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Can Cold Brew Coffee Be Convenient? A Pilot Study For Caffeine Content in Cold Brew Coffee Concentrate Using High Performance Liquid Chromatography

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Sarah Lane at University of Victoria
Sarah Lane
Josh Palmer
Josh Palmer
Josh Palmer
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Brian R Christie at University of Victoria
Brian R Christie
Jürgen Ehlting at University of Victoria
Jürgen Ehlting
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Abstract and Figures

Cold brew coffee is a brewing method that is increasing in prevalence. While it has been anecdotally suggested that this method may provide a more aromatic and flavourful coffee product, there is little research published that looks at the concentration of caffeine or other coffee substituents in cold brew coffee. The potential alteration in chemical composition in cold brew provides a few interesting avenues for research. Can caffeine in cold brew be quantified by conventional methods? If so, how does the caffeine profile of cold brews relate to hot brew methods? Here we report the caffeine content and variability in small batch cold brew coffee and show that HPLC/UV-Vis, a standard method for quantitation of caffeine in other extraction methods, is useful for detection of caffeine in cold brew coffee. The mean concentration of caffeine in an average 355 mL serving was found to be 207.22 ± 39.17 mg over five distinct batches of cold brew coffee concentrate. Cold brew preparation methods produce similar quantities of caffeine as hot brew preparation, yet may have increased storage capabilities including improved retention of flavonoids and other secondary metabolites. Therefore, cold brew may provide utility in clinical trials examining caffeine and the effect of other components of coffee as it is commonly consumed.
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The Arbutus Review •2017 •Vol. 8, No. 1 •http://dx.doi.org/10.18357/tar81201716816
Can Cold Brew Coffee be Convenient? A Pilot
Study for Caffeine Content in Cold Brew Coffee
Concentrate Using High Performance Liquid
Chromatography
Sarah Lane, Josh Palmer, Dr. Brian R. Christie, Dr. Juergen Ehlting, Cuong H. Le∗
University of Victoria
slane@uvic.ca
Abstract
Cold brew coffee is a brewing method that is increasing in prevalence. While it has been anecdotally
suggested that this method may provide a more aromatic and flavourful coffee product, there is
little research published that looks at the concentration of caffeine or other coffee substituents in
cold brew coffee. The potential alteration in chemical composition in cold brew provides a few
interesting avenues for research. Can caffeine in cold brew be quantified by conventional methods?
If so, how does the caffeine profile of cold brews relate to hot brew methods? Here we report the
caffeine content and variability in small batch cold brew coffee and show that HPLC/UV-Vis, a
standard method for quantitation of caffeine in other extraction methods, is useful for detection
of caffeine in cold brew coffee. The mean concentration of caffeine in an average 355 mL serving
was found to be 207.22
±
39.17 mg over five distinct batches of cold brew coffee concentrate. Cold
brew preparation methods produce similar quantities of caffeine as hot brew preparation, yet may
have increased storage capabilities including improved retention of flavonoids and other secondary
metabolites. Therefore, cold brew may provide utility in clinical trials examining caffeine and the
effect of other components of coffee as it is commonly consumed.
Keywords: Cold Brew; Coffee; Caffeine; HPLC; Extraction;
Caffeine
is North America’s most popular psychoactive drug and is consumed at a dietary level
by 90% of the USA’s population (Frary, Johnson, & Wang, 2005; Heckman, Weil, Mejia,
& Gonzalez, 2010). Caffeine is a naturally occurring alkaloid, and its popularity in part
stems from its actions as a generalized stimulant through non-selective inhibition of adenosine
receptors in the brain (Fisone, Borgkvist, & Usiello, 2004; Nehlig, Daval, & Debry, 1992). This
inhibition, alongside systemic vasodilation and improved calcium intake, results in a boost to physical,
psychomotor, and cognitive abilities and improvements to subjective factors, such as mood and
alertness (Einother & Giesbrecht, 2013; Ferré, 2008). Since the primary source of caffeine intake
for adult populations is coffee, it is important to consider caffeination effects in a dietarily relevant
vehicle (Wanyika, Gatebe, Gitu, Ngumba, & Maritim, 2010). However, coffee as a beverage category
shows a large variability in caffeine quantity between preparation methods, and not all are ideally
suited for research purposes.
In general, caffeine content is dependent on the brew water temperature, length of contact time,
extraction pressure, grind size of bean, coffee bean roast method, the Coffea species, and cultivar
the beans originated from (Barone & Roberts, 1995; Wanyika et al., 2010). Ultimately, these factors
∗
This work was supported by an NSERC Discovery grant to Juergen Ehlting. The authors are also very appreciative
of Sam Jones of 2% Jazz Coffee for the generous donation of cold brew concentrate used in this study.
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The Arbutus Review •2017 •Vol. 8, No. 1 •http://dx.doi.org/10.18357/tar81201716816
are chosen to reflect both cultural and individual preferences of flavour, aroma, and caffeine content
(Gloess et al., 2013). A unifying factor across most brewing processes is the use of hot water to
improve the solubility of many coffee constituents (Farah, 2012). However, coffee can be brewed
using cold water if the grounds are given adequate time to steep. This extraction method, coined
“cold brew,” has experienced a recent surge in popularity, breaking into the inventory of major
coffee distributors within the last two years (“Nariño 70 Cold Brew,” 2017). Cold brew extraction
utilizes lukewarm to refrigerated water and steeps the coffee grinds for upwards of 12 hours. The
low temperature better retains volatile organic components, and therefore the coffee maintains its
flavour in long term storage or in open environments. These compounds are difficult to study in hot
extraction methods, as the high temperature of water necessary for brewing increases the volatility
of many of the flavourful secondary metabolites and causes them to be lost or altered (Albanese,
Di Matteo, Poiana, & Spagnamusso, 2009; Salamanca, Fiol, González, Saez, & Villaescusa, 2017).
