Brewed Coffee Research Articles

Assessing the antioxidant potential of soft beverages in the Turkish market: a comprehensive study

ABSTRACT Soft beverages are an important part of fluid intake; however, it should be the main target to choose the right beverages according to healthy nutrition. This study aimed to determine, evaluate, and create a database of the total antioxidant capacity (TAC) contents of widely consumed soft beverages in local markets in Turkey. A total of 394 beverages, including 60 carbonated, 100 non-carbonated, 136 tea (teabags for cups and teapots and, shredded tea leaves), 75 coffee (instant and brewed), and 23 fermented beverages, with expiration dates at most half their shelf life, were analyzed. Shredded tea leaves and brewed coffees were prepared with different brewing techniques. TAC was analyzed on the MINDRAY-BS400 device using commercial kit ABTS (2,2’-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) and results are presented as mmol Trolox Equivalent(TE)/L. Statistical analyses were performed using SPSS 26. The mean TAC of all beverages was 3.7 ± 1.4 mmolTE/L (.120–5.535 mmolTE/L), with the highest content of tea and coffee (4.3 ± .6 mmol TE/L) and the lowest carbonated beverages (1.4 ± 1.5 mmolTE/L) (p < .05). The overall results showed that all soft beverages have antioxidant activity; however, the right choice of soft beverages might contribute to the dietary TAC and increase fluid intake.

Profiling flavor characteristics of cold brew coffee with GC-MS, electronic nose and tongue: effect of roasting degrees and freeze-drying.

Roasting is an important process in the formation of coffee flavor characteristics, which determines the quality of coffee and consumer acceptance. However, the influence of roasting degree on the flavor characteristics of cold brew coffee has not been fully described. In the present study, the flavor characteristics of cold brew coffee with different roasting degrees were compared in detail by using chromatographic and electronic sensory approaches, and the flavor changes induced by freeze-drying were investigated. Pyrazine and heterocyclic compounds were the main aroma compounds in coffee, and gradually dominated with the increase of roasting. Pyridine was consistently present in cold brew coffees of different roasting degrees and showed significant gradient of quantity accumulation. Aroma compounds such as pyrazine, linalool and furfuryl acetate were the main contributors to coffee roasting, floral and fruity flavor. Freeze-drying preserved the fruity and floral aromas of medium-roasted cold brew coffee, whereas reducing the bitterness, astringency and acidity properties that are off-putting to consumers. The higher consumer acceptance and enjoyment in medium roast cold brew coffee may be related to its stronger floral and fruity aroma. The aroma profile qualities of freeze-drying processed medium roasted cold brewed coffee were more dominant and more suitable for freeze-drying processing than medium dark roasting. Application of freeze-drying for cold brew coffee will promote the convenience of drinking. The present study provides valuable technical guidance in improving the flavor and quality of cold brew coffee, and also promotes its commercialization process. © 2024 Society of Chemical Industry.

Exploitation of spent coffee ground (SCG) as a source of functional compounds and growth substrate for probiotic lactic acid bacteria

Spent coffee ground (SCG) represent a food waste with functional potential, produced in high amount worldwide. SCG derive from coffee brewing and are mainly composed of insoluble matter and different efforts is still necessary to find innovative processes for their valorization. In this work, different methodologies including physical (cryogenic milling and microwave assisted extraction, MAE) and biological (optimized enzyme-assisted extraction, EAE) were exploited to solubilize compounds trapped within the abundant fiber network. MAE led to the highest concentration of soluble fiber and oligosaccharides thus solubilizing insoluble fiber. The total soluble matter increased almost 8 folds by using MAE and EAE in combination due to high insoluble fiber hydrolysis into monosaccharides (up to 17 g/100g), soluble melanoidins (up to 72 mg/g) and caffeic acid (up to 2.22 mg/g). The extract was also characterized for the highest antioxidant potential demonstrating the positive impact of combined process. The EAE promoted the release of nutrients in SCG extract which were used as a growth substate by the selected probiotic Lactiplantibacillus plantarum LP19. This work demonstrates how different technologies and their combination can be used to valorize SCG demonstrating the possibility to obtain novel SCG-derived functional ingredients and/or products.

