Eρευνητικά ενδιαφέροντα

My research interests are in the 3 following areas.

1. Biosynthesis of flavour and colour compounds

Having spent five years (PhD and postdoctoral research) working with tissue cultures of strawberry (Fragaria x ananassa) and Datura stramonium, I have a strong ongoing interest in the biosynthesis of flavour and colour compounds in plants and finding novel ways to promote the biogenesis of secondary metabolites (e.g. elicitation using cells walls of bacteria).

In strawberry, my latest research has focused on the study of the symbiotic relationship of strawberry cells with the endophytic bacterium Methylobacterium extorquens (CABI. former International Mycological Institute, UK, registration number: IMI 369321, isolated and identified from strawberry tissue cultures). It was found that the strawberry-derived 1,2-propanediol is oxidised by the bacteria to 2-hydroxy-propanal (lactaldehyde) which is then used by the plant cells in the biosynthesis of one of the most important strawberry flavour components: 2,5-dimethyl-4-hydroxy-2H-furan-3-one (DMHF). It was found that the bacterial and plant alcohol dehydrogenases (ADH) follow a symbiotic pattern in cell-free extracts of Methylobacterium extorquens and strawberry.

 

Figure 1: The strawberry-derived 1,2-propanediol is oxidised by the bacteria to lactaldehyde which is then used by the plant cells in the biosynthesis of DMHF, the most important strawberry flavour component.

 

 Our latest research has focused on the study of the alcohol dehydrogenase (ADH) enzymes of the plant and the bacterium and how the presence of the bacterium in strawberry cell free extracts can increase the production of DMHF. These results have been confirmed by other researchers [Μ. Verginer et al. (2010) FEMS Microbiol. Ecol., 74(1) 136-145] who found that the bacterial presence in strawberry leads to the formation of elevated levels of DMHF.

Our current efforts (in collaboration with the group of Dr A.M.Pirtilla in the University of Oulu in Finland) focus on the use of the “in sity hybridization” technique to monitor more closely the symbiotic relationship between the bacterium and strawberry cells.

 

2. Food Safety and Quality

Since 2003, I have been involved in auditing and consulting food industries on Food Safety Management and related infrastructure topics (i.e. HACCP, ISO22000, GHP, GMP, traceability, personnel training). Combining these consultancy activities with concerted research efforts, we have focused on evaluating the safety of the food served in hotels by detecting pathogens and using hygienic indices. We have recently completed a screening research programme on the verification of HACCP in the catering facilities of 5* hotels and other catering units in Greece. My goals are to study further the calibration methods used to monitor the implementation of HACCP and seek novel ways to validate the safety of the produced foods. In this context, we are currently carrying out some research on finding some chemical indexes (e.g. levels of lactic, acetic and proprionic acids) of food microbial contamination. Our results on contaminated meat have shown that the levels of these acids show a trend related to the numbers of the contaminating microorganisms.

Our research on this topic has recently expanded into the area of cross-contamination of the food chain caused by environmental pollution. We have screened heavy metal levels in food produced in the polluted area of Asopos river in Greece. Our current efforts focus on the study of the uptake of nickel (Ni) and chromium (Cr) by food tubers (potatoes, onions and carrots) grown in a greenhouse and irrigated with water spiked with various levels of Ni and Cr (this is an ongoing PhD project). Our results have shown that onions and potatoes absorb nickel from irrigation water and we have urged the Greek government to provide non-polluted water to the farmers. We have also found that the environmental pollution affects the levels of antioxidants (e.g. lutein and carotene) in the food tubers tested. Our results have shown that onions and potatoes absorb nickel from polluted irrigation water and we have recently announced them in an international conference which has been covered by the media and been submitted for publication in a peer-reviewed journal.

Given that the term “food security” incorporates both the availability of food on global, national, local and household levels and the satisfactory nutritional status of individuals, it is evident that our work should focus towards not only the sustainable production of food but also the production of safe and nutritional food (i.e. free of chemical and biological hazards but rich in nutritious elements, such as antioxidants).

With this concept in mind, I have been trying to assess the cross-contamination of the food chain with heavy metals. Our results could be used by governments and regulating bodies to evaluate the need for the provision of non-polluted irrigating water to the farmers.

