Brown Macroalgae (Phaeophyceae): A Valuable Reservoir of Antimicrobial Compounds on Northern Coast of Spain

The search for new sources of antimicrobial compounds has become an urgent need, due to the threat that the spread of bacterial resistance represents for global health and food safety. Brown macroalgae have been proposed as a great reservoir in the search for novel antimicrobial compounds. In this study, mid-polarity extracts were performed with a selection of 20 brown macroalgae species from northern Spain. The total polyphenol, carbohydrate and protein contents were quantified by spectrophotometry. The volatile organic compounds (VOCs) of whole macroalgae were also studied as a biomarker of their metabolic state in the representative species of the tested families by gas chromatography-mass spectrometry (GC-MS). The antimicrobial potential of the extracts was assessed by a disk diffusion assay against 20 target bacteria and further determinations of the minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) were performed by a microdilution assay for the active extracts. Ericaria selaginoides, Bifurcaria bifurcata and Dictyota dichotoma showed an antimicrobial effect against six Gram-positive strains: Bacillus cereus, Bacillus subtilis, Geobacillus stearothermophilus, Listeria monocytogenes, Staphylococcus aureus and Staphylococcus haemolyticus. The phenolic content was generally higher in the extracts that showed antimicrobial activity, followed by carbohydrates and low contents of proteins. The results obtained in this study reveal the potential of brown macroalgae as a promising alternative source of antimicrobial compounds as functional ingredients for the application in industrial fields.info:eu-repo/semantics/publishedVersio

Taurine, homotaurine, GABA and hydrophobic amino acids content influences “in vitro” antioxidant and SIRT1 modulation activities of enzymatic protein hydrolysates from algae

Prevention and control of diseases and delaying the signs of ageing are nowadays one of the major goals of biomedicine. Sirtuins, a family of NAD+ dependent deacylase enzymes, could be pivotal targets of novel preventive and therapeutic strategies to achieve such aims. SIRT1 activating and inhibiting compounds, such as polyphenols and bioactive peptides, have been proposed to be involved in the development of many human diseases. The objective of this work was to assess and compare the antioxidant and SIRT1 modulation activities of enzymatic protein hydrolysates (EPHs) from a wide number of algae species (24 commercial samples and 12 samples harvested off the Atlantic coast of northern Spain). High antioxidant activities were observed in EPHs from red and green seaweed species. Moreover, 19 samples exhibited SIRT1 activation, while EPHs from the 16 samples were SIRT1 inhibitors. Pearson’s correlation test and Principal Component Analysis revealed significant correlations between (1) total peptide and hydrophobic amino acid content in EPHs and their antioxidant activities, and (2) concentrations of taurine, homotaurine, and amino acid gamma aminobutyric acid in EPHs and their SIRT1 modulation activity.info:eu-repo/semantics/publishedVersio

Antimicrobial potential of Ericaria selaginoides extracts against Listeria monocytogenes in “mató”, a Catalan fresh cheese

The objective of this work was to assess the antimicrobial effect of crude extracts and non-polar and mid-polar subfractions of the brown macroalga Ericaria selaginoides, using a mid-polarity extraction medium. The activity was evaluated through challenge testing against Listeria monocytogenes in Catalan “mató” (fresh cheese) selected as a food matrix. Three concentrations were tested, representing 2 ×, 4 × and 10 × Minimum Bactericidal Concentration values obtained for crude extract in previous in vitro assays. Ericaria selaginoides extracts inhibited L. monocytogenes growth in a dose-dependent manner. Intermediate concentrations of the three extracts were able to notably reduce the growth rate of the pathogen. Highest concentration of crude extract and non-polar subfraction were able to completely inhibit the growth of L. monocytogenes during the 10 days of storage at 8 °C. Moreover, a slight listericidal effect was observed in presence of the non-polar subfraction, reducing the L. monocytogenes level by ca. 3 log after 10 days of refrigerated storage. These results prove the potential of E. selaginoides extracts as a source of valuable antimicrobial compounds that can be used as natural food ingredients to develop safer fresh dairy food.info:eu-repo/semantics/publishedVersio

