Coffee Roasting Process Research Articles

Diagnosis and prognosis of soybean roaster failures using particle swarms

In industry, the monitoring and diagnosis of production processes are crucial issues in ensuring plant reliability, performance and quality. In particular, food processing operations, such as coffee roasting, are subject to numerous risks of failure that can impact on productivity and the quality of the final product. In this context, the main objective of this study was to develop an innovative method for the diagnosis and prognosis of failures in a coffee roasting process. The proposed method differs from standard approaches by using the particle swarm optimization (PSO) algorithm applied to the analysis of signatures of key process variables. This new approach has improved fault detection, with a recognition rate of over 90% for the main types of fault identified, such as heating problems, air obstructions or leaks. In addition to diagnostics, the method has also demonstrated its effectiveness in prognosticating the state of health of the process, with an average error on the prediction of remaining service life reduced to 15%, compared with 35% for fixed-threshold methods. This work has therefore enabled us to develop an innovative method offering superior performance to standard approaches for the diagnosis and prognosis of failures in the roasting process.

The Development of Sustainable Biocomposite Materials Based on Poly(lactic acid) and Silverskin, a Coffee Industry By-Product, for Food Packaging Applications

Aligned with the principles of the circular economy and aiming at the production of environmentally friendly materials for food packaging applications, sustainable biocomposite films based on poly(lactic acid) (PLA) and coffee silverskin (SS), were developed. Coffee silverskin is a by-product of the coffee roasting process, while PLA is one of the most promising bio-based polymers. Several composites were prepared with different loadings of SS, ranging from 2.5 to 20 wt.%, via the solution casting method. The findings indicated that the effective dispersion of coffee silverskin in PLA was successfully accomplished and that a bleaching treatment of the filler leads to better interfacial interaction. The addition of silverskin, in any proportion, did not affect the melting point and glass transition temperature of the polymer matrix or the oxygen permeability of the film. Moreover, the degree of swelling was increased, more so for the films with modified particles, whereas the water vapor transmission rate and permeability increased only after the addition of high amounts (>10%) of surface-treated silverskin. A gradual decrease in color lightness was measured with the increasing concentration of silverskin, and the color was more intense in the untreated samples. The antioxidant activity of the films increased gradually with increasing additions of coffee silverskin due to the presence of compounds such as polyphenols. The chemical treatment of coffee silverskin resulted in the films having improved mechanical properties, as the chemical treatment facilitated stronger bonding between the base material and the additive. Therefore, sustainable composites with enhanced antioxidant activity can be produced by the incorporation of a food industry by-product into a PLA matrix.

Exposures and Health Effects of Diacetyl and 2,3-Pentanedione in a Coffee Processing Facility

Diacetyl and 2,3-pentanedione are alpha-diketones that are generated during the coffee roasting process and have been shown to be related to respiratory symptoms, abnormal lung function, and in rare cases, an irreversible disease called obliterative bronchiolitis. This study measured personal exposures in a coffee roastery in New Zealand using thermal desorption tubes and explored the prevalence of respiratory symptoms with a health questionnaire. Exposures from task samples were highest for grinding (Geometric Mean (GM): 22.5 ppb diacetyl; GM: 19.3 ppb 2,3-pentanedione), followed by packaging (GM: 10.8 ppb diacetyl; GM: 9.3 ppb 2,3-pentanedione) and then roasting (GM: 4.7 ppb diacetyl; GM: 4.1 ppb diacetyl). 8-h time-weighted average (TWA) diacetyl exposures exceeded the National Institute of Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) of 5 ppb for Roaster/Packager (GM: 6.6 ppb) and Grinder (GM: 5.3 ppb). 8-h TWA concentrations were below the NIOSH REL of 9.3 ppb for 2,3-pentanedione (Roaster/Packager, GM: 5.7 ppb; Grinder, GM: 4.6 ppb). Workers reported nose, eye symptoms and systemic symptoms (flu-like illness or achy joints, fever or chills, or unusual tiredness or fatigue). The results indicated that exposure was highest for tasks involving ground coffee beans and that coffee processing workers can be exposed to alpha-diketones above the NIOSH RELs. Further research into alpha-diketone exposure and health effects, and control measures to minimise exposure are recommended.

Sustainable Valorization of Coffee Silverskin: Extraction of Phenolic Compounds and Proteins for Enzymatic Production of Bioactive Peptides.