This change to the brewing process will alter both the profiles of caffeine and other secondary
psychoactive metabolites, as well as flavour and stability of the product.
Despite an increase in the prevalence of cold brew coffee, to our knowledge at the time of
writing, few peer-reviewed studies have been published examining the relative amount of caffeine, or
secondary psychoactive components, in cold brews. Although the cold brew market has increased by
580% between 2011 and 2016, much of it is in the ready-to-drink category, which is often bottled with
additional ingredients that are not ideal for research purposes (Barry, 2016; Sisel, 2016). Smaller
producers that make it in-house are therefore potentially more appropriate, but small batches may
lead to more variability. This study examines if caffeine content in cold brew can be adequately
quantified by HPLC/UV-Vis, the standard method of detecting caffeine in hot extractions, and
how caffeine content from cold brew concentrate prepared by an independent small-batch coffee
company relates to general recommended dosages per serving published from other extraction
methods (Cano-Marquina, Tarín, & Cano, 2013).
Materials and Methods
Reagents
Methanol (MeOH, HPLC grade) and formic acid (FA, reagent grade) were purchased from
Caledon Laboratories Ltd (Georgetown, ON, CA), and acetonitrile (ACN, HPLC grade) was
purchased from Fisher Scientific (Markham, ON, CA). Double distilled water was purified by a
Super-Q water filtration system (model ZDPP02254, Millipore, Bedford, MA, USA) before use.
Caffeine standard for the purpose of instrument calibration was obtained from ESA Biosciences
(model 70-6565, analytical grade, Chelmsford, MA, USA).
Apparatus
Analysis was performed using high performance liquid chromatography (HPLC), and based on
standard methods such as those reported by Naegele (2013). Method was developed for caffeine
determination of cold brew concentrate on a Dionex UltiMate 3000 (model HPG-3400A, Thermo
Fischer Scientific, Waltham, MA, USA) equipped with a solvent rack with inline degasser (model
SRD-3400, Thermo Fischer Scientific), a binary high pressure gradient pump (model HPG-3400,
Thermo Fischer Scientific), and an autosampler (model ACC-3000T, Thermo Fischer Scientific) with
a 20
µL
sample loop. A UV-Vis photodiode array (model PDA-3000, Thermo Fischer Scientific)
with a flow cell pathlength of 10 mm was used to detect analytes. The column was a Kinetex Reverse
Phase C18 (2.6
µm
; 100
Å
, 150 x 4.6 mm, model 00F-4462-E0, Phenomenex, Torrance, CA, USA).
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The Arbutus Review •2017 •Vol. 8, No. 1 •http://dx.doi.org/10.18357/tar81201716816
The binary mobile phase was A: 0.4% FA in ddH
2
O (v/v) and B: 0.4% FA in ACN (v/v). Elution
was a gradient of 0 - 10 min, 80:20 (A:B), 10 - 20 min 50:50, at a flow rate of 0.5 mL/min, with a
column temperature of 30
◦C
. Full loop sample injection was controlled at 10
◦C
with an injection
volume of 20 µL, and the detection wavelength was 272 nm.
Sample Preparation
Five individual batches of cold brew coffee were prepared independently by 2% Jazz Coffee
(Victoria, BC, CA) according to their proprietary standard method on randomly selected days. A
500 mL sample of each batch was collected and stored at 4
◦C
until preparation of sample for analysis.
One mL of each sample was loaded onto a Strata
TM
-X Polymeric Reverse-Phase column (model
8B-S100-FBL, Phenomenex), eluted in 1 mL MeOH, and diluted 1:20 in ddH
2
O, before running the
sample on the HPLC. Samples were run in triplicate.
Determination of Linearity, Recovery, and Calibration
A standard curve was prepared by dilution of an analytical grade caffeine standard (model
70-6565, ESA Biosciences) with an original concentration of 0.250 mg/mL to 0.200 mg/mL, 0.150
mg/mL, 0.100 mg/mL, 0.050 mg/mL and 0.025 mg/mL in ddH
2
O, which was run in triplicate.
Matrix effects of other components in coffee on caffeine recovery were assessed by method of standard
addition. 0.075 mL of coffee sample was spiked with an analytical grade caffeine standard and
diluted to 0.150 mL with ddH
2
O to achieve a total spike concentration of 0 mg/mL, 0.020 mg/mL,
0.040 mg/mL, 0.060 mg/mL, 0.080 mg/mL and 0.100 mg/mL. Limit of detection was determined
using a serially diluted low range standard curve of 0.040 mg/mL, 0.020 mg/mL, 0.010 mg/mL,
0.005 mg/mL, 0.0025 mg/mL, and 0.00125 mg/mL. Standard error, LOQ, and LOD were calculated
using Microsoft Excel 2016 as outlined by Shrivastava and Gupta (2011).
