Cold Brew Research Articles

Norovirus (NoV) is a symptomatic virus that is the leading cause of gastrointestinal disease. It spreads easily through the fecal-oral route and contact with contaminated food or surfaces. Maintaining a high level of hygiene in food industry settings and refocusing food production on isolating and testing natural compounds that exhibit antimicrobial and antioxidant properties are important elements in preventing NoVs infection. This study evaluated plant extracts prepared by cold brew and cold concentrate techniques for their antioxidant and antiviral activity. The extracts obtained demonstrated high antioxidant activity, with notable variation depending on the plant material, ranging from moderate to very strong levels. Correspondingly, high antiviral potential was observed, reaching the nearly complete inactivation of the virus. Remarkably, the highest virucidal effects were already achieved at relatively elevated, but not maximal, antioxidant activity levels. The results of the study indicate that cold water extraction techniques allow for the obtention of plant extracts showing strong virus-inactivating activity and favorable antioxidant activity.

High-pressure carbon dioxide (HPCD) has been widely used in the extraction of high-quality bioactive compounds. The flavor profiles of cold brew coffee (CBC) prepared by HPCD, traditional cold brew (TCB), and ice drip (ID) were comprehensively evaluated by chromatographic approaches, and their variations were investigated by multivariate statistical methods. ID produced the lightest coffee color while HPCD produced the darkest. No significant difference was found in pH among the three coffee processes. The concentrations of chlorogenic acids and caffeine were the highest in ID but the lowest in HPCD. Seventeen of the forty-eight volatiles were identified as key aroma compounds, contributing nutty, cocoa, caramel, baked, and other coffee flavors to all CBCs. Among them, linalool (OAV = 100.50) was found only in ID and provided ID with unique floral and fruity notes; 2-methyl-5-propylpyrazine (OAV = 17.70) was found only in TCB and gave a roasted aroma. With significantly lower levels of medicine-like and plastic off-flavors, HPCD had a refined aroma experience featuring nutty, cocoa, and caramel notes, though their contents were not the highest. Orthogonal partial least squares discriminant analysis (OPLS-DA) identified 36 aromas that could differentiate three cold brew methods, with TCB and HPCD being the most similar. Aroma sensory tests showed that no significant difference was perceived between TCB and HPCD. These findings provide a profound understanding of CBC flavor produced by cold brew methods from the aspect of composition, indicating that HPCD has great potential to realize TCB-like flavor characteristics in a shorter time.

The chemical basis of aroma/taste and color formation in green tea infusion during cold brewing revealed by metabolomics analysis.

ABSTRACTThe unique flavor and taste of cold brew coffee have made it popular in recent years. As the name suggests, it is cold‐brewed, which means the absence of a thermal process in the brewing. Hence, after the roasting step, it only has to rely on the product pH and storage temperature to control the foodborne pathogens such as Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes. The purpose of this study is to investigate the effect of pH (4.9 and 5.3) and temperature (4°C and 23°C) on Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes in cold brew coffee. Cold brew coffee samples were inoculated with these organisms for 30 days, and survival data were collected. Results showed that pH affected the survival of Salmonella and E. coli. At pH 4.9, Salmonella was reduced by 5 log CFU/ml after 7 days, reaching the limit of detection in 11 days. However, at pH 5.3, 5 5‐log reduction occurred after 14 days, taking 25 days to reach the limit of detection. At 23°C, both Salmonella and E. coli showed increased survival, making temperature an important factor. Listeria showed resistance to pH variations at both temperatures. Lower RMSE values for Salmonella (pH 4.9) and Listeria (pH 4.9) were observed in the log‐linear model, making it a better fit. However, the Weibull model showed a better fit for Salmonella (pH ‐5.3), Listeria (pH ‐5.3), and E. coli (pH ‐4.9, 5.3). Overall, lower temperatures increase survival, while higher temperatures enhance the reduction in E. coli.These findings are crucial for enhancing the safety of cold‐brew coffee and providing valuable recommendations to producers, regulators, and consumers.

