Sensory Analysis, Caffeine, Chlorogenic Acid and Non-Volatile
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Research Article 37 DOI: 10.22146/ifnp.58664 https://journal.ugm.ac.id/ifnp ISSN 2597-9388 Sensory Analysis, Caffeine, Chlorogenic Acid and Non-Volatile Taste Compounds of Arabica Coffee (Coffea arabica) Fermented with Sugar Addition for Brew Taste Kresna Mulya Santosa1, Supriyadi1*, Sri Anggrahini1 & Yudi Rahmadian1 1 Department of Food Science and Technology, Faculty of Agricultural Technology Universitas Gadjah Mada, Jl. Flora No.1 Bulaksumur, Yogyakarta 55281 Indonesia *) Corresponding Email: [email protected] Abstract: Arabica coffee is the most popular variety of coffee among the people because it has a more complex flavor than other coffee varieties. This study aims to determine sensory properties and non-volatile components in Arabica coffee fermented with sugar addition. The sensory assessment showed that the best cupping score was the samples fermented with the addition of 0.55% fructose with a total score of 85.25 compared to honey (H) and Fullwash (FW) samples. Fermentation with the addition of 0.55% fructose could produce better coffee compared to samples (H) and (FW). Fermentation with the sugar addition of 0.55% could affect non-volatile components such as soluble sugars, organic acids, amino acids, caffeine, and chlorogenic acid. The content of chlorogenic acid and caffeine analysed by HPLC was found relatively stable in green and roasted beans. Amino acids analysed by LCMS showed glutamate was the highest amino acid in all samples and were supposed to have a role in Maillard reaction contributing to coffee flavor. In conclusion, fermentation with the addition of 0.55% sugar in coffee processing could generally enhance the coffee flavor for brew taste with its potential as functional drink. Keywords: Arabica coffee, sugar fermentation, sensory attributes, non-volatile compounds, coffee flavour INTRODUCTION on the Specialty Coffee Association of America (SCAA) Aroma and taste are the coffee brewed’s main character, cupping quality classification. which formed from a series of post-harvest processing. Wet coffee processing had higher acid content, but the High-quality coffee flavor is described as a pleasant sugar content is lower than the dry processing (Duarte et al., sensation from the combination of balance between 2010; Knopp et al., 2005). The content of sugars in coffee flavor, body, and aroma with no flavor defects such as beans affects the production of non-volatile compounds over-fermented, earthy, and oily (Mori et al., 2003). as precursors of coffee flavor. Several attempts have been The aroma and taste of coffee are the combinations of made by farmers to improve the quality of coffee beans. several constituents of volatile chemicals such as acids, One of the efforts carried out by using juice as fermentation aldehydes, ketones, and phenolic compounds with non- believed to increase the content of sugars and organic acids volatile components such as sugars, proteins, amino acids, correlated to coffee’s sensory value. Low sugar content organic acids, and caffeine (Lee et al., 2015). Volatile and in the wet-processed coffee may be enhanced by adding non-volatile compounds of coffee are influenced by coffee sugar during the fermentation process. However, it is also varieties, regions, processing methods, levels of roasting, unclear what kind of added sugars can contribute to the grinding size, and brewing method (Illy and Viani, 2005). coffee sensory. Among the processing methods, the fermentation process is the most influential stage in the formation of coffee flavors One of flavor formation is through the Maillard reaction. (Bressani, 2018; Yusianto and Widyotomo, 2013). Wong et al. (2008) concluded that the Maillard reaction is a reaction of specific amino acids and reducing sugars The fermentation process is one step in the wet processing producing the flavor of caramel, fruity, and flowery. Dorfner of coffee beans. It contributes to forming precursor et al. (2003) and Bytof et al. (2005) stated that sucrose compounds of flavors such as organic acids, amino acids could contribute in the formation of flavor and color in and reducing sugars. The process not only degrades the coffee through a caramelization process after the roasting mucilage layer, but also occurs a chemical process that is process. Given the importance of the sugar compounds in useful in the character and flavor formation of the coffee. the formation of coffee flavor, it is necessary to study the (Avvallone et al., 2001; Jackels et al., 2006; Lin, 2010). addition of sugars during fermentation. The purpose of this Uncontrolled fermentation can damage the coffee flavor, research was to study the effect of the addition of glucose, due to the growth of microorganisms that naturally exist fructose, and sucrose with a different concentration level on the surface of the coffee fruit (FAO, 2004). Previous during the