Coffee silverskin (CS), a by-product of the coffee roasting process, has high protein content (16.2-19.0%, w/w), making it a potential source for plant protein and bioactive peptide production. This study aims to develop innovative extraction methods for phenolic compounds and proteins from CS. The conditions for hydrothermal (HT) extraction of phenolic compounds from CS were optimized by varying CS loading (2.5-10%, w/v), temperature (110-130 °C), and time (5-30 min) using a one-factor-at-a-time (OFAT) approach. The highest TPC of 55.59 ± 0.12 µmole GAE/g CS was achieved at 5.0% (w/v) CS loading and autoclaving at 125 °C for 25 min. Following hydrothermal extraction, CS protein was extracted from HT-extracted solid fraction by microwave-assisted alkaline extraction (MAE) using 0.2 M NaOH at 90 W for 2 min, resulting in a protein recovery of 12.19 ± 0.39 mg/g CS. The CS protein was then subjected to enzymatic hydrolysis using protease from Bacillus halodurans SE5 (protease_SE5). Protease_SE5-derived CS protein hydrolysate had a peptide concentration of 0.73 ± 0.09 mg/mL, with ABTS, DPPH, and FRAP values of 15.71 ± 0.10, 16.63 ± 0.061, and 6.48 ± 0.01 µmole TE/mL, respectively. Peptide identification by LC-MS/MS revealed several promising biological activities without toxicity or allergenicity concerns. This study's integrated approach offers a sustainable and efficient method for extracting valuable compounds from CS, with potential applications in the food and pharmaceutical industries.

Analysis of Temperature Distribution on the Coffee Roaster Drum for a Capacity of 2 kg Using Computational Fluid Dynamics (CFD)

Coffee, one of Indonesia's largest commodities, is often processed using traditional methods and tools that rely heavily on manual labor and can be labor-intensive. To make the coffee roasting process more efficient and reduce the need for human effort, a coffee roasting machine can be used. This study aimed to analyze coffee roasting drums using computational fluid dynamics (CFD) to determine the optimal drum thickness and rotation speed in a coffee roasting machine. The study considered three different thicknesses (1mm, 2mm, and 3mm) and three different rotation speeds (60rpm, 65rpm, and 70rpm). The coffee roasting drum was modeled using CFD. The study's results showed that a drum thickness of 2mm and a rotation speed of 70rpm achieved the best heat distribution during roasting, reaching the desired temperature in 900 seconds. This information could be used to design a more efficient coffee roasting machine or improve the performance of existing machines.

Design of coffee roaster with controlled temperature system to maintain the sustainability of coffee roasting process

One of the most important process in producing coffee beverage is the roasting stage. Nowadays, roasting process is done using mechanic process by giving high temperature to coffee beans. However, the temperature is not controlled and the capacity tend too high or low, expensive and need a qualified coffee roaster to do this stage, which is not suitable for small and micro bussiness. This research aimed to answer those problems by designing a roasting machine that could control the temperature with a capacity of 4 kg per process. Result showed that the roasting machine could roast the coffee bean in 52 minutes to achieve the medium to dark roast level, and it is suitable for the small and micro bussiness according to the roasting profile and from the economic analysis this machine is feasible. Moreover, this coffee roaster is energy efficient and could provide a better livelihood for the user to produce the roasted beans even with no roasting experience.

The Potential of NIR Spectroscopy and Chemometrics to Discriminate Roast Degrees and Predict Volatiles in Coffee.

This study aimed to establish a rapid and practical method for monitoring and predicting volatile compounds during coffee roasting using near-infrared (NIR) spectroscopy coupled with chemometrics. Washed Arabica coffee beans from Ethiopia and Congo were roasted to industry-validated light, medium, and dark degrees. Concurrent analysis of the samples was performed using gas chromatography-mass spectrometry (GC-MS) and NIR spectroscopy, generating datasets for partial least squares (PLS) regression analysis. The results showed that NIR spectroscopy successfully differentiated the differently roasted samples, similar to the discrimination achieved by GC-MS. This finding highlights the potential of NIR spectroscopy as a rapid tool for monitoring and standardizing the degree of coffee roasting in the industry. A PLS regression model was developed using Ethiopian samples to explore the feasibility of NIR spectroscopy to indirectly measure the volatiles that are important in classifying the roast degree. For PLSR, the data underwent autoscaling as a preprocessing step, and the optimal number of latent variables (LVs) was determined through cross-validation, utilizing the root mean squared error (RMSE). The model was further validated using Congo samples and successfully predicted (with R2 values > 0.75 and low error) over 20 volatile compounds, including furans, ketones, phenols, and pyridines. Overall, this study demonstrates the potential of NIR spectroscopy as a practical and rapid method to complement current techniques for monitoring and predicting volatile compounds during the coffee roasting process.

