Development of mathematic model for coffee decaffeination with leaching method

Abstract

A simple mathematic model for caffeine kinetic description during the extraction process (leaching) of coffee bean was developed. A non­steady diffusion equation coupled with a macroscopic mass transfer equation for solvent was developed and them solved analytically. The kinetic of caffeine extraction from coffee bean is depend on initial caffeine content, final caffeine content, caffeine content at certain time, mass­transfer coefficient, solvent volume, surface area of coffee beans, process time, radius of coffee bean, leaching rate of caffeine, caffeine diffusivity and a are constan, solvent concentration, activation energy, temperature absolute and gas constant. Caffeine internal mass diffusivity was estimated by fitting the model to an experiment using acetic acid and liquid waste of cocoa beans fermentation. The prediction equation for leaching rate of caffeine in coffee beans has been found. It was found that Dk (m2/sec)=1.345x10­7—4.1638x10­7, and kL (m/sec)=2.445x10­5—5.551x10­5 by acetic acid as solvent depended on temperature and solvent concentration. The prediction equation for length of time to reduce initial caffeine content to certain concentration in coffee beans has been developed, Caffeine diffusivity (Dk) and mass­transfer coefficient (kL) was found respectively 1.591x 10­7—2.122x10­7 m2/sec and 4.897x10­5—6.529x10­5 m/sec using liquid waste of cocoa bean fermentation as solvent which depend on temperature and solvent concentration. Key words: Coffee, caffeine, decaffeination, leaching, mathematic model.

Caffeine Extraction from Raw and Roasted Coffee Beans

“…Bichel (), Spiro and Selwood (), Spiro and Chong (), and Widyotomo et al. () used a spherical shape for the beans and a constant interface concentration to analyze the caffeine distribution in coffee beans, whereas Espinoza‐Perez et al. () used rectangular shape and varied the interface concentration.…”

“…Bichel (), Spiro and Selwood (), Spiro and Chong (), and Widyotomo et al. () assumed that the interfacial concentration is constant at outer spherical surface of beans, but the interfacial concentration increases with time during extraction in their studies. This difficulty was overcome in this study by using single coffee bean and eight fresh water bottles to maintain a very dilute caffeine concentration in water during extraction.…”

“…Extensive studies have been conducted on caffeine extraction from raw and roasted beans by developing models to fit experimental data (Bichsel, ; Cassel, Vargas, Martinez, Lorenzo, & Dellacassa, ; Espinoza‐Perez, Vargas, Robles‐Olvera, Rodriguez‐Jimenes, & Garcia‐ Alvarado, ; Hulbert, Biswal, Mehr, Walker, & Collins, ; Spiro & Selwood, ; Spiro & Chong, ; Widyotomo, Purwadaria, & Syarief, ). Most of the researchers developed models based on the spherical shape of coffee beans or plant seeds and conducted the caffeine extraction experiments using coffee beans (Bichsel, ; Spiro & Selwood, ; Spiro & Chong, ; Hulbert et al., ; Widyotomo et al., ). With a few exceptions, the feature of the beans was simplified to be an infinite rectangular slab with a finite thickness and non‐steady state, one‐dimension diffusion equation was applied (Cassel et al., ; Espinoza‐Perez et al., ).…”

Umur Simpan Kopi Lengkuas Instan Menggunakan Metode Accelerated Shelf Life Testing (Aslt) Dengan Pendekatan Persamaan Arrhenius

“…Hasil pengujian kadar air berdasar tabel 7 terdapat kecenderungan kadar air yang terus bertambah selama proses penyimpanan. Kenaikan kadar air produk semakin besar seiiring dengan suhu dan kelembaban penyimpanan yang semakin tinggi pula (Widyotomo, Atmawinata and Purwadaria, 2011). Kadar air yang semakin meningkat dapat dikarenakan sifat bahan yang cenderung higroskopis dan sifat permeabilitas bahan kemasan yang digunakan produk, serta tingkat kelembaban udara sekitar atau lingkungan penyimpanan terhadap produk.…”