MODEL MATEMATIS PERUBAHAN SIFAT FISIK SELAMA PROSES PENGOLAHAN GULA SEMUT DENGAN MELAKUKAN PENETAPAN BRIX PADA AKHIR EVAPORASI

EMA YUDIASTUTI WULANDARI, Dr. Joko Nugroho W.K.,STP, M.Eng

2011 | Tesis | S2 Mekanisasi/Teknik Pertanian

Gula semut merupakan hasil pengentalan nira dari beberapa jenis tanaman, dengan langkah mengubah gula yang terlarut menjadi gula padat dalam bentuk butiran kristal. Pengentalan nira tercapai dengan cara pemberian panas yang disertai pengontrolan suhu bahan pada 120oC selama proses evaporasi hingga diperoleh titik jenuh pada Brix tertentu dan selanjutnya pembentukan butiran kristal dilakukan dengan pendinginan dalam proses kristalisasi. Selama pengolahan dilakukan pengadukan secara manual. Penelitian ini bertujuan untuk menentukan kondisi yang tepat dalam melakukan pembentukan butiran kristal dari bahan dasar nira kelapa, gula kelapa, gula pasir dan mengembangkan model matematis perubahan kadar air, kadar padatan, massa kristal yang keluar dari larutan selama pengolahan serta menentukan penguapan air, ukuran diameter, densitas, dan warna gula semut yang dihasilkan. Hasil penelitian menunjukkan bahwa kondisi yang tepat untuk menandakan titik jenuh telah tercapai adalah bahan mengandung Brix 83,4% hingga 91,0% saat akhir evaporasi. Dengan suhu pemanasan tetap, maka Brix akhir evaporasi yang semakin tinggi akan mempercepat penurunan kadar air bahan saat evaporasi, memperlambat penurunan kadar air bahan saat kristalisasi dan pengeringan, mempercepat kenaikan kadar padatan saat evaporasi dan kristalisasi, serta mempercepat kenaikan massa kristal yang keluar dari larutan saat evaporasi. Gula semut berbahan dasar nira kelapa, gula kelapa, gula pasir berturut-turut mengalami penguapan air 79,2-87,7% ; 4,93-35,37% ; 22,09-32,83% dan ukuran diameter rerata 1,11-2,22mm ; 0,97-1,59mm ; 1,19-1,60mm serta densitas 0,52-0,61gram/ml ; 0,59-0,64gram/ml ; 0,57-0,60gram/ml. Gula semut berbahan dasar nira kelapa mempunyai warna lebih terang daripada gula kelapa. Dengan alat citra digital, gula semut pada ketiga bahan dasar memiliki warna merah paling dominan.

Brown sugar is a result of juice coagulation out of several kinds of plant, by changing the soluted sugar into a crystal grain shaped solid sugar. Juice coagulation is reached by a heating supply along with a material temperature controlled in 120oC during the evaporation until it reaches the saturated point in a certain Brix and furthermore the shaping of crystal grain is to do the refrigerating in the crystallization. During the processing, the stirring is done manually. The objective of this research is to determine an appropriate condition in shaping crystal grain from a raw material of palm juice, palm sugar, cane sugar and developing the mathematical model of moisture content changing, solid content, crystal mass coming out from the liquid during the process and to determine the evaporation of water, the size of diameter, density, and the color of the resulted brown sugar. The research indicated that the appropriate condition to indicate that the saturated point has been reached was the material containing 83.4% until 91.0% of Brix at the end of evaporation. By a constant temperature of heating, the greater Brix at the end of evaporation would fasten the slope of the moisture content of material during evaporation, slow the slope of moisture content of material down during the crystallization and drying, fasten the increase of the solid content during evaporation and crystallization and fasten the increase of crystal mass coming out from the liquid during evaporation. The brown sugar based of palm juice, palm sugar, cane sugar in a row had a evaporation of water 79.2-87.7% ; 4.93-35.37% ; 22.09-32.83% and the average size of diameter 1.11-2.22mm ; 0.97-1.59mm ; 1.19-1.60mm and density 0.53-0.62gram/ml ; 0.60-0.64gram/ml ; 0.58-0.61gram/ml. The palm juice based brown sugar had a lighter color than the palm sugar. By the device of the digital image, brown sugar of the three raw materials had the most dominant red color.

Kata Kunci : gula semut, evaporasi, kristalisasi, model matematis