Application of elemental analysis via energy dispersive x-ray fluorescence (ED-XRF) for the authentication of Maltese extra virgin olive oil

Elemental analysis using energy-dispersive X-ray fluorescence on extra virgin olive oils and seed oils revealed the presence of two major concentration related clusters, one containing elements of pedological origin, whilst the other consisted of heavy metals. Seed oils were found to contain a higher concentration of titanium when compared to extra virgin olive oils, whilst extra virgin olive oils derived from the Maltese Islands had a significantly higher concentration of barium and phosphorus on using the Kruskal–Wallis one-way ANOVA (p-value < 0.05 for both elements). Application of stepwise linear canonical discriminate analysis proved to be highly superior to PCA, as it was able to distinguish between seed oils from extra virgin olive oils and distinguish between foreign and locally produced extra virgin olive oils.peer-reviewe

Application of 1h and 13c nmr fingerprinting as a tool for the authentication of Maltese extra virgin olive oil

The application of 1H and 13C nuclear magnetic resonance (NMR) in conjunction with chemometric methods was applied for the discrimination and authentication of Maltese extra virgin olive oils (EVOOs). A total of 65 extra virgin olive oil samples, consisting of 30 Maltese and 35 foreign samples, were collected and analysed over four harvest seasons between 2013 and 2016. A preliminary examination of 1H NMR spectra using unsupervised principle component analysis (PCA) models revealed no significant clustering reflecting the geographical origin. In comparison, PCA carried out on 13C NMR spectra revealed clustering approximating the geographical origin. The application of supervised methods, namely partial least squares discriminate analysis (PLS-DA) and artificial neural network (ANN), on 1H and 13C NMR spectra proved to be effective in discriminating Maltese and non-Maltese EVOO samples. The application of variable selection methods significantly increased the effectiveness of the different classification models. The application of 13C NMR was found to be more effective in the discrimination of Maltese EVOOs when compared to 1H NMR. Furthermore, results showed that different 1H NMR pulse methods can greatly affect the discrimination of EVOOs. In the case of 1H NMR, the Nuclear Overhauser Effect (NOESY) pulse sequence was more informative when compared to the zg30 pulse sequence, since the latter required extensive spectral manipulation for the models to reach a satisfactory level of discrimination.peer-reviewe

Application of ATR-FT-MIR for tracing the geographical origin of honey produced in the Maltese Islands

Maltese honey has been produced, marketed, and sold as an exclusive local gourmet food product for countless years. Yet, thus far, no study has evaluated the individuality of this local food product. The evaluation of the parameters and properties which characterise the provenance and floral source of honey have been the subject of various studies worldwide, owing to the price and potential beneficial properties of this food product. Models analysing the potential of attenuated total reflection mid-infrared (ATR-FT-MIR) spectroscopy in discriminating and classifying local honey from that of foreign origin were investigated using 21 Maltese honey samples and 49 honey samples collected from abroad (Sicily, Greece, Sweden, Italy, France, Estonia and other samples of mixed geographical origin). Through a combination of spectroscopic techniques, spectral transformations, variable selection and partial least squares discriminant analysis (PLS-DA), chemometric models which successfully classified the provenance of local and non-local honey were developed. The results of these models were also corroborated with other classification and pattern recognition techniques, such as linear discriminate analysis (LDA), support vector machines (SVM) and feed-forward artificial neural networks (FF-ANN).peer-reviewe

The first identification of the uniqueness and authentication of Maltese extra virgin olive oil using 3D-fluorescence spectroscopy coupled with multi-way data analysis

The potential application of multivariate three-way data analysis techniques, namely parallel factor analysis (PARAFAC) and discriminant multi-way partial least squares regression (DN-PLSR), on three-dimensional excitation emission matrix (3D-EEM) fluorescent data were used to identify the uniqueness and authenticity of Maltese extra virgin olive oil (EVOO). A non-negativity constrained PARAFAC model revealed that a four-component model provided the most appropriate solution. Examination of the extracted components in mode 2 and 3 showed that these belonged to different fluorophores present in extra virgin olive oil. Application of linear discriminate analysis (LDA) and binary logistic regression analysis on the concentration of the four extracted fluorophores, showed that it is possible to discriminate Maltese EVOOs from non-Maltese EVOOs. The application of DN-PLSR provided superior means for discrimination of Maltese EVOOs. Further inspection of the extracted latent variables and their variable importance plots (VIPs) provided strong proof of the existence of four types of fluorophores present in EVOOs and their potential application for the discrimination of Maltese EVOOs.peer-reviewe

Turning waste into a resource : isolation and characterization of high‐quality collagen and oils from Atlantic bluefin tuna discards

At the behest of the Green Deal, circular economy concepts are currently being widely promoted, not least within the aquaculture sector. The current study aims to demonstrate the technical feasibility of extracting collagen and fish oils from waste Atlantic bluefin tuna biomass originating from the Maltese aquaculture industry. For collagen, a three‐stage methodology, consisting of pre‐treatment, extraction, and retrieval, was applied to biomass originating from bone, skin, muscle, and internal organs (offal) in order to extract both acid‐soluble collagen (ASC) and pepsin‐soluble collagen (PSC). The chemical identity of the extracted collagen was confirmed through the conduction of hydroxyproline and SDS‐PAGE tests as well as through FTIR, whilst the extracted collagen was also tested for its microbiological and heavy metal profiles. The collagen yield was found to be highest for skin tissue and for PSC‐based protocols and is comparable to the yield cited in the literature for other tuna species. Oils were extracted through low temperature, high temperature, and enzymatic means. The fatty acid profile of the extracted oils was assessed using GC‐FID; this indicated high proportions of EPA and DHA. Yield indicated that the enzymatic extraction of oil is most effective. High heat and the presence of iron‐containing muscle starting material promote oxidation and rancidity. Further effort into the optimization of both collagen and lipid extraction protocols must be invested, with a special focus on the production of high‐value fractions that are much closer to the quality required for human use/consumption.peer-reviewe

