This study evaluated the effect of grape stems extracts on motility, surface energy and adhesion of L. monocytogenes to stainless steel and polypropylene surfaces. Stem extracts from Red Globe grapes ...showed a higher content of total phenolics than Carignan stems. Moreover, both extracts reduced adhesion of Listeria to stainless steel (0.77-2.22 log CFU cm
−2
) and polypropylene (0.71-2.38 log CFU cm
−2
) and completely inhibited bacterial motility at 4.5 and 5 mg mL
−1
of Red Globe and Carignan extracts, respectively. Similarly, both extracts affected the surface energy of bacteria and modified the adhesion potential of L. monocytogenes to both surfaces. Otherwise, caffeic, ferulic and gallic acids, catechin and rutin, presented in both extracts, reduced adhesion of L. monocytogenes to stainless steel (0.39-2.04 log CFU cm
−2
) at 10 mM. In conclusion, Red Globe and Carignan grape stem extracts inhibited adhesion of L. monocytogenes to stainless steel and polypropylene surfaces by inhibiting motility and modifying its adhesion potential.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
In the present study total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity and antimicrobial properties of grape (Vitis vinifera var. Red Globe) stem extract is reported. ...Also, the identification of main phenolic compounds was carried out by UPLC-PAD analysis. TPC and TFC of extract were 37.25 g GAE kg
−1
and 98.07 g QE kg
−1
, respectively. Extract showed an antioxidant capacity of 132.60 and 317 g TE kg
−1
for DPPH and ABTS radical scavenging capacity, respectively. The main phenolic compounds identified were rutin, gallic acid, chlorogenic acid, caffeic acid, catechin and ferulic acid. Extract inhibited the growth of
Listeria monocytogenes
,
Staphylococcus aureus
,
Salmonella enterica
subsp.
enterica
serovar Typhimurium, and
Escherichia coli
O157: H7 at MIC range 16–18 g L
−1
. Extract affected the different phases of bacterial growth. In addition, application of Extract (25 g L
−1
) as a sanitizer was effective to reduce the populations of all bacteria inoculated in lettuce (0.859–1.884 log reduction) and spinach (0.843–2.605 log reduction). This study emphasizes the potential of grape processing byproducts as an emergent and attractive source of bioactive compounds with antioxidant properties and antimicrobial activity against important foodborne pathogens. The study demonstrated that stem extract could be used to control the presence of human pathogenic bacteria in fresh leafy vegetables.
Biofilms are detrimental to human life and industrial processes due to potential infections, contaminations, and deterioration. Therefore, the evaluation of microbial capability to form biofilms is ...of fundamental importance for assessing how different environmental factors may affect their vitality. Nowadays, the approaches used for biofilm evaluation are still poor in reliability and rapidity and often provide contradictory results. Here, we present what we call biofilm electrostatic test (BET) as a simple, rapid, and highly reproducible tool for evaluating in vitro the ability of bacteria to form biofilms through electrostatic interaction with a pyroelectrified carrier. The results show how the BET is able to produce viable biofilms with a density 6-fold higher than that on the control, after just 2 h incubation. The BET could pave the way to a rapid standardization of the evaluation of bacterial resistance among biofilm-producing microorganisms. In fact, due to its simplicity and cost-effectiveness, it is well suited for a rapid and easy implementation in a microbiology laboratory.
Globe artichoke (Cynara cardunculus L. var. scolymus) is rich in flavonoids which contribute to its health-promoting properties. With the aim of understanding the genetic control of flavonoid ...accumulation in artichoke, we isolated an artichoke full-length cDNA sequence encoding flavonoid 3′-hydroxylase (F3′H), a major enzyme of the flavonoid hydroxylation pattern. In silico studies confirmed that the deduced amino acid sequence of CcF3′H is highly similar to F3′Hs isolated from other Asteraceae. The Northern blot analysis demonstrated that CcF3′H was highly expressed in leaves and in specific parts of the heads. Its expression differed slightly among artichoke cultivars. The overexpression of CcF3′H in tobacco plants led to the accumulation of flavonoids and to an increase of flower colour intensity, thus identifying CcF3′H as promising candidate for genetic engineering. CcF3′H represents the first structural gene of the flavonoid biosynthesis isolated from C. cardunculus, and its characterization sheds light on the accumulation of flavonoids.
