Modeling of extraction of total polyphenols from Zingiber officinale

In this paper, kinetics of extraction of total polyphenols from Zingiber officinale was investigated. Samples were extracted using water at different temperatures and the extraction was realized under mixed and unmixed medium to observe the changes in the kinetics. Four different models, namely Peleg, Mass Transfer, Logarithmic and Page’s Models, were used for mathematically describing the physical behavior of the extraction. The yields of polyphenols determined as gallic acid equivalents ranged between 2.29-5.23 mg/g depending on the temperature and mixing conditions. Peleg’s model, having the highest regression coefficients at all conditions investigated for steady-state conditions, and Mass transfer model for unsteady-state conditions were found as the best fit to the experimental data. Also, molecular and convective diffusivities and activation energy of extraction were evaluated in this study. It was found that increase in temperature and mixing rate increased the diffusion coefficients because they decreased the activation energy of extraction. It has been found that temperature was much more effective than mixing rate, on the process.

Zingiber officinale bitkisinden toplam polifenollerin ekstraksiyonunun modellenmesi

Bu çalýþmada, Zingiber officinale’den toplam polifenollerin ekstraksiyonun kinetiði incelenmiþtir. Numuneler farklý sýcaklýktaki suyla ekstrakte edilmiþ ve kinetik deðiþimleri gözlemlemek için ekstraksiyon karýþtýrýlmýþ ve karýþtýrýlmamýþ ortamlarda gerçekleþtirilmiþtir. Ekstraksiyonun fiziksel davranýþýný matematiksel ifadelerle tanýmlamak için Peleg, Kütle Aktarýmý, Logaritmik ve Page Modelleri olmak üzere dört farklý model kullanýlmýþtýr. Gallik asit eþdeðeri olarak belirlenen polifenol verimlerinin sýcaklýk ve karýþtýrma koþullarýna baðlý olarak 2.29-5.23 mg/g arasýnda deðiþtiði bulunmuþtur. Araþtýrýlan tüm koþullarda en yüksek regresyon katsayýsýna sahip olan Peleg Modeli’nin yatýþkýn durumda, Kütle transfer modelinin ise yatýþkýn olmayan koþullarýn ifadesinde deneysel verilere en uygun model olduðu belirlenmiþtir. Ayrýca, bu çalýþmada ekstraksiyonun moleküler ve konvektif diffüzivitesi ve aktivasyon enerjisi de hesaplanmýþtýr. Ekstraksiyonun aktivasyon enerjisini azalttýðý için sýcaklýk ve karýþtýrma hýzýndaki artýþýn difüzyon katsayýlarýný arttýrdýðý belirlenmiþtir. Proseste, sýcaklýðýn karýþtýrma hýzýna oranla çok daha etkili olduðu tespit edilmiþtir.