Papers by Athanasia Goula
Current Analytical Chemistry, Feb 11, 2020
Background: Medicinal plants consist a rich source of natural pharmacologically active compounds.... more Background: Medicinal plants consist a rich source of natural pharmacologically active compounds. The aim of the current work, was the study and optimization of the extraction conditions of phenolic constituents from important medicinal and aromatic plants, id. Sideritis raeseri, Sideritis scardica and Origanum vulgare, implementing microwave assisted extraction technique. Methods: Optimization was based on various parameters affecting extraction procedure, such as the duration of microwave radiation, the ratio of plant material mass to the solvent, the type and the concentration of the solvent. Results: The results revealed that 10 min of microwave radiation provided the maximum extraction yield of the phenolic constituents. The ratio of the plant material mass and the solvent had minor effect to the extraction efficiency. Conclusion: The examined solvents provided an extraction yield of phenolic constituents following the order: EtOH
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Powder Technology, 2017
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One of the main problems in tzatziki quality is the phenomenon of synerisis, which is observed wh... more One of the main problems in tzatziki quality is the phenomenon of synerisis, which is observed when the gel structure collapses and water gets squeezed out. The aim of this project was to minimize synerisis and increase the shelf life of the product during storage at refrigerating temperatures without changing product texture and flavor. This was achieved by the addition of hydrophilic proteins that trap the water within the gel structure minimizing the synerisis effect. Low expressible moisture content prevents grow of microorganisms and, thus, improves the overall quality of the product. Firstly, different samples consisted of yogurt and solutions of albumin, whey proteins, sodium caseinate added in yogurt were prepared. The water content of the samples was that of a real tzatziki system (83% water). The samples of protein-yogurt-water solutions where prepared by adding proteins to yogurt solutions in ratios of 1% and 5% w/w. Measurements of water-holding capacity, moisture conten...
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International Journal of Dairy Technology, 2015
The phenomenon of syneresis becomes more profound in increased moisture yoghurt‐based products. S... more The phenomenon of syneresis becomes more profound in increased moisture yoghurt‐based products. Such a product is the traditional Greek appetizer tzatziki that contains cucumber, a vegetable with a high moisture content. During the manufacture of tzatziki, the addition of cucumber causes the protein network to break up, provoking an increase in syneresis. The aim of this study was to investigate a tzatziki manufacturing procedure that will lead to significantly decreased syneresis. Two different manufacturing procedures were compared: the extra moisture coming from cucumber was introduced before or after fermentation. The effect of adding whey protein concentrate (WPC), albumin, sodium caseinate or a mixture of these was also studied. The results show that the addition of extra moisture before yoghurt fermentation leads to a significantly lower syneresis (7.5%) and higher consistency (2000 cp) than those obtained in the case of addition after fermentation (25% and 1500 cp, respectiv...
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Innovative Food Science & Emerging Technologies, 2015
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International Journal of Food Engineering, 2014
Pomegranate juice was concentrated by conventional heating at different temperatures (45, 50, 55,... more Pomegranate juice was concentrated by conventional heating at different temperatures (45, 50, 55, 60, and 65°C), and the effect of temperature on evaporation rate and on thermal degradation of total phenolics was investigated. Concentration kinetics modeling was developed based on thin-layer drying models. The logarithmic model was found to give better predictions than the others. The temperature dependence of the model constants was expressed by polynomial relationships. In addition, a first-order decay model, with an Arrhenius and a polynomial dependency on temperature and water content, respectively, was used to describe the joint influence of temperature and moisture content on the thermal degradation of total phenolics in a concentration process of pomegranate juice.
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Journal of Food Processing & Technology, 2011
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LWT - Food Science and Technology, 2005
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Journal of Near Infrared Spectroscopy, 2003
The use of near infrared (NIR) reflectance spectroscopy for the rapid and accurate measurement of... more The use of near infrared (NIR) reflectance spectroscopy for the rapid and accurate measurement of moisture, sugar, acid, protein and salt was explored in a diverse group of tomato juice products. Partial and overall calibrations were performed on four different tomato juice products. Partial calibrations for each product included samples of the specific product, whereas overall calibration used samples of all the products. Samples were analysed employing traditional chemical methods and scanned using an Instalab 600-Dickey-John NIR apparatus to obtain NIR spectra. Calibrations were achieved with the use of multilinear regression between chemical and spectral data from each calibration data set. A separate set of samples was used to validate the calibrations. Linear regression was applied to compare the results obtained by NIR spectroscopy for all constituents of the validation set with those obtained by the reference methods. In addition, the root mean square error of prediction ( R...
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Journal of Food Engineering, 2005
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Journal of Food Engineering, 2006
Lycopene is the principle pigment found in tomatoes and is important not only because of the colo... more Lycopene is the principle pigment found in tomatoes and is important not only because of the color it imparts but also because of the recognized health benefits associated with its presence. Heating and drying of tomato products under different processing conditions to manufacture tomato juice, pulp, powder etc. may cause degradation of lycopene. For an exact calculation of the rest
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Journal of Food Composition and Analysis, 2001
This work examines the possibility of using near infrared (NIR) spectroscopic method for the prod... more This work examines the possibility of using near infrared (NIR) spectroscopic method for the production process control of the traditional Greek feta cheese. A NIR apparatus (Instalab 600-Dickey–John) was employed. Moisture, fat and protein determinations were selected as calibration set for the instrument. Samples were drawn from well-defined critical points of production. In all the samples conventional chemical methods were
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Innovative Food Science & Emerging Technologies, 2010
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Food and Bioproducts Processing, 2012
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Drying Technology, 2007
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Drying Technology, 2007
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Drying Technology, 2008
... Al-Kahtani , HA ; Hassan , BH Spray drying of roselle (Hibiscus sabdariffa L.) extract . ... ... more ... Al-Kahtani , HA ; Hassan , BH Spray drying of roselle (Hibiscus sabdariffa L.) extract . ... El-Tinay , AH ; Ismail , IA Effect of some additives and processes on the characteristics of agglomerated and granulated spray-dried roselle powder . ...
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Drying Technology, 2012
A new technique for lycopene microencapsulation by spray drying using dehumidified air as the dry... more A new technique for lycopene microencapsulation by spray drying using dehumidified air as the drying medium was developed and the optimum operating conditions for encapsulation efficiency were determined. A pilot-scale spray dryer was employed for the spray-drying process. The modification made to the original design consisted of connecting the dryer inlet air intake to an absorption air dryer. The dextrose
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Papers by Athanasia Goula