Anastasia Badeka

Characterisation and classification of Greek pine honeys according to their geographical origin based on volatiles, physicochemical parameters and chemometrics.

The aim of the present study was to characterise and classify Greek pine honeys according to geographical origin, based on the determination of volatile compounds and physicochemical parameters using MANOVA and Linear Discriminant Analysis. Thirty-nine pine honey samples were collected during the harvesting period 2011 from 4 different regions in Greece known to produce good quality pine honey. The analysis of volatile compounds was performed by Headspace Solid Phase Microextraction-Gas Chromatography/Mass Spectroscopy. Fifty-five volatile compounds were tentatively identified and semi quantified. Physicochemical parameter analysis included the determination of pH, free, lactonic and total acidity, electrical conductivity, moisture, ash, lactonic/free acidity ratio and colour parameters L(∗), a(∗), b(∗). Using 8 selected volatile compounds and 11 physicochemical parameters, the honey samples were satisfactorily classified according to geographical origin using volatile compounds (84.6% correct prediction), physicochemical parameters (79.5% correct prediction) and the combination of both (74.4% correct prediction).

Shelf-life extension of refrigerated Mediterranean mullet (Mullus surmuletus) using modified atmosphere packaging.

The present work evaluated the quality and freshness characteristics and the effect of modified atmosphere packaging (MAP) on the shelf-life extension of refrigerated Mediterranean mullet using microbiological, biochemical, and sensory analyses. Fresh open sea red mullet (Mullus surmuletus) were packaged in four different atmospheres: M1, 10%/20%/70% (O2/ CO2/N2); M2, 10%/40%/50% (O2/CO2/N2); M3, 10%/60%/30% (O2/CO2/N2); identical fish samples were packaged in air. All fish were kept under refrigeration (4 +/- 0.5 degrees C) for 14 days. Of the three gas atmospheres, the 10%/40%/50% (M2) and 10%/ 60%/30% (M3) gas mixtures were the most effective for inhibiting growth of aerobic microflora in mullet samples until day 10 of refrigerated storage. H2S-producing bacteria and pseudomonads were part of the mullet microflora and their growth was partly inhibited under MAP conditions. Between these two bacterial groups, H2S-producing bacteria (including Shewanella putrefaciens) were dominant toward the end of the storage period, regardless of the packaging conditions. Brochothrix thermosphacta and lactic acid bacteria were found to be members of the final microbial flora of MAP and air-packaged mullet, whereas the Enterobacteriaceae population was lower than other bacterial groups. Of the chemical freshness indices determined, thiobarbituric acid values were variable in mullet samples irrespective of packaging conditions indicative of no specific oxidative rancidity trend. Based on sensorial data and aerobic plate count, trimethylamine nitrogen and total volatile basic nitrogen limit values in the range of ca. 15 to 23 and 52 to 60 mg N/100 g of fish muscle were obtained, respectively, for mullet packaged under modified atmosphere and air. Sensory analyses (odor and taste attributes) showed that the limit of sensorial acceptability was reached after ca. 6 days for the samples packaged in air, 8 days for the M1 and M3 samples, and after 10 days for the M2 samples. Respective shelf-life extension for fresh whole mullet was ca. 2 days (M1 and M3 gas mixtures), and 4 days (M2 gas mixture).

Characterization and classification of Western Greek olive oils according to cultivar and geographical origin based on volatile compounds.

The aim of the present study was to characterize and classify olive oils from Western Greece according to cultivar and geographical origin, based on volatile compound composition, by means of Linear Discriminant Analysis. A total of 51 olive oil samples were collected during the harvesting period 2007-2008 from six regions of Western Greece and from six local cultivars. Forty-five of the samples were characterized as extra virgin olive oils. The analysis of volatile compounds was performed by Headspace Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry (HS-SPME-GC/MS). Fifty-three (53) different volatile compounds were tentatively identified and semi-quantified. Using selected volatile compound composition data (selection was based on the application of ANOVA to total volatiles to determine those variables showing substantial differences among samples of different geographical origin/cultivar), the olive oil samples were satisfactorily classified according to geographical origin (87.2%) and cultivar (74%).

Effect of low-dose radiation on microbiological, chemical, and sensory characteristics of chicken meat stored aerobically at 4 degrees C.

