Cold Brew Coffee Research Articles

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

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.

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.

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 brewing sonoreactor for reducing the time of cold brew from several hours to minutes while maintaining sensory attributes

This research designed and developed an ultrasonic reactor for a fast and on demand production of cold brew coffee, remarkably reducing the brewing time from 24 h to less than 3 min. The technology was engineered by utilizing resonance to induce ultrasonic waves around the walls of the brewing basket of an espresso machine. The sound transmission system comprised a transducer, a horn and a brewing basket. This arrangement transformed the coffee basket into an effective sonoreactor that injected sound waves at multiple points through its walls, thereby generating multiple regions for acoustic cavitation within the reactor. Furthermore, acoustic streaming induced greater mixing and enhanced mass transfer during brewing. The design was accomplished by modeling the transmission of sound, and acoustic cavitation. Brew characterization and chemical composition analysis was performed, considering factors such as pH, acidity, color, and the composition of caffeine, fatty acids, and volatiles. The efficiency of the extraction increased by decreasing the basket loading percentage (BLP). For instance, sonicating at 100 W doubled the extraction yield and caffeine concentration, from 15.05 % to 33.44 % at BLP = 33 %, and from 0.91 mg/mL to 1.84 mg/mL at BLP = 67 %, respectively. The total fatty acids increased from 1.16 mg/mL to 9.20 mg/mL, representing an eightfold increase, at BLP = 33 %. Finally, a sensory analysis was conducted to evaluate appearance, aroma, texture, flavor, and aftertaste, which demonstrated that coffee brewed for 1 and 3 min in the sonoreactor exhibited almost undistinguishable properties compared to a standard 24 h brewing without ultrasound.

Assessment of the physical stability of cold brew coffee in retorted beverages

In recent years, the coffee market has launched many ready-to-drink cold brew coffee beverages (CBC). When bottled, producers face issues with the stability as consumers perceive the sedimentation phenomenon as a quality defect. As the physical stability in CBC is an emerging topic, it is necessary to characterize the sediment and understand its origin to identify mitigation alternatives. In this regard, regular and decaffeinated CBC in glass bottles over a period of 60 days were analyzed by microscopy and particle size distribution. Nano, amorphous and semi-crystalline particles were identified. Nanoparticles increased in the ∼0.1 μm range in the sediment of the regular CBC. Caffeine (+10%) and chlorogenic acid (CQAs) levels (+50%) in the supernatant filtrate increased after 60 days, which by scanning electron microscopy (SEM) revealed the topology of the identified particles, with a clear presence of the crystalline needles of caffeine, protein and potassium. X-ray diffraction analysis revealed that some peaks (3 out of 10), were associated with caffeine and sucrose, suggesting a complexation from the CQA presence; and supporting that the sediment might be mostly potassium chlorogenate complex. As the phenomenon was prevalent in the regular CBC, the presence of caffeine in the formation is key.

Marketing Strategy Plan of Coca-Cola Company in the UK

Marketing is crucial to the success of an enterprise. This report is to develop a marketing strategy plan for Coca-Cola company, including seven parts: introduction, situation analysis, market segmentation, innovation, resource allocation, conclusion and recommendation. Situational analysis includes macro-environmental factors, such as policy, economy, society and technology; Industry elements like competitors, suppliers and substitutes; Internal factors, such as the strengths and weaknesses of Coca-Cola. Coca-Cola divided the market into different segments and target each segment with suitable products, which including provides Coca Cola range with different varieties for age segment (18-35); Multiple size of bottles target family size segment; Multiple bottles with different materials target income group; Sugar and calories-free drink target health-conscious group; “Christmas Celebration Bottle Bow” target specific occasion - Christmas. In terms of innovation, Coca-Cola launched new products, including Coca-Cola energy, Simply smoothie and Honest cold brew coffee. Moreover, it also developed new packaging material which is KeelClip™ and is going to replace all the plastic packaging from all can multi-packs. In addition, Coca-Cola innovated its service, which is the adding of loyalty scheme to vending machine. Coca-Cola uses financial planning model to determine the budget and other resources that should be allocated to each project, it invested lots of money into Diet coke and new packaging technology. The recommendation for the future development is expanding markets to health and food areas as well as target other age group (50-54) and introduce suitable products.

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.

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.

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.

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.

High-Pressure Processing for Cold Brew Coffee: Safety and Quality Assessment under Refrigerated and Ambient Storage.

