No abstract

No abstract

Bioetanol merupakan senyawa alkohol yang diperoleh melalui proses fermentasi dengan bantuan mikroorganisme. Proses pembuatan bioetanol ini melalui beberapa tahapan yaitu proses pretretment, proses hidrolisis, proses fermentasi, dan proses distilasi. Proses pretretment merupakan proses yang penting dalam pembuatan bioetanol dikarenakan proses ini menjadi tolak ukur dari proses selanjutnya. Bioetanol dapat dibuat dari bahan-bahan yang mengandung gula. Salah satunya adalah tanaman bambu. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh variasi NaOH dan tekanan terhadap kandungan lignoselulosa serbuk bambu betung. Proses delignifikasi pada penelitian bambu betung ini menggunakan NaOH sebagai alkali dan pemanasan bertekanan menggunakan autoclave dengan tekanan absolute 3 bar, 3.5 bar, dan 4 bar. Adapun kandungan hemiselulosa, selulosa dan lignin kontrol (non-treatment) adalah 10,81%., 45,02% dan 28,35%. Setelah dilakukannya pretreatment diketahui bahwa terjadi penurunan kandungan hemiselulosa, selulosa dan lignin yaitu pada perlakuan tekanan absolute 3 bar dan konsentrasi NaOH 1,5M kandungan hemiselulosa terendah adalah 2,96%, kandungan lignin terendah adalah 3,71% dan kandungan selulosa terendah yaitu 18,38%. Untuk kandungan selulosa tertinggi adalah pada perlakuan tekanan absolute 4 bar dan konsentrasi NaOH 1,5M yaitu 30,52%.

Isothermal drying rates and desorption isotherms of lemon juice were measured and compared with the data for a simulated lemon juice, sucrose, maltodextin and citric acid. The dr ying rates of lemon juice were much lower than the values for the simulated lemon juice and maltodextrin. Equilibrium water contents of lemon juice were much higher than those for other sugars, and similar to the values for the simulated lemon juice and citric acid.

Cabya (Piper retrofractum Vahl) is a widely utilized herbal plant for Indonesian traditional medicine. Up to date, the commonly applied storage method for this plant is in dried form, and makes it less effective for distribution process and less attractive for consumers preference, i.e. consumers usually prefers to consume herbal product in powdered form. In the attempt to provide an optimized storage condition of dried cabya powder, the study was conducted to analyze the sorption isotherm behavior of dried cabya powder and to obtain the fittest sorption isotherm model by comparing obtained data to five commonly used sorption isotherm models, i.e. BET, Oswin, Smith, Caurie, and GAB model. The sorption isotherm data was obtained using static gravimetric method in 24 h of interval weighing observation. Six saturated salt solution, i.e. KOH, MgCl2, KI, NaCl, KCl, and KNO3 were employed for water activity (aw ) in the range of 0.063 - 0.936. The observation was conducted at three different temperatures, i.e. 25±2°C, 35±2°C, and 45±2°C with triplicates. The results indicated that GAB model satisfactorily describe the sorption isotherms behavior of dried cabya powder. The mathematical form of isosteric heat equation of dried cabya powder in adsorption and desorption were also presented.