Optimization of brewing time and temperature for caffeine and tannin levels in Dampit coffee leaf tea of Robusta (Coffea canephora) and Liberica (Coffea liberica)

Sudarminto Setyo Yuwono,Elok Zubaidah,Cynthia Amelia Tedja,Kiki Fibrianto,Dewi Melani Hariyadi

doi:10.5219/1212

Abstract

Coffee constitutes a plant product high in economic value. Extremely abundant throughout Indonesia, different varieties can be found in each region. Coffee leaves represent a by-product of coffee production which are disposed of without being subjected to further processing. One advantage of coffee leaf waste is that it can be made into coffee leaf tea, to prevent various diseases. The caffeine and tannin content can be optimized by temperature and brewing time. Research on coffee leaf tea remains limited, with little study of Liberica coffee leaf tea. This investigation was to determine the optimal brewing time and temperature of Robusta (Coffea canephora) and Liberica (Coffea liberica) coffee leaf tea. This research used the Response Surface Methodology (RSM) method with Central Composite Design (CCD). Data analysis using RSM method was conducted incorporating two factors. The first factor was the brewing temperature with a minimum value of 91 °C and a maximum value of 99 °C. The second factor was brewing time with minimum and maximum values of three and seven minutes respectively. Identifying the optimal treatment was based on two factors, caffeine and tannin content. Optimized processes were applied to conduct organoleptic tests on 110 untrained panelists using the Rate-All-That-Apply (RATA) method to highlight the majority attributes experienced by the panelists. The optimal brewing temperature and duration for robusta coffee leaf tea were 93.43 °C and 4.80 minutes which produced caffeine and tannin levels of 74.90 mg.100mL-1 and 293.01 µg.g-1 respectively. In contrast, in the case of Liberica coffee leaf tea, the optimal brewing conditions comprised a temperature of 91.65 °C and duration of 4.84 minutes which produced caffeine and tannin levels of 72.52 mg.100mL-1 and 415.87 µg.g-1. Results of sensory analysis showed that the majority produced five significant characteristics, namely: sweet flavor, fire flavor, sweet taste, bitter taste and astringent mouthfeel.

Highlights

Coffee represents an extremely abundant plant commodity which can potentially be developed into an increasing source of income for Indonesia
In the case of Liberica coffee leaf tea, the optimal brewing conditions comprised a temperature of 91.65 °C and duration of 4.84 minutes which produced caffeine and tannin levels of 72.52 mg.100mL-1 and 415.87 μg.g-1
Research conducted by Kristiningrum, Cahyanti and Wulandari in 2016 into Jember Arabica and Robusta coffee leaves indicated that old coffee leaves had a moisture content of 75.79 – 82.82%

Summary

Introduction

Coffee represents an extremely abundant plant commodity which can potentially be developed into an increasing source of income for Indonesia. The economic value of coffee is relatively high compared to that of other plantation crops. According to statistics produced by the General Directorate of Plantations (2016), in 2017 plantations in Indonesia occupied an estimated area of 1,227,787 hectares capable of producing 637,539 tons of coffee. Dampit in East Java, at an altitude of 300 – 460m above sea level, is a renowned coffee producing area (Malang Electronic Data Manager, 2014). According to the Central Statistics Agency of Malang Regency (2018), the total coffee production of the Dampit Subdistrict was 2,387 tons from a total cultivated area of 3,373 ha, within which the seedling area covered 6 ha, the productive plant area 2,965 ha and the mature plant area 372 ha. The two former types contain high levels of active compounds such as quilonic acid, pirogalic acid and, caffeine (Ciptaningsih, 2012)

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