Konstanta Laju Pengeringan Daun Sambiloto Menggunakan Pengering Tekanan Rendah

https://doi.org/10.22146/jrekpros.550

Sri Rahayoe(1*), Budi Rahardjo(2), Siti Kusumandari(3)

(1) 
(2) 
(3) 
(*) Corresponding Author

Abstract


Pada penelitian ini dilakukan pengeringan bahan herbal dan obat-obatan tradisional yang peka terhadap panas yaitu daun sambiloto menggunakan pengering bertekanan rendah. Tekanan yang rendah akan membuat titik uap air akan turun sehingga air akan menguap pada suhu di bawah 100°C. Suhu rendah ini juga bertujuan untuk mengurangi tingkat kerusakan kandungan kimia bahan peka panas. Sedangkan tujuan penelitian adalah menganalisis konstanta laju pengeringan daun sambiloto selama proses pengeringan menggunakan pengering tekanan rendah. Pengeringan daun sambiloto dilakukan pada suhu dan tekanan yang bervariasi yaitu variasi suhu 30°C, 40°C, 50°C dan variasi tekanan 61 kPa, 48 kPa dan 35 kPa. Pengeringan daun sambiloto dilakukan dari kadar air ± 70% hingga ± 10%. Selama proses pengeringan perubahan kadar air diukur dengan interval waktu 10, 20, 30, 60, 90, 120, 150 dan 210 menit. Pengukuran kadar air dilakukan dengan cara termogravimetri. Analisis konstanta laju pengeringan menggunakan persamaan lapis tipis. Hasil penelitian menunjukkan nilai konstanta laju pengeringan pada tekanan rendah berkisar 0,01-0,0175 men1. Pengeringan menggunakan tekanan rendah dapat meningkatkan laju pengeringan. Persamaan empiris konstanta laju pengeringan sebagai fungsi suhu dan tekanan yang dinyatakan sebagai kprediksi = 0,00075T0,823P-0,021 dapat diaplikasikan untuk memprediksi perubahan kadar air daun sambiloto selama pengeringan pada tekanan rendah.

Kata kunci: konstanta laju pengeringan, pengeringan bertekanan rendah, daun Sambiloto

Herbs (traditional medicine) such as sambiloto leaves are senisitive to heat, therefore the drying process of herbs were performed at low-pressure. At low pressure, evaporation of water in the herbs can be carried out at a temperature below 100°C. The low temperature of drying may reduce the destruction of heat-sensitive chemicals inside the herbs. The present study aimed at analyzing the drying-rate constant of sambiloto leaves during low-pressure drying. Sambiloto leaves were dried at varied temperature of 30°C, 40°C, and 50°C, and varied pressure of 61 kPa, 48 kPa, and 35 kPa. The water content of sambiloto leaves was reduced from ± 70% to ± 10%. The change in water content was measured after 10, 20, 30, 60, 90, 120, 150 and 210 minutes, by using thermogravimetry technique. The drying-rate constant was calculated using the equation of thin films. The drying-rate constant was 0.01 – 0.0175 min-1. It was observed that the drying-rate increases as the pressure decreases. To predict the change of water content in sambiloto leaves during low-pressure drying process, an empirical equation for the drying-rate constant as a function of temperature and pressure was derived from the experimental data, kprediction= 0,00075T0,823P-0,021.

Key words: drying-rate constant, low-pressure drying, sambiloto leaves

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DOI: https://doi.org/10.22146/jrekpros.550

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