Specific Methane Yield of Wetland Biomass in Dry and Wet Fermentation Technologies

Our study evaluated the specific methane yield (SMY) of selected wetland species subjected to wet and dry anaerobic digestion: Carex elata All. (CE), a mixture (~50/50) of Carex elata All. and Carex acutiformis L. (CA), Phragmites australis (Cav.) Trin. ex Steud. (PA), Typha latifolia L. (TL) and Phalaris arundinacea L. (PAr). Plants were harvested in late September, and therefore, the study material was characterised by high lignin content. The highest lignin content (36.40 ± 1.04% TS) was observed in TL, while the lowest (16.03 ± 1.54% TS) was found in CA. PAr was characterised by the highest hemicellulose content (37.55 ± 1.04% TS), while the lowest (19.22 ± 1.22% TS) was observed in TL. Cellulose content was comparable in almost all plant species studied and ranged from 25.32 ± 1.48% TS to 29.37 ± 0.87% TS, except in PAr (16.90 ± 1.29% TS). The methane production potential differed significantly among species and anaerobic digestion (AD) technologies. The lowest SMY was observed for CE (121 ± 28 NL kgVS−1) with dry fermentation (D–F) technology, while the SMY of CA was the highest for both technologies, 275 ± 3 NL kgVS–1 with wet fermentation (W–F) technology and 228 ± 1 NL kgVS–1 with D–F technology. The results revealed that paludi-biomass could be used as a substrate in both AD technologies; however, biogas production was more effective for W–F. Nonetheless, the higher methane content in the biogas and the lower energy consumption of technological processes for D–F suggest that the final amount of energy remains similar for both technologies. The yield is critical in energy production by the AD of wetland plants; therefore, a promising source of feedstock for biogas production could be biomass from rewetted and previously drained areas, which are usually more productive than natural habitats.

Studi Fermentasi Biji Kopi Menggunakan Enzim Proteolitik

Wet fermentation by added proteolytic enzyme can be used for upgrade the taste of coffee. The enzyme was obtained from plant because of ease to get and fulfill the term of Indonesia’s constitution about halal product assurance. This study used two types of proteolytic enzyme; bromelain and zingibain that originated from pineapple and ginger, respectively. Coffee beans were fermented with weight ratio 1:4 and 3:4 (enzyme’s source: coffee beans), and compared with a non-adding control and commercial coffee. Samples were collected after 1, 2 and 3 days. Roasted beans were physical and chemical evaluated according to Indonesia National Standard (SNI-01-3542-2004). Also, the sensorial evaluation of the roasted coffee beans was determined by organoleptic test. Physical and chemical evaluation consist of water content, ash content, coffee extract, ash alkalinity and caffeine content. Sensorial evaluation includes color, aroma and flavor.

OPTIMIZATION OF PHENOLIC COMPOUNDS IN ROBUSTA GREEN BEANS COFFEE THROUGH THE WET FERMENTATION PROCESS WITH THE RESPONSE SURFACE METHODOLOGY

Coffee is a refreshing drink that has potential as an antioxidant shown by its total phenol content. Fermentation is used to increase the phenolic compound content in coffee. The purpose of this study was to optimize the wet fermentation process to produce optimal phenolic compounds in green bean coffee. The process optimization was carried out by using Response Surface Methodology with three independent variables, namely the addition of yeast, added sugar, and fermentation time. The results of the quadratic model equation research to get the optimal process, namely Y= 65.18 + 0.56X1 + 2.66X2 + 16.26X3 + 1.51X1X2 + 0.18X1X3 + 0.66X2X3 + 9.29X12 + 23.71X22 + 6.08X32 with r2 of 0.8242 The optimum value of the wet fermentation process is based on the predictive value of the quadratic model, namely the addition of yeast 3.25%; added sugar 21.38%; and 124.73 hours of fermentation time resulted in a total phenol of 10.22 mg GAE / g.

Microbiological and Chemical Characteristics of Wet Coffee Fermentation Inoculated With Hansinaspora uvarum and Pichia kudriavzevii and Their Impact on Coffee Sensory Quality

Hansinaspora uvarum and Pichia kudriavzevii were used as starter cultures to conduct inoculated wet fermentations of coffee beans, and their growth, metabolic activities and impact on the flavor, aroma and overall sensory quality of coffee were compared with spontaneous fermentation (control). H. uvarum and P. kudriavzevii dominated the fermentations, growing to maximum populations of about 10.0 log CFU/ml compared with 8.0 log CFU/ml in the spontaneous fermentation. The dominance of the inoculated yeasts led to faster and more complete utilization of sugars in the mucilage, with resultant production of 2–3 fold higher concentrations of metabolites such as glycerol, alcohols, aldehydes, esters, and organic acids in the fermented green beans. Cup tests showed coffee produced from the inoculated fermentations, especially with P. kudriavzevii, received higher scores for flavor, aroma and acidity than the control. The findings of this study confirmed the crucial role of yeasts in the wet fermentation of coffee beans and their contribution to high quality coffee, and demonstrated the potential H. uvarum and P. kudriavzevii as starter cultures in the process.

