Eleni P. Kalogianni

TraceALL: a semantic web framework for food traceability systems

Purpose – The purpose of this paper is to describe TraceALL which is a Semantic Web (SW), ontology‐based, service‐oriented framework which aims to provide the necessary infrastructure enabling food industry (particularly SMEs) to implement traceability applications using an innovative generic framework.Design/methodology/approach – The framework builds upon the idea of the Semantic Web and provides an open and extensible underlying platform that allows different traceability interconnected applications to be designed and developed. More specifically, the framework provides a formal, ontology‐based, general‐purpose methodology to support knowledge representation and information modelling in traceability systems. Additionally, it suggests an open application framework based on widely used Semantic Web standards. Finally it provides a set of core services for storing, processing and retrieving traceability information in a scalable way. These components, taken together, facilitate the efficient development o...

Evolution of volume fractions and droplet sizes by analysis of electrical conductance curves during destabilization of oil-in-water emulsions

Destabilization of hexane-in-water emulsions is studied by a continuous, non-intrusive, multi-probe, electrical conductance technique. Emulsions made of different oil fractions and surfactant (C(10)E(5)) concentrations are prepared in a stirred vessel using a Rushton turbine to break and agitate droplets. During the separation of phases, electrical signals from pairs of ring electrodes mounted at different heights onto the vessel wall, are recorded. The evolution of the local water volume fractions at the locations of the electrodes is estimated from these signals. It is found that in the absence of coalescence, the water fraction evolution curve from the bottom pair of electrodes is compatible with a bidisperse oil droplet size distribution. The sizes and volume fractions of the two droplet modes are estimated using theoretical arguments. The electrically determined droplet sizes are compared to data from microscopy image analysis. Results are discussed in detail.

Amylose-fatty acid inclusion complexes as examined by interfacial tension measurements.

Amylose forms complexes with fatty acids under certain conditions, these complexes affect the functional properties of foods and could be potentially used as delivery systems of essential fatty acids in the human organism. This work uses dynamic and equilibrium interfacial tension measurements in order to investigate these complexes. First, the interfacial tension at the water/air interface under the conditions of complex formation (KOH 0.1N, pH=12.7) was measured for three fatty acids (capric, myristic and oleic) at different concentrations. Then, amylose-fatty acid complexes were formed at three different fatty acid to amylose ratios covering a range above and below the saturation concentration of the amylose helix. For all examined systems the dynamic interfacial tension of the mixed amylose-fatty acid solution was significantly higher than this of the fatty acid solution, showing that some of the fatty acid was no longer available to adsorb at the interface and suggesting its inclusion in the complex. Besides, the dynamic interfacial tension of the mixed system was lower compared to the pure amylose solution indicating that some of the fatty acid did not participate in the complexes even at fatty acid/amylose ratios well below the saturation concentration of amylose. Using the isotherm of the three fatty acids it was shown that the fatty acid excess depended on fatty acid-to-amylose ratio.

Height–time and weight–time approach in capillary penetration: Investigation of similarities and differences

Capillary penetration is commonly used in a wide range of applications such as oil recovery, textile engineering and food technology. Furthermore, it is a useful tool for surface characterization of powders and porous media. Two are the commonest experimental methods to study capillary penetration: the height-time and the weight-time technique. However, it is not clear whether the two approaches provide the same results. This work aims to investigate similarities and differences between the two approaches and assess whether it is possible to replace one with another. To this end, capillary penetration experiments were performed in different porous media where the pore size distribution and shape varied. Height and weight data were recorded simultaneously. It was found that results of the two experimental approaches are not always equivalent and that this depends on the porous medium properties. In some cases results depended on the degree of saturation of the porous medium with the penetrating liquid. An analysis of weight-time data to provide pore size distribution as a function of pore volume is proposed. Furthermore, two different approaches of the fractal theory were applied and the time exponent, the material fractal dimension and the tortuosity fractal dimension were determined.

Effect of oleic acid on the properties of protein adsorbed layers at water/oil interfaces: An EPR study combined with dynamic interfacial tension measurements

Multiphase food systems consist of complex interfacial layers where surface active molecules complete compete for adsorption and interact with one another affecting the interfacial properties and the behavior of the food systems involved. The present work focuses on the examination of interactions between proteins playing an which play an important role in milk-rich food systems (namely κ-casein and β-lactoglobulin) and oleic acid (an anionic surfactant abundant in food systems) at the oil/water interface. An interesting feature of this system is that the molecules interacting at the interface originate from different phases and do not transfer/dissolve significantly to the other phase. The systems were examined using Electron Paramagnetic Resonance (EPR) spectroscopy and Dynamic Interfacial Tension measurements (dynamic interfacial tension and dynamic interfacial dilatational rheology). This combination of experimental methods provided the dynamics of adsorption at the interface and the mechanical properties of the interface allowing valuable insight on the interactions of the different molecules. The above information was coupled with direct information on fatty acid mobility in the oil bulk phase and indirect information on the degree of relative fatty acid/protein adsorption at the interface by EPR. Overall a synergistic effect of the protein and fatty acid on decreasing interfacial tension of the oil/water interface was evidenced. The fatty acid interacted differently with the random coil κ-casein and globular β-lactoglobulin in terms of relative adsorption and in terms on its effect on mechanical properties. Thermal denaturation of β-lactoglobulin affected the proteins interaction with the fatty acid due to conformational changes and exposure of non-polar sites.

Cross-cultural consumer perceptions of service quality in restaurants

Purpose This paper aims to present results from a research that analyzed consumer perceptions of service quality in restaurants in four European cities – Belgrade (Serbia), Manchester (UK), Thessaloniki (Greece) and Porto (Portugal). Design/methodology/approach A total of 802 respondents have been interviewed using a structured questionnaire. The service quality statements covered food quality, building exterior, restaurant interior and layout, seating comfort, restrooms and servicing. Findings Within all analyzed categories (city, gender and age), servicing of food and taste of food were the most influential factors. However, this study confirmed that there are different patterns in analyzed cities. For each factor analyzed, in at least two cities, results for the items were significantly different. Consumers from different cities showed different perceptions regarding service quality in restaurants. Gender of consumers plays a significant role in the perception of interior, restroom and servicing factors in restaurants. Age of respondents was the category with no significant difference with respect to food quality, layout, restrooms and servicing. Research limitations/implications Given the great cultural and other differences within the four cities/countries, more research is necessary to determine if similar results would be derived from different samples across various other continental and Mediterranean European cities. Originality/value In addition to increasing the theoretical understanding of the cultural aspects of the service quality, this paper can be of managerial relevance.