Study of Coffee Bean Displacement Inside Drum Roaster Using Force Balance Analysis

The drum roaster's design and operating method significantly affect the coffee roasting process. The coffee bean displacement inside the drum roaster can be observed to compare the drum roaster's different designs and operating methods. The coffee bean movement is crucial since it affects the heat transfer distribution among coffee beans inside the drum roaster. The more dynamic displacement of coffee beans gives more even heat distribution. Force balance analysis can be used to predict the coffee bean displacement since it can predict particle movement with mutable variables. This paper compares the coffee bean displacement inside the drum roaster with flippers and without flippers using simple force balance analysis. The analysis involves tangential force, centrifugal force, frictional force, and the beans' weight itself. The analysis shows that the radius of the drum roaster (r) and angular acceleration (ω) significantly change the resultant force's dynamic, and the various tilt angle of flippers (β) did not too significantly affect it. The bigger radius (r) and angular acceleration (ω) generate a stronger centrifugal force influencing the bean's equilibrium. The direction change of force resultant applied to the bean is more smooth in the drum with flippers than without flippers. Keywords: Coffee bean displacement, Drum coffee roaster, Force balance analysis, Resultant force Turning point duration

Design and Development of a Coffe Blending Device with Carbon Monoxide (CO) Level Identification Based on Artificial Neural Networks

Coffee is categorized into three types Robusta, Arabica, and Liberica. The roasting process is the most crucial step in developing the aroma, flavor, and underlying color that determine coffee quality. The coffee roasting process produces complex aroma compounds that impart the desired taste and aroma characteristics of coffee. This research aims to design a coffee content detection tool by determining the carbon monoxide (CO) level in Arabica, Robusta, and Liberica coffee. The research uses the Backpropagation artificial neural network method with 2 hidden layers, including 4 input layers and 3 output layers, to identify the tested coffee varieties. The highest carbon monoxide (CO) levels were found in Arabica Special coffee, with an ADC level of 662 carbon monoxide gas. The lowest carbon monoxide (CO) levels were detected in Liberica coffee, with an ADC level of 105 carbon monoxide gas. Coffee identification was carried out using an artificial neural network method with a success rate of 98% for Liberica coffee, 100% for Arabica coffee, and 98% for Robusta coffee.

Effect of curing strength in lime – coffee husk ash mixture on clay

Coffee husk is a fibrous material obtained from coffee beans. It is a waste from coffee industries. In order to reduce the disposal problem, utilization of waste in civil engineering works is very important. This study has been carried out to explore the utilization of coffee husk ash for improving properties of Kumarakom clay. Kumarakom clay is known to be very problematic in construction field. It is considered neither suitable for building houses nor for construction of roads. Coffee husk is a by-product of coffee roasting process. After removal of coffee beans, a huge amount of coffee husk is generated later, the ash obtained after burning of coffee husk i.e; Coffee Husk Ash (CHA) is used in this study. The Kumarakom clay can be stabilized with different percentages (5, 10, 15, 20, 25) of coffee husk ash and variation in strength can be determined by Unconfined Compression Strength (UCS) test and proctor compaction test. The optimum percentage is obtained at 20% of CHA addition. Finally, the curing strength test is conducted for varying percentages of CHA – clay mix and optimum percentage of CHA – lime mix for about 7, 14, and 28 days.

Hybrid materials based on deep eutectic solvents for the preconcentration of formaldehyde by SPME in coffee beverages

Coffee is one of the most widely consumed beverages. It can be prepared from green or roasted beans or from instant coffee. Unfortunately, in addition to the aroma obtained in the coffee roasting process, among others, formaldehyde can be produced. In this study, thin-film solid-phase microextraction was used to preconcentrate trace amounts of formaldehyde in different types of coffee with different roasting levels. For this purpose, 18 hybrid materials based on deep eutectic solvents were synthesized and tested as sorbents in thin-film solid-phase microextraction. The coffee samples were brewed, and then formaldehyde present in them was derivatized using the Nash reagent. The sample preparation procedure was optimized for selected DES-based sorbent using a central composite design method and validated. Formaldehyde was determined in almost all samples of second-crack coffee (roasted at 240 °C) at 0.17–0.75 ng mL−1 and in darker-colored instant coffees at 0.18–0.54 ng mL−1.

