Pretreatment at mild condition is the strategy to minimize energy consumption, to reduce toxic compounds influencing to further process, and to obtain the high reducing sugar yield as fermentation substrate from cellulose and hemicellulose of oil palm empty fruit bunches (OPEFB). The yield still could be increased by optimizing pretreatment condition and varying several process alternatives. In this study, the effect of acetic acid addition and its corresponding concentration (5–15%), pretreatment temperature (115–125 °C), time (60–90 minutes), and two-stage pretreatment (0.01–1M NaOH pretreatment followed by autohydrolysis and autohydrolysis followed by 0.1–1% acetic acid pretreatment) were evaluated. The residual solid after pretreatment was then enzymatically hydrolyzed by Cellic CTec2. The result showed that the addition of acetic acid was able to increase the yield of reducing sugar. In addition, the reducing sugar yield could be still increased when the temperature was escalated, but the extended pretreatment time gave the decline of reducing sugar yield. This yield, however, was still lower than this from NaOH pretreatment followed by autohydrolysis. The maximum yield of this pretreatment could be attained by 1 M NaOH concentration at 125 °C for 60 minutes with solid loading 10% (0.71 g/g-OPEFB).

<em>Quality and techno-economic improvement is important to increase export value of coffee in Indonesia. Complex roasting is one excellent method in increasing the added value of coffee, such as Coffea arabica var. Sigarar Utang which is the best coffee variety in Indonesia. The study was carried out at The Indonesian Industrial and Beverage Crops Research Institute (IIBCRI), Sukabumi, West Java, from January to November 2020 which aimed: (1) to evaluate the effect of initial temperature and roasting degree on the quality of Sigarar Utang coffee bean, and (2) to evaluate the mass balance and economic feasibility of the best roasting treatment. This study was designed in a factorial completely randomized design, using 2 factors, and 2 replications. The first factor was the initial temperature which consisted of 2 levels (185 ^oC dan 210 ^oC), and the second factor was the roasting degree which consisted of 2 levels (light-medium and medium-dark). The variables observed were the water content, ash content, bulk density, brix, titratable acidity, pH, radical scavenging (antioxidant) activity, and caffeine content. The results showed that the complex roasting method with an initial temperature of 210 ^oC and mild-moderate roasting degrees generated a quality of Sigarar Utang coffee originating from Gunung Putri, IIBCRI, closest to the quality I of SNI 01-3542-2004. The roasted coffee beans have a special taste (score 86.51) which is a high added value. The production economic value is feasible to be adopted by small-medium scale coffee industry.</em>

Pretreatment of oil palm empty fruit bunches (OPEFB) catalyzed by weak acids (oxalic, formic, and citric acid) in an autoclave under moderate condition is one of the appropriate pretreatment alternatives to recover reducing sugar both from cellulose and hemicellulose. This sugar can be fermented to be various bioprocess products. In this study, the effect of weak acid concentration (1–5% for oxalic acid; 5–20% for formic and citric acid), pretreatment temperature (115–125°C), time (60–90 min), and solid loading (5–10%) was investigated. To improve total reducing sugar yield, residual solid after pretreatment was subsequently hydrolyzed by Cellic CTec2. With the increasing weak acid concentration, pretreatment temperature, and time, more reducing sugar was obtained in spent liquor of pretreatment. On the contrary, the increase of solid loading declined the reducing sugar yield. After residual solid was enzymatically hydrolyzed, the amount of reducing sugar significantly elevated for nearly all weak acids, except 5% oxalic acid pretreatment. However, the pretreatment by 5% oxalic acid gave the maximum yield of total reducing sugar at 125°C for 60 min and using 5% solid loading. The reducing sugar obtained in spent liquor and hydrolysate at this optimum condition was 0.245 g/g OPEFB and 0.352 g/g OPEFB, respectively.