Quantitative Analysis of Phytochemical Compounds and Antihyperglycemic Potential of Robusta Coffee from West Lampung

West Lampung Regency in Lampung Province produces high quality robusta coffee with a distinct, strong bitter flavour. Bitter flavour indicates the amount of bioactive substances produced by plants called phytochemicals. The aim of this study is to analyse the phytochemical compounds and antihyperglycemic potential of robusta coffee beans from West Lampung, Indonesia. Quantitative phytochemical analysis was carried out using the thin layer chromatography method and spectrophotometry. Animal experimental design using robusta coffee on hyperglycemia conditions in mice which was induced by alloxan 170 mg/kgBW subcutaneously and given by 1 ml of brewed robusta coffee for 10 days. The robusta coffee from West Lampung contained total caffeine 4,014.87 µg/g, total flavonoid content (TFC) 93.6 mg quercetin equivalent per gram of sample, with total alkaloid content (TAC) 0.848 mg of quinine equivalent per gram of sample, total tannin content (TTC) 182.3 mg of tannic acid equivalent per gram of sample, and total saponin content (TSC) 24.2 mg of quillaja bark equivalent per gram of sample. The administration of 1 ml/mice/day of robusta coffee brewed for 10 days did not show a decrease in blood sugar level in hyperglycemic mice, due to the short duration of the study, so the role of coffee in decreasing hyperglycemia conditions has not been optimally observed.

Identification of antioxidant and flavour marker compounds in Kalosi-Enrekang Arabica brewed coffee processed using different postharvest treatment methods.

The online version contains supplementary material available at 10.1007/s13197-024-05948-8.

Identification of mozambioside roasting products and their bitter taste receptor activation

Arabica coffee contains the bitter-tasting diterpene glycoside mozambioside, which degrades during coffee roasting, leading to yet unknown structurally related degradation products with possibly similar bitter-receptor-activating properties.The study aimed at the generation, isolation, and structure elucidation of individual pyrolysis products of mozambioside and characterization of bitter receptor activation by in vitro analysis in HEK 293T-Gα16gust44 cells.The new compounds 17-O-β-d-glucosyl-11-hydroxycafestol-2-on, 11-O-β-d-glucosyl-16-desoxycafestol-2-on, 11-O-β-d-glucosyl-(S)-16-desoxy-17-oxocafestol-2-on, 11-O-β-d-glucosyl-15,16-dehydrocafestol-2-on, and 11-O-β-d-glucosyl-(R)-16-desoxy-17-oxocafestol-2-on were isolated from pyrolyzed mozambioside by HPLC and identified by NMR and UHPLC-ToF-MS. Roasting products 11-O-β-d-glucosyl-(S)-16-desoxy-17-oxocafestol-2-on, 11-O-β-d-glucosyl-15,16-dehydrocafestol-2-on, and 11-O-β-d-glucosyl-(R)-16-desoxy-17-oxocafestol-2-on had lower bitter receptor activation thresholds compared to mozambioside.Molecular docking simulations revealed the binding modes of the compounds 11-O-β-d-glucosyl-15,16-dehydrocafestol-2-on and 11-O-β-d-glucosyl-(R)-16-desoxy-17-oxocafestol-2-on and their aglycone 11-hydroxycafestol-2-on in the two cognate receptors TAS2R43 and TAS2R46.The newly discovered roasting products 17-O-β-d-glucosyl-11-hydroxycafestol-2-on, 11-O-β-d-glucosyl-(S)-16-desoxy-17-oxocafestol-2-on, 11-O-β-d-glucosyl-15,16-dehydrocafestol-2-on, and 11-O-β-d-glucosyl-(R)-16-desoxy-17-oxocafestol-2-on were detected in authentic roast coffee brew by UHPLC-ToF-MS and could contribute to coffee's bitter taste impression.