The Potential of the Biodigester as a Useful Tool in Coffee Farms

Coffee is a highly productive agricultural product in the department of Tolima. The wet fermentation process of coffee generates about 80% of the waste, which is highly contaminated with organic matter that pollutes water sources, so anaerobic co-digestion techniques are implemented in coffee wastewater using Taiwan type biodigesters. According to the study of three biodigesters fed with coffee waste and animal manure, the aim is to show their potential application in coffee farms. These biodigesters generated a biogas production with CH4 concentrations between 49.1% ± 4.6 and 58.1% ± 2.4 in volume, in addition to the benefit of the biol used as fertilizer in the crops. The biogas produced can be used for cooking and can save around USD 40.17 in natural gas. Therefore, the biodigester is a potential tool to mitigate the harmful effects of coffee cultivation on the surrounding ecosystem and can project coffee production in a sustainable direction.

GHG Emissions and Efficiency of Energy Generation through Anaerobic Fermentation of Wetland Biomass

We conducted the Life Cycle Analysis (LCA) of energy production from biogas for maize and three types of wetland biomass: reed Phragmites australis, sedges Carex elata, and Carex gracilis, and “grassy vegetation” of wet meadows (WM). Biogas energy produced from maize reached over 90 GJ ha−1, which was more than four times higher than that gained from wetland biomass. However, an estimation of energy efficiency (EE) calculated as a ratio of energy input to the energy produced in a biogas plant showed that the wet fermentation (WF) of maize was similar to the values obtained for dry fermentation (DF) of sedge biomass (~0.30 GJ GJ−1). The greenhouse gases (GHG) emissions released during preparation of the feedstock and operation of the biogas plant were 150 g CO2 eq. kWhel.−1 for DF of sedges and 262 g CO2 eq. kWhel.−1 for WF of Phragmites. Compared to the prevailing coal-based power generation in Central Europe, anaerobic digestion (AD) of wetland biomass could contribute to a reduction in GHG emissions by 74% to 85%. However, calculations covering the GHG emissions during the entire process “from field to field” seem to disqualify AD of conservation biomass as valid low-GHG energy supply technology. Estimated emissions ranged between 795 g CO2 eq. kWhel.−1 for DF of Phragmites and 2738 g CO2 eq. kWhel.−1 for the WM and, in most cases, exceeded those related to fossil fuel technologies.

PENGARUH PAPARAN MEDAN MAGNET EXTREMELY LOW FREQUENCY (ELF) TERHADAP pH DAN DAYA HANTAR LISTRIK PADA PROSES FERMENTASI BASAH KOPI LIBERIKA (Coffea liberica) DENGAN PENAMBAHAN α-AMILASE

ABSTRAKPenelitian ini bertujuan untuk mengkaji pengaruh paparan medan magnet Extremely Low Frequency (ELF) terhadap pH dan daya hantar listrik pada proses fermentasi basah kopi liberika dengan penambahan α-amilase. Jenis penelitian ini merupakan penelitian eksperimen dengan randomized subjects post test only control group design. Pada penelitian ini terdapat 7 perlakuan yang terdiri dari kelompok kontrol dan kelompok eksprimen yang dipapar medan magnet ELF dengan variasi intensitas 300 µT dan 400 µT dan variasi lama paparan 30 menit, 60 menit, dan 90 menit. Pengambilan data dilakukan pada jam ke-24, jam ke-48, hari ke-3, hari ke-4, dan hari ke-5 setelah proses fermentasi. Hasil penelitian menunjukkan bahwa paparan medan magnet Extremely Low Frequency (ELF) berpengaruh terhadap pH dan daya hantar listrik pada proses fermentasi basah kopi liberika dengan penambahan α-amilase yang ditunjukkan dengan bervariasinya grafik. Pengukuran kopi liberika dengan paparan medan magnet ELF intensitas 400 µT selama 30 menit paling berpengaruh terhadap pH kopi liberika. Sedangkan, pengukuran kopi liberika dengan paparan medan magnet ELF intensitas 300 µT selama 30 menit dan 90 menit paling berpengaruh terhadap daya hantar listrik kopi liberika yang telah difermentasi secara basah dengan penambahan α-amilase. Kata kunci: medan magnet ELF; pH; daya hantar listrik; fermentasi; kopi. ABSTRACTThe purpose of the research is to examine the effect of Extremely Low Frequency (ELF) magnetic field to pH and electrical conductivity in the wet fermentation process of liberica coffee with the addition of α-amylase. Type of the research is an experimental research with randomized subjects post test only control group design. There is seven treatments consist of control group and experimental group exposed to ELF magnetic field with 300 µT and 400 µT intensity variation and for 30, 60, and 90 minutes for long variations. For hours 24, 48, day 3, day 4, and day 5, can make data retrieval after fermentation process. The result explain is effect of Extremely Low Frequency (ELF) magnetic field to pH and electrical conductivity in the wet fermentation process of liberica coffee with the addition of α-amylase was take effect to indicated by the variation of the graph. The process ELF magnetic field with 400 µT intensity for 30 minutes most influential on pH of liberica coffee. Meanwhile, the process ELF magnetic field with 300 µT intensity for 30 and 90 minutes most influential on electrical conductivity of liberica coffee in the wet fermentation with the addition of α-amylase. Keywords: ELF magnetic field; pH; electrical conductivity; fermentation; coffee.