Effects of ultrasound treatment on physicochemical, sensory, and structural properties of cold brew coffee

ABSTRACTThe ethanoic extract of hot‐brew spent‐coffee ground (HSCG) and cold‐brew spent‐coffee ground (CSCG) were prepared with ultrasound‐assisted extraction and subjected to thermal processes and in vitro digestion prior to analyze the inhibition ability of advanced glycation end products (AGEs) formation, a potential risk factor for Alzheimer's disease. The obtained HSCG and CSCG extracts contained mainly chlorogenic acid derivatives, according to liquid chromatography‐mass spectrometer chromatogram. The glycation process was performed by using bovine serum albumin (BSA)/ glucose system with 3 weeks incubation. In the presence of HSCG and CSCG extracts at 250 μg/mL, after thermal treatment (pasteurization and sterilization) and in vitro digestion, the glycation process through the fructosamine, AGEs, and amyloid cross β structure formation was monitored, and these extracts exhibited an anti‐glycation property at early and advanced stages after pasteurization and in vitro digestion compared to no thermal treatment. However, at high temperature of sterilization, the suppress of anti‐glycation property had resulted and were related with the amount of antioxidant and the ability of antioxidant scavenging as presented in a dose manner. The calculated % caffeine bio‐accessibility of HSGC extracts was 65.8%, 64.8%, and 52.4% in non‐thermal, pasteurized, and sterilized samples while the higher bio‐accessibility was found in CSCG sample as of 67.4, 66.6, and 63.1, respectively. A high correlation of TPC values, thermal treatments and in vitro digestions with the AGEs was detected. Polyphenols and caffeine content in these extracts were found to be responsible for the AGEs and amyloid cross β structure inhibition which might potentially reduce the risk of Alzheimer's disease.

Dietary intake represents a significant exposure pathway for phthalates (PAEs) and nonphthalate plasticizers (NPPs). However, the associated exposure risk linked to tea consumption remains unclear. This study analyzed 10 PAEs and 10 NPPs in six types of tea collected from 18 provinces in China. Both PAEs and NPPs were detected in all samples, with concentrations ranging from 309 to 8150 ng/g for PAEs and 42.2 to 899 ng/g for NPPs, respectively. Source apportionment analysis indicates that packaging materials are important sources of plasticizer contamination in tea. The concentrations of di-isobutyl phthalate (DiBP), benzyl-butyl phthalate (BzBP), and trioctyl trimellitate (TOTM) in tea exhibited a significant correlation with those found in packaging materials (r: 0.414-0.465, p < 0.01). Five transformation products (TPs) of plasticizers were identified in brewed tea samples through suspect screening analysis, raising concerns about their potential health effects. Comparisons suggest that cold brewing may result in higher plasticizer exposure than hot brewing after a single brew. However, as the brewing times for hot brewed tea increased, the risk of human exposure rose, ultimately exceeded that of cold brewed tea. This study provides national-scale data on plasticizer contamination in Chinese tea and valuable insights into tea consumption practices.

The aim of this research was to prepare ready-to-drink coffee from date seed powder and to evaluate the coffee drink during storage at 40 ℃. The proximate composition, physicochemical properties, total phenolic content, total flavonoid content, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the powder were determined. The total suspended solids (TSS) and pH of the ready to coffee drink decreased by increased the ADSP during 10 days of storage. Total phenolic content (TPC) ranged from 678.99-203.79 GE/100 g dry weight in different ready to coffee drink. The half-maximal inhibitory concentration (IC50) at the beginning was (23.67 - 42.12 µg/mL) indicating that ready-to-drink coffee has a very strong antioxidant activity. Increasing the storage periods decreased the TSS. The lightness values (L*-value) increased with time values whereas a* (red/green value) and b*- (blue/yellow value) values decreased. Microbial studies revealed that the total viable count for coffee ranged from 8.84×101 to 5.07×106 CFU/mL on the 8th day of storage. The sensory analysis indicated that the ready-to-drink coffee incorporated with 15% coffee brew was more acceptable than the others. This study suggests that date seeds can be considered a potential raw material for ready-to-drink coffee. KEY WORDS: Agglomeration, Cold brewing, Solubility, Ready-to-drink coffee, Antioxidant activity Bull. Chem. Soc. Ethiop. 2025, 39(7), 1257-1272. DOI: https://dx.doi.org/10.4314/bcse.v39i7.3

