본 연구에서는 엘살바드로산 Coffea arabica cv. Bourbon, 브라질산 Coffea arabica cv. Catuai, 에디오피아산 Coffea arabica cv. Heirloom, 콜롬비아산 Coffea arabica cv. Typica catura 등 2017년 6월에서 2018년 4월까지 수확된 아라비카 커피 4종을 선정하여 이화학적 특성과 항산화 활성을 조사 하였다. 미국 스페셜티 커피협회 8단계 분류법을 참고하여 4단계로 로스팅(Light medium, Medium, Dark, Very dark)을 한 후 에스프레소와 드립 방법으로 커피를 추출하였다. 이화학적 특성으로는 생두와 원두의 일반성분, 색도, 갈색도를 측정하였고, 커피 추출물의 pH, 가용성 고형분 함량, 총산도, 색도, 갈색도, 카페인과 클로로겐산 함량, 유기산 함량을 측정하였다. 항산화 물질은 커피 추출물에서 총 폴리페놀과 총 플라보노이드 함량을 측정하였고, 항산화 활성은 DPPH radical scavenging activity, Ferric-reducing antioxidant power (FRAP), Trolox equivalent antioxidant capacity (TEAC)를 측정하였다. 또한 로스팅에 따른 항산화 물질 함량과 항산화 활성과의 상관관계를 조사하였다. 수분함량, 총 산도, 환원당, 명도(L) 및 황색도(b), 클로로겐산 함량은 로스팅이 진행됨에 따라 감소하였으며, 반면 조지방, 조회분, pH 및 가용성 고형분, 카페인, 유기산 함량은 증가하였다. 유기산 함량은 대부분 로스팅이 진행됨에 따라 감소하였다. 로스팅 정도가 클수록 항산화 물질의 함량 및 항산화 활성이 감소하였으며, 커피 추출방법에 따라서는 드립 커피가 총 폴리페놀 및 플라보노이드 함량과 비례하여 항산화 활성이 증가하였다. 본 아라비카 커피의 이화학적 특성과 항산화 활성 연구 결과는 다양한 커피 제품 개발에 기본 자료로 이용될 수 있다.
This study was conducted to investigate the physicochemical characteristics and antioxidant activity of Arabica coffee extracts (espresso and drip) of four varieties (Coffea arabica cv. Bourbon from El Salvador, Coffea arabica cv. Catuai from, Brazil, Coffea arabica cv. Heirloom from Ethiopia, Coffea arabica cv. Typica caturra from Colombia) with four different roasting conditions (Light medium, Medium, Moderately dark, and Very dark). In Coffea arabica cv. Bourbon from El Salvador, the contents of moisture, titratable acidity, reducing sugar, L-value and b-value were decreased with roasting degree increased while the contents of crude fat, crude ash, pH, total dissolved solids, and organic acids were increased in coffee extracts. For caffeine, the content was increased with roasting proceeding. Contents of organic acids were decreased with roasting degree increased. Total polyphenol contents of espresso and drip coffee were the highest at light medium and the lowest at very dark. The total flavonoid contents of espresso and drip coffee were the highest at light medium and decreased as roasting progressed. TEAC antioxidant activity of espresso coffee had no significant difference but drip had the lowest at very dark. DPPH radical scavenging activity of espresso coffee showed the highest at light medium and medium, drip coffee was not significantly different. FRAP of espresso coffee and drip coffee were the highest at light medium roasting, and decreased at very dark as the roasting progressed. Antioxidant activities according to the contents of total polyphenol and total flavonoids showed a higher correlation with espresso coffee in DPPH and FRAP activities. In Coffea arabica cv. Catuai from El Brazil, the contents of titratable acidity, reducing sugar and organic acids were decreased with roasting degree increased while pH and the contents of total dissolved solids (TDS) increased in coffee extracts. Lightness (L) was decreased with roasting degree increased in both coffee beans and the extracts. Caffeine contents were increased to Moderately dark, and then decreased at Very dark in the coffee extracts. Chlorogenic acid contents were decreased with roasting degree increased in the coffee extracts. Contents of organic acids such as citric acid, malic acid, and oxalic acid were decreased with roasting degree increased. The contents of total polyphenols and flavonoids and antioxidant activities (TEAC, DPPH, and FRAP) were analyzed in espresso and drip coffee extracts with different roasting degrees. The contents of total polyphenol and flavonoids were decreased with increasing roasting degrees, both espresso and drip coffee extracts were showed the lowest at very dark roasting. TEAC was significantly decreased as roasting degree increased in drip. DPPH radical scavenging activity was decreased with roasting degree increased in both espresso and drip. In FRAP, espresso was not significantly different, however, that of drip was significantly decreased with increase of roasting degree. Antioxidant compounds and activities were tended to decrease as the roasting degrees increased. In Coffea arabica cv. Heirloom from Ethiopia, the contents of titratable acidity, reducing sugar, and organic acids were decreased with roasting degree proceeding while pH and the content of total dissolved solids (TDS) were increased in coffee extracts (espresso and drip). Lightness (L) was decreased with roasting degree increased in both coffee beans and the extracts. Caffeine was increased with roasting proceeding, but chlorogenic acid was decreased with roasting degree increased in the coffee extracts. Contents of organic acids such as acetic acid, citric acid, L-malic acid, and oxalic acid were decreased with roasting degree increased. Total polyphenol content of espresso coffee was the highest at moderately dark and drip coffee at light medium. The total flavonoid contents of espresso and drip coffee were the highest at light medium and decreased as roasting progressed. TEAC antioxidant activity showed higher activity than DPPH radical scavenging activity. The TEAC of espresso coffee was not significantly different, but the drip coffee had the highest value at light medium roasting. DPPH radical scavenging activity of drip coffee was consistent with that of TEAC, and espresso coffee showed the highest activity at moderately dark roasting. FRAP of espresso coffee and drip coffee were the highest at light medium roasting, and decreased at very dark as the roasting progressed. Antioxidant activities according to the contents of total polyphenol and total flavonoids showed a higher correlation with drip coffee than espresso coffee. In Coffea arabica cv. Typica caturra from Colombia, the contents of titratable acidity, reducing sugar and organic acids were decreased with roasting degree increased while pH and the contents of total dissolved solids (TDS) increased in coffee extracts. Lightness (L) was decreased with roasting degree increased in both coffee beans and the extracts. Caffeine contents were increased to Moderately dark, and then decreased at Very dark in the coffee extracts. Chlorogenic acid contents were decreased with roasting degree increased in the coffee extracts. Contents of organic acids such as citric acid, malic acid, and oxalic acid were decreased with roasting degree increased. Total phenols contents of espresso and drip coffee were the highest at light medium, medium and the lowest at very dark. The total flavonoid contents of espresso and drip coffee also were the highest at light medium and medium and decreased as roasting progressed. TEAC of espresso coffee had the highest value at moderately dark and drip was at medium. DPPH radical scavenging activities of espresso and drip coffee were at light medium. FRAP of espresso and drip coffee were the highest at light medium, medium and decreased at very dark as the roasting progressed. Antioxidant activities according to the contents of total phenols were showed more high correlation at drip in TEAC. Total flavonoids with antioxidant activities showed a higher correlation at espresso in TEAC. These results suggest that roasting degree affect the physicochemical and antioxidant activity of coffee extracts.