Development of new analytical methods for the determination of caffeine content in aqueous solution of green coffee beans

Abstract

BackgroundThis study was conducted to develop fast and cost effective methods for the determination of caffeine in green coffee beans. In the present work direct determination of caffeine in aqueous solution of green coffee bean was performed using FT-IR-ATR and fluorescence spectrophotometry. Caffeine was also directly determined in dimethylformamide solution using NIR spectroscopy with univariate calibration technique.ResultsThe percentage of caffeine for the same sample of green coffee beans was determined using the three newly developed methods. The caffeine content of the green coffee beans was found to be 1.52 ± 0.09 (% w/w) using FT-IR-ATR, 1.50 ± 0.14 (% w/w) using NIR and 1.50 ± 0.05 (% w/w) using fluorescence spectroscopy. The means of the three methods were compared by applying one way analysis of variance and at p = 0.05 significance level the means were not significantly different. The percentage of caffeine in the same sample of green coffee bean was also determined by using the literature reported UV/Vis spectrophotometric method for comparison and found to be 1.40 ± 0.02 (% w/w).ConclusionNew simple, rapid and inexpensive methods were developed for direct determination of caffeine content in aqueous solution of green coffee beans using FT-IR-ATR and fluorescence spectrophotometries. NIR spectrophotometry can also be used as alternative choice of caffeine determination using reduced amount of organic solvent (dimethylformamide) and univariate calibration technique. These analytical methods may therefore, be recommended for the rapid, simple, safe and cost effective determination of caffeine in green coffee beans.

Correlation between caffeine contents of green coffee beans and altitudes of the coffee plants grown in southwest Ethiopia

“…This indicated that the caffeine content of green coffee beans obtained from the plants growing at different altitudes of geographical location is significantly different. In support to this study different value of caffeine contents in green coffee beans have been reported by the previous researchers [6,8,[24][25][26][27]. For example, an average value of 1.10% (w/w) by HPLC methods for 42 Ethiopian coffee samples [6], and in the range 0.96−1.23% (w/w) for Arabic green coffee beans [27] were reported for their caffeine contents.…”

“…In summary, all the coffee samples have the caffeine level in the range of the caffeine contents of different Arabica coffee reported previously [6,8,[24][25][26][27]]. The variation in caffeine level of green coffee beans samples may be due to geographical origins which might have different altitude, soil type, rain fall and other agricultural as well as environmental conditions.…”

“…Therefore, choosing the right analytical method is essential for the accurate determination of caffeine in test samples. There have been numerous reports on the determination of caffeine in coffee samples following different analytical methods: gas chromatography [15,17,18], electrochemical methods such as voltammetry [19], and spectroscopic techniques including nuclear magnetic resonance spectroscopy [20], near infrared [21], high performance liquid chromatography [5,8,22,23], UV-Vis spectroscopy [4,7,24,25] and fluorescence spectroscopy [26]. However, there are only limited reports available on the comparative study of caffeine determination by different analytical methods for a given set of samples [5,23].…”

Determination of pH and acidity in green coffee using near‐infrared spectroscopy and multivariate regression

“…NIR spectroscopy is characterized by speed, reliability, simplicity, security, low operation cost, minimum sample processing, low instrumental maintenance, allowing various analyses simultaneously and not requiring the use of chemicals. 8,17,18 This technique has already proven useful for the prediction of several properties in coffee samples and has been applied in the determination of antioxidants, 19,20 caffeine, [21][22][23] cafestol and kahweol, 24 roasting degree prediction, 25 chemical composition of defective beans, 11 sensory characteristics 18,26,27 and geographical origin. 28 In this context, the objective of the work presented here was to evaluate the potential of NIR spectroscopy and spectral pre-processing methods associated with partial least squares regression (PLS-R) in determining the pH and acidity of green coffee samples.…”

Analytical Method Development and Validation for the Determination of Caffeine in Green Coffee Beans (Coffea Arabica L.) From Three Districts of West Java, Indonesia by High Performance Liquid Chromatography

“…Caffeine levels from Garut, Pangalengan, and Tasikmalaya were 1.454 ± 0.004%, 1.574 ± 0.082%, and 2.280 ± 0.004%.Caffeine (1,3,7-trimethylxanthine) is a central nervous system stimulant that prevents drowsiness, improves short-term memory, influences human circadian timing, and improves the effectiveness of particular drugs. It is an alkaloid which naturally found in the seeds, leaves or fruits of more than 63 plants species worldwide [1][2][3]. Caffeine is widely consumed by humans for many years as foods and beverages containing caffeine including coffee beverage [4][5][6].…”