Analisis Permeasi Air pada Dehidrasi Osmosis Pepaya (Carica papaya)

Abstract

Fruit preservation using low temperature drying is commonly initiated by osmotic dehydration process. The osmotic time is strongly influenced by the water permeation from the fruit to the osmotic solution. This research aimed to study the osmotic dehydration process of papaya by finding out the permeation rate of water to the osmotic solution across a semi permeable membrane. The effect of temperature and osmotic solution concentration on the permeation rate were also observed. The osmotic temperatures were 30, 40, 50, and 60oC, and the osmotic solution concentration were 55, 60, 65, and 70%. In order to study the water permeation through the semi permeable membrane, a simple mass transfer mathematical models based on Fick’s and Van’t Hoff laws were applied. Generally, higher temperature and osmotic solution concentration, higher water permeation rate was achieved. The results also showed that osmotic dehydration has the same identity or characteristic as drying process at high temperature. The water removal from product slices into the osmotic solution increased by the increase of osmotic period. The mass transfer coefficient and effective diffusivity of water increased when temperature and osmotic solution concentration were increased. However, the membrane permeability has a special characteristic at the ranges conditions studied.

ABSTRAK

Pengawetan buah dengan pengeringan suhu rendah pada umumnya diawali dengan proses dehidrasi osmosis. Lama waktu osmosis sangat dipengaruhi oleh permeasi air dari bahan ke larutan osmosis. Penelitian ini bertujuan untuk mempelajari proses dehidrasi osmosis dan kecepatan permeasi air dari pepaya ke larutan gula sebagai larutan osmosis melalui membran semipermeabel. Pengaruh suhu dan konsentrasi larutan osmosis terhadap kecepatan permeasi air juga diamati. Suhu osmosis adalah 30, 40, 50, dan 60oC, sedangkan konsentrasi larutan osmosis 55, 60, 65, dan 70%. Untuk mempelajari kecepatan permeasi air melalui membran, digunakan model matematis sederhana berdasar pada hukum Fick’s dan Van’t Hoff. Secara umum hasil pengamatan menunjukkan bahwa semakin tinggi suhu dan konsentrasi larutan osmosis kecepatan permeasi air juga semakin tinggi. Profil dehidrasi osmosis menunjukkan karakteristik yang sama dengan profil proses pengeringan suhu tinggi. Dengan bertambahnya waktu osmosis, air yang berpindah dari potongan pepaya ke dalam larutan osmosis juga semakin banyak. Pemodelan matematis memberikan gambaran bahwa koefisien transfer massa dan difusivitas efektif meningkat dengan naiknya suhu dan konsentrasi larutan osmosis Permeabilitas membran pada bahan menunjukkan karakteristik yang spesifik pada rentang kondisi operasi yang dipelajari.