Influence of coffee brewing methods on the chromatographic and spectroscopic profiles, antioxidant and sensory properties

Lipophilic and Hydrophilic Metabolites as Descriptors of Different Coffee Beverages

Coffee is a widely consumed beverage rich in bioactive phytochemicals. This study investigated the effect of brewing method on the profile of potential bioactive compounds in different coffee beverages using metabolomics and lipidomics based on UHPLC-MS/QTOF. The oil contents of the espresso coffee (EC), pot coffee (PC), instant coffee (IC), and filter coffee (FC) beverages studied were 0.13% ± 0.002, 0.12% ± 0.001, 0.04% ± 0.002, and 0.03% ± 0.003, respectively. Univariate analysis indicated significant differences (P < 0.001) in oil content when EC and PC beverages were compared with IC and FC beverages. Principal component analysis revealed similarities in the lipid profiles of FC and EC beverages and the hydrophilic profiles of PC and FC beverages. The EC beverage had the highest intensity of hydrophilic compounds such as adenine, theobromine, chlorogenic acid, and caffeine. The PC beverage was the most abundant in triglycerides, phosphatidylcholine, and diterpenes. Cafestol and kahweol esters, but not their free forms, were the most abundant diterpenes in the PC beverage. This work provides information on the differences in the profile of potentially bioactive compounds in four commonly consumed coffee beverage types and, thus, on the possible differences in the health effects of these coffee beverage types.

Integration of widely targeted metabolomics and the e-tongue reveals the chemical variation and taste quality of Yunnan Arabica coffee prepared using different primary processing methods

UPLC-Q-TOF-MS and electronic tongue analysis were applied to analyse the metabolic profile and taste quality of Yunnan Arabica coffee under seven primary processing methods. The total phenolic content ranged from 34.44 to 44.42 mg/g DW, the e-tongue results revealed the strongest umami sensor response value in the sample prepared with traditional dry processing, while the samples prepared via honey processing II had the strongest astringency sensor response value. Metabolomics analysis identified 221 differential metabolites, with higher contents of amino acids and derivatives within dry processing II sample, and increased contents of lipids and phenolic acids in the honey processing III sample. The astringency and aftertaste-astringency of the coffee samples positively correlated with the trigonelline, 3,5-di-caffeoylquinic acid and 4-caffeoylquinic acid content. The results contributed to a better understanding of how the primary processing process affects coffee quality, and supply useful information for the enrichment of coffee biochemistry theory.

Can a cup a day keep cancer away? A systematic review exploring the potential of coffee constituents in preventing oral squamous cell carcinoma

BACKGROUND

Coffee is one of the most consumed beverages in the world. Containing an abundance of bioactive molecules including polyphenols and flavonoids, the constituents of this beverage may exert antiproliferative, antioxidant and anti-inflammatory effects.

METHODS

We conducted a systematic review to summarise the available evidence on the anticancer effects of coffee constituents and their potential therapeutic use for oral squamous cell carcinoma (OSCC). Studies were identified through a comprehensive search of OVID MEDLINE, OVID EMBASE and Web of Science, including articles from any year up to 15 May 2023.

RESULTS

Of the 60 reviewed papers, 45 were in vitro, 1 was in silico and 8 were in vivo exclusively. The remaining studies combined elements of more than one study type. A total of 55 studies demonstrated anti-proliferative effects, whilst 12 studies also investigated migration and invasion of neoplastic cells. The constituents studied most frequently were quercetin and epigallocatechin gallate (EGCG), demonstrating various cytotoxic effects whilst also influencing apoptotic mechanisms in cancer cell lines. Dose-dependent responses were consistently found amongst the studied constituents.

CONCLUSION

Whilst there was heterogeneity of study models and methods, consistent use of specific models such as SCC25 for in vitro studies and golden hamsters for in vivo studies enabled relative comparability. The constituents of coffee have gained significant interest over the last 30 years, particularly in the last decade, and present an area of interest with significant public health implications. Currently, there is a paucity of literature on utilization of active coffee constituents for the therapeutic treatment of oral cancers.

