Kehilangan air dan penyerapan minyak pada wortel selama penggorengan hampa udara (deep fat vacuum frying)

SUTARSI, Prof. Dr. Ir Budi Rahardjo

2008 | Tesis | S2 Teknik Pertanian

Penggorengan merupakan metode memasak yang cepat dan mudah untuk menghasilkan makanan dengan sifat sensoris yang unik. Kehilangan air dan penyerapan minyak terjadi selama penggorengan. Fenomena tersebut dapat diprediksikan dengan model matematis. Tujuan penelitian untuk menghitung difusivitas air dan difusivitas minyak sebagai fungsi suhu, tekanan dan kadar air awal bahan. Kedua, mengembangkan model matematis kehilangan air dan penyerapan minyak bahan selama proses penggorengan hampa udara. Difusivitas massa air dan difusivitas massa minyak ditentukan dari persamaan difusi unsteady state. Kehilangan air dan penyerapan minyak bahan dinyatakan dengan model matematis. Proses transfer massa air dan minyak dinyatakan dengan hukum Ficks. Dalam penelitian ini digunakan wortel sebagai sampel. Sebelum digoreng wortel didehidrasi osmotik selama 2 jam, 4 jam kemudian digoreng dibawah kondisi suhu 80oC, 100oC, 110oC dan tekanan 20kPa, 30kPa dan 40kPa. Hasil penelitian menunjukkan difusivitas air sebagai fungsi suhu, tekanan dan kadar air awal bahan dalam fungsi "rumus" dan difusivitas minyak sebagai fungsi suhu, tekanan dan kadar air awal bahan dalam fungsi "rumus". Uji statistik menunjukkan bahwa data observasi mendekati data prediksi dengan nilai koefisien determinasi 0,9611 untuk kadar air dan 0,9713 untuk kadar minyak. Hal ini mengindikasikan model matematik yang dikembangkan valid. Oleh karena itu model dapat digunakan untuk memprediksikan riwayat kadar air dan kadar minyak bahan selama penggorengan hampa udara.

Frying is an easy fast cooking method to produce food with a unique sensory characteristic. A Water loss and an oil uptake were occurred during frying process. Those phenomena could be predicted using a mathematical model. The objective of this research were: first, to determine a moisture diffusivity and an oil diffusivity as a function of temperature, absolute pressure and moisture content and second, to develop a water loss model and an oil uptake model mathematically during frying process. The moisture diffusivity and the oil diffusivity were estimated by unsteady state diffusion equation. water loss and oil uptake during frying process were formulated on a mathematical models. Water mass transfer and oil mass transfer were formulated with Ficks law. Carrot was used as a sample in this research. Prior to frying, carrot slices were osmotic dehydrated 2 hours, 4 hours then deep fat vacuum fried. Samples were fried under different temperature (80oC, 100oC, 110oC) and different absolute pressure (20kPa, 30kPa, 40kPa). The result showed that the moisture diffusivity as a function of temperature, absolute pressure and moisture content in "formula" and the oil diffusivity as a function of temperature, absolute pressure and moisture content in "formula". A statistic test showed that the experimental data were found to fit well to predicted data with a determination coefficient 0,9611 for moisture content and 0,9713 for oil content. Those indicated that mathematical models were valid, therefore the models could be used to predict the history of water content and oil content during deep fat vacuum frying.

Kata Kunci : Wortel,penyerapan minyak,Penggorengan hampa udara,Difusivitas air,Difusivitas minyak