Brewed Coffee Research Articles

Effect of pretreatment and peracetic acid pulping on cellulosic materials converted from spent coffee grounds.

Spent coffee grounds (SCG) are the waste byproducts of coffee brewing. While SCG can be valorized to produce functional biopolymers due to their valuable structural components, the lignocellulosic structure of SCG is resistant to degradation because of the tightly bound lignin. Therefore, a pretreatment step is required before pulping with peracetic acid (PAA), an eco-friendlier alternative to traditional pulping methods, to facilitate the extraction of these desired cellulosic materials. Formic acid:acetic acid:deionized water (FA:AA:W=30:50:20) or 60% (v/v) ethanol pretreatments were applied to SCG to compare the characteristics of the resulting cellulosic materials after PAA pulping. Lignocellulose analysis showed that the lignin content (7.06%) of ethanol pretreated SCG was significantly lower (p<0.05), and the cellulose content (29.52%) was significantly higher (p<0.05) than the untreated SCG (15.50% and 11.50%, respectively), indicating that an adequate amount of lignin was removed to obtain the cellulosic materials after the pretreatment process. Morphological and structural changes in the lignin and hemicellulose were observed in all the pretreated SCG, which further confirmed that these components were degraded with pretreatments and pulping. Ethanol pretreated SCG showed the most optimal results based on the greatest lignin decrease seen from its lignocellulose composition, appearance, and structure. This study exemplified a conversion process to extract cellulosic materials from SCG more efficiently to utilize for cellulose-based products and verify its potential to be valorized as a waste byproduct. PRACTICAL APPLICATION: Coffee companies can provide the spent coffee grounds (SCG) they produce to develop cellulose-based materials to make biodegradable packaging products rather than throwing them out or burning them. Using SCG for producing cellulose-based materials can help promote sustainability and reduce food waste worldwide. SCG can be utilized as an alternative source based on their abundance and desired biopolymeric properties, providing innovative solutions to industries and increasing consumer awareness of this cause.

Coffee substitutes: A review of the technology, characteristics, application, and future perspective.

Despite being one of the most frequently consumed beverages worldwide, there are concerns that excessive consumption of coffee can have adverse effects, especially concerning the addictive and stimulating effects of the alkaloid caffeine, which contributes to coffee's popularity. It is known to increase the risk of hypertension and heart rate among predisposed individuals, adversely affecting the nervous system. Even though they differ in nature from those found in coffee, coffee substitutes can be considered economically and health-wise as a favorable alternative to natural coffee brews. This review summarizes the state-of-the-art varieties of plants used as coffee substitutes and discusses their production technology, chemical composition, nutritional properties, health benefits, economic challenges, and rationale for choosing the plant as a substitute for coffee. Various instant products and coffee substitute blends are also available on the market especially based on different kinds of plants and herbs like ginger, rye, date pits, quinoa, lupine, chicory, barley, rye, oak, and so on. These coffee substitutes have several advantages especially having no caffeine and containing different beneficial phytochemicals, although the results of the difference between the levels of harmful compounds in coffee and coffee substitutes were contradictory. Therefore, it is no wonder that the development of coffee substitutes, which are beverages that are able to mimic the taste and aroma of coffee, is on the rise at present.

Effect of ultraviolet irradiation on the shelf life and chemical composition of cold brew coffee

Effect of ultraviolet irradiation on the shelf life and chemical composition of cold brew coffee

Waste-Derived Caffeine for Green Synthesis of Rhenium Nanoparticles with Enhanced Catalytic Activity in the Hydrogenation of 4-Nitrophenol

Yearly, thousands of tons of wasted coffee grounds are produced according to high coffee consumption. Still, after the coffee brewing, wasted coffee grounds contain some amounts of caffeine (CAF). CAF, in turn, contains multiple O and N chelating atoms in its structure. These have a potential to be reductors for complexes of metals. In this context, within the present study, a set of CAF extracts derived from coffee beans and coffee grounds were obtained and then used for the one-step reduction of ReO4− ions with no additional toxic chemicals. Within this approach, CAF was applied as a secondary, green resource for the synthesis of unique rhenium nanoparticles (ReNPs) containing Re species at 0 and +6 oxidation states. The obtained ReNPs were identified and characterized with the use of X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Further, the capping and stabilization of ReNPs by CAF were verified with the aid of Fourier transformation infrared spectroscopy (FT-IR). The so-obtained “green” ReNPs were then used as a homogenous catalyst in the catalytic hydrogenation of 4-nitrophenol (4-NP). This new nanomaterial revealed a superior catalytic activity, leading to the complete reduction of 4-NP to 4-aminophenol within 40–60 min with a first-order rate constant of 0.255 min−1.

