Raffaele Coppola

Microencapsulation in food science and biotechnology

Microencapsulation can represent an excellent example of microtechnologies applied to food science and biotechnology. Microencapsulation can be successfully applied to entrap natural compounds, like essential oils or vegetal extracts containing polyphenols with well known antimicrobial properties to be used in food packaging. Microencapsulation preserves lactic acid bacteria, both starters and probiotics, in food and during the passage through the gastrointestinal tract, and may contribute to the development of new functional foods.

Preservation of Chicken Breast Meat Treated with Thyme and Balm Essential Oils

The present study evaluated the effects of thyme and balm essential oils on the 3-wk storage of fresh chicken breast meat at 4 °C. Thyme and, to a lesser extent, balm essential oils reduced DPPH (2,2-diphenyl-1-picrylhydrazyl) radical formation in the meat (25% to 30% and 20%, respectively). Treatment with the 2 essential oils also limited lipid peroxidation and the deterioration of sarcoplasmic proteins, helping to preserve the meat even after 2 wk of storage. Thyme and balm essential oils decreased the natural microflora present in the meat; total microbial content decreased down to 50% in comparison to the control samples. In addition, a clear effect on lactic acid bacterial growth was recorded. Balm essential oil significantly limited the growth of Salmonella sp., whereas thyme essential oil effectively inhibited the growth of Escherichia coli. Our data demonstrate that these 2 essential oils effectively reduced deteriorative processes in chicken meat and extended the shelf life of this fresh product. Practical Application: The essential oils of thyme and balm can protect the chicken meat from decomposition during the storage time.

Quorum Sensing and Phytochemicals

Most infectious diseases are caused by bacteria, which proliferate within quorum sensing (QS)-mediated biofilms. Efforts to block QS in bacteria and disrupt biofilms have enabled the identification of bioactive molecules that are also produced by plants. This mini review primarily focuses on natural QS inhibitors, which display potential for treating bacterial infections and also enhance the safety of food supply.

Production of functional probiotic, prebiotic, and synbiotic ice creams

In this work, 3 types of ice cream were produced: a probiotic ice cream produced by adding potentially probiotic microorganisms such as Lactobacillus casei and Lactobacillus rhamnosus; a prebiotic ice cream produced by adding inulin, a prebiotic substrate; and a synbiotic ice cream produced by adding probiotic microorganisms and inulin in combination. In addition to microbial counts, pH, acidity, and physical and functional properties of the ice creams were evaluated. The experimental ice creams preserved the probiotic bacteria and had counts of viable lactic acid bacteria after frozen storage that met the minimum required to achieve probiotic effects. Moreover, most of the ice creams showed good nutritional and sensory properties, with the best results obtained with Lb. casei and 2.5% inulin.

NMR metabolic profiling of organic and aqueous sea bass extracts: Implications in the discrimination of wild and cultured sea bass

The nuclear magnetic resonance (NMR) technique was used as analytical tool to determine the complete metabolic profiling of sea bass extracts: water-soluble metabolites belonging to different classes such as sugars, amino acids, dipeptides and organic acids as well as metabolites soluble in organic solvent such as lipids, sterols and fatty acids were identified. The metabolite profiling together with a suitable statistical analysis were used to discriminate between wild and cultured sea bass samples. Preliminary results show that discrimination between wild and cultured sea bass was obtained not only using fatty acid composition but also cholesterol and phosphatidylethanolamine and some water-soluble metabolites such as choline, trimethylamine oxide, glutamine, fumaric and malic acids.

Presence of yeasts in southern Italian sourdoughs from Triticum aestivum flour

Samples of sourdoughs obtained from 13 artisanal bakeries located in the Molise and Campania regions were analysed. The sourdoughs were produced with the exclusive use of Triticum aestivum wheat flour. pH values of sourdoughs from Molise were generally lower than those from Campania. The number of yeasts in the samples of sourdoughs from Molise was generally higher than in those from Campania, which in two cases evidenced counts about 2 log cfu x g(-1). By utilising and comparing traditional and biomolecular techniques of identification a complete picture of the isolates was obtained: 58 strains were identified as Saccharomyces cerevisiae, five as Candida colliculosa, four as C. lambica, three as C. krusei, three as C. valida and two as C. glabrata.

Chemical Composition and Biological Activity of the Essential Oil from Leaves of Moringa oleifera Lam. Cultivated in Mozambique

The antioxidant capacity and antimicrobial activity of the essential oil of Moringa oleifera (Moringaceae) grown in Mozambique was investigated. The chemical composition was studied by means of GC and GC-MS analysis. Hexacosane (13.9%), pentacosane (13.3%) and heptacosane (11.4%) were the main components. Ultra High Performance Chromatography-DAD analysis detected the flavonoids quercetin (126 μg/g) and luteolin (6.2 μg/g). The essential oil exhibited a relatively low free radical scavenging capacity. The antimicrobial activity of the essential oil was assayed against two Gram-positive strains (Bacillus cereus, Staphylococcus aureus), two Gram-negative strains (Escherichia coli, Pseudomonas aeruginosa), and five fungal strains of agro-food interest (Penicillium aurantiogriseum, Penicillium expansum, Penicillium citrinum, Penicillium digitatum, and Aspergillus niger spp.). B. cereus and P. aeruginosa, as well as the fungal strains were sensitive to the essential oil.

