การจำแนกลักษณะทางกายภาพ กลิ่น รสชาติ และกลิ่นรสของกาแฟโรบัสตาและอราบิกาในภาคใต้ของประเทศไทย

Abstract

The environment and agroclimatic conditions of the coffee growing area play an important role in the flavor of the coffee, which is a unique feature that attracts consumers to drink. This study aimed to explore and compare the morphological characteristics, physical properties, aroma and taste of native Robusta and Arabica coffee grown in southern Thailand. The study consisted of three experiments: 1) evaluation of physical properties and abnormalities of Robusta coffee beans; 2) sensory evaluation of aroma, taste, and flavor of Robusta and Arabica coffee; 3) evaluation of caffeine content and volatile aroma compounds in Robusta coffee beans. The results of the first experiment showed that the physical properties of coffee beans varied significantly according to the growing region. The coffee beans from Tha Sae district, Chumphon province (CP-TS-2), had greater physical properties with higher percentages of large beans than the other areas. Based on the seed classification, it was observed that Phato district in Chumphon province (CP-PT) had the highest number of normal seeds. Chana district in Songkhla province (SK-JN) had the highest number of peaberries, while Klong Thom district in Krabi province (KB-KT) had the least amount and the highest number of defects. The most defects commonly observed in all studied areas were black seeds (category 1 and 2), insect damage seeds (category 1 and 2), and broken seeds (category 2). The results of the second experiment indicated that the aroma, taste, and flavor of the coffee beans were influenced by the environmental factors of the planting area and farming practices. The coffee from Kra Buri district in Ranong province (RN-KR-1-D) was rated highest in Fine Robusta, while the other Robusta coffees were classified as Premium grade. Arabica coffee from Than To district in Yala province and Trang province received high scores in all areas and were rated in the Specialty grade for their quality. The third experimental results showed that the caffeine content of roasted coffee beans was not statistically different when considering processing. The coffee beans by the wet process had the highest caffeine content, followed by the honey process, while the dry process had the lowest caffeine content. The caffeine contents of coffee beans grown in the eastern and western parts of the southern region were not significantly different. The most volatile compounds were 1) furan compounds such as 2-Furanmethanol, 2-furancarboxal dehyde and 2-furancarboxaldehyde, 5-methyl- and 2) pyrazine compounds such as pyrazine, methyl-, pyrazine, 2,5-dimethyl- and pyrazine, 2,6-dimethyl-. When comparing the Cupping method to the GC-MS method, the results for yield were consistent for all features. These compounds were distinct agroclimatic of the aroma and flavor of coffee origin from the southern region of Thailand. Environmental factors and agroclimatic conditions in Robusta coffee plantations in the southern region affected the physical properties and the flavor quality of the coffee beans. Similarity, the flavors quality of Arabica coffee was similar as compound between Southern and Northern Thailand. Therefore, the study findings would be helpful in indicating the identification of the aroma and flavor of coffee from southern Thailand.