Roasting Temperature Research Articles

Insights into acrylamide and furanic compounds in coffee with a focus on roasting methods and additives

Roasting is necessary for bringing out the aroma and flavor of coffee beans, making coffee one of the most consumed beverages. However, this process also generates a series of toxic compounds, including acrylamide and furanic compounds (5-hydroxymethylfurfural, furan, 2-methylfuran, 3-methylfuran, 2,3-dimethylfuran, and 2,5-dimethylfuran). Furthermore, not much is known about the formation of these compounds in emerging coffee formulations containing alcohol and sugars. Therefore, this study investigated the effect of roasting time and degree on levels of acrylamide and furanic compounds in arabica coffee using fast and slow roasting methods. The fast and slow roasting methods took 5.62 min and 9.65 min, respectively, and reached a maximum of 210 °C to achieve a light roast. For the very dark roast, the coffee beans were roasted for 10.5 min and the maximum temperature reached 245 °C. Our findings showed that the levels of acrylamide (375 ± 2.52 μg kg−1) and 5-HMF (194 ± 11.7 mg kg−1) in the slow-roasted coffee were 35.0 % and 17.4 % lower than in fast-roasted coffee. Furthermore, light roast coffee had significantly lower concentrations of acrylamide and 5-HMF than very dark roast, with values of 93.7 ± 7.51 μg kg−1 and 21.3 ± 10.3 mg kg−1, respectively. However, the levels of furan and alkylfurans increased with increasing roasting time and degree. In this study, we also examined the concentrations of these pollutants in new coffee formulations consisting of alcohol-, sugar-, and honey-infused coffee beans. Formulations with honey and sugar resulted in higher concentrations of 5-HMF, but no clear trend was observed for acrylamide. On the other hand, formulations with honey had higher concentrations of furan and alkylfurans. These results indicate that optimizing roasting time and temperature might not achieve the simultaneous reduction of all the pollutants. Additionally, sugar- and honey-infused coffee beans are bound to have higher furanic compounds, posing a higher health risk.

Study on the mechanism of Na2CO3-roasting decomposition for water leach residue

In the process of treating cerium fluorocarbon-cerium lanthanide mixed rare earth concentrates by sulfuric acid roasting method, a large amount of waste leach residue containing iron, rare earths and phosphorus produced by flood neutralization needs to be solved urgently. In this paper, sodium carbonate roasting decomposition was used to treat the water leach residue, in which iron and rare earths were transformed into oxides, and the phosphorus was transformed into sodium phosphate. The main reactions and thermodynamic mechanisms of the roasting decomposition process were investigated by thermogravimetric analysis, phase analysis and chemical analysis. When the mass ratio of sodium carbonate to water leach residue is 1.5:1, the roasting temperature is 700 °C, and the roasting time is 1.5 h, the leaching rate of phosphorus with the roasted product reaches more than 98%. Meanwhile, the phase of the roasted product after washing mainly consists of iron oxide and rare earth oxides. The combination of sodium carbonate roasting decomposition and water leaching is effective for the treatment of water leach residue, which provides an experimental and theoretical basis for solving the problem of environmental and resource waste caused by the accumulation of a large amount of water leach residue. In addition, because sodium carbonate can achieve the separation of iron and phosphorus, this method also has certain reference value for the recovery and utilization of iron phosphate in lithium iron phosphate battery waste.

Phase transition of Fe-containing phase in naturally cooled and water-quenched copper slags during high-temperature treatment

Iron (Fe) accounts for the highest-content of valuable metal recoverable from copper slag, which is most effectively recycled using pyrometallurgical high-temperature treatment. It is believed that the roasting temperature significantly affects the physical structure of copper slag. Therefore, this paper used thermogravimetry-differential scanning calorimetry (TG-DTG-DSC), X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), and scanning electron microscopy (SEM) to examine the Fe phase transformation in water-quenched copper slag (WQCS) and naturally cooled copper slag (NCCS) after high-temperature treatment (700–1100 °C). The main Fe-containing phases in the WQCS were represented by fayalite (Fe2SiO4) and magnetite (Fe3O4). As the temperature increased, the Fe2SiO4 underwent oxidative decomposition and re-formation, with a phase transition law of Fe2SiO4→Fe2O3+Fe3O4→FeSiO3+Fe2SiO4, while that of the Fe3O4 was Fe3O4→Fe2O3→Fe3O4. The phase transition processes were more complex in the NCCS, where the main Fe-containing phases were Fe2SiO4, Fe3O4 and chalcopyrite (CuFeS2). The oxidative decomposition temperatures of the Fe2SiO4 ranged from 700 °C to 850 °C. As the temperature increased, the phase transition law of Fe3O4 was Fe3O4→Fe2O3→Fe3O4→Fe2O3. Lastly, at 700 °C, the CuFeS2 began to oxidize and decompose, with a phase transition law of CuFeS2→FeS + Fe2O3→Fe3O4.