Cascara, the dried husk of coffee cherries, has attracted attention as a potential beverage due to its unique flavour profile and potential health benefits. Traditionally, cascara is prepared using hot brewing methods. However, recent interest in cold brewing methods has led to research on how temperature affects the functional properties of cascara beverages. Colour (CIE L*a*b*), total dissolved solids and titratable acidity were determined in cascara beverages prepared at 5, 10, 15 and 20 °C. The concentration of phenols and flavonoids, as well as antioxidant properties were evaluated using spectrophotometric methods. Caffeine, chlorogenic acid and melanoidins were quantified by HPLC. The mineral composition was determined using inductively coupled plasma mass spectrometry (ICP-MS). The results were compared with a hot-brewed cascara beverage. Cold brewing resulted in significantly higher concentrations of total phenolic compounds, expressed as gallic acid equivalents (ranging from 309 to 354 mg/L), total flavonoids, expressed as quercetin equivalents (11.8-13.6 mg/L), and caffeine (123-136 mg/L) than the hot-brewed cascara beverage sample (p<0.05). Temperature had a noticeable effect on most variables, although the effect appeared to be random. In particular, concentrations of caffeine (p<0.01) and copper (p<0.001) were highest in beverages prepared at 20 °C and decreased with decreasing brewing temperature. Multivariate analysis showed that minerals (As, Co, Mn, Sn, Mg and Ca), hue and phenolic concentration contributed to the first principal component, which mainly differentiated the hot-brewed sample. Antioxidant-related variables, total titratable acidity and Se contributed most to the second principal component, which facilitated the separation of samples brewed at 5 °C. To our knowledge, this is the first study to suggest that temperature affects the functional properties of cascara beverage produced by the cold brewing method. Experimental evidence supports the existence of a direct proportionality between caffeine and copper concentrations and brewing temperature.

Synergistic effect of naringenin and mild heat for inactivation of E. coli O157:H7, S. Typhimurium, L. monocytogenes, and S. aureus in peptone water and cold brew coffee.

Introduction. Cold brewing is a relatively new method of preparing coffee. The goal research was to study the dynamics of biologically active compounds and antioxidant activity during cold extraction of coffee using Arabica coffee sold on the Russian consumer market. The Methods. Extraction was carried out for 24 hours in two versions differing in the temperature of the water for extraction (+20 °C and +4 °C). At different time intervals (5 minutes, 1, 3, 6, 12 and 24 hours) the following were determined in the extracts: spectrophotometrically for caffeine content, the amount of chlorogenic acids, phenolic compounds; antioxidant activity by the coulometric method. The coffee extract brewed in a French press for 5 minutes using the hot method served as a control sample. The Results. The main part of biologically active compounds passed into the extract after 6 and 12 hours when using water at a temperature of +20 °C and +4 °C for extraction, respectively, constituting more than 90 and 95 % of their total amount extracted in 24 hours. At the same time, their antioxidant activity was only 83.89 and 87.45 %. The content of biologically active compounds and the antioxidant activity of the extracts reached or exceeded the control after 24 hours of extraction. In drinks prepared for 6 and 24 hours (water temperature +20 °C) and 12 and 24 hours (water temperature +4 °C), soluble dry substances, pH, titratable acidity, and brown color intensity were additionally determined. At a higher temperature, coffee acquires a bitter taste during 24 hours of extraction, which reduces its organoleptic assessment. The Conclusion. To form optimal organoleptic and antioxidant properties when preparing Arabica coffee using cold brewing method, water at a temperature of +20 °C and +4 °C can be used with an extraction time of 6 and 24 hours, respectively.

The cold brew method consists of soaking roasted and ground coffee beans either in cold or ambient water (4–23 °C) for up to 24 h. Using this technique, a drink with a unique sensory profile is obtained. This study was conducted to determine the shelf life of a cold brew organic coffee drink (pH~5.0) made from organic beans subjected to three roast levels: light, medium and dark. The drink was pasteurized at 90 °C/30 s, ultra-clean filled into high-density polyethylene bottles, and stored at 4 °C in the dark. Physicochemical, enzymic tests, instrumental color analysis, and microbiological and sensory assays were carried out. The product remained microbiologically stable under refrigeration for all roast levels; however, the beverage made from light roasted beans failed at the beginning of the study, in contrast to the those prepared from medium and dark roasts, which achieved 150 days of shelf life.

Coffee contains several bioactive compounds, such as alkaloids and phenolic compounds, which contribute to its flavor and are influenced by the brewing method. The differences in coffee compounds based on brewing conditions have been studied in previous research, but no studies have yet utilized orbitrap mass spectrometry for this purpose. This study compared non-volatile and aromatic compounds in hot and cold brew coffee using high-resolution orbitrap mass spectrometry, followed by multivariate statistical analysis including principal component analysis and volcano plotting. A total of 163 non-volatile compounds and 93 volatile compounds were identified and annotated, with 18 non-volatile and 13 aroma-active compounds indicating differences between the brewing methods. Notably, certain quinic acids, such as 4,5-dicaffeoylquinic acid, and coumarin derivatives were more abundant in hot brew coffee, indicating that non-volatile compounds are significantly affected by extraction temperature. However, the major non-volatile compounds, including chlorogenic acid and trigonelline, are not affected by brewing conditions. For volatile compounds, phenolic compounds and indole were sensitive to temperature, while pyrazine and furan compounds were more influenced by extraction time. Additionally, in our results, several previously unreported bioactive compounds were detected in coffee, suggesting a need for further research to understand their potential functions and benefits.