In the present paper, the effect of cryo-protective sugars on the survival rate of different strains of Lactic Acid Bacteria (LAB, Lactobacillus acidophilus, Lactobacillus delbrueckii ...subspbulgaricus, Streptococcus salivarius subsp.thermophilus), after freezing or freeze-drying procedures, was compared. The cells were incubated at 4 °C in 32% final concentration sugar solutions (trehalose, maltose, sucrose, glucose and lactose), and viability was evaluated by the enumeration of colony-forming units. All sugars tested showed a protective effect on cell viability as compared to isotonic solution, especially after freeze-drying procedures (log c.f.u./ml ranging between 1.16 and 2.08, P < 0.001). Furthermore, the resistance to different stress agents (lysozyme, pepsin, bile salts) was estimated. Trehalose was the most effective sugar in preserving bacterial viability % (log c.f.u. trehalose/log c.f.u. isotonic solution) ranging between 124 and 175, P < 0.001 although each strain showed a different sensitivity. Finally, the protective effect of immobilization of LAB in Ca-alginate beads was compared to that exercised by trehalose. The immobilization induced a good survival rate but lower as compared to the trehalose effect, mainly after freeze-drying in the presence of the selective agents % (log c.f.u. alginate/log c.f.u. trehalose ranging between 81.1 and 94.5, P < 0.0001. The protective effect of trehalose was evident in particular for Lactobacillus delbrueckii subsp. bulgaricus in presence of lysozyme. Therefore, because of its chemical inertness and low cost, trehalose could be easily utilized as excellent bacterial preservative, both to improve the viability of starter cultures and to obtain probiotic formulations more resistant to a variety of stressful conditions.PUBLICATION ABSTRACT
In the framework of a project aimed to select some genotypes of Capsicum annum potentially exploitable for giving high-quality products, this research compared the total content of some bioactive ...compounds (polyphenols, flavonoids, carotenoids and ascorbic acid) and the antioxidant activity between of two cultivars of "Corno di Toro" sweet peppers, commonly named "Lampo" and "Teseo." They were also investigated for their in vitro antimicrobial action against different bacteria and fungi, as well as for their mutagenic and antimutagenic activities. A relevant content of the active compounds was found, showing cultivar Lampo a higher content of polyphenols and a greater antioxidant potential. The antimicrobial action was different, exhibiting the compounds from variety "Lampo" a discrete activity against Bacillus cereus, Escherichia coli and Penicillium expansum, whereas extracts from "Teseo" showed inhibition against E. coli and Debaryomyces hansenii. The antimutagenic activity, assayed with Ames test by using the Salmonella typhimurium Histidine-requiring strain TA100, was significant, with a percentage of mutagenicity inhibition comparable to the negative control. The two cultivars could be of great interest as relevant polyphenols sources and for their antimicrobial and antimutagenic properties. Sweet pepper (Capsicum annuum L.) is a broadly diffused plant. The information gathered from our work can contribute to a better selection of those genotypes of C. annum potentially exploitable for giving high-quality products, in terms of biochemical compounds and antioxidant activity. With the emergence of antibiotic-resistant microorganisms, it is reasonable to explore new sources of natural compounds with antibiotic activities: our study showed the possibility to use the extracts of two genotypes of a common edible plant, like sweet pepper, as harmless and economical antibacterial and antifungal compounds. In view of the fact that several human diseases, like cancer, are recognized as taking place from free radical damage, the inclusion in the diet of those genotypes of sweet pepper with noteworthy antimutagenic property could contribute in the prevention or limitation of such disease.