Variables Affecting the Extraction of Antioxidants in Cold and Hot Brew Coffee: A Review

Coffee beans are a readily available, abundant source of antioxidants used worldwide. With the increasing interest in and consumption of coffee beverages globally, research into the production, preparation, and chemical profile of coffee has also increased in recent years. A wide range of variables such as roasting temperature, coffee grind size, brewing temperature, and brewing duration can have a significant impact on the extractable antioxidant content of coffee products. While there is no single standard method for measuring all of the antioxidants found in coffee, multiple methods which introduce the coffee product to a target molecule or reagent can be used to deduce the overall radical scavenging capacity. In this article, we profile the effect that many of these variables have on the quantifiable concentration of antioxidants found in both cold and hot brew coffee samples. Most protocols for cold brew coffee involve an immersion or steeping method where the coffee grounds are in contact with water at or below room temperature for several hours. Generally, a higher brewing temperature or longer brewing time yielded greater antioxidant activity. Most studies also found that a lower degree of coffee bean roast yielded greater antioxidant activity.

Effect of Brewing Methods on Acrylamide Content and Antioxidant Activity: Studying Eight Different Filter Coffee Preparations

The aim of this study was to investigate the parameters affecting the extraction of positive molecules such as chlorogenic acids and antioxidants, as well as potentially carcinogenic substances such as acrylamide, in different coffee brewing methods. Three coffee varieties, each assigned a different roasting degree, were used to prepare coffee brews following eight different preparation methods. Acrylamide was quantified using the HPLC-MS/MS instrument, while chlorogenic acids and caffeine were quantified using the HPLC-DAD system. Three spectrophotometric analyses were also performed (DPPH, TFC and TPC) to evaluate antioxidant activity. The results showed that the main brewing parameters, which have the greatest influence on the final content of these compounds, were the volume of water used, more specifically the brewing ratio (coffee to water ratio), the extraction time and the particle size of the coffee powder. In addition, the variables that have the greatest impact on the discrimination of the preparation methods studied are total chlorogenic acid content, TFC, TPC, caffeine and the DPPH assay. For this reason, the recipe and infusion parameters used for each of the extraction systems are the key factors that determine the extraction of coffee components and, consequently, the quality of the cup.

Effect of Cold Brew Coffee Storage in Industrial Production on the Physical-Chemical Characteristics of Final Product

The purpose of this article is to present information about changes in physical properties (pH, TA, and color) and chemical components with bioactive activity in cold brew coffee beverages, during storage before and after HTST processing. Coffee samples were tested using industrial technology (12,000 bottles per batch). The antioxidant activity of the samples was analyzed using ABTS and FRAP methods, the concentration of polyphenols was determined using the UPLC-MS chromatography coupled with mass spectrometry method, and microbiological tests were performed according to PN-ISO/PN-EN ISO standards. The pH value decreased during coffee storage, and the color changed significantly in brightness. Polyphenol concentrations were calculated in the range of 1800 to almost 3400 mg/L, and the antioxidant capacity for ABTS and FRAP reached the ranges of the results successively: 123-195 µMol/100 mL and 158-212 µMol/100 mL. It was observed that HTST pasteurization has a beneficial effect on preserving the beverage in microbiological terms. Also, a positive effect of the process on the release of chemical components responsible for bioactive properties from the beverage was observed, followed by a reduction in antioxidant activity during the first 90 days of storage and between 180 and 270 days during storage.

Functional properties and sensory profile of coffee prepared by different brewing methods