MULTIDIMENSIONAL ANALYSIS OF PHYSICOCHEMICAL TRANSFORMATIONS AND SENSORY ATTRIBUTES OF GREEN AND ROASTED COFFEE

This research presents a comprehensive analysis of the physicochemical and sensory attributes of green and roasted coffee beans from Rwanda, Colombia, Ethiopia, and Peru. Advanced image processing tools were utilized for defect analysis. Water activity, pH, mass loss, and moisture were determined, and thermal analysis were performed. Substantial variations in physicochemical properties were found among coffee beans of different origins. Utilizing a multi-objective optimization algorithm, Ethiopian coffee emerged as possessing the most optimal physicochemical characteristics. The optimal roasting temperature range for Ethiopian coffee was found to be 216.49 °C to 230.15 °C, with longer roasting times at lower temperatures producing more evenly roasted coffee. This study provides valuable information to coffee producers and processors to optimize the roasting process and improve coffee quality.

Lipidomics and metabolomics reveal the molecular mechanisms underlying the effect of thermal treatment on composition and oxidative stability of walnut oil

Roasting walnut kernel significantly improves the oxidative stability and sensory properties of its oil. However, the effect of roasting temperatures on the molecular change of main components and micronutrients in walnut oil is still unclear. Herein, lipidomics and metabolomics were integrated to comprehensively profile the walnut oil obtained at different roasting temperatures (30 °C, 120 °C, 140 °C, 160 °C, and 180 °C). Lipidomics showed that the content of glycerolipids, sphingolipids, and glycerophospholipids decreased with roasting temperatures, while the oxidized fatty acids and triglycerides increased. Ratios of linoleic acid and linolenic acid varied with roasting temperatures and were most close to 4–6:1 at 140 °C, 160 °C, and 180 °C. Major classes of micronutrients showed a tendency to increase at the roasting temperature of 120 °C and 140 °C, then decrease at 160 °C and 180 °C. Liposoluble amino acids identified for the first time in walnut oil varied with roasting temperatures. Correlation analysis demonstrated that the higher contents of liposoluble amino acids and phenolics are positively associated with enhanced oxidative stability of walnut oil obtained at 140 °C. Furthermore, glutamine and 5-oxo-D-proline were expected to be potential biomarkers to differentiate the fresh and roasted walnut oil. The study is expected to provide new insight into the change mechanism of both major lipids and micronutrients in walnut oil during the roasting process.

Optimization of Roasting Conditions on the Functional Properties of Jackfruit Seed Flours

Roasting of jackfruit seeds may improve the functional properties of jackfruit seed flours produced, which is vital for applications in baking and confectionaries. The objectives of this study were to determine the optimum roasting conditions of jackfruit seeds and to evaluate the functional properties of roasted jackfruit seed flours. Response surface methodology (RSM) was employed to optimize the roasting process in a temperature range (120 - 170 ℃) and in a duration range (20 - 70 min). The roasting temperature had a significant effect (p < 0.05) on water absorption capacity (WAC) and water solubility index (WSI), while roasting time significantly influenced (p ˂ 0.05) WAC, oil absorption capacity (OAC), bulk density (BD), WSI and swelling power (SP) of the jackfruit seed flours. Based on the results obtained from RSM, the optimum roasting conditions were 162 ℃ for duration of 20 min. The predicted values were 1.45 g/g, 0.96 g/g, 0.49 g/ml, 9.74 % and 4.35 g/g for WAC, OAC, BD, WSI and SP, respectively with the overall desirability of 0.693. The optimum conditions obtained from RSM can be used to produce roasted jackfruit seed flours with desirable functional properties for future development of bakery products.