Characterization of key aroma compounds in cold brew coffee prepared by negative-pressure extraction technology and its changes during storage

Cold brew coffee is gaining popularity among consumers; however, its extraction is time consuming and it has a short shelf life. This study employed negative-pressure extraction to reduce the extraction time of cold brew coffee. Ninety-four volatile compounds, including furans, ketones, pyrazines, esters, aldehydes, azoles, pyrroles, phenols, pyridines, acids, and alcohols, were identified. The concentrations of these compounds varied with the extraction time. Sensory evaluation revealed the optimal extraction time to be 5 h, significantly enhancing the extraction efficiency of cold brew coffee. At this point, 9 key aroma compounds (OAV ≥1) were identified, with 2,3-diethyl-5-methyl-pyrazine and 3-ethyl-2,5-dimethyl-pyrazine predominant in the sample. We also investigated the changes in the physicochemical properties and key aroma compounds of cold brew coffee during refrigerated storage. The results showed a significant increase in acidity and total acid content, a notable decrease in antioxidant activity, and a decline in key aroma compounds with the extension of storage time. These findings indicated that the deterioration of cold brew coffee might be caused by the degradation of aroma compounds, leading to changes in the coffee's physicochemical properties. This study provides theoretical support for accelerating the extraction of cold brew coffee and extending its shelf life.

Lightweight Machine Learning Method for Real-Time Espresso Analysis

Coffee crema plays a crucial role in assessing the quality of espresso. In recent years, in response to the rising labor costs, aging population, remote security/authentication needs, civic awareness, and the growing preference for non-face-to-face interactions, robot cafes have emerged. While some people seek sentiment and premium coffee, there are also many who desire quick and affordable options. To align with the trends of this era, there is a need for lightweight artificial intelligence algorithms for easy and quick decision making, as well as monitoring the extraction process in these automated cafes. However, the application of these technologies to actual coffee machines has been limited. In this study, we propose an innovative real-time coffee crema control system that integrates lightweight machine learning algorithms. We employ the GrabCut algorithm to segment the crema region from the rest of the image and use a clustering algorithm to determine the optimal brewing conditions for each cup of espresso based on the characteristics of the crema extracted. Our results demonstrate that our approach can accurately analyze coffee crema in real time. This research proposes a promising direction by leveraging computer vision and machine learning technologies to enhance the efficiency and consistency of coffee brewing. Such an approach enables the prediction of component replacement timing in coffee machines, such as the replacement of water filters, and provides administrators with Before Service. This could lead to the development of fully automated artificial intelligence coffee making systems in the future.

Consumer perception of decocted coffee leaf tea originated from different altitude

It is commonly known that plantation location influences the composition of the coffee component as well as the leaves. Therefore, it was expected that the difference location will also affect the quality of decocted one. In this current study, effect of plantation location is investigated on Arabica and Robusta coffee leaf tea. Two different coffee plantations were chosen as the region of observation (560 ASL and 1700 ASL). All the coffee leaf tea was brewed by decoction method, in which sensorially optimized by Just about Right (JAR) method. The sensory attributes of concern were included sweet, sour, bitter taste and astringent mouth-feel. Considering consumer preference on the brewed coffee leaf tea, the decoction brewing condition were set on 95°C for 5 minutes. Additionally, coffee leaf tea grown at higher altitudes exhibits significantly greater total phenolic content (TPC) and antioxidant activity (p < 0.05). Not only does this tea have higher TPC and antioxidant activity at higher altitudes, but it also shows superior consumer sensory acceptability. This may be supported by the fact that higher altitude coffee leaf tea has more diverse sensory driver components than that of lower altitude coffee leaf tea as suggested by LC-MS.

Exploring the Impact of Various Manual Brewing Techniques on the Physicochemical and Sensory Characteristics of Brewed Coffee

Coffee cultivation in Indonesia primarily revolves around Arabica and Robusta. Liberica, a less-cultivated variety, often thrives in agroforestry systems, contributing to ecosystem preservation and biodiversity support. Exploration of coffee holds the potential to benefit farmers, coffee-related industries, and conservation initiatives. As a beverage product, coffee can have unique physical, chemical, and sensory characteristics influenced by various factors from farm to cup. Among these factors, brewing plays a crucial role. This study aims to determine the effects of popular manual brewing techniques (V60, French Press, and Vietnam Drip) on the physicochemical and sensory characteristics of Arabica and Liberica coffee. The study was conducted using a nested design. The analyses included pH, total dissolved solids, color parameters L* (brightness), IC50 and sensory evaluation by trained panelists. The results highlight that the different manual brewing techniques significantly affected the physicochemical and sensory characteristics of the brewed coffee. Interestingly, the effect of the brewing techniques was more pronounced in Arabica compared to Liberica coffee.

