Finding the optimum treatment procedure to delay honey crystallization without reducing its quality.

The current study investigated the effect of different thermal and non-thermal procedures for the estimation of the optimum conditions of treatment of different honey types (erica, cotton, thyme, eucalyptus and pine honey) to avoid or delay crystallization without losing the nutritional benefits of honey. Different physicochemical parameters, such as pollen analysis, hydroxymethylfurfural (HMF), diastase activity, acidity, and total phenolic compounds were used as quality indicators. The different treatment procedures were evaluated in different honey types and in different time periods. It was proved that to achieve a non-crystallised product that lasts over a year, samples must be heated at 72 oC or stored at -18 °C. However, only by storing samples at -18 °C kept the nutritional benefits of honey and provide similar results with the fresh unheated samples. All procedures were examined in a long-term period (one year) in order to have a complete and accurate result.

Chemical Composition of Essential Oils of Aromatic and Medicinal Herbs Cultivated in Greece-Benefits and Drawbacks.

The current study investigated and determined the major compounds of six essential oils derived from different plant species cultivated in Greece (Lavandula angustifolia, Origanum vulgare, Pistacia lentiscus var. chia, Citrus reticulata, Citrus limon and Crithmum maritimum). The results proved that all these essential oils have a high potential for use as food preservatives, since among the compounds determined were sabinene, b-myrcene, a-pinene, carvacrol and limonene, all of which were responsible for the strong antimicrobial activity against Staphylococcus aureus. However, the amounts of some compounds, such as linalool and citral, were at high levels, and this can be a danger for some sensitive population groups due to allergic reactions. The essential oil compounds which were identified using GC-MS and quantified through GC-FID represented more than 95% of the total essential oils of the investigated plant species. Finally, all essential oils provided high phenolic content.

Advanced multivariate techniques for the classification and pollution of marine sediments due to aquaculture.

Aquaculture production has globally increased and its environmental impact is not well understood and assessed yet. Therefore, in this work nine metals and metalloids (Cu, Cd, Pb, Hg, Ni, Fe, Mn, Zn and As) and three nutrients (P, N and C) that seem to accumulate in marine sediments, were determined under the fish cages (zero distance) and about 50 and 100 m away from them, in three aquacultures in Greece. The analysis of these data is crucial due to the negative impact of the intensive aquaculture activities on fish population, human health and marine environment. This study investigated the environmental impact associated with aquaculture cages on marine sediments, using Supervised Artificial Neural Networks (ANNs) in parallel with Classification Trees (CTs). Optimised models were constructed in order to detect the significance of each variable, predict the origin of the sediment samples and successfully visualise their results. Three popular ANN architectures, as multi-layer perceptrons (MLPs), radial basis function (RBF) and counter propagation artificial neural networks (CP-ANNs) were used to assess the impact of the intensive aquaculture activities on marine sediments. In addition, more traditional multivariate chemometric techniques like CTs were applied to the same data set for comparison purposes. The modelling study showed that P, N, Cu, Cd were the most critical (and polluting) factors of those metals studied. Moreover, single-element models achieved elevated predictive percentages. The results were justified due to the usual practices used for fish feeding or cages maintenance.

Development and validation of a HILIC-UV method for the determination of nucleotides in fish samples.

The aim of this work was the development of a simple, novel and accurate method for the determination of adenosine triphosphate (ATP) and its first five catabolites: adenosine diphosphate (ADP), adenosine monophosphate (AMP), inosine monophosphate (IMP), inosine (Ino) and hypoxanthine (Hx), in fish tissue, based on hydrophilic interaction liquid chromatography (HILIC). For this purpose, a stationary phase for polar and hydrophilic compounds (ZIC-pHILIC) was used. The effect of different chromatographic parameters and the molecular mechanism based on the van't Hoff plot were examined. The t-test and Dixon's Q-test were applied in order to examine statistical differences and outlier values. The recovery of the method ranged between 82.7% and 127% and the %RSD values were lower than 10% for all analytes determined. The method was applied in frozen sea bream samples stored at 0-4 °C. The Ki-, G-, H- and F values were calculated for the estimation of the level of fish freshness.

Determination of Vitamin E in Cereal Products and Biscuits by GC-FID.

A rapid, precise and accurate method for the determination of vitamin E (α-tocopherol) in cereal products and biscuits has been developed. The uncertainty was calculated for the first time, and the methods were performed for different cereal products and biscuits, characterized as "superfoods". The limits of detection and quantification were calculated. The accuracy and precision were estimated using the certified reference material FAPAS T10112QC, and the determined values were in good accordance with the certified values. The health claims according to the daily reference values for vitamin E were calculated, and the results proved that the majority of the samples examined showed a percentage daily value higher than 15%.

Development of a Rapid Method for the Determination of Caffeine in Coffee Grains by GC-FID-A Fully Validated Approach.

A simple method for the determination of caffeine in coffee grains by GC-FID (Gas Chromatography-Flame Ionisation Detector) is presented in the current work. The method was fully validated according to ISO (International Organization for Standardization) 17025 requirements and European Commission regulations. The accuracy, as provided by recovery experiments, was higher than 93%, and the precision, as provided by the (%) relative standard deviation under reproducibility conditions, was lower than 5%. A vast number of independent parameters that lead in the increase of uncertainty of methods were investigated. The analysis was performed without use of an internal standard, which was proven to be reliable according to several validation methods. The method was applied in real samples, and possible health claims were investigated.

