The Analysis of Chlorogenic Acid and Caffeine Content and Its Correlation with Coffee Bean Color under Different Roasting Degree and Sources of Coffee (Coffea arabica Typica)

Irvan Prawira Julius Jioe,Chia-Fang Tsai

doi:10.3390/pr9112040

Abstract

Coffee is one of the main economic crops in the world and is now widely grown throughout Taiwan. The process of roasting coffee begins with the heating and smooth expansion of raw beans, which leads to changes in appearance and color while affecting the flavor and taste of coffee. So far, most coffee manufacturers have used visual inspection or colorimeter methods to identify differences in coffee quality. Moreover, there is no literature discussing the correlation of roasted bean color with caffeine and chlorogenic acid content. Therefore, the purpose of this experiment was to analyze the chlorogenic acid and caffeine content and their correlation with bean color under different roasting degrees and from different sources to establish basic data for the rapid identification of coffee quality in the future. In this experiment, the coffee Coffea arabica typica from Dongshan, Gukeng, and Sumatra’s Indonesian rainforest was used, and the beans were roasted into four degrees: raw bean, light, medium, and dark roast, to investigate the appearance of the coffee beans and its correlation with caffeine and chlorogenic acid content. The results showed that with a higher roasting degree, caffeine content increased gradually, except for Indonesian beans, but the chlorogenic acid content in all samples showed a declining trend with the increase in roasting degree. The correlation between the chlorogenic acid content and the color space value of the coffee bean color shows that L*, a*, and h° in both ground and unground coffee are highly correlated. The C* value of the ground and unground coffee showed a correlation coefficient of r = 0.159 ns and 0.299 ns, respectively. The correlation between the caffeine content and the color space value of the unground coffee bean shows that the a*, b*, and C* value is highly correlated with the caffeine content. The color space values of ground coffee beans show no correlation with caffeine.

Highlights

Coffee is one of the main economic crops in the world, grown in more than 60 countries in tropical and subtropical areas [1], where the main varieties grown are arabica and robusta [2]
The color of Dongshan arabica raw coffee beans is close to the hex (8E7B58) color code; the color of Gukeng arabica raw coffee beans is close to the hex (846F4C) color code; the color of Indonesian arabica raw coffee beans is near the hex (918263) color code
After grinding, the color of raw coffee beans changes drastically, whereas Dongshan arabica raw ground coffee beans are close to hex (B09056) color code; Gukeng arabica raw ground coffee beans are close to ex (A88B5D) color code; Indonesian arabica raw ground coffee beans are near the ex (AE9678)

Summary

Introduction

Coffee is one of the main economic crops in the world, grown in more than 60 countries in tropical and subtropical areas [1], where the main varieties grown are arabica and robusta [2]. In 1884, coffee beans were introduced into Taiwan from the Philippines. These days, coffee has been widely planted in Taiwan in the Nantou Huisun Forest Farm, Gukeng in Yunlin, Zhongpu, Fanlu, Zhuqi, and Alishan in Chiayi, and Dongshan in Tainan [3]. Coffee beans contain high amounts of phenolic compounds [4] such as chlorogenic acid, caffeine, caffeic acid, etc., which can be used for dietary purposes [5]. Phenolic compounds and chlorogenic acid have a highcontent of about 6–12% in raw coffee beans [6]. Chlorogenic acid was discovered in coffee in

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Discussion

Conclusion