Cassava leaves are a crucial source of alternative protein resources for both humans and livestock in developing societies in African and Asian countries that do not have easy access to available protein sources. Hence, cassava has the capacity to promote the economic development of these countries and provide food security. However, it has some disadvantages due to the anti-nutrient compounds present in its tissues, which limits the nutritional value of cassava leaves. Thus, proper processing of cassava leaves is essential in order to reduce the anti-nutrients to a safer limit before utilization. This study focuses on reducing the tannin content of cassava leaves during solid-state fermentation using Saccharomyces cerevisiae. In addition, the Box-Behnken design of the Response Surface Methodology was applied to optimize various process parameters, such as carbon concentration, nitrogen concentration, moisture content, and incubation time for maximum reduction of tannin content in cassava leaves. A quadratic model was developed for the reduction of tannin content, which resulted in a perfect fit of the experimental data (p < 0.01). The optimal conditions were found at 1.4% (w/w) of carbon concentration, 0.55% (w/w) of nitrogen concentration, 57% (v/w) moisture content, and an incubation time of 96 h. The minimum tannin content obtained under these conditions was 0.125%, which indicated a reduction of 89.32 % in tannin content. Conversely, the protein content was increased with a further increase in fermentation time from 24 to 96 h (from 10.08 to 14.11-16.07 %). Furthermore, the ability of Saccharomyces cerevisiae to produce tannase under solid-state fermentation of cassava leaves was also studied. The maximum yield was obtained with an enzyme activity of 0.53 U/gds after 72 h of incubation.

LASC catalyst synthesis process was carried out using iron metal (Fe) and its characterization properties were tested. There are five stages carried out, namely, the manufacture of the LASC Fe(DS)3 catalyst, lactic acid dehydration, polycondensation of lactic acid into l-lactic acid oligomers (OLLA), depolymerization of oligomers into l-lactide, and the ROP process to convert l-lactide into Polymers. l-lactic acid (PLLA). The analysis used is as follows, Karl-Fisher; Spectroscopy Fourier Transform Infrared (FTIR); and Nuclear Magnetic Resonance (HNMR); Gel Permeation Chromatography (GPC); Thermogravimetry Gravity Analysis (TGA) and X-Ray Diffraction (XRD). Based on the experimental results, the catalyst Fe(DS)₃ has a crystallinity value of 24% which indicates an amorphous nature and is easy to react. The value of the thermal stability of the catalyst is at 180 °C where the catalyst is able to process up to a temperature of 180 ^°C. Each step of the ROP is validated by FTIR analysis which shows that the components of the group are in accordance with the expected product. The comparison of the crystallinity values of PLA produced with FeCl₃ and Fe(DS)₃ were 37.5 and 49%, respectively. Melting temperature (Tm) values are 111 and 107 ^°C, respectively, Td values are 327 and 352 °C, and the resulting molecular weights are 23,720 and 20,232 g/mol. Based on the results obtained, it can be seen that the use of a LASC catalyst in the form of Fe(DS)₃ is more effective than without using a LASC catalyst.

Iswanto T, Shovitri M, Altway A, Widjaja T, Kusumawati DI, Lisdiyanti P. 2019. Isolation and identification of caffeine-degrading bacteria from soil, coffee pulp waste and excreted coffee bean in Luwak feces. Biodiversitas 20: 1580-1587. The present study deals with the isolation and identification of caffeine-degrading bacteria obtained from the caffeine contaminated environment or caffeinated wastes. These bacteria are useful for various biotechnological applications especially in increasing the potential utilization of caffeinated wastes and producing the high-value chemicals. The suspected caffeine-degrading bacteria have been isolated from the soil of coffee plantation area, coffee pulp waste, and the excreted coffee bean in fresh feces of Luwak (Paradoxurus hermaphroditus or Asian Palm Civet) by growing them on the caffeinated agar medium (CAM) containing basal salt medium (M9) and caffeine as a sole source of carbon and nitrogen. CAM-supplemented with 1.5 to 10 g L-1 of caffeine has been used for screening of the potential bacteria which able to grow in high caffeine concentration. Molecular identification based on 16S rRNA gene sequence was performed to identify the selected bacteria. The result revealed that there were 11 and 3 strains of 12 selected bacteria which could grow on the CAM-supplemented with caffeine up to 7 and 10 g L-1, respectively. Based on 16S rRNA gene sequence and phylogenetic analysis, those bacteria were from 5 Gram-negative species, namely Pseudomonas japonica (4/12), Methylobacterium populi (5/12), Raoultella ornithinolytica (1/12), Klebsiella quasipneumoniae (1/12), and Stenotrophomonas chelatiphaga (1/12). Further investigations to determine their metabolic pathway, enzyme, and growth kinetics in the caffeinated medium may provide insights into its possible utilization for scientific or other applications.

Coffee pulp waste composition consist of cellulose, hemicellulose, lignin, pectin and caffeine, tannin, and polyphenol as inhibitor substance. The high cellulose compound in coffee pulp can be used for alternative raw materials in the manufacture of biogas. This study aims to define the composition of the mixture of microorganisms of Pseudomonas putida, Trichoderma harzianum, and Aspergillus niger that are best to use in coffee pulp pretreatment to degrade inhibitor substance. The best result of pretreatment will be applied to biogas production. The first step is to do a pretreatment of the coffee pulp with variable Pseudomonas putida : Trichoderma harzianum : Aspergillus niger with a ratio of 1:1:1, 1:2:1, 1:1:2, 1:2:2, 2:1:1, 2:1:2, 2:1:1 (v:v:v), then variables that are most excellent in degrading inhibitor substance are selected. The second step, is doing anaerobic fermentation for 20 days at mesophilic temperature (30-40°C) on a reactor working volume of 4.5 L. In the making of biogas, a varied starter as much as 10% of the total are put into the reactor in the form of a mixture of cow dung : rumen fluid with a ratio of 1:0, 0:1, 1:1, 1:2, 2:1 (w/v). The parameters measured include the decreasing of the inhibitor substance, Chemical Oxygen Demand (COD), biogas (CH₄ and CO₂) and calorific value of combustion (Heating value). This study results a composition of ingredients within the pretreatment process which includes a mixture of microorganisms with a ratio of Pseudomonas putida : Trichoderma harzianum : Aspergillus niger is 1:2:1 (v:v:v). For biogas, a mixture of cow dung and rumen fluid can produce higher methane gas is the ratio of cow dung : rumen fluid is 1:2 (w/v) with the concentration of methane (CH₄) formed at 1.825%. At the concentration of methane is 1.825%, the heating value obtained is 76.032 kcal/kg with volume biogas 0.0032 m³/ kg converted of COD.