Coffee is one of the main sources of antioxidants in the diet of many countries. The purpose of this research was to assess the effect of different brewing methods, particle size, and coffee quality on the total phenolic content, antioxidant capacity (AC), and sensory profile of the beverage. The brewing methods yielded differences in taste with higher bitterness in immersion methods. However, the main factors that influenced coffee extraction and taste were particle size and coffee type. A finer particle size allowed for greater phenolic and caffeine (CA) extraction (2.82 mg GA/mL; 1.01 mg CA/mL), resulting in higher bitterness and astringency. Additionally, the type of coffee resulted in a higher CA content in commercial coffee (Specialty: 0.72 ± 0.10 mg CA/mL; Commercial: 1.13 ± 0.14 mg CA/mL). The results showed that using a ratio of 1:20 and 1:15 for commercial and specialty coffee, respectively, yielded differences in AC using the DPPH method (Specialty: 11.54 ± 1.12 µmol/mL; Commercial: 10.20 ± 1.88 µmol/mL) but not with the ABTS method (Specialty: 10.38 ± 1.23 µmol/mL; Commercial: 10.37 ± 1.13 µmol/mL). Similarly to the ABTS method, no differences in the total phenol content of the coffee cup were observed (Specialty: 2.52 ± 0.40 mg/mL; Commercial: 2.43 ± 0.28 mg/mL). Thus, the findings suggest that specialty coffee offers consumers a more balanced cup with less CA content. This allows for more coffee consumption without an excessive intake of CA. However, consumers can adjust the functionality, sensory profile, and CA content of a coffee cup by modifying the particle size and the brewing method used.

Discrimination of Filter Coffee Extraction Methods of a Medium Roasted Specialty Coffee Based on Volatile Profiles and Sensorial Traits

An untargeted gas chromatography-mass spectrometry (GC-MS) approach combined with sensory analysis was used to present the effects of different extraction methods (i.e., Pure Brew, V60, AeroPress, and French Press) on specialty graded Coffea arabica from Kenya. Partial Least Square Discriminant analysis and hierarchical clustering were applied as multivariate statistical tools in data analysis. The results showed good discrimination and a clear clustering of the groups of samples based on their volatile profiles. Similarities were found related to the filter material and shape used for the extraction. Samples extracted with paper filters (V60 and AeroPress) resulted in higher percentages of caramel-, and flowery-related compounds, while from metal filter samples (Pure Brew and French Press), more fruity and roasted coffees were obtained. Discriminant analysis allowed the identification of eight compounds with a high VIP (variable important in projection) discriminant value (i.e., >1), with 2-furanmethanol being the main feature in discrimination. Sensorial analyses were carried out through an expert panel test. The main evaluations revealed the French Press system as the lowest-scored sample in all the evaluated parameters, except for acidity, where its score was similar to V60. In conclusion, the data obtained from GC-MS analyses were in line with the sensorial results, confirming that the extraction process plays a fundamental role in the flavor profile of filter coffee beverages.

Chemical and Biological Characterization of Green and Processed Coffee Beans from Coffea arabica Varieties

Coffee is one of the most consumed beverages in the world; its production is based mainly on varieties of the Coffea arabica species. Mexico stands out for its specialty and organic coffee. In Guerrero, the production is done by small indigenous community cooperatives that market their product as raw material. Official Mexico Standards stipulate the requirements for its commercialization within the national territory. In this work, the physical, chemical, and biological characterizations of green, medium, and dark roasted beans from C. arabica varieties were carried out. Analysis by HPLC showed higher chlorogenic acid (55 mg/g) and caffeine (1.8 mg/g) contents in the green beans of the Bourbon and Oro Azteca varieties. The caffeine (3.88 mg/g) and melanoidin (97 and 29 mg/g) contents increased according to the level of roasting; a dissimilar effect was found in the chlorogenic acid content (14.5 mg/g). The adequate nutritional content and the sensory evaluation allowed the classification of dark-roasted coffee as premium coffee (84.25 points) and medium-roasted coffee as specialty coffee (86.25 points). The roasted coffees presented antioxidant activity without cytotoxic effects; the presence of CGA and caffeine supports the beneficial effects of drinking coffee. The results obtained will serve as a basis for making decisions on improvements to the coffees analyzed.