fermentation process to non-volatile taste experiments have been done by Bressani (2018) with adding compounds as precursors of developing coffee flavor. The the yeast starter in the fermentation process of the Arabica results of this research are considered useful for developing coffee (Caturai Amarelo). The addition of a starter is done the wet processing coffee to enhance the quality of the by directly into the fermentation tank. The differences coffee flavor for brew taste. in the treatment of this starter gave different results. The analysis showed an increase of organic acids in samples treated with the starter addition in the fermentation tank, and it correlated with the sensory value of coffee based IFNP, Vol. 17, No. 2 (2020) Indonesian Food and Nutrition Progress Research Article 38 MATERIALS AND METHODS developed by Specialty Coffee Association of America (SCAA, 2009), by giving a score between 1-10 on each Materials variable tested. Score 1 was the lowest score and 10 was Arabica coffee Cherries were generated from Matt Husen the highest score. Andungsari Coffee Plantation, Bondowoso Ijen - East Java Indonesia, located at an altitude of 1,400 meters above the Analysis of Organic Acids sea level. D-fructose, D-glucose, Sucrose, aquapro (HPLC Analysis of organic acids refers to the method (Ribeiro Grade) and O-phthalaldehyde (OPA) were obtained from et al., 2017), coffee powder (3 g) was added with 20 mL Merck (Germany). Standard organic acids (citric, acetic, distilled water at the room temperature. The sample was lactic, malic, succinic, propionic and butyric) were generated homogenized for 10 min using a magnetic stirrer and from Merck (Germany). Standard amino acids (l-alanine, filtered using a whatmann no.3 filter paper. The extract was l-arginine hydrochloride, l-aspartic, l-cysteine, l-glutamic centrifuged at 10.000 rpm, 4 °C for 10 min. Supernatant acid, l-glycine, l-histidine monohydrochloride monohydrate, was regulated to achieve a pH of 2.11 using a perchloric l-leucine, l-isoleucine, l-lysine monohydrochloride, acid solution (200 μM) before a second centrifugation under l-methionine, l-phenylalanine, l-proline, l-serine, l-threonine, the same condition. The second supernatant was filtered l-tyrosine, tryptophan and l-valine) were obtained from using a cellulose acetate filter (0.22 μm) prior to analysis Sigma-Aldrich (USA). Caffeine and chlorogenic acid were by HPLC system. The organic acids was determined by the also obtained from Sigma-Aldrich (USA) and all other HPLC system (ShimadzuRF-10AXL) equipped with C18 chemicals and reagents used were pro analysis and analytical column (7.9 mm x 30 cm). The mobile phase used was 100 grades. μM of perchloric acid solution and the flow rate of 0.6 mL/ min. The column temperature was maintained at 50 °C. The Sample Preparation detection of organic acids was read by using a wavelength Coffea arabica beans were harvested from selected of 210 nm. Identification and quantification were done by cherries and then soaked for 12 hours. After that, the comparing to calibration curve of standards compounds. coffee beans were pulped using a vis-pulper (Honda GX 160-5.5 HP, Indonesia). Depulped coffee beans (no later Sugar Analysis than 2 hours) were added with D-fructose, D-glucose and Analysis of soluble sugars refers to the method (Ribeiro et sucrose at the concentration of 0.55%, 1.1% and 1.65%, al., 2017), 10 g of coffee powder was added with 50 mL of respectively while honey and fullwash beans were without distilled water and extracted in the ambient temperature for any addition sugars. A total of 2.5 kg of beans were then 10 min using a magnetic stirrer. The extract was centrifuged put into perforated plastic bags with a thickness of 0.5 mm at 10.000 rpm, 4 °C for 10 min. Supernatant was regulated to and a length of 90 cm and fermented for 24 hours. After achieve a pH of 2.11 using 200 μM perchloric acid solution fermentation, the coffee beans were washed thoroughly, and then centrifuged again with the same condition. The then dried in the sun until the moisture content 12%. The supernatant was filtered by a cellulose acetate filter 0.45μm bean skin was then peeled using a huller machine (LM24- prior to analysis by HPLC. HPLC system (Shimadzu 2C, China) until a green bean was obtained. SCL-10A) was equipped with Restek columns Finnacle II Amino 5μm (150 x 4.6 mm) to determine the soluble Roasting and Milling of Coffee Beans sugars. 100 μM solution of perchloric acid was used as the Green beans (1 kg) were roasted using a machine (William mobile phase with a flow rate of 0.6 mL/min. The column Edison W600) following the method of Baggenstoss temperature was maintained at 40 oC and detected by a et al. (2008). The roasting process was done at a high Refractive Index Detector (RID). Standard sugar solution temperature for a short time. Roasting temperature was was used for confirmation purposes and determining the set at 200-210°C and maintained for 18 minutes.