3. Nutritional value of Mediterranean foods, with emphasis on fish and edible oils

As a Lecturer in Leeds, in 1999, I started collaborating with my current colleague in Athens, Professor C.A. Demopoulos on Platelet Activating Factor (PAF) and how various food can inhibit PAF and therefore prevent cardiovascular diseases. This research has grown significantly the last seven years. Since 2005, we have been working actively on fish farmed species (especially sea bream and sea bass) in collaboration with aquaculture industry. Our concept is to enrich the fish feeds with fractions of olive oil and olive pomace (OP) which have proven antiatherogenic properties. In this way, the novel functional fish will contain more antiatherogenic compounds and therefore protect the consumer from the development of cardiovascular diseases (CVDs).

Our scientific goal is to prove that such enriched food is not only beneficial to protect from the development of cardiovascular diseases but also to alleviate symptoms of heart problems with people.

Our sponsors are one leading aquaculture company, a health supplement producer in Greece and a Norwegian company producing health supplements rich in EPA and DHA.

In addition to our studies on CVDs, we are also evaluating the sensory properties of food by using descriptive analysis and creating a focused lexicon of sensory terms for each group of food. This sensory work is an essential tool in order to evaluate the flavour, taste and aftertaste of sea bream and sea bass produced with the OP enriched fish feed.

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Related Publications

For 1.

Research papers in peer reviewed journals

I. Zabetakis and M.A. Holden (1997) Strawberry flavour: analysis and biosynthesis. J. Sci. Food Agric. 74 421-434.

I. Zabetakis (1997) Enhancement of flavour biosynthesis from strawberry (Fragaria x ananassa) callus cultures by Methylobacterium species. Plant Cell Tiss. Org. Cult. 50 179-183.

P. Koutsompogeras, A.Kyriacou and I. Zabetakis (2006). Characterizing NAD-dependent alcohol dehydrogenase enzymes of Methylobacterium extorquens and strawberry (Fragaria x ananassa, cv. Elsanta). J. Agric. Food Chem.  54  235-242.

P. Koutsompogeras, A.Kyriacou and I. Zabetakis (2007). The formation of 2,5-dimethyl-4-hydroxy-2 H-furan-3-one by cell free extracts of Methylobacterium extorquens and strawberry (Fragaria x ananassa, cv. Elsanta). Food Chem. 104 1654-1661.

P. Koutsompogeras, A. Kyriacou and I. Zabetakis (2010). Characterization of NAD-dependent alcohol dehydrogenase enzymes of strawberry’s achenes (Fragaria x ananassa cv. Elsanta) and comparison with respective enzymes from Methylobacterium extorquens. LWT Food Sci. Technol. 43 828-835.

 

For 2.

Research papers in peer reviewed journals

Ε. Kourouvani, N. Gdontelis and I. Zabetakis (2006) Safety evaluation of the food served in Tourist Accommodation Enterprises by detection of pathogens and hygienic indices. Ital. J. Food Sci. 18 447-452.

Μ. Tsachaki, A. Arnaoutopoulou, L. Margomenou, S.C. Roubedakis and I. Zabetakis (2010). Development of a suitable lexicon for sensory studies of the anise-flavoured spirits ouzo and tsipouro. Flavour Frag. J.  25 468-474.

E. Flemotomou, T. Molyviatis and I. Zabetakis (2011). The effect of trace elements accumulation on the levels of secondary metabolites and antioxidant activity in carrots, onions and potatoes. Food Nutr. Sci. 2 1071-1076.

C.G. Kirkillis, I.N. Pasias, S. Miniadis-Meimaroglou, N.S. Thomaidis and I. Zabetakis (2012). Concentration levels of trace elements in carrots, onions and potatoes cultivated in Asopos region, Central Greece. Analytical Letters 45 551-562.

C. Nasopoulou, P. Poulios, M. Magli, N. Gdontelis, K. Papanotasand I. Zabetakis (2012). Verification of Hazard Analysis and Critical Control Point in hotels and catering units: evaluation of the cleaning and disinfection procedures and microbiological monitoring of hot and cold meals. Food and Nutrition Sciences 3 606-613.

S. Stasinos and I. Zabetakis (2013). The uptake of nickel and chromium from irrigation water by potatoes, carrots and onions. Ecotox. Environ. Safe. 91 122-128.

 

 

For 3.

Research papers in peer reviewed journals

A. Panayiotou, D. Samartzis, T. Nomikos, E. Fragopoulou, H.C. Karantonis, C.A. Demopoulos and I. Zabetakis (2000) Lipid fractions with aggregatory and anti-aggregatory activity towards platelets in fresh and fried cod (Gadus morhua): correlation with Platelet-Activating Factor (PAF) and atherogenesis. J. Agric. Food Chem 48 6372-6379.