Results and Discussion
The analysis of caffeine in cold brew coffee reported here was based on HPLC, the separation of
chemical compounds that, when paired with an ultraviolet/visible light detector, allows quantification
of these compounds by measuring light absorption as they exit the column and are eluted. In this
study, the wavelength used was 272 nm, close to the absorption maximum of caffeine. For absolute
quantification, this was compared to an analytical grade caffeine standard analyzed under the same
conditions. Retention time for the caffeine standard was 4.5 min, and it had absorbance maxima at
275.7 nm and 231.0 nm (Figure 1).
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The Arbutus Review •2017 •Vol. 8, No. 1 •http://dx.doi.org/10.18357/tar81201716816
Figure 1.
HPLC trace of 0.100
mg/mL
caffeine standard measured at an absorbance wavelength of
272
nm
; inset of UV trace for caffeine peak obtained from 3D chromatogram. Caffeine
standard has a retention time of 4.5
min
; UV trace shows
λmax
at 231.0
nm
and 275.7
nm.
Employing various caffeine concentrations, the linear range for the detection method was observed
to be between 0.025 mg/mL and 0.150 mg/mL, with an R
2
value of 0.9904 (Figure 2). This indicates
very high linearity within this range. The limit of detection (LOD) was 0.000527 mg/mL, whose
Figure 2.
a. Complete range of caffeine concentrations analysed during development of method used
to quantify caffeine in cold brew coffee samples. b. Lower range of caffeine concentrations
used in determination of LOD and LOQ scores. LOD: 0.000527
mg/mL
; LOQ: 0.00160
mg/mL
. c. Linear range of the calibration curve used for quantification of caffeine in
cold brew coffee samples. Linear equation is y=1698x+16.889,R2=0.9904
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The Arbutus Review •2017 •Vol. 8, No. 1 •http://dx.doi.org/10.18357/tar81201716816
value is determined from parameters of the regression line of the calibration curve (Shrivastava &
Gupta, 2011). The limit of quantitation (LOQ) was 0.00160 mg/mL by a similar method and is
an indication of the lowest measurement that can be obtained accurately. This was at the lowest
part of the linear region, further suggesting that quantifications within the range of the standard
curve are highly reliable. To assess technical variability, replicate injections of pure caffeine at a
concentration of 0.100 mg/mL were performed. The coefficient of variation was 1.20%, with a mean
observed concentration of 0.1069
±
0.0008 mg/mL. To assess effects of other compounds in coffee
extracts, pure caffeine was added to a sample of coffee at a final spike concentration ranging from 0
mg/mL to 0.100 mg/mL (Figure 3). This process establishes the amount of caffeine that can be
Figure 3.
Method of standard addition curve for recovery of caffeine under the matrix influences of
cold brew coffee concentrate. Linear equation is y=1797.9x+48.409;R2=0.9963.
recovered from coffee by considering other potential molecular interactions that might affect how
caffeine is detected. The relationship between all concentrations tested showed a linear increase in
caffeine detected (R
2
= 0.9963), which suggests that the matrix effect of coffee’s other components
on the recovery of caffeine is consistent over this range. The recovery of the caffeine spike under
matrix effects was 97.4%, sample spike concentration of 0.100 mg/mL caffeine. This suggests losses
owing to experimental parameters were negligible.
A total of five independent cold-brew coffee batches were analyzed. All samples showed a distinct
HPLC peak eluting at the same time as the caffeine standard (4.5 min) (Figure 4). The absorption
spectrum of this peak closely resembles that of the standard (compare insets in Figures 1 and
4), thereby identifying this peak as caffeine. Additional peaks were detected (Figure 4), which
eluted at different times and showed distinct absorption profiles when compared to the caffeine
standard. These signals thus refer to other compounds present in the coffee samples, which were
not further investigated here. The average caffeine content per batch was 1.1678
±
0.2207 mg/mL.
To assess the amount of caffeine per serving, caffeine was normalized to the average volume of
cold brew concentrate used by 2% Jazz Coffee (1:1 concentrate to water ratio) in the making of
a 355 mL (12 fl. oz.) beverage. The mean caffeine content per serving was 207.22
±
39.17 mg
(Table 1). This is within the range of values reported by other companies manufacturing cold brew
coffee drinks when normalized to the same serving size. One analysis of Swiss Water
R
brand coffee
reported their caffeine content of cold brew concentrate in a 1:2.268 (concentrate to water) dilution
as equivalent to 238 mg (Strumpf, 2015). Starbucks
R
reported their cold brew beverage contained
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The Arbutus Review •2017 •Vol. 8, No. 1 •http://dx.doi.org/10.18357/tar81201716816
Figure 4.
HPLC trace of a representative coffee sample measured at an absorbance wavelength of 272
nm
; inset of UV/Vis trace for caffeine peak
(x)
obtained from 3D chromatogram. Peak
x
has a retention time of 4.5
min
; UV trace shows
λmax
at 231.0
nm
and 275.8
nm
, which
is consistent with parameters observed for the caffeine standard (see Fig. 1)
150 mg per serving (“Nariño 70 Cold Brew,” 2017). The value of caffeine reported for cold brew
here is also consistent with reported values for caffeine brewed using hot extraction methods (de
Mejia & Ramirez-Mares, 2014; Gloess et al., 2013). When reported values were adjusted to a 355
mL (12 fl. oz.) serving size, the caffeine content for regular drip coffee was 142.5-495 mg, and for
a single espresso (29.6 mL, 1 fl. oz.) caffeine content was 75-225 mg (de Mejia & Ramirez-Mares,
2014). In another study, espresso had an equivalent caffeine content of ~63 mg, but that varied by
machine (Gloess et al., 2013).