Linking sensory and proton transfer reaction–mass spectrometry analyses for the assessment of melon fruit (Cucumis melo L.) quality traits

Sixty-seven samples of ten melon types (Cucumis melo L.) were evaluated to determine the relationship between their quality traits: sensory attributes, pH, soluble solids, and volatile organic compounds. Fruits from the cantalupensis, conomon, dudaim, inodorus, and momordica cultivar groups were analyzed. The sensory profiles were assessed using ten attributes covering odor, flavor, and taste characteristics, whereas the volatile profiles were derived by proton transfer reaction–mass spectrometry. Fruits from the cantalupensis and inodorus cultivars showed an opposite pattern for several quality traits. Fruits from the dudaim cultivar were more related to the cantalupensis, whereas conomon and momordica showed an intermediate behavior between inodorus and cantalupensis. The attributes of odor and flavor intensity, ripe fruit odor, fermentative odor, and fermentative flavor correlated positively to C3–C9 esters (r = 0.43–0.73; p ≤ 0.01). Positive correlations were also observed for several alcohols (r = 0.36–0.82; p ≤ 0.05), including methanol, ethanol, and diol alcohols, as well as for several aldehydes (r = 0.43–0.85; p ≤ 0.01), such as acetaldehyde, butanal, methyl butanal, heptanal, and decanal. The attributes mentioned above were negatively correlated with two C9 aldehydes, 2,6-nonadienal and nonenal (r = − 0.45 to − 0.62; p ≤ 0.01), whereas sweetness was negatively correlated with two C6 green leaf volatiles, hexenal and 3-hexenol (r = − 0.50; − 0.67; p ≤ 0.001). The melon fruits presented distinct differences in the quality traits evaluated. These results provide information for the development of new cultivars with characteristic taste combinations without compromising other desirable fruit quality traits.info:eu-repo/semantics/acceptedVersio

Taurine, homotaurine, GABA and hydrophobic amino acids content influences “in vitro” antioxidant and SIRT1 modulation activities of enzymatic protein hydrolysates from algae

Abstract Prevention and control of diseases and delaying the signs of ageing are nowadays one of the major goals of biomedicine. Sirtuins, a family of NAD+ dependent deacylase enzymes, could be pivotal targets of novel preventive and therapeutic strategies to achieve such aims. SIRT1 activating and inhibiting compounds, such as polyphenols and bioactive peptides, have been proposed to be involved in the development of many human diseases. The objective of this work was to assess and compare the antioxidant and SIRT1 modulation activities of enzymatic protein hydrolysates (EPHs) from a wide number of algae species (24 commercial samples and 12 samples harvested off the Atlantic coast of northern Spain). High antioxidant activities were observed in EPHs from red and green seaweed species. Moreover, 19 samples exhibited SIRT1 activation, while EPHs from the 16 samples were SIRT1 inhibitors. Pearson's correlation test and Principal Component Analysis revealed significant correlations between (1) total peptide and hydrophobic amino acid content in EPHs and their antioxidant activities, and (2) concentrations of taurine, homotaurine, and amino acid gamma aminobutyric acid in EPHs and their SIRT1 modulation activity

Challenge Test in Catalan “Mató” Fresh Cheese to Assess the Antimicrobial Activity of Ericaria selaginoides Extracts against Bacillus cereus

Growing consumer demand for high-quality products coupled with minimally processed products and a minor use of synthetic food additives have increased the need to search for new sources of natural antimicrobials to ensure product safety. This study aimed to evaluate the antimicrobial activity of extracts from the brown algae Ericaria selaginoides against Bacillus cereus in typical Catalan fresh cheese (“mató”) by means of challenge testing. Three concentrations of a crude extract and its corresponding two subfractions (non-polar and mid-polar) obtained after purification showed an antimicrobial dose-dependent effect on B. cereus, from inhibition to inactivation. The best results were obtained with higher concentrations of the non-polar subfraction that caused a total inactivation of the inoculated pathogen after 2 or 4 days, followed by the mid-polar that inactivated B. cereus after 2 or 6 days. The results showed an improvement in the antimicrobial effect after purification compared with the effect observed when the crude extract was tested. Moreover, compounds of different chemical natures may be involved in this antimicrobial activity since it remained in both subfractions after purification. The results obtained in this work show the great potential of macroalgae extracts as natural food preservatives against B. cereus in fresh cheese.info:eu-repo/semantics/publishedVersio