Medium Roasting and Brewing Methods Differentially Modulate Global Metabolites, Lipids, Biogenic Amines, Minerals, and Antioxidant Capacity of Hawai'i-Grown Coffee (Coffea arabica)

In the United States, besides the US territory Puerto Rico, Hawai'i is the only state that grows commercial coffee. In Hawai'i, coffee is the second most valuable agricultural commodity. Health benefits associated with moderate coffee consumption, including its antioxidant capacity, have been correlated to its bioactive components. Post-harvest techniques, coffee variety, degree of roasting, and brewing methods significantly impact the metabolites, lipids, minerals, and/or antioxidant capacity of brewed coffees. The goal of our study was to understand the impact of roasting and brewing methods on metabolites, lipids, biogenic amines, minerals, and antioxidant capacity of two Hawai'i-grown coffee (Coffea arabica) varieties, "Kona Typica" and "Yellow Catuai". Our results indicated that both roasting and coffee variety significantly modulated several metabolites, lipids, and biogenic amines of the coffee brews. Furthermore, regardless of coffee variety, the antioxidant capacity of roasted coffee brews was higher in cold brews. Similarly, total minerals were higher in "Kona Typica" cold brews followed by "Yellow Catuai" cold brews. Hawai'i-grown coffees are considered "specialty coffees" since they are grown in unique volcanic soils and tropical microclimates with unique flavors. Our studies indicate that both Hawai'i-grown coffees contain several health-promoting components. However, future studies are warranted to compare Hawai'i-grown coffees with other popular brand coffees and their health benefits in vivo.

Acids in brewed coffees: Chemical composition and sensory threshold

Coffee brewed on light, and very light-roast coffee beans have emerged as a recent trend among specialty coffee drinkers. The acidity of such light-roast coffee, and coffee in general, is an important sensory characteristic, as there is demonstrated a clear correlation between the roast level and perceived acidity in brewed coffee. The acidity is believed to be strongly linked to the content and composition of organic acids in coffee. Still, there is limited literature on acid content in brewed coffee and on the relevance of specific acid concentrations to sensory perception. In this study, we determined concentrations of acids and sugars in French-press brewed specialty coffee. We used varying roast degrees in the light to very light range using five coffees from different geographical locations (Brazil, Bolivia, and Kenya) and determined the sensory detection threshold and recognition for selected acids. The concentration of all individual acids except one (formic) either significantly decreased (citric, malic, and chlorogenic acid) or increased (acetic, lactic, phosphoric, quinic, and glycolic acid) systematically with an increasing roast degree, while no systematic trends were found between the different coffee samples. The sugar content decreased with an increasing roast degree. The sensory detection threshold for malic, acetic, and lactic acid was determined to be above the actual concentration of said acids in the coffee and just below for phosphoric acid, indicating that these compounds are unlikely to individually be perceived in coffee. Only citric acid can be clearly detected in the threshold test (not identified by experts in coffee) in concentrations above the measured concentrations, as the detection threshold was below (<0.16 g/L) the concentration found in the investigated coffees (0.23-0.60 g/L). The measured citric acid concentration was found to be much higher for the Brazil coffees (0.49 ± 0.08 g/L) compared to the Bolivia coffee (0.40 ± 0.11 g/L), and the Kenya coffees (0.30 ± 0.07 g/L). Furthermore, none of the acids added to the coffee were correctly recognized by coffee experts when spiked with measured average concentrations. Combined, the results question the direct relation between individual organic acids and acidity in coffee and point towards a more complex understanding of perceived acidity.

Chemical and sensory characterization of coffee from Coffea arabica cv. Mundo Novo and cv. Catuai Vermelho obtained by four different post-harvest processing methods

BACKGROUND

After the harvest, green coffee beans are dried on the farm using several methods: the wet process, natural process, pulped natural process, or mechanical demucilaging. This study evaluated how the choice of a specific processing method influenced the volatile organic compounds of the coffee beans, before and after roasting, and the sensory characteristics of the beverage. Coffea arabica beans of two varieties (cv. Mundo Novo and cv. Catuai Vermelho) were subjected to these four processing methods on a single farm in the Cerrado area of Brazil.

RESULTS

Analysis by gas chromatography-mass spectrometry headspace solid-phase microextraction identified 40 volatile organic compounds in green coffee beans and 37 in roasted beans. The main difference between post-harvest treatments was that naturally processed green beans of both varieties contained a different profile of alcohols, acids, and lactones. In medium-roasted beans, those differences were not observed. The coffee beverages had similar taste attributes but distinct flavor profiles. Some of the treatments resulted in specialty-grade coffee, whereas others did not.

