Abstract

The relationship between antioxidant activities and physicochemical properties of several fractions obtained from freeze-dried (FD) coffee were investigated. The nine kinds of fraction were consecutively extracted from FD coffee with solvents in increasing order of polarity, and the higher polarity of the solvent the higher extraction yield of the fraction. The antioxidant activities of the fractions were determined by Rancimat and oven test on edible oils. The antioxidant activities of the fractions increased in the order of acetone>ethanol>methanol>50% methanol/water>water fraction, and the antioxidant activities of them were higher on lard than on soybean oil. The antioxidant activity of each fraction was strongly related to the contents of total phenol, total nitrogen content and acidity, whereas color intensity, reducing power, carboxylic acid content showed little contribution to the activity. All fractions had three peaks maxima at 208, 275 and 324 nm on UV-visible spectra, but the only one at 324 nm was linealy proportional to the antioxidant activities of the fractions.

동결건조 커피의 순차용매 분획물별 항산화력과 이화학적 성질을 대비하여 그 유효 분획물의 항산화특성을 고찰하였다. 동결건조 커피를 극성도의 크기에 따라 9가지 용매로 추출하여 얻은 각 분획물을 식용유지에 첨가하여 Rancimat과 oven test로 항산화 효과를 시험하였다. 용매별 추출 수율은 분획물의 극성도가 높아질수록 증가하는 경향을 보였다. 분획물의 항산화력은 acetone>ethanol>ethyl acetate>methanol>50% methanol>water 분획물의 순이였으며, 대두유보다 돈지에서 더욱 효과적이었다. 각 분획물의 항산화력은 갈색도와 환원력의 강도 및 유기산 함량과는 관련이 없었으나 총phenol, 산도 및 caffeine을 포함한 총질소함량과 깊은 관련이 있었다. 또한, 각 분획물의 UV-visible spectra는 $200{\sim}220\;nm$, $260{\sim}280\;nm$ 및 $320{\sim}340\;nm$ 범위의 봉우리로 구분되었으며, 이중 $320{\sim}340\;nm$ 부근이 각 분획물의 항산화력의 크기와 일치하였다.

Keywords

• antioxidant;
• freeze-dried coffee;
• UV-visible spectrum