Brewing Excellence: Improving Coffee Quality with the V60 Stirred-agitation Technique

Manual coffee brewing is the preferred method owing to its capacity to produce a more delicate and diverse range of flavors. While extensive research has been conducted on the process of coffee brewing, there has been limited discourse on the impact of agitation techniques on the quality of the steeping phase. The primary objective of this study is to explore the influence of agitation methods, specifically V60 and Kalita, on the quality of the steeping process. A survey-based investigation was conducted, analyzing sensory attributes such as flavor, aftertaste, acidity, body, balance, sweetness, overall flavor, acid intensity, and body level. A panel of twenty skilled baristas participated as evaluators. The findings of this research demonstrate that agitation plays a crucial role in achieving optimal extraction during the coffee brewing procedure. The particular agitation method employed distinguishes the brewing process and the final steeping outcome. Notably, the use of stirred agitation in the V60 method results in a well-balanced steeping flavor characterized by an acidic orange aroma and a subtle undertone of brown sugar, all without leaving a lingering, cloying aftertaste. The brewed coffee produced using this method exhibits a moderate level of acidity and body, alongside a subtly sweet flavor profile that contributes to an enhanced overall taste experience.

Evaluation of the Possible Effect of the Grinders Installed in Fully Automatic Espresso Coffee Machines on the Element Content in Brewed Coffees

Evaluation of the Possible Effect of the Grinders Installed in Fully Automatic Espresso Coffee Machines on the Element Content in Brewed Coffees

An investigation of the shelf life of cold brew coffee and the influence of extraction temperature using chemical, microbial, and sensory analysis.

This study advances the industry's understanding of the shelf life of ready-to-drink bottled cold coffees and demonstrates that lower brewing temperatures lead to greater flavor stability over shelf life. The findings also provide brewing parameters that can help guide product developers in modulating the flavor of commercial cold coffees.

EVALUATION OF THE ANTIBACTERIAL ACTIVITY OF ARABICA COLD BREW AND ARABICA SPENT COFFEE GROUNDS ON STREPTOCOCCUS MITIS

Spent coffee grounds or coffee waste pose a growing environmental problem as it can harm the ecosystem by releasing greenhouse gases into the atmosphere during their decomposition process [1]. On the other hand, spent coffee ground extracts have been shown to contain polyphenols, trigonelline, phenolic acids, and melanoidins which show strong antibacterial activity toward Gram+ bacteria and yeast [2]. Given its activity towards Gram+ bacteria, this study seeks to find an alternative use of spent coffee grounds, aiming to mitigate their environmental impact. This research focuses on the investigation on whether arabica spent coffee grounds could be used as a natural alternative to iodine mouthwash solution, a commonly used product to kill dental plaque bacteria. Arabica coffee extract was prepared by a 24-hour cold brew procedure then spent coffee grounds extract was produced from the Arabica coffee waste. To obtain results, the antibacterial activity of both spent coffee grounds and coffee on S. mitis was analyzed using the well diffusion test and inhibition zones were measured and compared. The caffeine contents of the Arabica coffee grounds were quantified using HPLC. From our quantitative analysis, the spent arabica coffee grounds collected from the cold brew procedure consist of less caffeine, compared to that of the cold brew, but still showed antibacterial activity towards S. mitis. The inhibition zone of the spent coffee grounds was significantly lower than cold brew coffee but still comparable to iodine mouthwash solution. Our novel findings indicate that spent coffee grounds can be used as a natural antibacterial and an alternative to povidone-iodine mouthwash which leads to reduction of environmental harm from coffee waste.