Multiresponse Optimization of Value-Added Sesame Seed Candy

Sesame seed candy, traditionally produced from sesame seeds and sugar, is a confection. This study focuses on the optimization of value-added sesame seed candy from sesame seed, ginger, cinnamon, and honey employing numerical and graphical optimization, via desirability function technique. Experiments were conducted using a four-component constrained D-optimal mixture-process experimental design and the formulated candies were characterized. The formulation design constraints were: sesame seed (40 – 70%), ginger (10 – 30%), cinnamon (10 – 30%), honey (10 – 30%); while the processing factor were roasting temperature (100 – 150 ) and roasting time (10 – 30mins). Consumer acceptability was measured by 50 semi-trained regular consumers using a 9-point hedonic scale. The formulation that produced optimal candy of the highest desirability index of 0.506 was 43.53% sesame Seed,10% ginger, 16.47% cinnamon, and 30% honey, with 110 roasting temperature. and .27 min mixing time. The quality properties of the optimal value-added sesame seed candy were 7.95% moisture content, 20.76% dietary fibre, 37.89% protein, 10.40% carbohydrate, 17.20% fat content, 249.71mg calcium, 0.029mg/100g vitamin C, 353.54kcal energy value, 5.78 hardness, 6 taste, 5.74 colour, 5.87 chewiness, 5.92 gumminess, 5.6 crispness, 6.11 flavour, and overall acceptability of 6.20; based on 9-point hedonic scale. Sesame seed, the major ingredient in the candy production, has a composition of about 50 – 52% oil, 17-19% protein, 48.5% crude oil, 9.4% crude fibre, 4.2% ash. and 16-18% carbohydrate. Compared with the traditional sesame seed candy, the optimal value-added sesame seed candy was of higher quality.

Evaluation of different roasting condition on yield, physico-chemical characteristics, and antioxidant activity of cold-pressed sacha inchi (Plukenetia volubilis) oil

Sacha inchi (Plukenetia volubilis) seed oil, which is extracted from sacha inchi seeds, may possibly establish a nutritive source which prosperous of nutraceutical value. It is paramount to assess the oil production potential of industrial oilseeds for manufacturing applications. Roasting is a key procedure for preparing oils of plant origin, which leads to crucial changes in the oil quality. With the aim of evaluating new sources for the industrial production of edible oil, the effect of different temperatures (60, 80, 100, and 120 °C) and times (10, 20, and 30 min) of roasting as an important pretreatment was evaluated on the yield, physical-chemical and qualitative properties of cold-pressed sacha inchi seed oil. Results showed that the oil yield, acid value (AV), peroxide value (PV), p-anisidine value, and oil stability index (OSI) increased, whereas the iodine value (IV) and conjugated diene (CD) content decreased with treatment temperature and time. There were no obvious different in the fatty acid composition. Prolonged roasting temperature and time increased tocopherol, phytosterol, squalene, total phenolic content (TPC), and antioxidant activity. Current findings indicated that thermal processing may have positive effect towards the quality and nutritional content of sacha inchi seed oil.

Preliminary Investigation on the Thermodynamic Evaluation and Phase Evolution of Soda Ash-Assisted Roast Treatment of Alluvial Columbite for Recovery of Niobium and Tantalum

AbstractAlkaline roasting of a low-grade alluvial silica-based columbite bearing mineral from the Rayfield–Jos deposits (located in South Jos, Plateau state, Federal Republic of Nigeria) was conducted with specific emphasis on the evaluation of thermodynamic reactions as well as the mineral phase evolution during the extraction of Nb and Ta. An isothermal roasting procedure was investigated in order to understand the effects of different soda ash to sample mass ratios as well as the roasting temperatures on the measure or rate of the recoveries of Nb and Ta complexes. Thus, the feasibility rate of a successful alluvial columbite mineral roasting was determined to be influenced by certain optimal process conditions or optimum values of the study parameters, such as alkali to sample mass ratio and, more essentially, the roasting temperature. Therefore, the thermodynamic feasibility of the alkali-carbothermic roasting procedure was also investigated and the resulting chemical reactions were evaluated using the HSC chemistry 9.0 software. Premised on this, the results obtained as well as the thermodynamic data realized from the study demonstrated the feasibility of successful dissolutions of Nb and Ta into a pregnant leached-liquor stream (PLS), without the use of the conventional harmful, hazardous, toxic, and environmentally unfriendly hydrofluoric (HF) acid.