Study on biogas production from coffee wastes and cow-dung fermentation and its use towards reducing emissions from coffee roasting

The production of high-quality coffee for export is an important industry in Indonesia. However, coffee processing produces unavoidable waste and emissions to the environment; 1 kg of cherry beans (CB) needs 3 kg of water for processing (2 kg for CB selection by floating, 1kg for wash-fermentation). One kg CB generates several waste and product streams: cherry skin (44%), beans (20%), parchment (5%), pulp (4%), silverskin (0.5%), and volatiles (26.5%). This study utilized the wastewater from the washed-coffee processing such as fermentation wash water and coffee pulp. The materials were mixed with cow dung from local farms for anaerobic processing in a one-gallon digester. This research took into consideration three variations: cow dung mixed with water in the same amount (1:1); cow dung and fermentation washing wastewater (1:1); and cow dung and pulp (1:1). The resulting biogas was analyzed with gas chromatography for comparison. Biogas yield was used to estimate the potential for supplying heat and electricity for use in the coffee roasting process. Alternative energy sources were also considered in the following combinations: biogas-electricity (solar panels) and LPG-electricity (fossil). A life cycle assessment was performed on scenarios to calculate global warming potential (GWP). This study will be used as a pilot project toward a zero-waste and zero-emission coffee industry. The scenario with the lowest GWP can be used as a reference for the sustainability of coffee production.

From Coffee Waste to Active Ingredient for Cosmetic Applications.

Coffee silverskin (CS) is the thin epidermis covering and protecting the coffee bean and it represents the main by-product of the coffee roasting process. CS has recently gained attention due to its high content in bioactive molecules and the growing interest in valuable reutilization of waste products. Drawing inspiration from its biological function, here its potential in cosmetic applications was investigated. CS was recovered from one of the largest coffee roasters located in Switzerland and processed through supercritical CO2 extraction, thereby generating coffee silverskin extract. Chemical profiling of this extract revealed the presence of potent molecules, among which cafestol and kahweol fatty acid esters, as well as acylglycerols, β-sitosterol and caffeine. The CS extract was then dissolved in organic shea butter, yielding the cosmetic active ingredient SLVR'Coffee™. In vitro gene expression studies performed on keratinocytes showed an upregulation of genes involved in oxidative stress responses and skin-barrier functionality upon treatment with the coffee silverskin extract. In vivo, our active protected the skin against Sodium Lauryl Sulfate (SLS)-induced irritation and accelerated its recovery. Furthermore, this active extract improved measured as well as perceived skin hydration in female volunteers, making it an innovative, bioinspired ingredient that comforts the skin and benefits the environment.

Analisis Kinerja Alat Raosting Kopi Kapasitas 2kg Tipe Silinder Horizontal

Roasting is a process of frying coffee without oil using high temperatures which aims to speed up the process of frying coffee beans. The coffee roasting process aims to form the taste and aroma of the coffee beans. The coffee roasting equipment used in this study was a horizontal cylinder type coffee roaster with a capacity of 2 kg. This machine rotates with an electric dynamo. It has a cylindrical tube with a length of 27.5 cm and the heat comes from an LPG (Liquefied petroleum gas) stove. The purpose of this research is to test the performance of coffee roasting equipment. The data that needs to be measured from this coffee roasting tool is the need for electrical power used, roasting capacity and the change in color of the coffee when it is roasted. The electric power used is 12 volts 15 amperes. The results of the dark roast test at 200°c at 21 minutes. The maximum capacity of this horizontal cylinder type roasting machine is 2 kilograms

Application of Response Surface Methodology to Optimize the Extraction Process of Bioactive Compounds Obtained from Coffee Silverskin

The present research focused on the extraction optimization of bioactive compounds from coffee silverskin (CS), a by-product generated in large amounts worldwide during the coffee roasting process. The effect of the different extraction conditions has been investigated by the exploitation of the response surface methodology (RSM). The antioxidant activity assays, such as ABTS and FRAP, total phenolics content (TPC), browning index (BI), and chromatographic analysis of caffeine and chlorogenic acids contents have been performed to evaluate the CS extracts characteristics. The most favorable extraction conditions on the maximum recovery of antioxidant bioactive compounds were found to be as follows: 50% aqueous solution of ethanol (v/v) in solvent solid ratio of 45 mL/g CS, during 30 min at 60 °C. The CS extract prepared in this extraction variant reached the values for ABTS, FRAP, TPC, and BI approximately 101.6 µmol Trolox/g d.m. CS, 132.3 µmol Fe (II)/g d.m. CS, 52.3 µmol GAE (gallic acid equivalent) per g d.m. CS, and 0.3, respectively. Additionally, this extract is rich in caffeine (6 mg/g d.m. CS) and chlorogenic acids (0.22 mg/g d.m. CS). In conclusion, this research demonstrates that CS could be considered as a valuable by-product of bioactive compounds with potential applications in the food industry.