Assessment of aerobic and respiratory growth in the Lactobacillus casei group.

One hundred eighty four strains belonging to the species Lactobacillus casei, L. paracasei and L. rhamnosus were screened for their ability to grow under aerobic conditions, in media containing heme and menaquinone and/or compounds generating reactive oxygen species (ROS), in order to identify respiratory and oxygen-tolerant phenotypes. Most strains were able to cope with aerobic conditions and for many strains aerobic growth and heme or heme/menaquinone supplementation increased biomass production compared to anaerobic cultivation. Only four L. casei strains showed a catalase-like activity under anaerobic, aerobic and respiratory conditions and were able to survive in presence of H2O2 (1 mM). Almost all L. casei and L. paracasei strains tolerated menadione (0.2 mM) and most tolerated pyrogallol (50 mM), while L. rhamnosus was usually resistant only to the latter compound. This is the first study in which an extensive screening of oxygen and oxidative stress tolerance of members of the L. casei group has been carried out. Results allowed the selection of strains showing the typical traits of aerobic and respiratory metabolism (increased pH and biomass under aerobic or respiratory conditions) and unique oxidative stress response properties. Aerobic growth and respiration may confer technological and physiological advantages in the L. casei group and oxygen-tolerant phenotypes could be exploited in several food industry applications.

Phenolic Composition and Antimicrobial and Antiquorum Sensing Activity of an Ethanolic Extract of Peels from the Apple Cultivar Annurca

This study investigated the phenolic composition and antioxidant capacity of an ethanolic extract from the peel of the Annurca (Malus domestica var. Annurca), which is widespread in the Campania region of southern Italy. The antimicrobial effect of the extract on different pathogens was also examined. The potential antiquorum sensing activity of the extract was tested by using the microorganism Chromobacterium violaceum. Ultra-performance liquid chromatography revealed that rutin, epicatechin, dicaffeoylquinic acid, and caffeic acid were the most abundant phenolic compounds in the extract; these compounds constituted 27.43%, 24.93%, 16.14%, and 15.3% of the total phenols, respectively. The test for 2,2-diphenyl-1-picryl-hydrazyl free radical-scavenging activity showed that the extract possessed an impressive antioxidant capacity (50% effective concentration of 2.50 μg/g of product). Furthermore, the extract clearly exhibited antimicrobial activity against Bacillus cereus (11- to 14-mm diameter of inhibition halo, depending on the strain) and Escherichia coli serotype O157:H7 (10-mm diameter of inhibition halo). No activity was observed against the probiotic lactobacilli tested or against Staphylococcus aureus. Antiquorum sensing activity was reported for the first time for apple extracts. In conclusion, these results indicate the potential of this extract for treating some microbial infections through cell growth inhibition or quorum sensing antagonism, thereby validating the health benefits of apples.

Homology-based modeling of Universal Stress Protein from Listeria innocua up-regulated under acid stress conditions

An Universal Stress Protein (USP) expressed under acid stress condition by Listeria innocua ATCC 33090 was investigated. The USP was up-regulated not only in the stationary phase but also during the exponential growth phase. The three dimensional (3D) structure of USP was predicted using a combined proteomic and bioinformatics approach. Phylogenetic analysis showed that the USP from Listeria detected in our study was distant from the USPs of other bacteria (such as Pseudomonas spp., Escherichia coli, Salmonella spp.) and clustered in a separate and heterogeneous class including several USPs from Listeria spp. and Lactobacillus spp. An important information on the studied USP was obtained from the 3D-structure established through the homology modeling procedure. In detail, the Model_USP-691 suggested that the investigated USP had a homo-tetrameric quaternary structure. Each monomer presented an architecture analogous to the Rossmann-like α/β-fold with five parallel β-strands, and four α-helices. The analysis of monomer-monomer interfaces and quality of the structure alignments confirmed the model reliability. In fact, the structurally and sequentially conserved hydrophobic residues of the β-strand 5 (in particular the residues V146 and V148) were involved in the inter-chains contact. Moreover, the highly conserved residues I139 and H141 in the region α4 were involved in the dimer association and functioned as hot spots into monomer–monomer interface assembly. The hypothetical assembly of dimers was also supported by the large interface area and by the negative value of solvation free energy gain upon interface interaction. Finally, the structurally conserved ATP-binding motif G-2X-G-9X-G(S/T-N) suggested for a putative role of ATP in stabilizing the tetrameric assembly of the USP. Therefore, the results obtained from a multiple approach, consisting in the application of kinetic, proteomic, phylogenetic and modeling analyses, suggest that Listeria USP could be considered a new type of ATP-binding USP involved in the response to acid stress condition during the exponential growth phase.