A new strategy for clean utilization of zinc oxide dust: Preparation of spinel zinc ferrite by solid phase reaction and its catalytic degradation of organic wastewater

The resource utilization of zinc oxide dust (ZOD) is mainly focused on the efficient recovery of zinc by acid leaching at present. Because of a large amount of iron in ZOD and zinc components existing in multi-phase, the problems of low zinc recovery and the separation of zinc and iron ions in the leaching solution are unavoidable. Considering the characteristics of ZOD and the advantages of spinel zinc ferrite (ZnFe2O4) in the advanced oxidation degradation of organic wastewater, a new strategy for clean utilization of ZOD is proposed. The leaching efficiency of soluble zinc components in ZOD reached 96.7 % by selective dissolution with low concentration sulfuric acid solution, and the leaching solution without iron ions can be directly used for electrolytic zinc recovery. The insoluble components of zinc and iron in the leaching residue were converted into ZnFe2O4 by solid phase roasting. By adjusting the roasting temperature, time and molar ratio of Fe/Zn in roasting process, the proportion of zinc elements in the form of ZnFe2O4 reached 99.56 % and a single spinel zinc ferrite product was obtained. Zinc ferrite product activated by ball milling for 2 h (ZFO-2) showed very high catalytic activity in the treatment of organic wastewater by peroxonosulfate (PMS). In the presence of 1 mM PMS and 1 g/L ZFO-2 at 20 °C, the ZFO-2/PMS system achieved a removal rate of over 90 % within 40 min for wastewater containing RhB, MO and MG (10 mg/L). In addition, ZFO-2 is ferromagnetic and easily recovered by magnetic separation. The new strategy proposed in this paper takes into account the efficient recovery of soluble zinc components and the cooperative high-value utilization of insoluble components of zinc and iron in ZOD, which is a comprehensive utilization method with more sustainable resource allocation.

Preparation of superior magnetite concentrate from waste tailings with clean energy: Semi-industrial utilization, economic profits, and environmental benefits

The effective utilization and clean recycling of tailings are important to solve land occupation and waste mine pollution problems. A semi-industry experiment of hydrogen-based mineral phase transformation for tailings is conducted with a roasting temperature of 500 °C, a reducing gas concentration of 20 %, a total gas volume of 12 m3/h, and a handing capacity of 100 kg/h. A concentrate product with an iron grade of 66.75 % and a recovery of 82.79 % was obtained. The detail roasted iron phases of 23.96 % Fe3O4 (A) and 47.93 % Fe3O4 (B) were obtained. The maximum saturation magnetization increased from 6.69 to 18.96 A·m2·kg−1 after roasting. The surface of Fe3O4 occurred on the iron mineral surface. The SEM-EDS results showed the order of reduce behavior. In addition, the pollutions of the roasting process were controlled strictly, and the final benefit was calculated to be $33.86 million.

Facile fabrication of nickel-cobalt oxide for efficient oxygen evolution reaction from ammonia leaching solution of spent lithium-ion batteries

Ammonia leaching has been gained considerable attention for its ability to selectively extract nickel and cobalt from spent ternary cathode material. Despite its efficacy, the subsequent recovery of ammonia leachate remains challenging. Herein, a short-process and sustainable method for the synthesis of nickel-cobalt oxide via ammonia evaporation of ammonia leachate and heat treatment of the resultant precursor has been proposed. The ammonia evaporation process, conducted at an evaporation temperature of 130 °C with hydrazine hydrate as a reducing agent, facilitated the precipitation of ∼95% Ni and ∼99% Co as a precursor. Subsequently, the effect of precursor roasting temperature on electrode material synthesis was systematically studied. The precursor was roasted at 300 °C to successfully synthesize nickel-cobalt oxide. Physical and electrochemical characterizations revealed that the nickel-cobalt oxide possesses a significant specific surface area of 161.150 m2/g, and exhibits excellent oxygen evolution reaction performance, evidenced by an overpotential of 350.7 mV at 10 mA/cm2 and a Tafel slope of 159.8 mV/dec. Overall, the proposed method not only promotes the recycling and utilization of ammonia reagents and mother liquor, but also introduces an innovative approach for the synthesis of nickel-cobalt oxide as an electrode material.

