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The Caffeine Content in Coffee Beverages Commercially Distributed in Indonesia

S Sukrasno*, Irena Aria Rivera, Komar Ruslan Wirasutisna

School of Pharmacy, Institut Teknologi Bandung, Bandung, Indonesia

Abstract: Coffee beverages are widely consumed by Indonesian, however, some of them encounter the adverse effect after drinking coffee, such as difficulty to sleep, arrhythmia and pain in the stomach. This work was aimed at determining the caffeine content of coffee beverages that are commercialized in Indonesia, covering coffee powders, coffee instants and brewed coffees. Samples were collected from the market and coffee shops. The caffeine from the samples were extracted followed by fractionation using liquid-liquid extraction with ethyl acetate. Caffeine presence in the ethyl acetate fraction was then separated on TLC and the quantity analyzed using TLC scanner. Twenty coffee samples were analyzed and the caffeine contents were ranging from 13 mg to 159 mg per-serve. Caffeine in coffee instants were approximately 50 mg per-serve, while some products of coffee powders and brewed coffees higher than 100 mg per-serve. The level of caffeine in the coffee beverage distributed in Indonesia is still below the maximal recommended level in various countries.

Keywords: caffeine contents, coffee products, Indonesian market

Received June 25, 2018; Revised August 25, 2018; Accepted August 31, 2018

Citation: S Sukrasno, Irena Aria Rivera, Komar Ruslan Wirasutisna, The Caffeine Content in Coffee Beverages Commercially Distributed in Indonesia. Journal of Food and Nutrition Research, 6 (8). 513-517. January 2018. doi:10.12691/jfnr-6-8-5

1. Introduction

Drinking coffee has been a traditional habit of the people throughout the world. Mostly, a coffee drink is prepared by roasting coffee beans followed by grinding and the addition of hot water into a cup containing coffee powder. There are some variations in serving coffee, with or without sugar, with or without milk. Currently coffee can be served directly from the coffee powder, instant coffees that have been mixed with other ingredients or even using dried coffee extract, using coffee machine that can serve different style of coffee drink such as espresso, cappuccino, latte, and served using a special recipe in coffee shops.

Roasting coffee is designed to degrade chlorogenic acid that was claimed to induce pain in the gastric. Roasting temperature is ranging from 230°C to 250°C with roasting time from 12 to 21 minutes. Light roasting eliminates approximately 50 % chlorogenic acid content while after heavy roasting only traces amounts of chlorogenic acid can be detected [1]. Nowadays chlorogenic acid is becoming popular as a health food or food supplement, especially to prevent obesity [2]. Chlorogenic acid demonstrated a number of biological activities such as hypoglycemia, anti hyperlipidemias, antibacterial activities, antioxidant and anticarcinogenic activities [3]. During roasting not only chlorogenic acid degraded but part of caffeine also evaporates directly from a solid into vapor that can be recovered through condensation to form caffeine crystals.

There are at least two kinds of coffee beans, Coffea arabica L. and Coffea robusta, now named as Coffea canephora Pierre ex A. Froehner, the former contains less caffeine, but more expensive than the latter. The caffeine content of C. arabica beans is approximately 1 %, while in C. robusta 2 % [4]. The conventional coffee brew is usually prepared by adding two table spoons of ground roasted beans with hot water. The intensity of coffee bean roasting influences the caffeine content of the bean. The level of roasting includes light, medium and heavy roasting with light roasting contain the highest caffeine content [5].

A number of side effects may be encountered during drinking coffee such as insomnia, increase heart rate or atrial fibrillation, gastric pain, increase urinary frequency, anxiety and increase blood pressure [2]. The side effect of coffee brew from certain brands was so obvious and consistent, but not shown by the other brands. One of the possible side effects is the level of caffeine present in the coffee brew in addition to the individual sensitivity. Indeed, certain individuals are very sensitive toward coffee brew or caffeine containing beverage or drug and do not drink coffee at all. Accordingly, we are interested to evaluate the caffeine content in various coffee products including conventional coffee powder, instant coffee and brewed coffee available in Indonesian market.

