RANCANGBANGUN DAN UJI KINERJA MESIN FREEZE DRYER UNTUK PENGERINGAN BUAH-BUAHAN

RONAL SITINDAON, Dr. Joko Nugroho W.K, STP, M.Eng. ; Prof.Dr.Ir. Bambang Purwantana, M.Agr.

2018 | Skripsi | S1 TEKNIK PERTANIAN

Tingkat losses buah-buahan di Indonesia masih tergolong tinggi, maka untuk mengurangi tingkat losses yang tinggi ini maka dilakukan pengeringan. Freeze drying merupakan metode pengeringan terbaik untuk mengeringkan buah karena dapat mempertahankan karakteristik khas buah seperti warna, rasa, dan aroma. Penelitian mengenai rancangbangun mesin freeze dryer masih sangat terbatas. Tujuan dari penelitian ini yaitu merancangbangun mesin freeze dryer dan menguji kinerja pengeringannya serta menentukan variasi perlakuan terbaik ditinjau dari kualitas buah kering yang dihasilkan. Dalam penelitian ini, mesin freeze dyer dirancang untuk memenuhi persyaratan sublimasi air yaitu tekanan ruang pengering lebih kecil sama dengan 75,85 cmHg dan suhu sampel lebih kecil sama dengan -18 oC. Kemudian hasil perancangan diuji kinerja pengeringannya pada buah sirsak dengan dua perlakuan setting suhu pemanas setelah tahap pembekuan selesai. Pertama, pemanasan suhu tinggi selama 30 jam. Kedua, pemanasan suhu rendah selama 22 jam kemudian dilanjutkan suhu tinggi selama 8 jam. Pengaplikasian suhu tinggi dilakukan pada dua variasi suhu yaitu 60 oC dan 70 oC pada tiap perlakuan. Hasil perancangan dengan pompa vakum Robin Air dan kompressor 1 HP diisi refrigeran HFC R404A menunjukkan mesin freeze dryer telah mampu menurunkan tekanan hingga -76 cmHg dan menurunkan suhu sampel hingga -24 oC. Mesin freeze drying telah berhasil mengeringkan buah sirsak dari kadar air sekitar 82% menjadi sekitar 13% . Perlakuan terbaik yaitu siklus pembekuan selama 6 jam dilanjutkan pengeringan primer dengan mempertahankan suhu bahan sekitar -6 oC selama 22 jam dan diakhiri menaikkan suhu plat heater hingga 70 oC selama 8 jam. Perlakuan ini telah mampu mempertahankan karakteristik mutu buah segar seperti warna, aroma, dimensi, dan tekstur.

Indonesia has a high classified fruit losses level. Drying is necessary in order to reduce these high losses. Freeze drying is the best method to preserve fruit because it can maintain fruit special characteristic such as color, flavor, and aroma. The research about designing freeze drying machine is still very limited. This research was aimed to design freeze drying machine, to test its drying performance, and to determine the best treatment variation based on the quality of dried fruit produced. In this research, freeze drying machine designed to allow water sublimation by decreasing the drying chamber pressure less than or equal to 75,85 cmHg and sample temperature less than or equal to -18oC. Then the designed machine underwent a drying performance test towards soursop fruit with two heater setting treatment after its freezing stage finished. The first treatment, high temperature was used to heat the sample for 30 hours. The second treatment, low temperature was used to heat for 22 hours continued by high temperature for 8 hours. There were two variation of high temperature applied, which were 60oC and 70oC for each treatment. The drying performance test result showed that the design with Robin Air vacuum pump and compressor 1 HP filled with refrigerant HFC R404A freeze drying machine was able to decrease pressure and temperature until -76 cmHg and -24oC, respectively. Freeze drying machine was successfully dried soursop fruit from water content at around 82% to around 13%. The best treatment was resulted from freezing for 6 hours continued by maintaining sample temperature at approximately -6oC for 22 hours and then finished by increasing plate heater temperature until 70oC for 8 hours. This treatment was able to preserved fruit quality characteristic such as color, aroma, dimension and texture.

Kata Kunci : rancangbangun, freeze dryer, uji kinerja pengeringan/ design, freeze dryer, drying performance test