Cold brew coffee in this study showed some variability between batches, with a standard deviation
of 39.17 mg over five samples and a range of 99.36 mg, normalized to serving size (Table 1). The
Table 1
Caffeine content in individual coffee concentrate batches prepared using standard cold brew method from 2%
Jazz Coffee.
Batch Caffeine Content (mg/mL) Caffeine Content per Serving (mg/355mL)
1 1.3408 ±0.0143 237.74 ±2.54
3 1.1069 ±0.0028 196.41 ±0.50
4 0.8619 ±0.0027 152.94 ±0.47
5 1.1087 ±0.0042 196.73 ±0.75
Average 1.1678 ±0.2207 207.22 ±39.17
Note: Batches were independently brewed on randomly selected days and stored at 4◦Cuntil tested.
Caffeine content per serving is normalized to 355
mL
(12 fl. oz.) to represent the standard volume
of concentrate used by 2% Jazz Coffee in the preparation of cold brewed coffee for the consumer.
average percentage variance per serving is 14.6
±
9.5%. This variance agrees with studies that
suggest variation in aroma, flavour, and other components of coffee is natural and based on grind,
roast, and other factors that are difficult to account for (Barone & Roberts, 1995; Wanyika et al.,
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The Arbutus Review •2017 •Vol. 8, No. 1 •http://dx.doi.org/10.18357/tar81201716816
2010). However, the range of caffeine content for other coffee preparations, 150 mg for a single
espresso and 352.5 mg for brewed coffee, is significant as reported by de Mejia and Ramirez-Mares
(2014). This value is much greater than the range reported here for cold brew, 99.36 mg, which is
suggestive of a much narrower variance in cold brew than in hot extractions. If the batch variance in
cold brew production could be minimized further, then cold brew concentrate may have a significant
advantage over hot preparation methods as a research tool.
Conclusion
Here we show that caffeine content in small batch cold brew can be quantified by HPLC/UV-Vis
and when normalized to a serving proportion is similar in caffeine content to various hot coffee brews.
The variability in small batches reflects the variable nature of both the roasting and brewing process,
but remains within the range of caffeine deemed acceptable for public consumption (Cano-Marquina
et al., 2013). Because cold brew concentrate has the potential for improved shelf life, better retention
of secondary metabolites and volatiles, and can be brewed in volume, it may be useful in a research
setting as a reliable source of caffeine in a commonly ingested form. Future studies should look
at characterising the components of cold brew coffee that are not retained in hot extractions and
their effect on the consumer. Other studies might examine the kinetics of caffeine release, optimal
brew time, and other variables that contribute to the batch variability observed in this study, which
would improve its potential for use in clinical caffeine trials.
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... N.F. Cerca et al. these beverages may pose a risk of microbial growth if satisfactory hygienic-sanitary conditions are not adopted throughout the entire coffee processing chain and beverage production (Puro, 2016;FDA, 2017;Lane, Palmer, Christie, Ehlting, & Le, 2017;Northrop, 2018;López, 2020;Lachenmeier, Noack, Röhnisch, & Seren, 2021). ...
... In hot brews, the contents of bioactive compounds agree with those obtained by Bravo et al. (2012) and Kalschne et al. (2019). While Lane et al. (2017) and Rao et al. (2020) observed similar average amount of caffeine in cold and hot brews, Angeloni et al. (2019b) observed lower content of caffeine in cold brews only when compared to espresso coffee, but not when compared to other hot brew methods such as French press, Aeropress®, HarioV60®, and Italian coffee maker. Such a tendency was also observed in this study, given that more concentrated cold brews exhibited similar or lower caffeine content compared to less concentrated hot brews. ...
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Gıda ve içecek sektöründe “sürdürülebilir üretim” ve “sıfır atık yaklaşımı” için geleneksel ayırma, saflaştırma ve derişiklendirme yöntemlerine alternatif olarak membran süreçlerinin uygulanması oldukça popüler ve gelişmekte olan bir konudur. Gıda ve içecek sektöründe uygulama çeşitliliğine bağlı olarak uygun membran süreçlerinin kullanımının yaygınlaşmasının başlıca sebepleri; (i) geleneksel yöntemlere göre işlem basamaklarını azaltarak süreci kısaltması, (ii) geleneksel yöntemde uygulanan yüksek sıcaklığa bağlı olarak gıda ve içeceklerin içerdikleri besin ve aroma bileşenlerindeki değişikliklerin minimize edilerek son ürün kalitesini arttırması, (iii) yüksek ayırma seçimliliği ve verimi, (iv) gıda içerisinde yer alan yararlı bileşenlerin zarar görmesini engelleyecek optimum koşullarda çalışma imkânı sunarak gıda güvenliğini sağlayan daha sağlıklı ve çevreci bir sistem olmasıdır. Basınç destekli mikrofiltrasyon (MF), ultrafiltrasyon (UF), nanofiltrasyon (NF) ve Ters Ozmoz (TO) membran süreçleri, geniş bir parçacık aralığında bileşenlerin etkin biçimde ayrılmasına ve dolayısıyla membran uygulamalarının gıda ve içecek sektöründe geniş bir uygulama alanı bulmasına imkan tanımaktadır. Ayrıca membran süreçleri geleneksel yöntemlere göre enerji tüketimi açısından daha ekonomiktirler. Bu derleme makalede, gıda ve içecek sektöründe yer alan alkolsüz (süt, meyve suyu, kahve vb.) ve alkollü (şarap ve bira) içeceklerde membran teknolojilerinin geleneksel yöntemlere göre sağladığı avantajlar, membran teknolojilerinin temel ilkeleri, kullanılan membran tipleri ve uygulama alanları ile endüstriyel ölçekte gerçek uygulama örnekleri hakkında detaylı bilgilere ve bu konuda yapılan çalışmalara yer verilmiştir.