Roasting and brewing significantly influence the flavor and characteristics of coffee. Factors affecting the roasting process include the roasting machine, temperature, and duration of roasting. Cold brew brewing is the extraction of coffee using cold water, stored at temperatures below 30oC for 12 to 24 hours. This study aims to determine the physicochemical characteristics, particularly caffeine content and pH, followed by organoleptic testing compared to commercial coffee with 30 panelists on parameters (flavor, bitterness, aroma, color, overall) of Temanggung robusta coffee cold brew. The research employed a Completely Randomized Design (CRD) with variations in roasting levels. The temperatures and times used for the roasting levels were: light roasting at 210 oC for 7 minutes, medium roasting at 215 oC for 9 minutes, and dark roasting at 225 oC for 11 minutes. The data were statistically analyzed using analysis of variance (ANOVA) followed by the Duncan Multiple Range Test (DMRT) at a significance level of 5% using SPSS 27. The results showed that the caffeine content of Temanggung robusta coffee cold brew ranged from 489.18 to 735.87 mg/L. The average pH was found to be between 5.72 and 5.96. In the organoleptic test, panelists provided differing scores on aroma and color parameters, with average scores on a scale of 1-5: for color, scores ranged from 2 (not bright) to 4 (fairly bright), and for aroma, average scores ranged from 2.5 (not quite sharp) to 3.3 (fairly sharp).

ABSTRACT In the past three decades specialty coffees have gained greater visibility in the high-end consumer marketplace. These coffees include Arabica varieties grown in northern Thailand, the borderlands area of the Golden Triangle. In the 1970s Thai Royal Project initiatives sought to eradicate upland minority groups’ swidden rotational farming and opium cultivation. Despite minorities’ issues of land access, geopolitics of the Cold War, and citizenship challenges, Royal Project crop replacement schemes offered a technical, management-based solution. These projects imposed alternative crops, including avocado, macadamia, and coffee. Through interviews with Akha and Lisu coffee growers, roasters, and marketers in three villages in Chiang Rai Province, supplemented with discussions among neighboring Chinese and Lahu villagers, this paper explores varied coffee livelihoods in the changing context of the uplands. Ethnicized coffee marketing has latched onto royalist and touristic narratives about hill tribes, presenting individuals as culturally quaint loyal subjects who are doing better for the nation by growing coffee. However, these stories occlude Cold War histories, social stratification, and ecological damages resulting from coffee production.

IntroductionHardtank® is a pressure-modulated, solvent-free cold extraction that shortens brewing while maximizing bioactive recovery from roasted coffee.MethodsWe produced a Nitro Cold Brew beverage from roasted Yellow Bourbon beans using Hardtank® (550 g : 10,000 mL water, 30 min, 0.3–1.5 bar) and compared its composition and antioxidant activity with laboratory extracts from roasted and green beans obtained by hot water infusion (93 °C, 5 min) and by methanol extraction (70% reflux, 2 h; 100% reflux, 2 h; 70% shake, 5 min). We measured caffeine, chlorogenic acid (and derivatives), total phenolics, total flavonoids, and antioxidant activity by the ferric reducing antioxidant power and DPPH radical tests, expressed as Trolox equivalents.Results and discussionNitro Cold Brew contained 375.8±2.4 mg phenolics + flavonoids per 100 mL, 72.4±1.1 mg caffeine per 100 mL, and 78.2±2.3 mg chlorogenic acid per 100 mL, with ferric reducing antioxidant power 27.9±0.5 mM and DPPH 11.7±0.6 mM. Using 70% methanol reflux as the 100% reference, Hardtank® achieved 135.3% for phenolics + flavonoids, 119.7% for caffeine, and up to 172.3% for chlorogenic acid. Overall, Hardtank® yielded a ready-to-drink coffee with bioactive and antioxidant profiles comparable to or better than laboratory reflux extracts, while operating rapidly and without organic solvents, indicating promise for scalable production of functional coffee beverages.