T.Nomikos, H.C. Karantonis, C. Skarvelis, C.A. Demopoulos and I. Zabetakis (2006). Antiatherogenic properties of lipid fraction of raw and fried fish.  Food Chem. 96 29-35.

C. Nasopoulou, T.Nomikos, C.A. Demopoulos and I. Zabetakis (2007). Comparison of antiatherogenic properties of lipids obtained from wild and cultured sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata). Food Chem. 100 560-567.

C. Nasopoulou, H.C. Karantonis, M. Andriotis, C.A. Demopoulos and I. Zabetakis (2008). Antibacterial and anti-PAF activity of lipid extracts from sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata). Food Chem. 111 433-438.

C. Nasopoulou, H.C. Karantonis, D.N. Perrea, S.E. Theocharis, D.G. Iliopoulos, C.A. Demopoulos and I. Zabetakis (2010). In vivo anti-atherogenic properties of cultured gilthead sea bream (Sparus aurata) polar lipid extracts in hypercholesterolaemic rabbits. Food Chem. 120 831-836

Μ. Tsachaki, A. Arnaoutopoulou, L. Margomenou, S.C. Roubedakis and I. Zabetakis (2010). Development of a suitable lexicon for sensory studies of the anise-flavoured spirits ouzo and tsipouro. Flavour Fragr. J. 25 468-474.

C. Nasopoulou, H. Karantonis and I. Zabetakis (2011). Nutritional Value of Sea Bream and Sea Bass (Invited Mini-Review) Dyn. Biochem. Process Biotech. Mol. Biol. 5 32-40.

C. Nasopoulou, A.B. Tsoupras, H.C. Karantonis, C.A. Demopoulos and I. Zabetakis (2011). Fish polar lipids retard atherosclerosis in rabbits by down-regulating PAF biosynthesis and up-regulating PAF catabolism. Lipids Health Dis.10 213.

C. Nasopoulou, G. Stamatakis, C.A.Demopoulos and I. Zabetakis (2011). Effects of olive pomace and olive pomace oil on growth performance, fatty acid composition and cardio protective properties of gilthead sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) Food Chem. 129 1108-1113.

C.Nasopoulou and I. Zabetakis (2012). Benefits of fish oil replacement by plant originated oils in compounded fish feeds. A review. LWT Food Sci. Technol. 47 217-224.

C. Nasopoulou, C.A. Demopoulos and I. Zabetakis (2012). Effect of freezing on quality of sea bass and gilthead sea bream. Eur. J. Lipid Sci. Technol. 114 733-740.

C. Nasopoulou, V. Gogaki, E. Panagopoulou, C.A. Demopoulos and I. Zabetakis (2013). Hen egg yolk lipid fractions with antiatherogenic properties. Anim. Sci. J. 84 264-271.

C. Nasopoulou and I. Zabetakis (2013). Agricultural and aquacultural potential of olive pomace. A review. J. Agric Sci. 5 116-127.

I. Zabetakis (2013). Food security and cardioprotection: the polar lipid link. J. Food Sci.78 R1101-R1104.

C. Nasopoulou, E. Psani, E. Sioriki, C. A. Demopoulos, I. Zabetakis (2013). Evaluation of Sensory and In Vitro Cardio Protective Properties of Sardine (Sardina pilchardus): The Effect of Grilling and Brining.. Food Nutr. Sci. 4 940-949.

C. Nasopoulou, T. Smith, M. Detopoulou, C. Tsikrika, L. Papaharisis, D. Barkas and I. Zabetakis (2014). Structural elucidation of olive pomace fed sea bass (Dicentrarchus labrax) polar lipids with cardioprotective activities. Food Chem. http://dx.doi.org/10.1016/j.foodchem.2013.08.091

E. Sioriki, C. Nasopoulou, C.A. Demopoulos and I. Zabetakis. Comparison of OP enriched and conventional gilthead sea bream. J. Aquat. Food Prod. T. (in press).

C. Nasopoulou, V. Gogaki, G. Stamatakis, L. Papaharisis, C.A. Demopoulos and I. Zabetakis. Evaluation of the in vitro cardio-protective properties of lipid fractions of olive pomace, olive pomace enriched fish feed and gilthead sea bream (Sparus aurata) fed with olive pomace enriched fish feed. Marine Drugs (in press).

 

Chapter in book

C. Nasopoulou and I. Zabetakis (2012). Designing novel functional food using Gas Chromatography. In “Gas Chromatography / Book 2”, http://cdn.intechopen.com/pdfs/30594/InTech-Designing_novel_functional_food_using_gas_chromatography.pdf