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... Kenya cold brew extract was observed to have the highest caffeine concentration, while Tanzania cold brew extract was found to have the lowest caffeine concentration (see Figure 2). In general, the caffeine concentrations in the cold brew extracts of peaberry coffee were found to be comparable to those in the hot brew extracts, in agreement with recent studies [55,66,67,[76][77][78][79]. Variation of caffeine content with bean origin has been reported previously [80][81][82][83][84]. Caffeine concentrations from previous studies of regular coffee beans using similar brewing methods ranged from 960 mg/L [55] to 1250 mg/L [85] for cold brew extracts [67,76,83], and 520 mg/L [85] to 1140 mg/L [77] for French press hot brew extracts [55,67,83]. ...
Physicochemical Analysis of Cold Brew and Hot Brew Peaberry Coffee
Article
Full-text available
  • Oct 2022
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.
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... However, in this study cold brewing enhanced the caffeine content as it was observed also by other researchers, who suggested that the higher caffeine content in cold infusions may be caused by extending the brewing time, which increases the intragranular diffusion [8,34]. Also, other authors found that caffeine is comparable between hot and cold brewing [9,35]. Similar conclusions about pH were reached by Cordoba et al. (2019) and Rao and Fuller (2018), where cold brew coffees exhibited higher pH values (less acidic) than their hot counterparts [2,13]. ...
Optimization of Sensory Properties of Cold Brew Coffee Produced by Reduced Pressure Cycles and Its Physicochemical Characteristics
Article
Full-text available
  • May 2022
  • MOLECULES
The use of vacuum cycles for the cold extraction of coffee is a new process that leads to a significant reduction in process time of Cold Brew compared to conventional methods. This research aimed at specifying the necessary parameters for producing a consumer-accepted cold brew coffee by applying vacuum cycles. This was achieved by investigating the effect of the number of cycles and of the applied pressure (vacuum) on the physicochemical characteristics of the cold brew coffee, i.e., total dissolved solids (TDS%), pH, acidity, phenol and caffeine content and color. Furthermore, sensory evaluation took place by members of the Specialty Coffee Association of America (SCAA) to specify parameters such as coffee blend, coffee/water ratio, total water hardness and grind size and secondly to determine the optimal pressure and number of cycles for a tasty final beverage. The sensory and physiochemical characteristics of cold extraction coffee were investigated by Principal Component Analysis (PCA). It became evident that coffee extraction by applying two vacuum cycles at 205 mbar pressure produced the lowest intensity of physiochemical properties (caffeine, phenols , acidity, TDS% and pH), and the highest score of sensory characteristics (fragrance, body, acidity , flavor, balance, and aftertaste). Caffeine and phenol concentration of the optimal beverage were 26.66 ± 1.56 mg/g coffee and 23.36 ± 0.79 mg gallic acid/g coffee respectively. The physiochemical characteristics were also compared to a beverage of hot extraction of the same blend and ratio of coffee to water.
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... Second-Cold brew coffee (different from iced coffee) can be prepared by steeping the coffee grounds in water at room temperature between 8 and 24 hours and then served with ice in it (48). A 12-oz (355 mL) cold brew coffee cup could contain approximately 195 mg of caffeine (49). Third-Instant coffee can be prepared by adding hot water to the granules or coffee powder. ...
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... (Gw, Sw) and natural (Bn, Spn) coffees, while the lowest levels were recorded for BOw coffee, both from the CB and P processes. According to Lane et al. 19 , traditional cold brew preparation methods produce quantities of caffeine similar to that in hot brews, which agrees with our results. Furthermore, the percolated cold brew process released 18% and 12% more caffeine than that by hot and cold extraction, respectively. ...
Influence of coffee brewing methods on the chromatographic and spectroscopic profiles, antioxidant and sensory properties
Article
Full-text available
  • Nov 2021
Cold brewing coffee has gained increasing popularity as a novel brewing method. A completely different flavour profile during cold brewing extraction (smooth and mild) is a result of the low-energy process, prolonged water-grind contact times and long preparation time. The aim of our research was to compare coffee drinks obtained with an innovative device for a faster, dynamic cold coffee extraction process (Hardtank) to drinks prepared traditionally in 24 h and hot brewed drinks. This study investigated the differences in chemical composition (volatile, non-volatile and lipid compounds), sensory properties and antioxidant capacity of coffee drinks from various extraction processes carried out at variable brewing temperatures, times and percolation modes. The results showed that the new cold maceration technique using coffee bed percolation (Hardtank) improved the quality of cold coffee drinks, making them similar in taste to hot coffee drinks. Among the studied extractions, the combination of a lower temperature (19.3 °C) and percolation process appeared to be the ideal setting for the most efficient extraction of compounds such as chlorogenic acids, gallic acid, caffeine, trigonelline, 5-(hydroxymethyl)furfural and lipids and consequently for their intake. In addition, FTIR spectra indicated an even 4 times greater quantity of lipids in Hardtank drinks than in classic cold brew and up to 5 times more lipids than in hot brew coffee, which contribute to the formation of the aroma and flavour. The decreased extraction time and use of coffee bed percolation could be beneficial for the quality and taste of cold brew products.