The enrichment and transformation mechanism of Pb and Cu in suspension magnetization roasting and magnetic separation from iron tailings

Magnetic iron concentrate (MIC) and nonmagnetic tailings (NT) are obtained from magnetization roasting of iron tailings (IT). MIC containing Pb adversely affects blast furnace ironmaking, while Cu in NT poses leaching risks. This study utilizes fast pyrolysis-suspension magnetization roasting to recover iron from IT. The enrichment of Pb, Cu, and the phase transformation mechanism of Cu in the process of suspension magnetization roasting and magnetic separation were clarified. Results show 96.13 % of Cu in IT is in limonite and 47.23 % of Pb is associated with iron. At 750 °C, with 10 % dosage of biomass pyrolysis and 10 min roasting, Pb, Cu and Fe contents in MIC are 0.96, 2.14 and 3.17 times that of NT. Increasing roasting temperature enhances Cu associated with iron enrichment into the MIC, while oxidation of free copper oxide associated with iron forms magnetic copper ferrite. Increased pyrolyzed biomass leads to over-reduction of magnetite associated with Cu to FeO associated with Cu, promoting magnetic copper ferrite decomposition into FeO and free copper oxide. This research holds significant importance in controlling the quality of MIC and the storage risk of IT, and provides theoretical guidance for the regulation and recovery of valuable metals in subsequent processes.

Removal of arsenic and recovery of tin from arsenic-containing multi-metallic materials by vacuum reduction roasting

Arsenic-containing multi-metallic materials, are typical hazardous wastes generated in the process of tin recovery from zinc smelting leach slag, exhibit low resource utilization and pose a significant risk of environmental pollution. This research proposed a vacuum reduction roasting technique utilizing anthracite as the reducing agent to remove arsenic and reclaim tin from such materials, characterized by high arsenic levels (8∼wt%) and the presence of several valuable metals. The results indicated that the arsenate in these materials was transformed into As2O3, which has better volatility, while SnO2 was converted to SnO and Sn. Moreover, under the optimal conditions of a roasting temperature of 750 °C, 10 % anthracite, and a roasting duration of 3 h, the arsenic removal efficiency reached 96.97 %, and the tin recovery rate was 84.48 %. Consequently, the arsenic concentration decreased to 0.53 %, and the tin concentration in the roasted product increased from 17.70 % to 31.41 %. The final product contained phases of arsenic and tin, including Sn, SnO2, and FeAs. Meanwhile, this study provides a promising solution for the green and efficient separation of tin and arsenic in typical arsenic-containing multi-metallic materials.

Optimisation of thermal regime and consolidation properties of high-silica magnesium-containing pellets

An in-depth study on the preparation process of high-silica magnetite magnesium pellets based on a grate-rotary kiln process is of great significance for promoting the utilisation of low-grade magnetite resources. When the magnetic hematite ratio is 30% and the proportion of magnesia is 1.5%, the performance of green pellets is the best. The preparation of high-silica magnesium pellets requires two stages of grate preheating for additional heating, and the appropriate preheating system is 1150°C for 15 min. The suitable magnetic hematite mixture ratio of pellets should not exceed 30%, and the reasonable magnesia ratio should not exceed 1.5%. Otherwise, the preheating temperature should be further increased, or the preheating time should be extended. The suitable roasting temperature is low, only 1225°C for 15 min, and the pellet strength can reach more than 2365N. Magnetic hematite and added magnesium flux inhibited the continuous crystallisation consolidation property in the pellet. The high SiO2 content in the gangue of high-silica magnetite impedes the recrystallisation consolidation of Fe2O3 particles in the pellet. At the same time, the primary Fe2O3 in the magnetic hematite mixed ore is less reactive than the new Fe2O3 in the magnetite oxidation. With the roasting process, the magnesium ferrite content in the pellet increases, and the recrystallisation consolidation is inhibited, so the grate-rotary kiln process to produce high-silica magnesium-containing pellets is suitable to use a higher preheating temperature to meet the requirements of grate-rotary kiln pellet strength.