A preliminary study was performed on fresh and irradiated
Tuber aestivum black truffles to investigate the presence of mutagenic and antimutagenic activities in the fresh product and to examine the ...possible effects of treatment with gamma rays. The study was performed on aqueous and ethanolic extracts from truffles, untreated or irradiated with a final dose of 1.5
kGy. Two
Salmonella typhimurium His
− strains, TA 98 and TA100, were used. The preliminary results indicate that black truffles may contain compounds having an inhibitory effect against direct and indirect acting mutagenic compounds. The irradiation did not lead to the formation of mutagenic compounds, but the level of antimutagenic activity was slightly decreased after the treatment.
The analysis of polyphenols of leaves and different parts (outer, intermediate and inner bracts, and receptacle) of heads in five globe artichoke cultivars of Campania region (Italy) and one ...accession of cultivated cardoon was performed. Data obtained suggest that the edible parts (receptacles with inner and intermediate bracts) of these cultivars of artichoke could represent a good source of health-promoting polyphenols and therefore encourage a nutriceutical use of this species, as an alternative to the more traditional phytopharmaceutical applications of leaf extracts. Moreover, it was demonstrated that single polyphenols accumulate preferentially in specific parts of the heads and in specific genotypes.
Abstract
To evaluate the effects on postprandial lipemia (PPL), of three fat rich meals, with similar composition but different physical structure (liquid, semisolid and solid).
Eight type 2 diabetic ...patients of both genders (6M/2F), age 51±9 yrs (M±SD), BMI 29±3 kg/m
2, with fasting plasma glucose levels 145±24 mg/dL, cholesterol 200±38 mg/dL and triglyceride 110±45 mg/dL. Participants consumed in the morning, after a 12-hour fast and at 1-week intervals, three test meals with similar volume and composition protein 36 g, lipid 30 g, carbohydrate 115 g, energy 3556 kJ (850 Kcal) but with the main source of fat represented by foods with different physical structure (milk, mozzarella-cheese, butter). Each patient underwent gastric emptying measurements by echography; plasma FFA, triglycerides, glucose and insulin were evaluated at baseline and every hour for six hours after each meal. Fasting plasma glucose, cholesterol and triglyceride concentrations were similar at the baseline of the three test meals. Average increases in postprandial plasma triglyceride levels after butter (88±28 mg/dL) and mozzarella-cheese (104±56 mg/dL) were not different than after milk (98±53 mg/dL). The plasma triglyceride peak was also similar after the three test meals but peak time after butter (315±42 min;
p<0.01) and mozzarella-cheese (277±31 min;
p<0.02) was significantly delayed compared to milk (225±28 min). Gastric emptying rate was similar after butter and milk (14±2, 13±6 mL/h) and significantly faster after mozzarella-cheese (18±5 mL/h;
p<0.03).
While the physical structure of fat-rich foods has no major effect on postprandial plasma triglyceride concentrations, it is able to influence the timing of triglyceride peak; gastric emptying time does not play a major role in modulating the postprandial response of triglycerides and glucose.
Plant-derived antifungals have an interesting potential to be used for the sustainable management of plant diseases. In this work, seven different local genotypes of Capsicum annuum, diffused in ...agricultural areas of Campania Region (Italy), were explored for their potential in providing phytochemical extracts suitable for antifungal applications. Bioactive hydro-methanolic extracts has been assessed for phenolic composition and antioxidant capacity and, then, assayed both in vitro and in planta for the suppression of Alternaria alternata, the causal agent of early blight of tomato. Ultra high-performance liquid chromatography-diode array detection (UPLC-DAD) analysis showed phenolic profiles of each extract, identifying and quantifying the individual known components, including gallic acid, chlorogenic acid, epicatechin, cumaric acid, rutin, ferulic acid and luteolin. The phenolic-rich extracts of all peppers varieties proved to be active against in vitro mycelial development of A. alternata. Dipping artificially infected tomato leaves using extracts at 10μg GAE ml⁻¹ of total phenolics, reduced foliar early blight disease severity closely to 50%, on average. The role played by the phenolic complex in the antifungal activity and in disease control efficacy of the extracts, has been discussed.
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