HMF and diastase activity in honeys: A fully validated approach and a chemometric analysis for identification of honey freshness and adulteration.

A fully validated approach for the determination of diastase activity and hydroxymethylfurfural content in honeys were presented in accordance with the official methods. Methods were performed in real honey sample analysis and due to the vast number of collected data sets reliable conclusions about the correlation between the composition and the quality criteria were exported. The limits of detection and quantification were calculated. Accuracy, precision and uncertainty were estimated for the first time in the kinetic and spectrometric techniques using the certified reference material and the determined values were in good accordance with the certified values. PCA and cluster analysis were performed in order to examine the correlation among the artificial feeding of honeybees with carbohydrate supplements and the chemical composition and properties of the honey. Diastase activity, sucrose content and hydroxymethylfurfural content were easily differentiated and these parameters were used for indication of the adulteration of the honey.

Evaluation of internal standardization for the determination of semivolatile analytes in difficult matrices by simultaneous multielement atomic absorption spectrometry.

The aim of the present work is to investigate the use of the internal standardization technique combined with permanent chemical modification for the determination of two semivolatile analytes, such as As and Se, in difficult matrices by electrothermal atomic absorption spectrometry. Bismuth and tellurium have been evaluated as internal standards to minimize matrix effects on the direct determination of selenium and arsenic in sediments, by simultaneous electrothermal atomic absorption spectrometry using graphite tubes with integrated platform, pre-treated with different masses of Zr and Ir as permanent modifier. A Perkin-Elmer SIMAA 6000 simultaneous multielement spectrometer was used to study the correlation between two integrated absorbance signals. Matrix effects were evaluated by calculating the slope ratio between the analytical curve obtained from reference solutions prepared in 1.0% (v/v) HNO3 and analytical curve obtained from IS additions in matrix solutions. The results showed that Te was the optimal internal standard and 200 µg Zr and 20 µg Ir was the optimal permanent chemical modifier for both analytes. The instrumental limits of detection for As and Se were 1.48 and 1.96 µg L(-1) without the use of an internal standard and 0.59 and 0.35 µg L(-1) when Te was used as an internal standard, respectively. Relative standard deviations for a sample with matrix effect containing 100 µg L(-1) As and 200 µg L(-1) Se were 1.3% and 2.3% (n=20) using 100 µg L(-1) Te, respectively, and for a standard solution sample containing 100 µg L(-1) As and 200 µg L(-1) Se were 3.0% and 1.2% (n=20) using 100µgL(-1) Te, respectively. The accuracy of the proposed method was evaluated by an addition-recovery experiment and by the analysis of different certified reference materials. The recovered values were in the 95-100% range for both analytes.

Study of the migration phenomena of specific metals in canned tomato paste before and after opening. Validation of a new quality indicator for opened cans.

A method for the simultaneous determination of Cd-Pb, As-Cu, Cr-Ni and Fe-Mn in canned tomato paste samples by Electrothermal Atomic Absorption Spectrometry was developed and validated. The validation procedure was conducted according to the terms of the European regulation for the official control of contaminants in foods. The validated method was applied for the determination of these metals and metalloids in 13 different tomato paste samples and the results showed that Cd content was higher than the maximum permissible value of 0.050 mg kg(-1) as proposed in European Regulation (EC) No 1881/2006 concerning fresh fruits and vegetables. Furthermore, a new quality indicator was evaluated in order to provide information about tomato paste quality and the appropriate storage time of an opened canned tomato paste. Finally, a migration test was accomplished based on the calculation of mass balance and the comparison of the elemental content in canned tomato paste samples and in aseptic paper pack and it was proved that Fe and Pb were the main metals migrating in tomato paste samples.

Environmental impact of intensive aquaculture: investigation on the accumulation of metals and nutrients in marine sediments of Greece.

The impact of intensive aquaculture activities on marine sediments along three coastal areas in Greece was studied. The content of nine metals/metalloids (Cu, Cd, Pb, Hg, Ni, Fe, Mn, Zn, As), and three nutrients (P, N and C), that seem to accumulate in marine sediments, was determined under the fish cages (zero distance) and away (50 or 100 m) from them. Elevated concentrations for phosphorus, nitrogen, copper, zinc and cadmium were recorded in the areas where farming establishments are moored. In parallel, the intrinsic differences between the aquaculture facilities and their seasonal variations were investigated. The individual characteristics of each farm (local water currents, facilities' capacity, transferring mechanisms or the geological background) were the determinant factors. On the contrary, significant seasonal differences were not recorded. Statistical techniques, as the non-parametric Mann-Whitney U and Kruskal-Wallis tests and principal components analysis (PCA), factor analysis (FA) and discriminant analysis (DA), were used for the evaluation of the results. These chemometric tools succeeded to discriminate the sampling points according to their distance from the cages or the origin of the sample. Variables' significance, correlations and potential accumulation sources were also investigated.