Defects of Coffee Beans with Different Postharvest Processes and Roasting Temperatures on Volatile Compounds of Coffee Beans from Coffee Small-Scale Industries of West Lampung Indonesia

Specialty coffee is processed by performing high standards nationally (SNI) and internationally (SCAA). Good handling in the small coffee industry is essential to producing coffee raw materials as a refreshing drink. The aroma released from the best coffee beans gives an emotional flavor to the drinker - the aroma produced from the best coffee beans with different post-harvest methods. This study analyzed the physical quality of moisture content, coffee bean defects from dry processing post-harvest handling (natural and honey), and different roasting temperature differences to produce volatile compound profiles from three small-scale coffee industries. Six samples of raw materials from 3 small-scale coffee industries were selected by purposive sampling with the criteria that the processing farmer had performed SNI standards. Six coffee samples from the September harvest in 2022. Observations were made in the laboratory for analysis of moisture content and quality defects of coffee beans, then roasted by the industry and analyzed descriptively and multivariate analysis for volatile compounds. The moisture content of coffee beans from all coffee industries has met the requirements following SNI 01-2907-2008, that the moisture content is not more than 12.5 %. All coffee beans produced have 50 % potential as fine robusta coffee beans because they have no primary defects. Increasing the roasting temperature on all coffee beans increases volatile compounds. Coffee beans processed with honey produced more volatile compounds than the natural post-harvest method. The caffeine content in all post-harvest processing processes in the three industries has a difference in concentration due to differences in roasting temperature and time. The study that in the three-ground coffee small-scale industries processed by the natural post-harvest method, carbamic acid compounds were suspected to be from carbamate class insect pesticides (carbofuran) and the fungicide pyraclostrobin. Considering that pesticide residues harm human health, it is essential to implement measures to educate farmers to use organic fertilizers and ensure consumer safety. HIGHLIGHTS Kopi merupakan komoditas unggulan Provinsi Lampung Indonesia Kopi cacat mempengaruhi Kualitas mutu biji kopi Kopi yang dihasilkan IKM merupakan Kopi robusta petik buah merah Terdapat temuan kontaminasi dari senyawa kimia carbamate acid dari pemakaian herbisida/insektisida yang digunakan petani GRAPHICAL ABSTRACT

Carbothermal reduction between MOF-derived carbon and spent battery powder for metal recovery: Thermogravimetric behavior and kinetic analysis

The combined hydrometallurgical and pyrometallurgical process is an innovative method for recycling spent batteries. This process includes a carbothermic reduction step that reduces the valence of valuable metals in the batteries, facilitating subsequent leaching, which is a crucial stage in the recycling process. Additionally, the use of new carbon materials in electrode materials for ternary lithium batteries, referred to as LIBs, is increasing. These materials typically have high porosity and a large specific surface area. In this study, two types of nanoporous carbon (NC) commonly used in electrodes, namely Al-PCP-800 and ZIF-8–800, were prepared to investigate their effects on the carbothermic reduction stage of recycling spent batteries. The carbothermal reduction reactions of spent LIBs powder mixed with activated carbon and the two types of NC were examined using a thermogravimetric balance (TG/DTG). Kinetic characteristics were calculated in the interval of maximum weight loss rate using five kinetic models: VM, RPM, URCM, KAS, and FWO. The kinetic analysis revealed that the KAS and FWO models, which exhibited higher correlation coefficients, more accurately described the carbothermic reduction reactions. TG analysis showed that the sample mixed with 25 % ZIF-8–800 achieved the lowest temperature at the weight loss peak for the maximum weight loss rate, 769°C at a heating rate of 20 °C/min. Additionally, the reaction activity of NC with the positive material in the spent LIBs powder was stronger than that of activated carbon. Among the models, the sample mixed with 25 % ZIF-8–800 exhibited the lowest activation energies, recorded at 171.83, 28.48, 122.22, 199.49, and 143.45 kJ/mol, respectively. XRD and XPS characterizations of the roasted products from the spent LIBs powder mixed with the three carbon materials at various roasting end temperatures demonstrated that the cathode materials initially decomposed into Mn3O4, NiO, CoO, Li2O, and Li2CO3. At higher temperatures, Mn3O4, NiO, and CoO were further reduced to MnO, pure metallic Co, and pure metallic Ni, respectively. The sample mixed with ZIF-8–800 showed the most substantial reduction of metallic elements, with the relative contents of pure metallic Ni, pure metallic Co, and low-valent Mn elements reaching 5.50 %, 4.41 %, and 71.29 %, respectively, at a final roasting temperature of 800 °C. Therefore, NC demonstrated greater reactivity in the reduction reactions with the cathode material in the spent LIBs powder, ranking in the order of ZIF-8–800 > Al-PCP-800 > activated carbon.