2. Materials and Methods

Coffee samples consisted coffee powder, coffee instant and coffee brews that were bought from the market and coffee shops. Caffeine present in the sample was extracted and then analyzed by TLC scanner (Camag).

2.1. Caffeine Standard Solution

Caffeine marker 25 mg was dissolved in 20 ml ethyl acetate then transferred into 25 ml measuring flask and the volume adjusted to 25 ml. This solution contained 1,000 ppm caffeine. Into 5 ml measuring flask were transferred 125, 250, 500, 750 and 1,000 μl caffeine solution and the final volume adjusted to 5 ml to make a caffeine solution at 25, 50, 100, and 200 μg/ml respectively.

2.2. TLC of Caffeine

TLC of caffeine was conducted on Silica plate 20x20 cm, thickness 100 m, particle size 10-12μm (E Merck) with solvent system 5% acetic acid in ethyl acetate.

2.3. Maximum Wavelength Measurement

Caffeine standard solution 10 l was applied on TLC plate using CAMAG linomat 5 and developed using the developing solvent and the AUC measured at 200-400 nm. The densitogram of the spot that give maximum AUC was then used as the wavelength for AUC measurement.

2.4. Calibration Curve

Each of known concentration caffeine was applied on TLC plate using CAMAG linomat 5 and developed using the TLC solvent. Subsequently the AUC of caffeine peak was measured at 275 nm. The regression curve was then prepared by using concentration and AUC data, the calibration equation and the regression coefficient calculated. Linearity, limit of detection and limit of quantification was calculated from the calibration curve experiment

2.5. Precision and Accuracy Test

Caffeine solution was prepared by dissolving 10; 15 and 20 mg in 100 ml ethyl acetate that has been used to extract roasted corns. As much as 10μl sample was applied on TLC plate SiGel 60 GF254 using Camag Linomat 5, and developed using 5% acetic acid in ethyl acetate. The AUC of caffeine spots was measured using Camag TLC Scanner 3 at 275 nm. Measurement was conducted in three replicates. Precision was measured by calculating the variation coefficient, while accuracy by calculating the recovery. The acceptable variation coefficient according to UNODC is ≤ 2% and for the recovery between 95 % - 105 % [6].

2.6. Sample Preparation

One gram of coffee powder was mixed with 25 ml water and boiled for 10 minutes, filtered through filter paper, the residue was then reextracted twice with 10 ml water each followed by filtration and the filtrates combined. Coffee brew was transferred to a 500 ml flask, adjust the volume with hot water and mixed well, subsequently 50 ml was taken as a sample for fractionation. The sample was transferred to a separatory funnel and extracted three times with 25 ml ethyl acetate respectively. Combined ethyl acetate fraction was evaporated to dryness and redissolved in 5 ml ethyl acetate for further analysis. Dilution was conducted if the size of caffeine spot was too big compared to the calibration experiment data.

2.7. TLC Densitometry

Ten microlitre of sample was applied on TLC plate coated with SiGel 60 GF254 using CAMAG linomat 5 and developed using 5 % acetic acid in ethyl acetate. The AUC was measured using CAMAG TLC Scanner 3 at 275 nm. Each sample was measured twice and the average calculated.

3. Results

3.1. Method Validation

Calibration curve and equation was made by measuring the density of caffeine spot after TLC of caffeine at various concentrations. The TLC densitogram of caffeine after being developed with 5 % acetic acid in ethyl acetate is as shown in Fig 1. The AUC of caffeine spot at various concentrations is as shown in Table 1. The calibration equation was Y= 40,629 X + 1,844.5, with R²= 0.995. Acceptable value for regression coefficient is 0.995 [6]. The limit of detection (LOD) was calculated based on the regression equation and it was found to be 0.556 ppm, while the limit of quantification (LOQ) was 1.854 ppm.

