Microwave Drying of Black Olive Slices : Effects on Total Phenolic Contents and Colour

Öz

In this study, the drying behaviour of black olive slices using microwave was investigated and the effects of microwave power on total phenolic content and colour were determined. Black olive slices were dried at different power levels (180, 360, and 540 W) using a microwave cabin. The results showed that the drying time of the olive slices decreased considerably as the microwave power increased. The total phenolic content of the product dried at 540 W was found to be significantly lower than those dried at 180 or 360 W. For the microwave power range studied, the use of an irreversible first-order model adequately described the decrease in the total phenolic content. The effects of microwave power level on changes of the surface temperatures and weight loss of the olive slices were also determined. The temperature increase and the weight loss were the highest at 540 W during drying. Changes in the colour values (L*, a*, and b*) of the black olive slices during drying were statistically different (P<0.05) for each microwave power level and the maximum change in brightness occurred drying at 360 W. It is thought that results obtained in this study will provide valuable data for the design of microwave drying systems used for drying of olive slices in pilot or industrial scales.

Anahtar Kelimeler

• olive, microwave, kinetic, modeling, total phenolic content, colour.

Siyah Zeytin Dilimlerinin Mikrodalga ile Kurutulması ve Toplam Fenolik Madde ve Renk Üzerine Etkileri

Öz

Bu çalışmada, mikrodalga kullanılarak siyah zeytin dilimlerinin kuruma davranışları incelenmiş ve mikrodalga gücünün toplam fenolik madde ve renk üzerine etkileri belirlenmiştir. Siyah zeytin dilimleri üç farklı güç seviyesinde (180, 360 ve 540 W) mikrodalga kabin kullanılarak kurutulmuştur. Sonuçlar zeytin dilimlerinin kuruma süresinin mikrodalga gücü arttıkça önemli ölçüde azaldığını göstermiştir. 540 W gücünde kurutulan ürünün toplam fenolik madde içeriğinin, 180 ve 360 W güçlerinde kurutulanlarınkinden önemli ölçüde daha düşük olduğu belirlenmiştir. Çalışılan mikrodalga güç aralığı için, tersinmez birinci dereceden kinetik modelin kullanılması toplam fenolik madde içeriğindekiazalmayı başarıyla tanımlamıştır. Mikrodalga güç seviyesinin yüzey sıcaklığı ve ağırlık kaybı değişimi üzerine etkileri de incelenmiştir. 540 W gücünde kurutma sırasında sıcaklık artışı ve ağırlık kaybı en fazla olmuştur. Kurutma sırasında her mikrodalga güç seviyesi için siyah zeytin dilimlerinin renk değerlerindeki (L*, a*, b*) değişim istatistiksel olarak anlamlı bulunmuştur (P<0.05) ve en fazla parlaklık değişimi 360 W gücünde kurutmada gerçekleşmiştir. Bu çalışmada elde edilen sonuçların zeytin dilimlerinin pilot veya endüstriyel ölçekte kurutulması amacıyla kullanılacak mikrodalga kurutma sistemlerinin tasarımları için değerli veri sağlayacağı düşünülmektedir.

Anahtar Kelimeler

• zeytin, mikrodalga, kinetik, modelleme, toplam fenolik madde, renk

Kaynakça

1. Pereira JA, Pereira APG, Ferreira ICFR, Valentao P, Andrade PB, Seabra R. 2006. Table olives from Portugal: Phenolic compounds, antioxidant potential, and antimicrobial activity. J Agric Food Chem, 54 (22): 8425-8431.
2. Boskou G, Salta FN, Chrysostomou S, Mylona A, Chiou A, Andrikopoulos NK. 2006. Antioxidant capacity and phenolic profile of table olives from Greek market. Food Chem, 94: 558–564.
3. Erbay Z, Icier F. 2009. Optimization of drying of olive leaves in a pilot scale heat pump dryer. Drying Technol, 27 (3): 416-427.
4. Anon 2013. http://en.wikipedia.org/wiki/ Kalamata_(olive) (17.02.2013, 20:22)
5. Marsilio V, Campestre C, Lanza B. 2001. Phenolic compounds change during California-style ripe olive processing. Food Chem, 74: 55-60.
6. Demir V, Gunhan T, Yagcioglu AK. 2007. Mathematical modelling of convection drying of green table olives. Biosystems eng, 98: 47-53.
7. Ongen G, Sargin S, Tetik D, Kose T. 2005. Hot air drying of green table olives. Food Technol and Biotechnol, 43 (2): 181-187.
8. Krokida MK, Maroulis ZB, Kremalis C. 2002. Process design of rotary dryers for olive cake. Drying Technol, 20 (4 and 5): 771-788.