Cold brew coffee (CBC) has gained in popularity due to its distinct sensory experience. However, CBC can pose a risk for bacterial pathogens if not stored properly. High-Pressure Processing (HPP) is a nonthermal technology that can improve the safety of CBC while maintaining its quality. In this study, CBC made from ground roasted coffee grains was processed at 600 MPa for 3 min and stored at 4 or 23 °C for 90 days. The microbiological quality indicators remained stable throughout the study period. Physicochemical and quality parameters, such as pH, total dissolved solids, titratable acidity, color, total phenolic compounds and antioxidant activity, were not significantly affected by HPP. Both unprocessed and HPP CBC samples showed changes in pH, titratable acidity and color stability after 60 days at 23 °C. Unprocessed CBC samples spiked with Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enterica showed decreased counts, but the pathogens were still detectable after 60 days at 4 °C and after 90 days at 23 °C. HPP achieved a >6-log10 reduction in the species tested, with non-detectable levels for at least 90 days at both storage temperatures. These findings suggest that HPP can effectively control vegetative pathogens and spoilage microorganisms in CBC while preserving its quality attributes.

Evaluation of Physicochemical Characteristics and Sensory Properties of Cold Brew Coffees Prepared Using Ultrahigh Pressure under Different Extraction Conditions.

Although cold brew coffee is becoming increasingly popular among consumers, the long coffee extraction time is not conducive to the further development of the market. This study explored the feasibility of ultrahigh pressure (UHP) to shorten the time required for preparing cold brew coffee. The effects of pressure and holding time on the physicochemical characteristics and sensory evaluation of UHP-assisted cold brew coffee were also determined. The extraction yield; total dissolved solid, total phenol, and melanoid content; antioxidant capacity; and trigonelline and chlorogenic acid contents of UHP-assisted cold brew coffee increased as the pressure increased. The extraction yield and the total dissolved solid, total phenol, total sugar, and chlorogenic acid and trigonelline contents were higher when the holding time was longer. The HS-SPME-GC/MS analysis demonstrated that the furan, aldehyde, and pyrazine contents in coffee increased as the pressure and holding time increased. The pressure did not significantly impact the concentrations of volatile components of esters and ketones in coffee samples. However, the increase in holding time significantly increased the ester and ketone contents. The sensory evaluation results revealed that as pressure rose, the intensities of nutty, fruity, floral, caramel, and sourness flavors increased, whereas bitterness and sweetness decreased. Longer holding time increased nutty, caramel, sour, bitter, sweet, and aftertaste flavors. Principal component analysis (PCA) results indicated that holding time is a more crucial factor affecting the physiochemical indices and flavor characteristics of coffee. UHP can shorten the preparation time of cold brew coffee. Pressure and holding time significantly affected the physiochemical indices and volatile components of UHP-assisted cold brew coffee. UHP-assisted cold brew coffee had lower bitterness, higher sweetness, and a softer taste than conventional cold brew coffee.

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.

Ultrafast extraction of cold brew coffee in a planetary rotating bed reactor: A kinetic study on the pushback effect

AbstractGiven the rising demand for cold brew coffee, innovative approaches are required to address the present difficulties in its production. This motivates the consideration of the planetary rotating bed reactor (PRBR) as a solid–liquid extraction technology. The PRBR consists of cylindrical mesh chambers that contain the solid phase and move in two superimposed rotations. This motion pattern enhances mass transfer through alternating radial forces: the pushback effect (PBE). To evaluate the utility of the PRBR and the role of PBE, we investigated the kinetics and energy demand of cold brew coffee extraction. For this purpose, we varied rotational speeds and PBE conditions in a 1 L lab‐scale reactor. Kinetics was determined by in‐line monitoring of electrical conductivity correlated with the eluate's weight‐based total dissolved solids and caffeine by high‐performance liquid chromatography. Energy consumption was derived from strain gauge torque measurements. Our findings reveal that saturation of the extraction rate with respect to the rotational speed is evident both with and without PBE. However, PBE significantly reduces extraction time by 75% while requiring 60% less mechanical energy. The fastest conditions probed 95% of the maximum extraction yield within 12 s, effectively being >99% faster than static immersion. We believe these findings, along with further procedural advantages, qualify the PRBR as a viable technology for cold brew coffee production.Practical ApplicationsThe relevance of an economical and sustainable preparation of cold brew coffee extends from the industrial to the gastronomic to the domestic environment. Challenges and limitations relate to process time, particle separation, product and extraction yield, and taste problems due to over‐extraction. The planetary rotating bed reactor (PRBR) promises to address all these issues by combining extraction and separation in a simultaneous and ultrafast process. The present study confirms the superiority of PRBR's action mechanisms in terms of rapidity and energetic efficiency for extraction. Due to the excellent scalability of both the design and the physical effect, the PRBR is intended for large‐scale production of ready‐to‐drink products and local production in coffee shops or private households. By modifying the particle feed, even continuous operation is conceivable. Further applications are, for example, dry‐hopping of beer, fast‐aging of spirits, and preparation of various liquid foods.