Intra-serotype SAT2 chimeric foot-and-mouth disease vaccine protects cattle against FMDV challenge

The genetic diversity of the three Southern African Territories (SAT) types of foot-and-mouth diseasevirus (FMDV) reflects high antigenic variation, and indications are that vaccines targeting each SAT-specific topotype may be needed. This has serious implications for control of FMD using vaccines as wellas the choice of strains to include in regional antigen banks. Here, we investigated an intra-serotypechimeric virus, vSAT2ZIM14-SAT2, which was engineered by replacing the surface-exposed capsid-codingregion (1B-1D/2A) of a SAT2 genome-length clone, pSAT2, with that of the field isolate, SAT2/ZIM/14/90.The chimeric FMDV produced by this technique was viable, grew to high titres and stably maintained the1B-1D/2A sequence upon passage. Chemically inactivated, oil adjuvanted vaccines of both the chimericand parental immunogens were used to vaccinate cattle. The serological response to vaccination showedthe production of strong neutralizing antibody titres that correlated with protection against homolo-gous FMDV challenge. We also predicted a good likelihood that cattle vaccinated with an intra-serotypechimeric vaccine would be protected against challenge with viruses that caused recent outbreaks insouthern Africa. These results provide support that chimeric vaccines containing the external capsid offield isolates induce protective immune responses in FMD host species similar to the parental vaccine.MSD Animal Health (previously Intervet SPAH)http://www.elsevier.com/locate/vaccine2016-06-30hb201

Photocatalytic activity of titanium dioxide nanotubes following long-term aging

Anodic titanium dioxide (TiO2) nanotubes were found to be active photocatalysts. These photocatalysts possess a high surface area, even when supported, rendering them potential candidates for water treatment. In this work, photocatalytic surfaces were produced by anodizing commercially pure Ti plates using two different electrolyte compositions and correspondingly diverse process parameters. Changes in the physical and chemical stability as well as photocatalytic activity were studied over a fifty-two-week aging process. During this period, the nanotubular surfaces were exposed to flowing synthetic greywater, solar irradiation, and the natural environment. The physical and phase stability of the materials anodized using the organic electrolyte were found to be outstanding and no degradation or change in crystalline structure was observed. On the other hand, materials anodized in the aqueous electrolyte proved to suffer from light-induced phase transition from anatase to rutile. Surfaces synthesized in the organic electrolyte were more resistant to fouling and showed a better tendency to recover photocatalytic activity upon cleaning. In conclusion, the nanotubes produced in the organic electrolyte proved to be stable, rendering them potentially suitable for real-life applications.peer-reviewe

Effect of the surface morphology of TiO2 nanotubes on photocatalytic efficacy using electron-transfer-based assays and antimicrobial tests

The application of titanium oxide nanotubes for the removal of contaminants from freshwater is a rapidly growing scientific interest, especially when it comes to water conservation strategies. In this study we employed four different titanium oxide nanotube surfaces, prepared by a two-electrode anodic oxidation. Two of the surfaces were synthesised in aqueous media, while the other two surfaces were synthesised in ethylene glycol. One of the arrays synthesised in the organic medium was impregnated with silver nanoparticles, while the remaining surfaces were not. The chemical reactivity of the various surfaces was assessed using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,20 -azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as free electron sensitive probe molecules, in parallel with tannic acid degradation and copper ion reducing capacity. The potential antimicrobial activity of the surfaces was assessed against a panel of microorganisms composed of yeast, fungi, Gram-positive and Gram-negative bacteria. Field emission scanning electron microscopy revealed that surfaces produced in the aqueous medium had a smaller tube length and a smaller tube diameter. It was noted that one of the materials using sodium sulfate as the supporting electrolyte had the most irregular nanostructure morphology with tubes growing to the side rather than vertically. The structural variation of the surfaces directly reflected both the chemical and biological activity, with the nanotubes formed in ethylene glycol showing the fastest rates in the stabilization of DPPH and ABTS radicals, the fastest tannic acid decomposition under various pH conditions and the fastest metal reducing activity. Furthermore, the surface containing silver and its bare counterpart showed the most effectivepeer-reviewe

Suitability of different titanium dioxide nanotube morphologies for photocatalytic water treatment

Photocatalysis has long been touted as one of the most promising technologies for environmental remediation. The ability of photocatalysts to degrade a host of different pollutants, especially recalcitrant molecules, is certainly appealing. Titanium dioxide (TiO2) has been used extensively for this purpose. Anodic oxidation allows for the synthesis of a highly ordered nanotubular structure with a high degree of tunability. In this study, a series of TiO2 arrays were synthesised using different electrolytes and different potentials. Mixed anatase-rutile photocatalysts with excellent wettability were achieved with all the experimental iterations. Under UVA light, all the materials showed significant photoactivity towards different organic pollutants. The nanotubes synthesised in the ethylene glycol-based electrolyte exhibited the best performance, with near complete degradation of all the pollutants. The antibacterial activity of this same material was similarly high, with extremely low bacterial survival rates. Increasing the voltage resulted in wider and longer nanotubes, characteristics which increase the level of photocatalytic activity. The ease of synthesis coupled with the excellent activity makes this a viable material that can be used in flat-plate reactors and that is suitable for photocatalytic water treatment.peer-reviewe