Identification of Chlorogenic Acid, Caffeine, Melanoidin, Sucrose, and Protein Content of Local Indonesia Arabica Coffee Base on Its Cupping and Variety Variation

The increased demand for high-quality coffee led to the need to evaluate coffee quality for market acceptance. Indonesia has Arabica, which has the potential for high selling value. Arabica coffee varieties, including Ateng, Lini S, and Sigararutang, affect the content of compounds in coffee beans, such as chlorogenic acid, caffeine, melanoidin, sucrose, and protein. The objective of this study was to analyze the impact of Arabica coffee varieties on the compound composition and flavor characteristics of coffee. The UV-Vis spectrophotometric methods were used to determine the quantity of chlorogenic acid, caffeine, melanoidin, sucrose, and protein in different Arabica coffee varietals. The study revealed that the content of these compounds differed among the varieties. The Lini S variety had the highest chlorogenic acid and caffeine content, while the Ateng variety had the highest melanoidin, sucrose, and protein content. The varying levels of chlorogenic acid and caffeine in coffee significantly impact its flavor, resulting in a unique sour and bitter taste in coffee brew. Melanoidin, a high-molecular-weight brown compound, contributes to the malty flavor of coffee, along with sweet, nutty, caramel, and spice notes. Sucrose adds a sweet hint to coffee brew, while protein has a relatively minimal influence on coffee flavor.

The Comparison Of Bioactive Compounds Between Brewed and Extracted Robusta Coffee From West Lampung

Indonesia is ranked fourth highest in coffee production in the world. One type of coffee export commodity, namely Robusta coffee, is produced from the West Lampung region. Robusta coffee contains various bioactive compounds that act as antioxidants. This study aims to analyze the differences between brewed and extracted robusta coffee related to the bioactive compounds. The method used in this study began with coffee sample preparation, followed by brewing and ethanolic extracting the robusta coffee, measurement of TPC (total phenolic content in gallic acid equivalent), TFC (total flavonoid content in quercetin equivalent), and antioxidant activity using the DPPH method. The results showed that the TPC values were 11.27 mgGAE/g for brewed coffee and 61.98 mgGAE/g for extracted coffee, while the TFC values for brewed coffee were 11.99 mgQE/g and extracted coffee were 18.40 mgQE/g. The highest antioxidant activity value was obtained from extracted robusta coffee with an IC50 89.43 ppm which classified as strong enough antioxidant, while the antioxidant activity of brewed coffee has an IC50 218.74 ppm which classified as moderate antioxidant. TPC and TFC in this study showed a direct proportional relationship with antioxidant activity. The samples with the highest total phenolic and total flavonoid also exhibited the highest antioxidant activity.

Influence of coffee roasting degree on antioxidant and metabolic parameters: Comprehensive in vitro and in vivo analysis

This study aimed to assess the impact of roasting degree on antioxidant and metabolic parameters in vitro and in vivo. In vitro, we evaluated radical scavenging, lipid peroxidation, and the activity of digestive enzymes (α-glucosidase, α-amylase, and lipase). In vivo, we first examined coffee's effect on carbohydrate and lipid absorption in healthy rats, followed by a chronic evaluation of metabolic disorders and antioxidant markers using a diet-induced obesity model. In vitro results revealed that increased roasting degree reduced the antioxidant capacity of coffee brews. All brews showed lower inhibition of α-glucosidase and α-amylase, and lipase inhibition compared to the positive control (acarbose or orlistat). In vivo, all roasting degrees consistently reduced postprandial glucose levels by 20%. Notably, coffee with a high roasting degree (HRD) decreased serum triglycerides (TG) by ∼44% after a lipid load, while other roasts did not. Chronic administration of unroasted (UN) or HRD coffee significantly reduced weight gain compared to the obese control (∼15% and ∼10%, respectively). Notably, all coffee samples improved lipid metabolism parameters. UN and HRD coffee significantly decreased adipocyte volume by 58% and 48%, respectively, compared to the obese control. Additionally, all groups exhibited less than 30% hepatic lipid droplets independent of roasting degree. HRD treatment notably increased liver catalase (CAT) activity and reduced lipid peroxidation in serum (∼90%), liver (∼59%), and adipose tissue (∼37%) compared to the obese control group. These findings suggest that HRD in coffee may confer certain biological advantages.

Liquid Chromatography-High-Resolution Mass Spectrometry (LC-HRMS) Fingerprinting and Chemometrics for Coffee Classification and Authentication.