Coffee Bioactive N-Methylpyridinium: Unveiling Its Antilipogenic Effects by Targeting De Novo Lipogenesis in Human Hepatocytes.

Type 2 diabetes and nonalcoholic fatty liver diseases (NAFLDs) are promoted by insulin resistance (IR), which alters lipid homeostasis in the liver. This study aims to investigate the effect of N-methylpyridinium (NMP), a bioactive alkaloid of coffee brew, on lipid metabolism in hepatocytes. The effect of NMP in modulating lipid metabolism is evaluated at physiological concentrations in a diabetes cell model represented by HepG2 cells cultured in a high-glucose medium. Hyperglycemia triggers lipid droplet accumulation in cells and enhances the lipogenic gene expression, which is transactivated by sterol regulatory element binding protein-1 (SREBP-1). Lipid droplet accumulation alters the redox status and endoplasmic reticulum (ER) stress, leading to the activation of the unfolded protein response and antioxidative pathways by X-Box Binding Protein 1(XBP-1)/eukaryotic Initiation Factor 2 alpha (eIF2α) Protein Kinase RNA-Like ER Kinase and nuclear factor erythroid 2-related factor 2 (NRF2), respectively. NMP induces the phosphorylation of AMP-dependent protein kinase (AMPK) and acetyl-CoA carboxylase α (ACACA), and improves the redox status and ER homeostasis, essential steps to reduce lipogenesis and lipid droplet accumulation. These results suggest that NMP may be beneficial for the management of T2D and NAFLD by ameliorating the cell oxidative and ER homeostasis and lipid metabolism.

Environmental impact assessment of alternative technologies for production of biofuels from spent coffee grounds

AbstractIn the strategy to combat climate change that has been caused by the world's overdependence on fossil fuels, current research is focusing on the decarbonisation of the energy sector through the production of renewable cleaner energy, such as biofuels. Spent coffee grounds (SCGs), the waste stream of the coffee brewing industry, are a potential feedstock for the production of valuable products, including biofuels. However, the environmental implications for the valorisation of this valuable waste need to be investigated. This study assesses the environmental impacts of six biomass‐to‐fuel processing technologies using SCGs as a feedstock, with the aim of identifying the most environmentally friendly technology. A cradle‐to‐gate life‐cycle assessment (LCA) was conducted on fast pyrolysis, fermentation, anaerobic digestion (AD), hydrothermal liquefaction (HTL), gasification, and biodiesel production. The mass and energy balances obtained from Aspen Plus simulations served as the life‐cycle inventory data. Using the ReCiPe 2016 midpoint (H) and Eco‐Indicator 99 as the assessment methods, potential environmental impacts were calculated in OpenLCA software. Electricity generation and carbon dioxide emissions were the biggest contributors of environmental impacts. For each category, the maximum result was set to 100% and the results of the other variants were displayed in relation to this result. AD, with the smallest total weighted score (160), was the most environmentally friendly biomass‐to‐fuel processing route, while HTL, with the biggest total weighted score (893), was the worst. A sensitivity analysis indicated that the environmental performance of biofuel production from SCGs was highly influenced by energy input flows and the source of energy generation.

Study on ultrasound-assisted extraction of cold brew coffee using physicochemical, flavor, and sensory evaluation