Karakteristik Teh Jelai (Coix Lacryma-Jobi.L) dengan Perlakuan Waktu dan Suhu Roasting yang Berbeda

Jelai (Coix Lacryma Jobi.L) seeds are grains that have the potential to be processed into herbal teas which are served either hot or cold. Jelai tea can be processed through a high-temperature roasting process to enhance the aroma and taste. Temperature and length of roasting time are factors that affect grain characteristics. The purpose of this study was to evaluate the effect of temperature and roasting time on water content, color of barley powder and the effect of temperature and roasting time on pH, total dissolved solids, and organoleptic of jelai tea. The study used a factorial completely randomized design (CRD) with two factors: (t) roasting temperature (180oC, 200oC, 220oC) and (f) roasting time (5 minutes, 10 minutes, 15 minutes). The roasting temperature and time reduced the water content of jelai powder from 11.04% to 1.57% (wb), increased the dissolved solids from 0.26 oBrix to 5.16 oBrix, and lowered the pH from 7.04-6.79. The higher the temperature and roasting time, the darker the color of the powder and the barley tea (brown), increase the burning aroma (burn aroma), nutty smelling, burn flavor and the sour taste of jelai tea. The highest results were obtained at 220oC combined roasting time of 10 minutes and 15 minutes. Overall, the level of panelist acceptance of jelai tea was in the rather favorable category for all treatments (2.77 – 3.42).

Process and mechanism of preparing metallized blast furnace burden from metallurgical dust and sludge

Metallurgical dust and sludge are solid waste resources with recycling value. In recent years, rotary hearth furnace has become the most important means to treat metallurgical dust and sludge because of its wide range of raw materials and strong treatment capacity. In this study blast furnace ash and converter sludge were selected as the research objects, and high-quality metallized pellets were prepared based on the rotary hearth furnace process. The strength changed of pellets, the reduction process of iron oxides and the removal process of zinc during the roasting of pellets in rotary hearth furnace were studied. To explore the reasonable roasting condition for preparing metallized pellets in rotary hearth furnace. The optimum roasting temperature of the pellets was 1250℃ and the roasting time was 25 min. The compressive strength, metallization rate and dezincification rate of metallized pellets reached 1361N, 97.44% and 95.67%, respectively. The efficient resource utilization of various metallurgical dust and sludge is realized.

Effect of Variations of Roasting Temperature on the Physicochemical Properties of Robusta Coffee (Coffea canephora L.)

Robusta coffee has become the most planted coffee in Indonesia and a vital commodity. Robusta coffee is characterized by a more caffeine content, bitter taste, and slightly more acidic compared to that of Arabica coffee. The roasting process is important factors contributing to shape taste, aroma, and the physical characteristics of coffee beans. This study seeks to compare the physicochemical properties of Robusta coffee originated from West Lampung and Tanggamus, and to assess the impact of roasting temperature (light at 190°C, medium at 200°C, and dark at 210°C). Measurement was conducted in duplicate. The findings indicated significant differences (p<0.05) in ash content, moisture content, and pH between coffee from West Lampung and Tanggamus, while color and caffeine content did not differ significantly (p>0.05). The geographic origin of coffee beans influences their physicochemical properties. Moreover, all examined parameters (ash content, moisture content, pH, color, and caffeine content) show a direct relationship with the roasting temperature. Consequently, roasting temperature plays a pivotal role in shaping the physicochemical properties of coffee beans. Keywords: Caffeine, Coffee, Region, Roasting, Temperature.