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Cold-Brew-Kaffee: Untersuchung zu Konsumentenerwartung und Verkehrsauffassung
Article
Full-text available
  • Jan 2023
  • DEUT LEBENSM-RUNDSCH
Zusammenfassung Cold-Brew-Kaffee hat sich in den vergangenen Jahren zu einem Trendgetränk entwickelt. Lebensmittelrechtliche Anforderungen hierzu wurden noch nicht festgelegt. Mit Hilfe einer Online-Umfrage wurde daher die Erwartung konsumierender Personen untersucht und daraus eine mögliche Verkehrsauffassung abgeleitet. Rund 70 % der befragten Verbraucherinnen und Verbraucher erwarten demnach, dass gemahlener Röstkaffee mit kaltem Wasser übergossen, der Aufguss einige Stunden unter gelegentlichem Rühren gekühlt und anschließend abfiltriert wird. Die erwartete Extraktionszeit sollte zwischen 2 und 8 Stunden liegen. Davon abweichende Praktiken, wie die Verwendung von heiß-extrahiertem Kaffee oder die Verwendung von heiß-extrahiertem Kaffeeextrakt, wird von den teilnehmenden Personen mehrheitlich abgelehnt, und könnten somit täuschungsrelevant sein. Nach den Ergebnissen der Umfrage würde sich die Mehrheit der Verbraucherinnen und Verbraucher Cold-Brew-Kaffee bestellen, wenn dieser neben anderen Heiß-und Kaltgetränken angeboten wird. Cold-Brew-Kaffee bietet sich aufgrund seiner Zubereitungsart mit einem erfrischenden und wenig bitteren Geschmack als alternatives Sommergetränk an. Abstract Cold-brew coffee has become a trendy drink in recent years. Food law requirements have not yet been established. With the help of an online survey, the expectations of consumers were therefore investigated , and possible trade conceptions were derived from this. According to the survey, around 70 % of the survey participants expect ground roasted coffee to be poured over with cold water, the infusion to be cooled for a few hours under occasional stirring and then filtered off. The expected extraction time should be between 2 and 8 hours. Deviating practices such as the use of hot-extracted coffee or the use of hot-extracted coffee extract are rejected by most respondents and can therefore be deceptive. According to the results of the survey, the majority of consumers would order cold brew coffee if it was offered alongside other hot and cold beverages. Cold brew coffee offers itself as an alternative summer drink due to its preparation method with a refreshing and less bitter taste.
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Gıda ve içecek endüstrisinde membran teknolojileri
Article
  • Oct 2021
Gıda ve içecek sektöründe “sürdürülebilir üretim” ve “sıfır atık yaklaşımı” için geleneksel ayırma, saflaştırma ve derişiklendirme yöntemlerine alternatif olarak membran süreçlerinin uygulanması oldukça popüler ve gelişmekte olan bir konudur. Gıda ve içecek sektöründe uygulama çeşitliliğine bağlı olarak uygun membran süreçlerinin kullanımının yaygınlaşmasının başlıca sebepleri; (i) geleneksel yöntemlere göre işlem basamaklarını azaltarak süreci kısaltması, (ii) geleneksel yöntemde uygulanan yüksek sıcaklığa bağlı olarak gıda ve içeceklerin içerdikleri besin ve aroma bileşenlerindeki değişikliklerin minimize edilerek son ürün kalitesini arttırması, (iii) yüksek ayırma seçimliliği ve verimi, (iv) gıda içerisinde yer alan yararlı bileşenlerin zarar görmesini engelleyecek optimum koşullarda çalışma imkânı sunarak gıda güvenliğini sağlayan daha sağlıklı ve çevreci bir sistem olmasıdır. Basınç destekli mikrofiltrasyon (MF), ultrafiltrasyon (UF), nanofiltrasyon (NF) ve Ters Ozmoz (TO) membran süreçleri, geniş bir parçacık aralığında bileşenlerin etkin biçimde ayrılmasına ve dolayısıyla membran uygulamalarının gıda ve içecek sektöründe geniş bir uygulama alanı bulmasına imkan tanımaktadır. Ayrıca membran süreçleri geleneksel yöntemlere göre enerji tüketimi açısından daha ekonomiktirler. Bu derleme makalede, gıda ve içecek sektöründe yer alan alkolsüz (süt, meyve suyu, kahve vb.) ve alkollü (şarap ve bira) içeceklerde membran teknolojilerinin geleneksel yöntemlere göre sağladığı avantajlar, membran teknolojilerinin temel ilkeleri, kullanılan membran tipleri ve uygulama alanları ile endüstriyel ölçekte gerçek uygulama örnekleri hakkında detaylı bilgilere ve bu konuda yapılan çalışmalara yer verilmiştir.