Cold brew coffee is popular with consumers due to its simple preparation and unique taste. However, traditional cold brew coffee extraction is time consuming and inefficient, which can be improved by ultrasound-assisted extraction to enhance the product market potential. In this study, the flavor profiles and sensory differences of coffee prepared at three different ultrasonic temperatures, as well as traditional cold brew and hot brew coffee, were evaluated by consumer-based sensory evaluation, Rate-All-That-Apply, combined with the determination of the content of volatile and non-volatile components. The results showed that ultrasound assisted cold brew coffee prepared at 25 °C had a good extraction effect, with chlorogenic acid (CGA) and organic acid contents of 1.05 mg/mL and 0.97 mg/mL, respectively, which were higher than the traditional cold brew coffee obtained after 12 h of preparation, with contents of 0.53 mg/mL and 0.85 mg/mL, respectively. And the total content of volatile compounds can almost reach the results of traditional cold brew for 12 h, which were 1.25 mg/kg and 1.42 mg/kg, respectively. Sensory evaluation indicated that ultrasonic treatment enhanced the sensory attributes such as nutty and cocoa flavors in the coffee. Consumers preferred the cold brew coffee obtained via ultrasound-assisted extraction. These samples presented higher levels of sweetness, floral, and fruity flavors, which were associated with 2,5-Dimethyl-3-(2-methylpropyl)pyrazine, 2,3-Dimethyl-5-(3-methylbutyl)pyrazine, (S)-(+)-4-sec-Butylpyrazole, and styrene. In this study, we demonstrated that ultrasound-assisted extraction can help reduce the time to prepare cold brew coffee and make it possible to commercialize ultrasound-assisted cold brew coffee.

Dual-frequency countercurrent ultrasonic-assisted extraction of the cold brew coffee and in situ real-time monitoring of extraction process

Dual-frequency countercurrent ultrasonic-assisted extraction of the cold brew coffee and in situ real-time monitoring of extraction process

Brewing Terminologies Used by Baristas: Contextualized Instructional Material for Technical, Vocational, and Livelihood Students

As coffee industries grow, the demand for good coffee is not simply enough nowadays. As a result, lexicons related to coffee, coffee beans, flavors, tools and equipment, and its processes are ever growing; hence, it can be considered “alive”. This study aims to gather coffee-related lexicons to create contextualized learning materials for Technical Vocational Learning (TVL) students, addressing the shortage of resources needed to enhance their coffee brewing skills. This study utilized two methods of acquiring data: 17 baristas from selected traditional coffee shops in the Philippines as participants of the study and books, articles and websites as the corpus of the study. Qualitative content analysis was used to identify common terminologies and their contextualized conceptual and operational definitions, as well as unique lexicons used by local baristas, which were then categorized into flavors, tools and equipment, and processes. After collecting 76 terminologies, it underwent thematic analysis and was categorized according to themes, such as coffee beans, flavors, serving sizes, tools and equipment, and processes. By incorporating these lexicons in the context of education, it will enhance students’ knowledge about coffee culture, industry practices and professional terminology, all of which are necessary for effective communication. This study contributes to the continuous evolution of language in the coffee industry by documenting and analyzing the diverse terminologies used.

Comparison of Ultra-High-Pressure and Conventional Cold Brew Coffee at Different Roasting Degrees: Physicochemical Characteristics and Volatile and Non-Volatile Components

The impact of the roasting degree on ultra-high-pressure cold brew (UHP) coffee remains unclear, although it has been found that UHP technology accelerates the extraction of cold brew (CB) coffee. Therefore, this study investigated the effects of three different degrees of roasting (light, medium, and dark) on the physicochemical characteristics, volatile and non-volatile components, and sensory evaluation of UHP coffee. Orthogonal partial least-squares-discriminant analysis (OPLS-DA) and principal component analysis (PCA) were used to assess the effects of different roasting degrees. The results showed that most physicochemical characteristics, including total dissolved solids (TDSs), extraction yield (EY), total titratable acidity (TTA), total sugars (TSs), and total phenolic content (TPC), of UHP coffee were similar to those of conventional CB coffee regardless of the degree of roasting. However, the majority of physicochemical characteristics, non-volatile components, including the antioxidant capacity (measured based on DPPH and ABTS) and melanoidin, caffeine, trigonelline, and CGA contents increased significantly with an increase in roasting degree. The sensory evaluation revealed that as the roasting degree rose, the nutty flavor, astringency, bitterness, body, and aftertaste intensities increased, while floral, fruity, and sourness attributes decreased. The HS-SPME-GC/MS analysis showed that most volatile components increased from light to dark roasting. Moreover, 15 representative differential compounds, including hazelnut pyrazine, linalool, butane-2,3-dione, and 3-methylbutanal, were identified by calculating the odor-active values (OAVs), indicating that these contributed significantly to the odor. The PCA showed that the distance between the three roasting degree samples in UHP coffee was smaller than that in CB coffee. Overall, the effect of roasting degrees on UHP coffee was less than that on CB coffee, which was consistent with the results of physicochemical characteristics, volatile components, and sensory evaluation.