Textural properties of different melon (Cucumis melo L.) fruit types: Sensory and physical-chemical evaluation

Melon fruit properties are extremely different within the species and texture is one of the quality features that most influences its acceptance. The aim of this study was the comparison of melon textural traits, evaluating the linear correlations between both perceived and instrumentally determined texture of a distinctive group of genotypes representing wide species variability. Three landrace cultivars (the Korean ‘Songwhan charmi PI-161375’, the Indian ‘Calcuta PI-124112’, and the Iraqi ‘Irak C-1012’) and three elite cultivars (the Spanish ‘Piel de Sapo T111’, the French ‘Védrantais’, and the American ‘Dulce’), grown under the same conditions in the same place, were analyzed, together with four Spanish major commercial varieties (‘Piel de Sapo’, ‘Amarillo’, ‘Galia’ and ‘Cantaloupe’). Measurements of pH, Soluble Solids Content (SSC), weight losses, puncture tests (6 mm and 10 mm probes), texture profile analysis (TPA), and sensory analysis were performed in 38 fruits. Results showed wide parameter range depending on each particular type of melon. Significant differences were reported for five of six sensory descriptors: hardness (1.52–4.91), initial juiciness (1.77–7.45), crunchiness (0.29–4.58), mealiness (0.41–6.37) and chewiness (2.91–5.27); and for seven of nine physical-chemical parameters: hardness (921.3–4519.0), fracturability (587.4–4280.7), cohesiveness (0.027– 0.061), adhesiveness (−15.7 to −105.0), pH (5.21–6.53), SSC (4.8–14.0) and weight losses (18.0–66.0). Puncture tests parameters were good predictors of sensory hardness, crunchiness and chewiness, while TPA gave further information about initial juiciness, fibrousness and mealiness. Discriminant analysis showed that initial juiciness and mealiness were the most discriminant variables while any instrumental parameter showed particular discriminate ability between samples. These results prove the usefulness of sensory analysis to reflect melon textural traits, when compared to single physical-chemical approach, and could be extended to the middle-late stages of variety development breeding programs.This research was supported by the Spanish Ministry of Economy and Competitiveness, INIA (Project RTA2011-00123-00-00). Tiago Bianchi acknowledges the FPI-INIA PhD fellowship.Peer reviewe

Bioequivalence of meat products treated with high pressure processing

The effects of high pressure on the composition of food products have not been evaluated extensively. Since, it is necessary to take in consideration the possible effects in basis to the changes induced in the bio molecules by the application of high pressures. The main effect on protein is the denaturation, because the covalent bonds are not affected; however hydrogen bonding, hydrophobic and intermolecular interactions are modified or destroyed. 1 High pressure can modify the activity of some enzymes. If this is done the proteolysis and lipolysis could be more or less intense and the content of free amino acids and fatty acids will be different. This could be related to the bioavailability of these compounds. Low pressures (100 MPa) have been shown to activate some enzymes (monomeric enzymes). Higher pressures induce loss of the enzyme activity. However some enzymes are very stable (ex. Lipase ~ 600 - 1000 MPa). Lipoxygenase is less stable, and there is little information about the effects on antioxidant enzymes. Other important issue is the influence of high pressure on oxidation susceptibility. This could modify the composition of lipids if the degree of the oxidation would have been higher or lower than in the traditional product. Pressure produces the damage of cell membranes favouring the contact between substrates and enzymes, exposure to oxidation of membrane fatty acids and loos of the efficiency of vitamin E. These effects can also affect to protein oxidation. In this study different compounds were analysed to establish the differences between non-treated and high-pressure treated products