Effects of grind size, temperature, and brewing ratio on immersion cold brewed and French press hot brewed coffees

This study investigated the effects of coffee ground particle size (282–1057 µm volume-weighted mean particle diameter), extraction temperature (4–37 °C), steeping time (5 min to 18 h), and brew ratio (1:3–1:11 ground:water, w/w) on the physicochemical properties of coffee brews prepared using an immersion cold brewing method. The results showed that the extraction rate and yield increased with increasing brewing temperature and decreasing grind size. Brew ratio significantly affected the extraction yield and titratable acidity of the brews, but not the extraction rate. The ratio between the absorbance at 420 nm and total dissolved solid increased with increasing brewing time, suggesting that non-enzymatic browning reactions might have occurred during the extraction process. Strong positive correlations of total dissolved solids with brew physicochemical properties (total phenol content, caffein content, titratable acidity, absorbance at 420 nm) were observed. Compared with hot brew, the cold brew coffees had significantly higher pH (5.18 vs 5.38) and surface tension (61.6 vs 64.5 mN/s) values, but lower titratable acidity (0.97 vs 0.86 g/L), total polyphenol content (4.08 vs 3.40 g/L), and viscosity (1.12 vs 1.08 cSt) values. The findings from this study are expected to be useful for baristas to control extraction efficiency/yield and manipulate brew compositional profiles to impart unique sensory characteristics of cold brew coffee beverages.

Extraction technology and influencing factors of cold brew coffee

Coffee especially cold brew coffee is widely popular around the world, so people have conducted deep research on how to make a cup of coffee. This paper studies the types of coffee beans, the chemical composition of coffee beans, the roasting degree of coffee beans and the extraction technology. Among them, there are a lot of biochemistry reactions such as Maillard and Caramel reaction. Moreover the extraction technology focuses on the cold extraction technology, which is compared with the hot extraction technology in the content of flavor substances. In addition, the flavoring substances are matched with their aroma to compare the flavor differences between hot brew and cold brew coffee. Finally, the adjustable influencing factors in the cold extraction technology were studied and summarized to provide theoretical reference and practical guidance for the flavor improvement and industrial production of cold brew coffee. Furthermore, there will emerge other problems of coffee producing which will be issues to solve in the future.

Optimization of Cold Brew Coffee Using Central Composite Design and Its Properties Compared with Hot Brew Coffee.

The cold brew coffee (CBC) trend is increasing globally; nevertheless, there is limited literature on this popular beverage. Many studies have focused on the health benefits of green coffee beans and coffee brewed by conventional hot water methods. Thus, whether cold brew conveys similar benefits is still unclear. This study aimed to investigate the influences of brewing conditions on physicochemical properties using response surface methodology in order to optimize the brewing parameters and compare the resulting CBC with the coffee from the French Press method. Central Composite Design was used to evaluate the effects and optimize the brewing parameters (i.e., water temperature, coffee-to-water ratio (C2WR), coffee mesh size, and extraction time) on total dissolved solids (TDS). Physicochemical properties, antioxidant activity, volatile compounds, and organic acids were compared between CBC and its French Press counterpart. Our results showed that water temperature, C2WR, and coffee mesh size significantly influenced the TDS of CBC. The optimized brewing conditions were water temperature (4 °C), C2WR (1:14), coffee mesh size (0.71 mm), and 24-h extraction time. At similar TDS, caffeine content, volatile compounds, and organic acids were higher in CBC, while other properties showed no significant difference. In conclusion, this study showed that at similar TDS, CBC has characteristics generally similar to hot brew coffee, except for the caffeine and sensory-related compound content. The model for the prediction of TDS from this study may benefit food services or industries for the optimization of brewing conditions to obtain different characteristics of CBC.