Moisture Adsorption Properties of Black and Green Tea and Heat of Sorption (Turkish with English Abstract)

Year 2011, Volume: 36 Issue: 2, 89 - 96, 01.04.2011

Ö. Faruk Gamlı

Abstract

Moisture adsorption curves of the green and black teas were determined by using saturated salt solution ranged from 0.1-0.9 water activity values with standard gravimetric methods at 15 and 25 °C. GAB, BET, Oswin, Kuhn, Filonenko-Chuprin, Cubic, Peleg and Halsey models used for expressing the moisture adsorption curves of green and black teas. It has been found that GAB model has higher regression coefficient (R2), lower RMSE % and SSE values compared to other mathematical models. Water activity (aw) values of black and green teas have been found as 0.3619 and 0.4659 respectively. Heat of sorption of black and green tea varied between 12.96-4.762 kj/mole and 12.18-4.946 kj/mole respectively at moisture levels varying between 4-6 g water/100 g dry basis.

Keywords

Aw, GAB, heat of sorption, isotherm, black and green tea, regression

Siyah ve Yeşil Çayın Nem Adsorpsiyon Özellikleri ve Sorpsiyon Isısı

Abstract

Siyah ve yeşil çayın 15 ve 25 °C’de nem adsorpsiyon eğrileri 0.1-0.9 arasında değişen su aktivite değerlerindeki tuz çözeltileri ile standart gravimetrik yöntemler kullanılarak belirlenmiştir. Yeşil ve siyah çayın nem adsoprsiyon eğrilerinin ifade edilmesinde GAB, BET, Oswin, Kuhn, Filonenko-Chuprin, Kübik, Peleg ve Halsey modelleri kullanılmıştır. Siyah ve yeşil çay numunelerinin nem adsorpsiyon eğrilerininin belirlenmesinde GAB modelinin diğer modellere oranla, yüksek regresyon sabiti (R2) ve düşük % RMSE ve SSE değerlerine sahip olduğu belirlenmiştir. Siyah ve yeşil çay örneklerinin aw değerlerinin 0.3619 ve 0.4659 olduğu belirlenmiştir. Siyah ve yeşil çay numunelerinin 4-6 g su/100 g k.m değerlerinde sorpsiyon ısılarının sırasıyla 12.96-4.762 kj/mol ve 12.18-4.946 kj/mol arasında deşişim gösterdiği belirlenmiştir.

Keywords

Aw, GAB, izoterm, siyah ve yeşil çay, regresyon, sorpsiyon ısısı

References

• Wetherilt H, Gürcan T, Löker M, Özay G. 1991. Türk çaylarının nesnel kalite parametrelerine göre değerlendirilmesi. GIDA, 16 (3). 209-216.
• Nas S, Öksüz M. 1987. Siyah çayda kalite. GIDA, 12, 3. 157-162.
• Ullah M R, N Gogoi, D Baruah. 1984. The effect of withering on fermentation of tea leaf and development of liquor characters of black teas. J Sci Food Agric. 35, 1142-1147.
• Chakraverty A, Ghodake H M, Goswami T K. 2006. Moisture sorption isotherms, heat of sorption and vaporization of withered leaves, black and green tea. Agricultural and Food Engineering Department, Indian Institue of Technology Kharagpur, India.
• Us F. 2007. Su ve buz. Gıda Kimyası, Hacettepe Üniversitesi Yayınları.
• Jay JM. 1986. Modern Food Microbiology, 3rd edition, pp 40-41, Van Nostrand Reinhold, New York.
• Nelson K A, Labuza T P. 1994. Water activity and food polymer science: implications of State on Arrhenius and WLF models in predicting shelf life. Food Eng, 22, 271-289.
• Wang N, Brennan J G. 1991. Moisture sorption isotherm characteristics of potatoes at four temperatures. Food Eng, 14, 269-287.
• Saracavos G G, Tsiourvas D A, Tsami E. 1986. Effect of temperature on the water adsorption isotherms of sultana raisins. Food Sc, 51, 381-383. 10. Labuza T P. 1984. Moisture sorption: Practical aspects of isotherms measurement and use. Am. Assoc. Cereal Chem., St. Paul, Minnesota.
• Boki K, Ohno S .1991. Equilibrium isotherm equations to represent moisture sorption on starch. Food Sci, 56, 1106-1110.
• Gogus F, Maskan M, Kaya A. 1998. Sorption isotherms of Turkish delight. J. Food Process and Preservation, 7 (22): 345-357.
• Hayoğlu I, Gamlı O F. 2007. Water sorption isotherms of pistachio nut paste. Int Food Sci and Tech. 42: 224-227
• Maskan M, Gogus F. 1997. The fittings of various models to water sorption isotherms of pistachio nut paste. J Food Eng, 14 (33): 227-237. 15. Gal S. 1987. The need fort he practical application of soprtion data. In. Physical Properties of Foods, pp 13-25, Elsevier Applied Science, London.
• Labuza T P, Acott K, Tatini S R. 1983. Water activity determination: a collaborative study of different methods. J Food Sci, 7 (41): 910-918.
• AOAC 1970. Official Methods of Analysis. Association of Official Agricultural Chemists. Eleventh Edition. 1015 p
• McCune T D, Lang K W, Steinberg M P. 1981. Water activity determination with the proximity equilibration cell. J Food Sci, 6 (46): 1978-1979.
• Arifoğlu U. 2005. Matlab 7.6. Simulink & Mühendislik Uygulamaları. Alfa Yayınları, İstanbul. 20. Doymaz, I. 2007. Air-drying characteristics of tomatoes. J Food Eng,78, 1291-1297.
• Mok C, Hettiarachchy A. 1990. Moisture sorption characteristics of ground sunflower nutmeat and its products. J Food Sci, 3 (55):786- 789.
• Vega-Galvez A, Miranda M, Diaz L P, Lopez L, Rodriguez,K, Di Scala K. 2010. Effective moisture diffusivity determination and mathematical modelling of the drying curves of the olive-waste cake. Bioresource Technol, 101:7265-7270.
• Calıkoglu E, Bayrak A. 2009. Çay işleme sırasında aroma maddelerindeki değişim. GIDA, 34 (2) 115-119.
• Mohammed L A, Kouhila M, Jamali A, Lahsasni S, Mahrouz M. 2004. Moisture sorption isotherms and heat of sorption of bitter orange leaves, J Food Eng, 67 (4), 491-498.
• Lahsasni S, Kouhila M, Mahrouz M, Fliyou M. 2003. Moisture Adsorption Desorption Isotherms of Prickly Pear Cladode at Different Temperatures. Energy Conversion and Manag, 44. 923-936.
• Chirife J, Iglesias H A. 1978. Equations for fitting water sorption isotherms of foods, Part I, A review. J Food Tech. 13, 159-174.
• Cigdem E, Bayrak A. 2003. Siyah çayların aroma maddeleri üzerine araştırma. GIDA, 28 (4). 439-447.
• Lomauro C J, Bakshi A S, Labuza T P. 1985. Evaluation of food moisture sorption equations; Part 1: Fruit, vegetables and meat products. Lebensm-Wiss. U-Tech. 18, 111-117.
• Maroulis Z B, Tsami E, Marinos-Kouris D & Saracacos G D. 1988. Applicatiopn of the Gab model to the moisture sorption isotherms for dried fruits. J Food Eng, 33(7):63-78.