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Effects of brewing conditions and coffee species on the physicochemical characteristics, preference and dynamics of sensory attributes perception in cold brews
Article
  • Dec 2021
  • FOOD RES INT
The study aimed to assess the dominant sensory attributes and preference for cold brews prepared with different coffee species under different brewing conditions. Four beverages were brewed using Arabica and Robusta coffees with either a coarser coffee grind and extraction at 5 °C or a finer grind and extraction at 15 °C. Coffee flavor and bitter taste were dominant sensory attributes of all beverages, regardless of material and preparation. While there were no differences in preference, the composition and dominant sensory attributes differed among the cold brews. The use of different coffee species had a greater impact on the composition and the perception of the attributes of the cold brews than brewing conditions. Sourness and coffee flavor were more dominant in Arabica cold brews, which had higher trigonelline content and acidity, but bitter taste dominance was further reported. Meanwhile, bitterness and astringent sensation were more dominant in Robusta cold brews, with higher caffeine and total chlorogenic acid content; however, a high coffee flavor dominance was also observed.
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Comparison of nine common coffee extraction methods: Instrumental and sensory analysis
Article
Full-text available
  • Jan 2013
The preparation of a cup of coffee may vary between countries, cultures and individuals. Here, an analysis of nine different extraction methods is presented regarding analytical and sensory aspects for four espressi and five lunghi. This comprised espresso and lungo from a semi-automatic coffee machine, espresso and lungo from a fully automatic coffee machine, espresso from a single-serve capsule system, mocha made with a percolator, lungo prepared with French Press extraction, filter coffee and lungo extracted with a Bayreuth coffee machine. Analytical measurements included headspace analysis with HS SPME GC/MS, acidity (pH), titratable acidity, content of fatty acids, total solids, refractive indices (expressed in °Brix), caffeine and chlorogenic acids content with HPLC. Sensory analysis included visual, aroma, flavor and textural attributes as well as aftersensation. The technical differences in the extraction methods led to a higher concentration of the respective quantities in the espressi than in the lunghi. Regarding the contents per cup of coffee, the lunghi generally had a higher content than the espressi. The extraction efficiency of the respective compounds was mainly driven by their solubility in water. A higher amount of water, as in the extraction of a lungo, generally led to higher extraction efficiency. Comparing analytical data with sensory profiles, the following positive correlations were found total solids - texture/body, headspace intensity - aroma intensity, concentrations of caffeine/chlorogenic acids - bitterness and astringency.
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Determination of caffeine content of tea and instant coffee brands found in the Kenyan market
Article
Full-text available
  • Jun 2010
Caffeine (1, 3, 5-trimethylxanthine), a mild addicting drug though used for medicinal purposes is the active ingredient that makes tea and coffee valuable to humans. In this study, the levels of caffeine in certain coffee (nescafe, africafe, dormans) and tea (chai mara moja, kericho gold, sasini, finlays premium) brands found in the Kenyan market were determined using high performance liquid chromatography (hplc) and UV/ Vis spectrophotometric methods. The levels of caffeine in all the tea and coffee brands were found to be within the documented range. The order of caffeine concentration in tea samples was found as follows: chai mara moja > finlays premium > kericho gold > sasini. In coffee it was found that the caffeine content of africafe > nescafe > dormans. Generally, higher concentration of caffeine in all the samples were realized with the UV/ Vis spectrophotometric method compared to hplc method indicating that acidified water was a better caffeine extractor than pure water.
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Methods for the determination of limit of detection and limit of quantitation of the analytical methods
Article
Full-text available
  • Jun 2011
  • Chron Young Scientists
The quality of an analytical method developed is always appraised in terms of suitability for its intended purpose, recovery, requirement for standardization, sensitivity, analyte stability, ease of analysis, skill subset required, time and cost in that order. It is highly imperative to establish through a systematic process that the analytical method under question is acceptable for its intended purpose. Limit of detection (LOD) and limit of quantification (LOQ) are two important performance characteristics in method validation. LOD and LOQ are terms used to describe the smallest concentration of an analyte that can be reliably measured by an analytical procedure. There has often been a lack of agreement within the clinical laboratory field as to the terminology best suited to describe this parameter. Likewise, there have been various methods for estimating it. The presented review provides information relating to the calculation of the limit of detection and limit of quantitation. Brief information about differences in various regulatory agencies about these parameters is also presented here.
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Caffeine as an attention enhancer: Reviewing existing assumptions
Article
Full-text available
  • Dec 2012
  • PSYCHOPHARMACOLOGY
Rationale Despite the large number of studies on the behavioural effects of caffeine, an unequivocal conclusion had not been reached. In this review, we seek to disentangle a number of questions. Objective Whereas there is a general consensus that caffeine can improve performance on simple tasks, it is not clear whether complex tasks are also affected, or if caffeine affects performance of the three attention networks (alerting, orienting and executive control). Other questions being raised in this review are whether effects are more pronounced for higher levels of caffeine, are influenced by habitual caffeine use and whether there effects are due to withdrawal reversal. Method Literature review of double-blind placebo controlled studies that assessed acute effects of caffeine on attention tasks in healthy adult volunteers. Results Caffeine improves performance on simple and complex attention tasks, and affects the alerting, and executive control networks. Furthermore, there is inconclusive evidence on dose-related performance effects of caffeine, or the influence of habitual caffeine consumption on the performance effects of caffeine. Finally, caffeine’s effects cannot be attributed to withdrawal reversal. Conclusions Evidence shows that caffeine has clear beneficial effects on attention, and that the effects are even more widespread than previously assumed.