Optimization of Microwave-Assisted Inorganic Salt Pretreatment for Production of Fermentable Sugars from Spent Coffee Ground

Spent coffee ground (SCG) is a solid waste that is generated in the coffee brewing process for coffee beverage production. SCG hold a great potential in reducing sugar production as it consists of high amount of carbohydrates. However, SCG is a lignocellulosic biomass (LCB) which requires pretreatment to degrade the lignocellulosic structure and enhance enzyme accessibility during saccharification process. Hence, this research aims to study the performance of microwave-assisted inorganic salt pretreatment for generation of reducing sugars. Different concentrations of NaCl was applied to determine their effects on reducing sugar produced as well as pH, and solid recovery. Pretreatment with 3% NaCl was found to yield the highest reducing sugar concentration of 43.56 mg/mL, hence it was selected for the subsequent optimization study. Process optimization was designed by using the Response Surface Methodology approach (RSM) with Central Composite Design (CCD), based on three pretreatment parameters; solid to liquid ratio (1:50 - 8:50), microwave power (300W – 800W) and irradiation time (1-10 minutes). The optimized conditions were achieved at solid to liquid of 8:50, microwave power of 800 watt and irradiation time of 10 minutes for a maximum response of 40.89 mg/mL. Moreover, it was observed that microwave-assisted NaCl pretreatment had significantly caused surface morphological changes of the SCG and the removal of functional groups in lignin, resulted in increment of the crystallinity value. In conclusion, microwave pretreatment is a promising green technology for fermentable sugar production from SCG.

Fan assisted extraction and low pressure chromatographic system with a phenyl monolithic column for amperometric determination of volatile α-dicarbonyl compounds in coffee brews

In this work, a low pressure chromatographic system featuring a single 0.5 cm length phenyl monolithic column and an amperometric detector was developed to determine volatile ⍺-dicarbonyl compounds in coffee brews. The analytical strategy relied on the extraction of the volatile ⍺-dicarbonyl compounds and their derivatization with o-phenylenediamine, prior to the determination of the resulting quinoxaline derivative compounds in the designed chromatographic system. The studies of the mobile phase composition and electrochemical conditions are presented. The extraction of the volatile ⍺-dicarbonyl compounds was performed resourcing to a recent approach based on the fan assisted extraction system. This system performs the full evaporation technique and allowed the quantitative recovery (>85 %) of diacetyl and 2,3-pentanedione from the coffee brew based on the following experimental conditions: sample volume 30 µL, extraction period 15 min, acceptor solution (water, acetonitrile, 90:10, v/v) volume 400 µL, and sample temperature 50 °C. The developed method showed no matrix effect for different coffee brews and the quantification of the studied analytes can be performed through the external calibration method. Detection limits of 3.6 × 10−6 mol/L for diacetyl and 12.9 × 10−6 mol/L for 2,3-pentanedione were obtained. Sample analysis rate was of 5 h−1 and the acetonitrile consumption was of ca. 450 µL per chromatographic run.

Coffee and mineral oil hydrocarbons: potential dietary intake

Levels of mineral oil hydrocarbons were measured in a large range of green and roasted coffee beans or ground powder. To better understand the consumer exposure to mineral oil hydrocarbons, the transfer to the brewed coffee was assessed under three different preparations. As a result, less than 5% of mineral oil hydrocarbons were transferred to the cup. With this low transfer rate, the coffee contribution to the mineral oils daily intake can be assessed to be very low, below 0.8% of the total exposure.

