EFFECT OF DIFFERENT ROASTING DEGREE ON THE TASTE CHARACTERISTICS OF FERMENTED ARABICA COFFEE USING SOLID STATE FERMENTATION METHODS

• Main Author: Aris Kriswantoro, Jayen
• Format: Theses
• Language: Indonesia
• Subjects: Ilmu hayati ; Biologi
• Online Access: https://digilib.itb.ac.id/gdl/view/36623
• Institution: Institut Teknologi Bandung

One of the leading agricultural commodities in Indonesia is coffee. Based on data projections from 2002 to 2015, national arabica coffee consumption continues to increase every year. This is influenced by the distinctive taste of coffee and its health benefits because it contains compounds that have antioxidant activity. Previous studies have proven that fermentation using bacterial isolates BF5C (2), UciSp14, and AF7E can improve the assessment of taste, flavor, and antioxidant activity, also change the characteristics of Indonesian Arabica coffee flavor. An important step that influences the presence of active compounds and the formation of coffee flavor is the roasting step. In this study, the effect of differences in the roasting degree on amino acid profiles and levels of polyphenols which are flavor precursors and antioxidant active compounds in coffee that has been fermented using all three bacterial isolates. The fermentation of green bean coffee using Solid State Fermentation method with the bacterial inoculum of 10% v/w (volume per weight). Volume comparison of each bacterial isolate BF5C(2):UciSp14:AF7E is 2: 2: 1 and the fermentation process is carried out for 8 hours at 37? C. Fermented green bean coffee is then roasted with a different roasting degree in increasing order from light (205? C), medium (219? C), to dark (230? C). The coffee beans were carried out several tests. The tests are color quantification using a chromamometer, total polyphenol content using Folin Ciocalteu reagent, water content by proximate test, amino acid content using Ultra Performance Liquid Chromatography (UPLC), also taste and flavor characteristics using Cupping Test. Based on the results of the study, the color quantification in sequence from the level of light to dark roasting for the brightness parameter decreases from 58.5 + 0.011 L* to 50.4 + 0.038 L*, for the red-green parameter decreases from 16 + 0.031 a* to 8.8 + 0.029 a*, and the yellow-blue parameter decreased from 12.7 + 0.007 b* to 1.9 + 0.015 b*. The levels of total polyphenols in fermented coffee bean are higher than those that are not fermented with an average increase of 28.07 ppm. The total polyphenol content sequentially from the level of light to dark roasting decreased from 498 + 2.57 to 382 + 9.45 ppm. The third value of the measurement parameter of the chromamometer (L*, a*, b*) and the total polyphenol content in coffee beans decreased with increasing roasting degree. The results of color quantification in all three roasting degrees are related to the total polyphenols content which have a coefficient of determination (R-squared or R2) of 0.961 + 0.039. Proximate analysis (total fat, protein, carbohydrate, ash, and water v content) showed that all parameters, except water content, had higher values for fermented coffee beans compared to controls. The moisture content in coffee beans decreases after roasting and decreasing as the roasting degree increases from 8.08% to 1.54%. Amino acid test results showed that fermentation can increase the levels of several amino acids, they are histidine, glycine, alanine, aspartic acid, isoleucine, leucine, threonine, tyrosine, valine, proline, phenylalanine, serine, glutamic acid, and arginine. Amino acids lysine has decreased after fermentation. In fermented coffee beans, the amino acid concentration at the level of light to dark roasting for threonine decreases from 3,630.43 mg/kg to 2,811.52 mg/kg, and for arginine decreases from 949.98 mg/kg to 370.3 mg/kg. Both of these amino acids have decreased along with the increase in roasting degree. Decrease of threonine coincides with the appearance of characteristics of smoky-burnt taste due to the formation of furan group compounds. Arginine is not able to reduce the bitterness of leucine, isoleucine, and valine because it decreases when the bitterness gets stronger as roasting degree increases. Decreasing levels of total polyphenols dominated by chlorogenic acid causes loss of acidity in coffee as roasting degree increases. This study shows that the higher the roasting degree, the value of color quantification, levels of total polyphenols, water content, threonine and arginine amino acid levels will be lower, these things have an influence on the change in flavor characteristics in fermented arabica coffee beans with a roasting degree different.