualitative and quantitative volatile organic compound (VOC) compositions, no noticeable correlation between volatilome profile and geographical origin was found. However, it emerged that for more isolated locations, it was possible to find the existence of microbial biotypes and sensory profiles with a strong identity, thus revealing the existence of highly traditional and evocative bread recipes in those geographical contexts
Quantitative determination of rapid biomass formation on pyro-electrified polymer sheets
No full text: The ability of a bacterial strain to form a biofilm is strictly related to its pathogenicity. Bacterial adherence and early biofilm formation are influenced by chemical, physical and biological factors that determine their pathogenic properties. We recently presented in literature the ability of pyro-electrified polymer sheets to promote rapid biofilm formation, based on what we called biofilm electrostatic test (BET) carriers. Here we performed a step forward by presenting a comprehensive characterization of the BET methodology through a quantitative evaluation of the biomass on the BET-carrier in the very early stages of incubation. Two bacterial suspensions of Escherichia coli were added to the surface of the BET-carrier, with one order of magnitude difference in initial optical density. The biofilms were stained at different incubation times, while the crystal violet assay and the live/dead reaction kit were used for evaluating the biomass and the viability, respectively. The BET-carrier systematically promoted a faster biofilm formation even in case of very diluted bacterial concentration. The results suggest that the BET-carrier could be used for evaluating rapidly the ability of bacteria to form biofilms and thus their inclination to pathogenicity, thanks to the challenging acceleration in biofilm formation
Effect of argon-enriched modified atmosphere on the over quality and bioactive compounds of ready-to-use broccoli rabe (Brassica rapa sylvestris L. var. esculenta) during the storage
No full textThis study evaluated the effect of argon-enriched modified atmosphere on the storage extension of ready-to-use broccoli rabe in leaf. Broccoli rabe samples (Brassica rapa sylvestris L. var. esculenta) were packaged in 90% argon and 10% O2 (modified atmosphere packaging 1); 80% argon, 10% CO2 and 10% O2 (modified atmosphere packaging 2) and evaluated for the physicochemical characteristics, microbiological parameters and bioactive compounds (glucosinolates) during the cold storage for 9 days. Results showed significant maintenance of colour, chlorophyll, phenols content and antioxidant activity in modified atmosphere packaging packages with respect to air control ones. An increasing biosynthesis of glucosinolates was observed in all packages to the inductive effect of CO2 produced; the amount of minerals unchanged during the storage. Overall appearance and odour evaluation pointed out a positive effect of argon atmospheres, in particular modified atmosphere packaging 1, for the keeping of the sensory attributes compared to those evaluated in air packaging
Essential Oils Diversity of Teucrium Species
No full textThe Mediterranean flora is characterized by an abundance of aromatic
plants. These plants make a significant contribution to the Mediterranean ecological
communities both in terms of species numbers and biomass. In this area, Teucrium
is a polymorphic and cosmopolitan genus of perennial plants, the largest of the
Lamiaceae family, which comprises more than 300 species, of which almost 50 are
native to Europe. The members of this genus are commonly known as germanders:
they are bitter, astringent and antirheumatic herbs, utilized as antispasmodic agents
for gastric ulcer and intestinal inflammation, as diuretic, antiseptic, antipyretic and
antihelmintic agents. Moreover, they were also used in food preparation. Teucrium
species are rich in essential oils and the presence of various biologically active
monoterpenoid and sesquiterpenoid with several biological activities has been
reported. This review summarizes the chemical features of the essential oils of
Teucrium species reported in literature: it provides an overview on their compositions
with particular reference to the more abundant components and to the reported
biological activities. Teucrium polium, T. chamaedrys, T. flavum and T. capitatum
are the most studied taxa concerning the volatile oil composition. Moreover, it is
possible to distinguish different types of essential oils, characterized by the prevalence
of a specific class of compounds: in particular, we recognized volatile oils rich
in caryophyllene and caryophyllene derivatives, α- and β-pinene, germacrene B and
D, α-, γ-, δ-cadinene and/or cadinol, limonene, and bisabolol/bisabolene. This richness
in chemodiversity confers to the essential oils from Teucrium species distinctive
biological properties and applications, often confirming the traditional and folk
uses of this genus. This review testifies the high great variability of Teucrium essential
oils and shows that the possible factors responsible for the chemical polymorphism of essential oils and consequently for their bioactivity need further
investigatio
Motility-based screening of probiotic bacteria candidates by label-free coherent light tester
No full textAmino acid-sesquiterpene lactone conjugates from the aerial parts of Centaurea pungens and evaluation of their antimicrobial activity
No full textTwo new amino acid-sesquiterpene lactone conjugates, named centaureolide A (1) and centaureolide B (2) along with a germacrane derivative (3), five flavonoids (4–8) and one quinic acid derivative (9) have been isolated from the aerial parts of Centaurea pungens (Asteraceae). Their structures were established by a combination of one- and two-dimensional NMR techniques, and mass spectrometry. The never reported sesquiterpene lactones have been determined as germacrane derivatives (1 and 2) characterized by the unusual occurrence of a proline moiety. In order to validate the use of the extract of C. pungens in folk medicine, the antimicrobial activity of the isolated compounds against the Gram-positive strains Bacillus cereus, Staphylococcus aureus and Listeria innocua and the Gram-negative strains Pseudomonas aeruginosa and Pseudomonas fragi was evaluated
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