Figure 1. Densitogram of caffeine marker

Table 1. AUC of caffeine spots at various concentrations

The results of accuracy and precision tests were as shown in Table 2 and Table 3. The accuracy was ranging from 96.2 to 100.4 % for samples between 100 to 200 ppm, while the precission that is indicated by the coefficient variation was ranging from 0.2 to 1.9 %

Table 2. Experiment for Accuracy Testing

Table 3. Precission testing

3.2. Densitogram of Caffeine in Coffee Extract

The spot of caffeine was detected using UV at 275 nm and the densitorgam of the extract from coffee powder, instant coffee and coffee brews are as shown in Figure 2. Caffeine appeared as a single major spot and other spots only appeared in the origin and some minor spots near the front of the development.

Coffee powder is mostly prepared by grinding roasted coffee beans and sold as bulk material and packed in a package with certain weight such as 100 g, 250 g or 500 g. On serving, two tablespoons of coffee powder (approximately 12.84 g) are transferred to a glass or a cup then hot water is added. Some coffee lovers added sugar, creamer or milk when they drink coffee. Five samples were evaluated for their caffeine content, and mostly contain relatively high caffeine. Kapal Api contained the least caffeine, 42.12 mg per-serve compared to other products. Two products, Aroma Robusta and Kopi bubuk senang contain very high caffeine content, 128.04 mg and 123.39 mg per-serve respectively.

Instant coffee is a coffee preparation that is presented as a package, usually in a sachet and use for once serving. For serving, usually a sachet of instant coffee is added with one glass or one cup of hot water. The main ingredient of instant coffee is mostly extract only or added with other ingredients that make the product ready to be consumed after the addition of hot water. Seven instant coffee products were analyzed in these experiments and the results were as shown in Table 2. Torabika was instant coffee with the lowest caffeine content (13.04 mg) and Good Day Cappuccino was the highest caffeine content (62.64 mg). Nescafe although the dosage is only 2 g, it contained relatively high caffeine (50.2 mg), this product may contain coffee extract only and may need sweetener, creamer or milk on serving.

Figure 2. Densitogram of caffeine extracted from the coffee powder (a), instant coffee (b) and brewed coffee (c)

Table 4. Caffeine in coffee powder

Some coffee drinks are served in various styles such as cappuccino, espresso, original, latte, etc. with special branding. The size of glass for serving is also varied, such as, large, medium or small sizes. Starbucks serves brewed in four cup sizes short (8 FL Oz), tall (12 FL Oz), grande (16 FL Oz) and venti (20 FL Oz) with caffeine content and size 180 mg, 260 mg, 330 mg and 415 mg respectively. We were also interested in analyzing their caffeine contents. Among 8 brands tested, Good Day White Vanilla contained the least caffeine content. Six out of eight brands contained relatively low caffeine content, less than 30 mg of caffeine for each serve. Three of them were relatively having high caffeine content, more than 90 mg per-serve. Calais America was coffee brew with the highest caffeine content in the samples tested. It contained 159.23 mg caffeine for each cup.

Table 5. Instant Coffee

Table 6. Caffeine in commercially brewed coffee

4. Discussion

Caffeine in coffee powder, coffee instant and coffee brew can be easily determined by using TLC densitometry. Extraction was performed by boiling in water similar to that of brewing coffee. Caffeine has high solubility in hot water (66 g in 100 m1), low solubility in cold water (2 g in 100 ml) and soluble in ethyl acetate. Preliminary liquid-liquid extraction using ethyl acetate is needed to fractionate caffeine from other compounds. Based on LOD and LOQ analysis, caffeine can be detected at 0.556 ppm and quantified at 1.854 ppm. In this experiment the spot of caffeine was detected using UV light at 275 nm without visualization as that of performed by Palacios et al. [10]. Based on LOQ and LOD calculation and considering the application volume was 5 l, under this system caffeine can be detected at approximately 5 ng and quantified at 20 ng.