9. Al-Harahsheh M, Al-Muhtaseb AH, Magee TRA. 2009. Microwave drying kinetics of tomato pomace: Effect of osmotic dehydration. Chem Eng and Processing,48: 524-531.
10. Maskan M. 2001. Kinetics of colour of kiwifruits during hot air and microwave drying. J Food Eng, (48):169-175.
11. Cui ZW, Sun LJ, Chen W, Sun DW. 2008. Preparation of dry honey by microwave–vacuum drying. J Food Eng, 84: 582-590.
12. Sarımefleli A, Coskun MA, Yuceer M. 2014. Modeling microwave drying kinetics of thyme leaves using ann methodology and dried product quality, J Food Process Preservation, 38: 558-564. 13. McLoughlin CM, McMinn WAM, Magee TRA. 2003. Physical and dielectric properties of pharmaceutical powders. Powder Technol, 134: 40-51.
13. Al-Harahsheh M, Al-Muhtaseb AH, Magee TRA. 2009. Microwave drying kinetics of tomato pomace: Effect of osmotic dehydration, Chem Eng Process, 48: 524-531.
14. Zhang M, Tang, J, Mujumdar, AS, Wang, S. 2006. Trends in microwave-related drying of fruits and vegetables, Trends in Food Sci & Technol, 17: 524-534.
15. Maskan M. 2001. Kinetics of colour change of kiwifruits during hot air and microwave drying. J Food Eng, 48: 169-175.
16. Kemahlıo¤lu K, Baysal T. 2002. Hububat Ürünlerinin ‹fllenmesinde Mikrodalga Uygulamaları. Online:http:www.usd.org.tr/bildiri/Bildiri/ S1.pdf. (in Turkish)
17. Eren Ö, Soysal Y, Öztekin S, Do¤antan ZS. 2005. Mikrodalga Sistemi ile Donatılmıfl Bir Bantlı Kurututucuda Maydanoz Kurutulması. III. Tarımsal Ürünleri Kurutma Tekni¤i Çalıfltayı, 2-4 Mayıs 2005, Antalya (in Turkish).
18. Alibafl ‹. 2007. Energy Consumption and Colour Characteristics of Nettle Leaves During Microwave, Vacuum and Convective Drying. Biosystems Eng, 96 (4): 495-502.
19. Özbek B, Dadalı G. 2007. Thin layer drying characteristics and modeling of mint leaves undergoing microwave treatment. J Food Eng, 83 (4):541-549.
20. Ozkan I, Akbudak B, Akbudak N. 2007. Microwave drying characteristics of spinach. J Food Eng, 78: 577-583.
21. Sharma GP, Prasad S. 2006. Optimization of process parameters for microwave drying of garlic cloves. J Food Eng, 75 (4): 441-446.
22. Tunçer ‹K. 2006. Mikrowellen Bandtrockner für die Trocknung von Gewürzpaprika. Deutsch- Türkische Agrarforschung, 8. Symposium vom 04. Oktober-08. Oktober 2005 an der Bundesforschungsanstalt für Landwirtschaft (FAL) in Braunschweig, Cuvillier Verlag-Göttingen.: 209-214.
23. Varith J, Dijkanarukkul P, Achariyaviriya A, Achariyaviriya S. 2007. Combined microwave-hot air drying of peeled longan. J Food Eng, 81 (2): 459-468.
24. Wang Z, Sun J, Chen F, Liao X, Hu X. 2007. Mathematical modeling on thin layer microwave drying of apple pomace with and without hot air pre-drying. J Food Eng, 80 (2):536-544.
25. Erbay Z, ‹cier F. 2009. Optimization of Drying of Olive Leaves in a Pilot-Scale Heat Pump Dryer, Drying Technol, 27 (3): 416-427.
26. Anon 1990. Dry matter content. In: Helrich, K. (Ed.), Official Methods of Analysis of the Association of Official Analytical Chemists. AOAC, Inc., USA. Method No. 920.151.
27. Singleton VL, Rossi JA. 1965. Colorimetry of total phenolics with phosphomolyndic– phosphotungstic acid reagents. Am J Enology and Viticulture, 16: 144-158.
28. Icier F, Yıldız H, Baysal T. 2006. Peroxidase inactivation and colour changes during ohmic blanching of pea puree. J Food Eng, 74: 424-429. 30. Erbay Z, Icier F. 2010. Thin layer drying behaviors of olive leaves (Olea europaea L.). J Food Process Eng, 33: 287-308.
29. Balbay A, Sahin O. 2012. Microwave drying kinetics of a thin-layer liquorice root. Drying Technol, 30: 859-864.
30. Geankoplis CH. 1983. Transport processes and separation process principles. 2nd Ed. Allyn and Bacon Series in Engineering, New York, USA. 33. Soysal Y. 2004. Microwave Drying Characteristics of Parsley. Biosystems Eng, 89: 167-173.
31. Wang J, Xi YS. 2005. Drying characteristics and drying quality of carrot using a two-stage microwave process. J Food Eng, 68: 505-511.
32. Gögüs F, Maskan M. 2001. Drying of olive pomace by a combined microwave-fan assisted convection oven. Nahrung/Food, 129-132.
33. Arslan D, Ozcan MM. 2010. Study the effect of sun, oven and microwave drying on quality of onion slices, LWT - Food Sci & Technol, 43: 1121-1127.
34. Akbudak N, Akbudak B. 2013. Effect of Vacuum, Microwave, and Convective Drying on Selected Parsley Quality, Int J Food Properties, 16(1): 205-215. 38. Fang S, Wang Z, Hu X, Li H, Long W, Wang R. 2010. Shrinkage and quality characteristics of whole fruit of Chinese jujube (Zizyphus jujuba Miller) in microwave drying, Int J Food Sci & Technol, 45, 2463-2469.
35. Çelen S, Kahveci K. 2012. Microwave drying behaviour of apple slices, J Process Mechanical Eng, 227 (4): 264-272.
36. ‹zli N, Yıldız G, Ünal H, Iflık E, Uylafler V. 2014. Effect of different drying methods on drying characteristics, colour, total phenolic content and antioxidant capacity of Goldenberry (Physalis peruvianaL.), Int J Food Sci & Technol, 49: 9-17.