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Caffeine and the central nervous system: Mechanisms of action, biochemical, metabolic and psychostimulant effects
Article
Full-text available
  • May 1992
Caffeine is the most widely consumed centralnervous-system stimulant. Three main mechanisms of action of caffeine on the central nervous system have been described. Mobilization of intracellular calcium and inhibition of specific phosphodiesterases only occur at high non-physiological concentrations of caffeine. The only likely mechanism of action of the methylxanthine is the antagonism at the level of adenosine receptors. Caffeine increases energy metabolism throughout the brain but decreases at the same time cerebral blood flow, inducing a relative brain hypoperfusion. Caffeine activates noradrenaline neurons and seems to affect the local release of dopamine. Many of the alerting effects of caffeine may be related to the action of the methylxanthine on serotonine neurons. The methylxanthine induces dose-response increases in locomotor activity in animals. Its psychostimulant action on man is, however, often subtle and not very easy to detect. The effects of caffeine on learning, memory, performance and coordination are rather related to the methylxanthine action on arousal, vigilance and fatigue. Caffeine exerts obvious effects on anxiety and sleep which vary according to individual sensitivity to the methylxanthine. However, children in general do not appear more sensitive to methylxanthine effects than adults. The central nervous system does not seem to develop a great tolerance to the effects of caffeine although dependence and withdrawal symptoms are reported.
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Coffee: Emerging Health Effects and Disease Prevention
Book
  • Feb 2012
Coffee: Emerging Health Benefits and Disease Prevention presents a comprehensive overview of the recent scientific advances in the field. The book focuses on the following topics: coffee constituents; pro- and antioxidant properties of coffee constituents; bioavailability of coffee constituents; health benefits and disease prevention effects of coffee; and potential negative impacts on health. Multiple chapters describe coffee's positive impact on health and various diseases: type 2 diabetes; neurodegenerative diseases (Parkinson's and Alzheimer's); cancer (prostate, bladder, pancreatic, breast, ovarian, colon and colorectal); cardiovascular health; and liver health. Coffee's positive effects on mood, suicide rate and cognitive performance are addressed as are the negative health impacts of coffee on pregnancy, insulin sensitivity, dehydration, gastric irritation, anxiety, and withdrawal syndrome issues. Written by many of the top researchers in the world, Coffee: Emerging Health Benefits and Disease Prevention is a must-have reference for food professionals in academia, industry, and governmental and regulatory agencies whose work involves coffee. © 2012 John Wiley & Sons, Inc. and the Institute of Food Technologists.
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Impact of caffeine and coffee on our health
Article
  • Oct 2014
  • TRENDS ENDOCRIN MET
Coffee is the most frequently consumed caffeine-containing beverage. The caffeine in coffee is a bioactive compound with stimulatory effects on the central nervous system and a positive effect on long-term memory. Although coffee consumption has been historically linked to adverse health effects, new research indicates that coffee consumption may be beneficial. Here we discuss the impact of coffee and caffeine on health and bring attention to the changing caffeine landscape that includes new caffeine-containing energy drinks and supplements, often targeting children and adolescents.
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Espresso coffee (EC) by POD: Study of thermal profile during extraction process and influence of water temperature on chemical–physical and sensorial properties
Article
  • Jun 2009
  • FOOD RES INT
In this work the thermal profiles of five coffee pods (pure Arabica, pure Robusta, and Arabica Robusta blends: A20R80, A80R20, and A40R60) at 90, 100 and 110 °C are reported. Moreover the chemical–physical and sensorial properties of espresso coffee (EC) obtained from five different coffee pods were investigated. The analysis of the thermal profiles highlighted that the extraction process can be considered as an isothermal process because, after a starting phase, the recorded temperatures stayed around a mean temperature (Tm). In addition the Tm recorded for each extraction temperature was significantly lower than those set up by the controller. The chemical–physical parameters of EC samples increased proportionally with extraction temperature highlighting that the effectiveness of extraction process scales up with percolation temperature. The solid and caffeine contents of the EC samples extracted at 110 °C are related to an over extraction process. Principal Component Analysis (PCA) was applied to identify relationships and differences among EC samples. Pure Arabica and A80R20 EC samples at 100 and 110 °C have shown sensorial attributes typical for a fine espresso coffee.
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The impact of coffee on health
Article
  • Mar 2013
Objective: Coffee is a beverage used worldwide. It includes a wide array of components that can have potential implication on health. We have reviewed publications on the impact of coffee on a series of health outcomes. Methods: Articles published between January 1990 and December 2012 were selected after crossing coffee or caffeine with a list of keywords representative of the most relevant health areas potentially affected by coffee intake. Results: Caffeine, chlorogenic acids and diterpenes are important components of coffee. Tolerance often acts as a modulator of the biological actions of coffee. There is a significant impact of coffee on the cardiovascular system, and on the metabolism of carbohydrates and lipids. Contrary to previous beliefs, the various forms of arterial cardiovascular disease, arrhythmia or heart insufficiency seem unaffected by coffee intake. Coffee is associated with a reduction in the incidence of diabetes and liver disease. Protection seems to exist also for Parkinson's disease among the neurological disorders, while its potential as an osteoporosis risk factor is under debate. Its effect on cancer risk depends on the tissue concerned, although it appears to favor risk reduction. Coffee consumption seems to reduce mortality. Conclusion: The information gathered in recent years has generated a new concept of coffee, one which does not match the common belief that coffee is mostly harmful. This view is further supported by the discovery of a series of phyto-components with a beneficial profile. Reasonable optimism needs to be tempered, however, by the insufficiency of the clinical data, which in most cases stem from observational studies.
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