Caffeine content in coffee drink in Indonesia varied from 11.81 mg/cup to 159.23 mg/cup. If caffeine content is classified by considering less than 25 mg/cup is low, 25-50 mg/cup moderate, > 50-100 mg/cup high and above 100 mg/cup very high; Good Day White Vanilla, Kopi ABC Exo, Torabika, ABC and Jco Cappucino were low; Kopiko 78 C, Starbuck Americano, Good Day Original, Luwak White Coffee Original, Indocaffee and Kapal Api moderate; Nescafe Black, Good Day Capuccino, Nescafe Black, Kopi Aroma Arabica and Excelso Arabica high, Starbucks Freshly Brewed Coffee, Calais America, Kopi Bubuk Senang and Kopi Aroma Robusta very high.

The maximum allowable caffeine intake is 400 mg [7] therefore, if someone drinks coffee twice a day, the total consumption of caffeine is still less than 400 mg. However, drinking more than three times a day need to consider the total caffeine that will be taken every day and some of the side effect might be encountered.

The highest caffeine content found in Indonesia for one time drink is still much lower compared to that of reported by McCusker et al [8]. One specialty of coffee brewed contained caffeine up to 253 mg. The result of repeated assays on one specialty in 6 consecutive days varied, ranging from 259.2 to 564.4 mg per-cup. Heckman [9] compiled that caffeine range for 8 Oz instant coffee 27-73 mg, plain and brewed coffee 102-200 mg while for espresso 240-720 mg.

It is very important for consummers to know the caffeine level in the coffeee beverage to anticipate the physiological responses that may occur after drinking coffee, especially when taking new brand of coffee. In addition, the time and the number of cups of coffee should be considered to maintain the sleeping quality. Although caffeine intake up to 400 mg per-day do not raise safety concerns, the unwanted physiological effects may arise, such as anxiety, insomnia, stomachache, atrial fibrilation, increase blood pressure and urination. The maximum amount of caffeine consumption has not been regulated yet. In general, the recommended maximal daily intake in a number of countries was 300 mg for pregnant woman and 400-500 mg for adults [7,9].

Cardiac arrhythmias are some times reported by individual drinking coffee, however this side effect only occur on certain individuals who are sensitive to caffeine. These individuals may susceptible to the small electrophysiological changes induce by caffeine [11]. Coffee promotes gastro-oesophagal reflux, but is not associated with dyspepsia and the activity is not caused by caffeine [12]. People with non-ulcer dyspepsia were more likely to experience dyspeptic symptoms after drinking coffee [13,14]. Caffeine intake will affect sleep quality, by reducing bed time and this effect is related to the caffeine consumption. The profound effect was observed at dose approximately 200 mg while population who took caffeine at 100 mg maintained their good sleep quality [15]

5. Conclusion

Caffeine from caffee bean and coffee brews can be quantified by simple and rapid methods using TLC Scanner with acceptable accuracy and precission. Caffeine content of coffee powder, coffee instant and coffee brewed commercially available in Indonesian market was still below the allowable maximum level.

References

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[12]   | Boekema, P.J., Samson, M., van Berge Henegouwen, G.P., Smout, A.J., “Coffee and gastrointestinal function: facts and fiction. A review”, Scand J Gastroenterol Suppl., 230: 35-9. 1999.
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[14]  
Shimamoto, T., Yamamichi, N., Kodashima, S., Takahashi, Y., Fujishiro, M., Oka, M., Mitsushima, T., Koike, K., “No Association of Coffee Consumption with Gastric Ulcer, Duodenal Ulcer, Reflux Esophagitis and Non-Erosive Reflux Disease: A Cross-Sectional Study of 8,013 Healthy Subjects in Japan”, PLoS ONE, 8(6): e65996, Jun 2013.

[15]   | Watson, E.J., Coates, A.M., Kohler, M., Banks, S.; “Caffeine consumption and sleep quality in Australian adults”, Nutrients, 8: 479. Aug 2016.