Studi Karakteristik Fisikokimia dan Organoleptik Bubuk Kopi dari Biji Cacat Hitam Kopi Robusta dengan Perbedaan Suhu Penyangraian

This research studied the effect of the level of black coffee bean defects and roasting temperature on the physicochemical content of coffee powder and the organoleptic content of robusta coffee brewing. This research used a factorial Randomized Complete Block Design (RCBD) with two replications. Parameters in this study, namely moisture content, ash content, pH, caffeine content, color intensity, and sensory. Data analysis in this research used ANOVA at the 5% level and a DMRT follow-up test. The research result show that there is an interaction between the treatment of the type of defective beans and roasting temperature on moisture content, ash, pH, color intensity of robusta coffee powder, and organoleptic brewing of robusta coffee. Different types of defective beans significantly affected the moisture content, ash, pH, caffeine, and color intensity of robusta coffee powder, while differences in roasting temperature significantly affected the water content, ash, pH, caffeine, and color intensity of robusta coffee powder. The best treatment for all physicochemical and organoleptic parameters is partially black beans with a roasting temperature of 180 °C.

Sensory analysis of the flavor profile of full immersion hot, room temperature, and cold brewed coffee over time

With the growing popularity of cold brewed coffee comes a need for brewing efficiency while preserving the desirable flavor profile. Despite the wide use of full immersion brewing techniques, the effect of brew time on the dynamic sensory profiles of full immersion brewed coffee remains underexplored. Here, we investigated the relationship between coffee sensory quality and extraction dynamics, measured as Total Dissolved Solids (TDS) and Extraction (E) of full immersion brewed coffee at various roast levels, and brewing temperatures (4 °C, 22 °C and 92 °C), over brew time using a generic descriptive analysis method. Specifically, different brew time points were selected for different temperatures based on five targeted coffee extraction stages. Furthermore, the unique experimental design also explored a sensory-driven engineering research process. Roast level had the greatest impact on the sensory profile of the coffees, followed by brewing temperature, but brew time, especially the longer brew times as TDS plateaued, had subtler impacts than expected. Twenty-five of 28 sensory attributes were significantly different among the 30 coffee samples, indicating a single source green coffee blend can produce a wide range of complex sensory profiles using different combinations of roast level, temperature, and brew time. Specifically, the intensity of sweetness was negatively correlated with TDS, and 19 other attribute intensities were positively correlated with TDS. Interestingly, we found that certain long time cold brews had similar sensory profiles to those of some short time hot brews, suggesting the sensory profiles of certain hot brews and cold brews could possibly be matched through controlled preparation. Overall, our study demonstrated an approach of integrating food engineering and sensory analysis for product development, and our findings provide valuable insights into the extraction dynamics and sensory quality of full immersion brewed coffee and opens new brewing avenues for the coffee industry.

A Comparative Analysis of Cold Brew Coffee Aroma Using the Gas Chromatography-Olfactometry-Mass Spectrometry Technique: Headspace-Solid-Phase Extraction and Headspace Solid-Phase Microextraction Methods for the Extraction of Sensory-Active Compounds.

Coffee, one of the most widely consumed commodities globally, embodies a sensory experience deeply rooted in social, cultural, and hedonic contexts. The cold brew (CB) method, characterized by cold extraction, is a refreshing and unique alternative to traditional coffee. Despite its growing popularity, CB lacks defined preparation parameters and comprehensive analysis of its aromatic composition. In this study, we aimed to obtain a representative extract of the volatile matrix of CB and characterize the aroma of sensory-active compounds using advanced techniques such as headspace-solid-phase Microextraction (HS-SPME) and headspace-solid-phase extraction (HS-SPE) for volatile compound extraction, followed by gas chromatography-olfactometry-mass Spectrometry (GC-O-MS) for compound identification. Optimization of the HS-SPME parameters resulted in the identification of 36 compounds, whereas HS-SPE identified 28 compounds, which included both complementary and similar compounds. In HS-SPME, 15 compounds exhibited sensory activity with descriptors such as floral, caramel, sweet, and almond, whereas seven exhibited sensory activity with descriptors such as chocolate, floral, coffee, and caramel. This comprehensive approach to HS-SPME and HS-SPE aroma extraction with GC-O-MS offers an efficient methodology for characterizing the aroma profile of CB, paving the way for future research and quality standards for this innovative coffee beverage.