Nowadays, the quality of natural products is an issue of great interest in our society due to the increase in adulteration cases in recent decades. Coffee, one of the most popular beverages worldwide, is a food product that is easily adulterated. To prevent fraudulent practices, it is necessary to develop feasible methodologies to authenticate and guarantee not only the coffee's origin but also its variety, as well as its roasting degree. In the present study, a C18 reversed-phase liquid chromatography (LC) technique coupled to high-resolution mass spectrometry (HRMS) was applied to address the characterization and classification of Arabica and Robusta coffee samples from different production regions using chemometrics. The proposed non-targeted LC-HRMS method using electrospray ionization in negative mode was applied to the analysis of 306 coffee samples belonging to different groups depending on the variety (Arabica and Robusta), the growing region (e.g., Ethiopia, Colombia, Nicaragua, Indonesia, India, Uganda, Brazil, Cambodia and Vietnam), and the roasting degree. Analytes were recovered with hot water as the extracting solvent (coffee brewing). The data obtained were considered the source of potential descriptors to be exploited for the characterization and classification of the samples using principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). In addition, different adulteration cases, involving nearby production regions and different varieties, were evaluated by pairs (e.g., Vietnam Arabica-Vietnam Robusta, Vietnam Arabica-Cambodia and Vietnam Robusta-Cambodia). The coffee adulteration studies carried out with partial least squares (PLS) regression demonstrated the good capability of the proposed methodology to quantify adulterant levels down to 15%, accomplishing calibration and prediction errors below 2.7% and 11.6%, respectively.

Influence of Cultivars and Cultivation Land Slope on Sensory Quality of Gayo Arabica Coffee

All processes involved influence the quality of brewed coffee. One factor that has not been explored well is the influence of environmental conditions, such as cultivation land slopes. This research examines the influence of cultivation area position on the taste quality of coffee from three local cultivars commonly cultivated in the Gayo Highlands. This research used a factorial randomized block design consisting of 2 factors: cultivar (V) and land area (H). The cultivars (V) observed were V1 = Timtim, V2= Borbor, V3 = Ateng Super, and V4 = multi variety. The expanse of coffee cultivation land (H) consists of M1 = flat expanse of land and M2 = sloping expanse of land with a slope of 25%-35%. The experiment was carried out with three replications. The results showed that the coffee brew from Ateng Super had higher acidity (low pH value, 4.90) than the other two cultivars. Cupping test results show that sloping land tends to produce better-tasting coffee brews. Borbor planted on sloping land produces coffee with the highest cupping score. The total cupping score for all treatments ranged from 80,04 – 85,08 with mean value 83,89, which shows that the coffee in this study meets the category of specialty coffee based on the standards of the Specialty Coffee Association of America (SCAA).

Beverages of Coffee and Phytochemicals Present in Coffea arabica and Coffea canephora – A Review

Coffee plant which belongs to Rubiaceae family, generally grows along the equator in tropical and subtropical areas. The generic name, coffee, covers about 100 species of plants, but the two main species used for making beverages are called Coffea arabica (Arabica, accounting for 60-70% of the world’s production) and Coffea canephora (Robusta). Coffee plant contains phytochemicals such as sugars, proteins, organic acids, flavonoids and polyphenols, etc. Coffee is a reputed folk medicinal plant containing phytochemicals, which exhibit mainly antioxidant, anticancer, and anti-diabetes properties. Caffeine is one of the most controversial phytochemicals present in coffee. Caffeine amount per 100 mL of coffee brew from medium roasted coffee can vary from 50 mg to 380 mg. A typical cup (240 mL) of coffee can contain 70-140 mg of caffeine and if one drinks more than 4 cups of coffee per day, he or she is considered to be addicted to caffeine, which may cause caffeinism. Nowadays decaffeinated coffee beverages are popular among people as it consists of extremely low caffeine content; about 1 mg per 100 mL. Decaffeination can be achieved by using organic solvents, carbon dioxide, water, or using different absorbents. Lots of coffee beverages are categorized by the brewing method and most of them are prepared by mixing the brew in water, milk or ice-cream. The scope of this overview is to discuss the importance of the types of phytochemicals present and the types of coffee beverages.