Prediksi Kadar Air Setimbang (Equilibrium Moisture Content) Beras Putih dan Beras Pecah Kulit dengan Variasi Kondisi Lingkungan Penyimpanan

Asyam Safa Prabaningrum, Hanim Zuhrotul Amanah, S.T.P., M.P., Ph.D. ; Dr. Sri Rahayoe, S.T.P., M.P.

2025 | Skripsi | TEKNIK PERTANIAN

Selama proses penyimpanan, kadar air beras akan mengalami perubahan sampai mencapai kadar air setimbang. Kadar air setimbang beras berubah seiring dengan perubahan suhu dan RH ruang penyimpanan. Penelitian kadar air setimbang beras umumnya masih terbatas pada penentuan nilainya pada kondisi ruang penyimpanan tertentu dan belum ada penelitian yang melakukan pemodelan menggunakan kurva ISA (isoterm sorpsi air) khusunya untuk beras coklat. Penelitian ini bertujuan untuk memodelkan perubahan kadar air setimbang beras coklat menggunakan kurva ISA.

Sebanyak 5 gram beras coklat varietas Pandan Wangi dan beras putih varietas IR64 dalam cawan disimpan dalam ruang penyimpanan pada suhu 5, 20, 28, dan 40ºC dan variasi kelembaban 11,2%; 32,4%;  43,1%; 51,2%; 75,5%; 84,1%; dan 97%. Sampel ditimbang setiap hari sampai berat sampel konstan yang menunjukkan kadar air beras sudah mencapai titik kesetimbangan. Kadar air beras diukur dengan menggunakan metode thermogravimetri. Data yang diperoleh selanjutnya digunakan untuk mengembangkan model kurva ISA menggunakan tujuh model matematis: GAB, Henderson, Chung-Pfost, Oswin, Smith, Langmuir, dan BET. Pengaruh suhu dan kelembaban terhadap kadar air setimbang dianalisis dengan menggunakan analisis statistik One Way ANOVA dan uji T-test.

Hasil penelitian menunjukkan bahwa suhu berkorelasi negatif terhadap EMC. Sedangkan RH berkorelasi positif terhadap EMC. Hasil penelitian menunjukkan bahwa pemodelan Chung-pfost menjadi model yang dapat menggambarkan perilaku EMC pada beras penyimpanan 5°C dengan baik. Selanjutnya, model GAB dan Henderson menjadi model yang dapat menggambarkan perilaku EMC pada beras penyimpanan 20°C - 40°C dengan baik.

During storage, the moisture content of rice will change until it reaches equilibrium moisture content. The equilibrium moisture content of rice changes with changes in storage room temperature and RH. Research on the equilibrium moisture content of rice is generally limited to determining its value under specific storage conditions, and there has been no research that models using the ISA (isotherm water sorption) curve, especially for brown rice. This study aims to model changes in the equilibrium moisture content of brown rice using the ISA curve.

Five grams of brown rice of the Pandan Wangi variety and white rice of the IR64 variety in dishes were stored in a storage room at temperatures of 5, 20, 28, and 40ºC and humidity variations of 11,2%; 32,4%; 43,1%; 51,2%; 75,5%; 84,1%; and 97%. The samples were weighed daily until the sample weight remained constant, indicating that the rice moisture content had reached equilibrium. The moisture content of the rice was measured using the thermogravimetric method. The data obtained were then used to develop an ISA curve model using seven mathematical models: GAB, Henderson, Chung-Pfost, Oswin, Smith, Langmuir, and BET. The effects of temperature and humidity on equilibrium moisture content were analyzed using One-Way ANOVA statistical analysis and T-test.

The results showed that temperature was negatively correlated with EMC, while RH was positively correlated with EMC. The results indicated that the Chung-Pfost model was the best model for describing EMC behavior in rice stored at 5°C. Furthermore, the GAB and Henderson models were the best models for describing EMC behavior in rice stored at 20°C–40°C.

Kata Kunci : beras, kondisi lingkungan, absorpsi-desorpsi, kadar air setimbang.