The effect of gamma-radiation (0.5, 1, and 2 kGy) on the shelf life of fresh skinless chicken breast fillets stored aerobically at 4 degrees C was evaluated. Microbiological, chemical, and sensorial changes occurring in chicken samples were monitored for 21 days. Irradiation reduced populations of bacteria, i.e., total viable bacteria, Brochothrix thermosphacta, lactic acid bacteria (LAB), and the effect was more pronounced at the highest dose (2 kGy). Pseudomonads, yeasts and molds, and Enterobacteriaceae were highly sensitive to gamma-radiation and were completely eliminated at all doses. Of the chemical indicators of spoilage, thiobarbituric values for nonirradiated and irradiated aerobically packaged chicken samples were in general low (<1 mg of malonaldehyde per kg of muscle) during refrigerated storage for 21 days. With regard to volatile amines, both trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values for nonirradiated aerobically packaged chicken increased steeply, with final values of ca. 20.3 and 58.5 mg N/100 g of muscle, respectively. Irradiated aerobically packaged chicken samples had significantly lower TMA-N and TVB-N values (P < 0.05) of ca. 2.2 to 3.6 and 30.5 to 37.1 mg N/100 g of muscle, respectively, during refrigerated storage for 21 days. Of the biogenic amines monitored, only putrescine and cadaverine were detected in significant concentrations in both nonirradiated and irradiated chicken samples, whereas histamine formation was noted only in nonirradiated samples throughout storage. On the basis of sensorial evaluation, low-dose irradiation (0.5 and 1.0 kGy) in combination with aerobic packaging extended the shelf life of fresh chicken fillets by ca. 4 to 5 days, whereas irradiation at 2.0 kGy extended the shelf life by more than 15 days compared with that of nonirradiated chicken.

Differentiation of Fresh Greek Orange Juice of the Merlin Cultivar According to Geographical Origin Based on the Combination of Organic Acid and Sugar Content as well as Physicochemical Parameters Using Chemometrics

The aim of the present study was to differentiate fresh Greek orange juice prepared from the Merlin cultivar according to geographical origin, based on organic acid/sugar content, and physicochemical parameter analysis, using chemometrics. For this purpose, oranges were collected during the harvesting period 2013–2014 from four different regions in Greece where Merlin oranges are produced. The analysis of organic acids and sugars was performed using a modified high pressure liquid chromatographic (HPLC–DAD/RI) method. Applying MANOVA and LDA analysis to the collected data, orange juices were successfully classified according to geographical origin (correct classification rate 83.3%). For validation purposes of the applied model, oranges from the harvesting period 2014–2015 were also collected and new instrumental and chemometric analysis carried out involving orange juice from both harvesting periods. Cumulative results showed that the classification rate remained practically constant, recording a correct classification rate of 80.4%, confirming the discriminatory power of the applied model. In order to further improve the overall classification rate, physicochemical parameter data were subjected to chemometric analysis along with organic acid and sugar content data. Results showed that the combination of organic acids, sugars, and physicochemical parameters somewhat increased the overall correct prediction rate to 82.0%. Present results enhance the potential of multi-parameter analysis for the correct geographical differentiation of Greek fresh orange juice, aiding to product quality and authenticity control.

Flow through Fluorescence Detection of Phosphate in Human Saliva Based on Sensitized Turn-On Photoluminescence of CdS Quantum Dots

ABSTRACT The development of fluorescent turn-on probes for the determination of inorganic anions based on fluorescent semiconductor nanocrystals (quantum dots) has recently attracted great attention. Methods reported so far enable anion sensing at elevated concentration levels and usually with low selectivity against other abundant matrix components. In this work, we describe an alternative approach that combines the appropriate modulation of nanocrystal surface chemistry (i.e., stabilization) with rational design and modulation of the experimental conditions (i.e., flow injection analysis) in order to deliver an expedient flow through method that enables the determination of phosphate at low concentration levels and with good selectivity. The developed method was successfully applied to the determination of phosphate in artificial and human saliva with good analytical features in terms of reproducibility and repeatability (2.3–9.2%), recoveries from fortified samples (96.0–112.0%), linearity of response curves to phosphate concentrations (R2 > 0.99), and satisfactory sensitivity (<1 µM), providing a significant improvement to previous fluorescent turn-on quantum dot probes.