CONCLUSION

The choice of a specific post-harvest processing method influences the volatile compounds found in green beans, the final beverage's flavor profile, and the cupping score, which can have a significant impact on the profitability of coffee farms' operations. © 2022 Society of Chemical Industry.

Physicochemical Analysis of Cold Brew and Hot Brew Peaberry Coffee

Peaberry coffee is the result of a natural mutation of coffee beans, and they make up only about 5–7% of coffee crops. A typical coffee cherry contains two seeds that are developed against each other, resulting in the distinctive half-rounded shape of coffee beans. However, failing to fertilize both ovules of one of the seeds or failure in endosperm development can cause only one of the seeds to develop, resulting in smaller, denser beans with a more domed shape. Peaberry coffees are said to be sweeter, lighter, and more flavorful since the peaberry beans receive all nutrients from the coffee cherry. Due to its exclusive nature, the chemical characteristic of peaberry coffee is not well understood. This study explores the acidities and antioxidant activity of peaberry coffee sourced from multiple regions. Total antioxidant capacity, total caffeoylquinic acid (CQA), total caffeine concentration, and pH levels were evaluated for peaberry coffee extracts prepared by cold and hot brewing methods. Little correlation between antioxidant activity and the concentrations of caffeine and CQA in peaberry beans was shown. Six methods were performed for the characterization of total antioxidant capacity including cyclic voltammetry, ABTS assay, and FRAP assay. Peaberry bean extract demonstrated higher average total caffeine concentrations compared to traditional coffee bean extracts.

Metabolomics-Based Approach for Coffee Beverage Improvement in the Context of Processing, Brewing Methods, and Quality Attributes

Coffee is a worldwide beverage of increasing consumption, owing to its unique flavor and several health benefits. Metabolites of coffee are numerous and could be classified on various bases, of which some are endogenous to coffee seeds, i.e., alkaloids, diterpenes, sugars, and amino acids, while others are generated during coffee processing, for example during roasting and brewing, such as furans, pyrazines, and melanoidins. As a beverage, it provides various distinct flavors, i.e., sourness, bitterness, and an astringent taste attributed to the presence of carboxylic acids, alkaloids, and chlorogenic acids. To resolve such a complex chemical makeup and to relate chemical composition to coffee effects, large-scale metabolomics technologies are being increasingly reported in the literature for proof of coffee quality and efficacy. This review summarizes the applications of various mass spectrometry (MS)- and nuclear magnetic resonance (NMR)-based metabolomics technologies in determining the impact of coffee breeding, origin, roasting, and brewing on coffee chemical composition, and considers this in relation to quality control (QC) determination, for example, by classifying defected and non-defected seeds or detecting the adulteration of raw materials. Resolving the coffee metabolome can aid future attempts to yield coffee seeds of desirable traits and best flavor types.

Comparison of chemical compounds and their influence on the taste of coffee depending on green beans storage conditions

Currently, there is no technology for the storage of green coffee (GrC), that results in obtaining high-quality roasted coffee (RC). The aim of this study was to evaluate the effects of storage temperature (- 10, 5, 10, 18, 20 °C), postharvest treatment method (natural (N), washed (W)) and type of packaging material (GrainPro (G), jute (J) bags) on the content of chlorogenic acids (CQAs), caffeine and trigonelline as well as the sensory profile of RC from the specialty sector after 12 months of regulated storage. Sensory analysis showed that natural coffees have better taste and higher quality than washed coffees after 12 months of storage. The highest total scores were obtained from the natural coffee stored in a GrainPro bag at - 10 °C followed by coffee stored in a jute bag at 10 °C which had the smallest decreases compared to the initial recorded values. No notable differences among CQA contents in washed coffees stored in either type of bag was seen but natural coffees stored in jute bags at 10 °C and 18 °C displayed the lowest drops relative to the initial values.