Produktivitas tanaman kopi di Indonesia cukup tinggi, agroindustri kopi dapat menghasilkan kulit kopi sekitar 60% dari bahan awal. Penelitian ini bertujuan untuk mengetahui karakteristik kulit kopi perkebunan rakat dari tiga daerah sentra penghasil kopi di Jawa Timur, yaitu Jember, Banyuwangi, dan Malang. Beberapa karakteristik yang dianalisis adalah kadar proksimat(air, abu, lemak, protein dan karbohidrat), kadar serat kasar dan kadar lignoselulosa (lignin, selulosa, dan hemiselulosa). Hasil penelitian menunjukkan bahwa kulit kopi memiliki karakteristik yang berbeda pada setiap daerah.

We have isolated 12 yeast isolates from five different rotten fruits by using a yeast glucose chloramphenicol agar (YGCA) medium supplemented with tetracycline. From pre-screening assay, four isolates exhibited higher substrate (glucose-xylose) consumption efficiency in the reaction tube fermentation compared to Saccharomyces cerevisiae dan Saccharomyces ellipsoids as the reference strains. Based on the fermentation process in gooseneck flasks, we observed that two isolates (K and SB) showed high fermentation efficiency both in sole glucose and mixed glucose-xylose substrate. Moreover, isolates K and SB produced relatively identical level of ethanol concentration compared to the reference strains. Isolates H and MP could only produce high levels of ethanol in glucose fermentation, while only half of that amount of ethanol was detected in glucose-xylose fermentation. Isolate K and SB were identified as Pichia kudriavzeevii (100%) based on large sub unit (LSU) ribosomal DNA D1/ D2 region.

Abstract. Sago is a genus of palm that can be utilized to produce fermentable sugars as substrate for bioethanol. Sago pith is a heterogeneous substrate consists of starch and fiber. Acid hydrolysis by microwave heating radiation can break down starch and fibers together in a very short time, so it is considered to be very efficient process. The use of microwave energy (as power level) and variation of heating time can produce fermentable sugar with certain characteristics. This study included the preparation and analysis of sago pith flour; process of acid hydrolysis (0.3 M and 0.5 M H 2 SO 4 ) using two steps microwave heating, first with power level 30% (1, 2 and 3 min) and second with power level 70% (3 min); and ethanol production. The conventional treatment (autoclaving at 121C for 15 min) was carried for the comparison. The highest fermentable sugar (105.7 g/l) was resulted from microwave heating with power level 30% for 2 min followed by the power level 70% for 3 min. This hydrolyzate then used as substrate for bioethanol fermentation and partially neutralized (pH 3, 4, 5) by using yeast Issatchenkia orientalis, and the highest ethanol (2.8 g/l) was produced in pH 5.

Chemical cross-linking was developed to prepare starch and chitosan-based hydrogels. First, the precursor of starch was synthesized through the reaction of carboxymethylation with sodium monochloroacetate, and then chitosan was grafted by using methacrylic acid as cross-linker. In this research, sago and cassava starches were used and mixed with chitosan, and the effect of methacrylic acid concentration was investigated to determine the grafting parameters and hydrogel characteristics. Compared to native starch and carboxymethylated starch, hydrogels from both starches have high ability to swell and high capacity to absorb water and oil. The highest grafting yield, grafting efficiency, and monomer conversion were achieved by experiment using 0.550 g of methacrylic acid per g of CMS-chitosan mixture. These hydrogels have a good potency as biodegradable absorbents for pharmaceutical and industrial application.

In the present study, carboxymethyl starch (CMC) were produced from different sources of starch and their physico-chemical properties were evaluated. Carboxymethylation was performed using different concentrations of sodium monochloroacetate (1.1, 1.3 and 1.5 mol/mol of anhydrous glucose units) in a three-necked round-bottom flask (250 mL) for approximately 3 h (250 rpm and 40°C) in a two-stage reaction comprising alkalization and etherification. The introduction of carboxymethyl groups was confirmed in the results by the appearance of a new peak in the FTIR spectrum in 1650.10-1649.76 cm-1 region. In addition, degree of substitution (DS) of produced CMS was ranged from 0.53-0.60. An increase in the concentration of sodium monochloroacetate (1.1, 1.3 and 1.5 mol/mol of anhydrous glucose unit) resulted in greater paste clarity, higher solubility and greater swelling than native starch. Furthermore, cassava starch (tapioca) produced a CMS exhibited greater swelling than sago starch, however by contrast, CMS-sago was more soluble and clearer than CMS-cassava.