Effect of coffee type composition ratio and brewing temperature on the physicochemical and organoleptic properties of Arabica-Excelsa brewed filter coffee

Effect of coffee type composition ratio and brewing temperature on the physicochemical and organoleptic properties of Arabica-Excelsa brewed filter coffee

The Effect of Fermentation Time Variation on Antioxidant Activity of Fermented Robusta Coffee Leaves (Coffea canephora Pierre ex A.Froehner) Brew

Antioxidants are electron-donor compounds that can delay, slow down and prevent free radical reactions. Fermentation is a chemical change that occurs due to the activity of microorganisms which can increase the amount of phenols in tea thereby increasing its antioxidant activity. Fermentation is carried out with the help of a Symbiotic Culture of Bacteria and Yeast (SCOBY) culture, which is commonly used in the production of kombucha. Kombucha is a fermented tea drink produced from leaves that contain high phenols such as robusta coffee leaves (Coffea canephora Pierre ex A.Froehner). Factors that affect the fermentation process are pH and fermentation time. This study aimed to explain the effect of fermentation time on the antioxidant activity of fermented robusta coffee leaves brew. Brewed robusta coffee leaves were made by brewing robusta coffee leaves simplicia powder, adding kombucha liquid starter, then fermented for 0; 3; 7; 14; and 21 days, then pH and antioxidant activity was measured using UV-Visible spectrophotometer using the 2,2-dipheny-1,1-picrylhydrazyl (DPPH) at a wavelength of 516 nm. This study showed that 0; 3; 7; 14; and 21 days fermented robusta coffee leaves brew have pH of 6,07; 4,62; 4,07; 3,21; and 2,74, and IC50 values is 285,1645 μg/ml; 219,7012 μg/ml; 192,2325 μg/ml; 187,0434 μg/ml; and 173,9249 µg/ml. There is an effect of fermentation time variation on the antioxidant activity of fermented robusta coffee leaves brew. Keyword: Antioxidant, Fermentation, pH, Robusta coffee leaves, Time variation

Optimizing Ultrasonic‐Assisted Extraction for Enhanced Yield of Phenolic Compounds and Antioxidant Activity in Cold Brew Coffee

ABSTRACTThis study aimed to identify the best conditions for ultrasonic‐assisted extraction (UAE) of DPPH and phenolic compounds from cold brew coffee using Box‐Behnken Design (BBD) and Response Surface Methodology (RSM). It explored the effects of solid‐liquid ratio (5%–15%), extraction time (40–50 min), and ultrasonic power (70%–80%) on these compounds, finding that all factors significantly influenced the outcomes. Statistical analysis showed the data fit a quadratic polynomial model well, with R2 values of 0.9981 for phenolic compounds and 0.9799 for DPPH radicals. Using 3D surface and contour plots from these models, the optimal extraction conditions for these compounds from cold brew coffee were determined. The highest yields of total phenolic compounds and DPPH radical were obtained when samples were extracted at a 10% solid–liquid ratio, 45 min extraction time, and 75% ultrasonic power. Under these optimal conditions, total phenolic compounds and DPPH radical were 64.10 ± 0.31 gGAE/mL and 61.90 ± 0.14%, respectively, with a maximum caffeine content of 213.13 ± 0.23 mg/L. Gamma irradiation at kGy also reduced cold brew coffee's microbial content. This research may be a new alternative for producing cold brew coffee that will save time and help extend the shelf life.

Coffee with Cordyceps militaris and Hericium erinaceus Fruiting Bodies as a Source of Essential Bioactive Substances.

Drinking coffee is a daily routine for many people. Supplement manufacturers have proposed adding powdered Cordyceps militaris, known for its ergogenic and immunostimulating properties, and Hericium erinaceus, known for its nerve growth factor (NGF)-stimulating properties, to coffee. The aim of this work was to compare the bioactive substances in three types of coffee: machine-brewed, instant, and traditionally brewed, prepared with the addition of H. erinaceus and C. militaris fruiting bodies. The analysis of bioactive substances was performed using AAS and RP-HPLC methods. Among the control samples of coffee, traditionally brewed coffee was the best source of bioelements. Considering the mushroom species tested, the best additional source of Mg, Zn, Cu, Na, K, and Ca was C. militaris. A slightly higher Fe content was determined for H. erinaceus. With the addition of C. militaris, the amounts of 4-feruloylquinic acid (18.6 mg/200 mL) and 3,5-di-caffeoylquinic acid (3.76 mg/200 mL) also increased. In conclusion, the C. militaris species has been proven to be a better source of bioactive substances as a coffee additive in the daily diet. The combination of brewed coffee and the tested mushrooms seems to be the most beneficial in terms of health-promoting effects.