This study examines the effect of fermentation duration and extraction methods (cold brew and hot brew) on the quality of robusta wine coffee. Wine coffee is a beverage resulting from the fermentation process of coffee extract which is providing a unique taste with a blend of coffee and alcohol flavors, along with a characteristic wine aroma. Through these two extraction methods, cold brew and hot brew offer different characteristics to the chemical parameters such as pH, reducing sugar content, alcohol content, caffeine content, and flavor. The research results indicate that cold brew yields a lighter flavor, while hot brew tends to have a stronger or more bitter taste. The duration of fermentation significantly affects the chemical parameters, with a decrease in pH and reducing sugar content as fermentation time increases. The alcohol content in cold brew reaches 19.93% on day 28, higher than hot brew which has 18.40% of alcohol. Organoleptic analysis results show that cold brew is preferred by the panelists, especially on the 28th day of fermentation.

The study investigated the effects of storage temperature, type of coffee, and brewing method on coffee's volatile compound profile and sensory quality. Three types of coffee were included in the study: Arabica, Robusta, and their 80/20 blend. Samples were stored at 5 °C and 20 °C for one month, after which the changes in the composition of volatile compounds were analysed and the sensory quality of espresso and cold brew coffee was assessed. The results showed that storing coffee at a lower temperature slows the changes in the profile of volatile compounds such as aldehydes, alcohols, pyrazines, and furans, helping preserve the desired aroma and flavour characteristics. Storage at higher temperatures resulted in greater changes in the volatile profile and sensory quality, with higher perceptions of earthy, sharp, and smoky notes and lower chocolatey and sweet notes. The brewing method also had a significant effect on the sensory quality. The espresso coffee had a higher intensity of coffee aroma, chocolate flavour, smoky aroma, and roasted notes. In contrast, cold brew coffee was perceived as sweeter, fruitier, and had more pronounced rum notes. The coffee type also significantly influenced the aroma and flavour profile. Arabica had a more harmonious and mild aromatic profile, while Robusta had a sharper aroma. The blend of Arabica and Robusta combined the characteristics of both coffees and offered a balanced aromatic profile.

Coffee is one of the most widely consumed beverages in the world due to its sensory and health benefits. The caffeine content, a bioactive compound of coffee, depends on many factors, including the brewing method, which is the subject of ongoing scientific research. In addition, various methods are used in studies to determine the caffeine content. However, it is worth noting that there is considerable variation in the individual analytical parameters within these methods. The aim of this study was to update the data on the effects of different brewing methods on the caffeine content of the brew and to present the current state of knowledge on techniques for the determination of this compound. A literature review was conducted, taking into account the latest studies in this field. The results showed that the caffeine content (mg/100 mL) of the brew prepared with the Cold Brew method was 48.50–179.95, Espresso—50.40–965.60, French Press—52.00–123.90, AeroPress—56.35–120.92, and Moka—128.00–539.90. These methods were characterized by different brewing parameters (time, water temperature and pressure, ratio of coffee to water), which differentiated the caffeine content. In addition, some methods were characterized by a wide range of caffeine content, suggesting that even minor variations in brewing method parameters may affect the content of this ingredient. High-performance liquid chromatography (HPLC) was the predominant method used. The detector wavelengths, along with other parameters of the HPLC method, such as gradient profiles and column temperatures, can affect the precision and accuracy of the analysis, and these differences can modify analyte retention and detection, leading to discrepancies in results. These results point to the need for studies that consider various brewing methods and a wide range of coffee types, including roast and origin, to accurately determine the effects of these factors on caffeine content determined by one precise method.

Cold brew coffee has gained significant popularity in the global market. This study examined the differences in chemical properties and flavor of cold brew coffee during storage, which was subjected to low-temperature pasteurization using induced electric field (IEF) at temperatures of 52 °C and 58 °C for 92 s, corresponding to 18.52 V/cm and 25.92 V/cm. Then, a high-temperature short-time (HTST) pasteurization was performed at 93 °C for 2 min as the control. Microbial analysis demonstrated that IEF treatment at 58 °C achieved a bactericidal effect. Both the IEF and HTST groups exhibited consistent trends in total sugar and total phenol content, showing approximately 28 μg GAE/mL after 28 days for IEF-2 group, compared to 25 μg/mL for HTST. Flavor analysis indicated that IEF group preserved the aroma characteristics during storage period. Further, IEF treatment effectively retained the key aroma compounds in cold brew coffee through GC–MS analysis, particularly pyrazine compounds with a relative content increased by 0.96 % in IEF-2 group after 28 days. Moreover, the bioactive compounds initially increased and subsequently decreased over the storage.