Assessing the Effectiveness of Fuzzy-PID Controller under Temperature Setpoint Changes During Coffee Roasting Process

Roasting coffee is an essential step in the production of coffee because it affects the flavour, aroma, and overall quality of the final product. Temperature control during the roasting process is essential to achieve a consistent and desired taste. This study seeks to assess the performance of a Fuzzy PID (FPID) controller during coffee roasting when the temperature setpoint varies. The temperature range in this study is from 34-200℃. The study employs an SR500 coffee roaster as the process plant, a FOPDT model structure, a PID-AMIGO benchmark controller, FPID-3 and FPID-5 controllers as the proposed controller. The study includes both simulation and real-time testing for the FPID-5 controller. The results for the FPID-5 controller indicated that the overshoot was reduced to 0.24% and 4.04% in simulation and 2.9% and 8.6% in real-time testing, representing an improvement of more than 90% in overshoot reduction compared to the PID controller. Thus, the proposed FPID-5 controller has been proven to effectively suppress overshoot during temperature setpoint changes in the coffee roasting process. Keywords— Arduino, FOPDT, Process control, temperature controller, real-time control.

Heat and mass transfer modeling of an artisan coffee roasting process: A comparative study

In order to achieve effective coffee roasting control, there is a need for coffee roasting process models that can solve in real-time. This paper contributes by evaluating the roasting process model performance for different roasting time periods and bean moisture contents. The method firstly involved selecting roasting profile models from literature on the basis of their computational efficiency and simplified geometry definition of the coffee bean structure. Three models were considered constituting different bean temperature and moisture content sub-models. Next the modeled results were compared with experimental results obtained from an instrumented commercial artisan roaster. It was found that all three models could sufficiently predict the roast profile from the modeled bean temperature and moisture content. However, all three consistently overestimated the moisture content during roasting. For longer roasting times, the final moisture content prediction was closer to the experimental value.

Identification of compounds that enhance bitterness of coffee brew

The bitterness perception of coffee is a key attribute that impacts consumer acceptance. Nontargeted liquid chromatography/mass spectrometry (LC/MS) flavoromics analysis was applied to identify compounds that enhance the bitter perception of roasted coffee brew. Orthogonal partial least squares (OPLS) analysis was used to model the comprehensive chemical profiles and sensory bitter intensity ratings of fourteen coffee brews with good fit and predictivity. Five compounds that were highly predictive and positively correlated to bitter intensity were selected from the OPLS model, further isolated, and purified using preparative LC fractionation. Sensory recombination testing demonstrated that five compounds significantly enhanced the bitter perception of coffee when presented as a mixture, but not when presented individually. In addition, a set of roasting experiments revealed the five compounds were generated during the coffee roasting process.

Aplikasi Artisan Sebagai Solusi Mempermudah Roastery (Studi Kasus: Pelaku Usaha Moon)

Roastery is an activity that is used to determine or make coffee powder that comes from coffee beans, coffee itself is a traditional drink that has many flavors which is used as an alternative drink for teenagers which of course has its bitter characteristics, this article also discusses regarding how coffee lovers can make coffee into a drink that can attract young people by making it better in terms of processing, with such demands an ARTISAN application was created which can help make coffee taste better and not cause a different taste because influenced by the heat temperature when roasting coffee. This research aims to deskriptif kualitatif dengan pendekatan studi kasus dan teknik pengambilan prove how the ARTISAN application can play a role in helping coffee entrepreneurs to get a good coffee and have the same taste due to the same temperature at the time of roasting. This study uses a qualitative descriptive research method with a case study approach and data collection techniques, namely direct observation, which produces a satisfaction for business people and coffee connoisseurs from the benefits of the ARTISAN application from the coffee roasting process.

Self-Tuned Fuzzy PID Temperature Controller Implementation in Hot-Air Coffee Roasting Process

Self-Tuned Fuzzy PID Temperature Controller Implementation in Hot-Air Coffee Roasting Process