臺灣咖啡生豆綠原酸組成與杯測品質之相關性分析

Abstract

綠原酸 (Chlorogenic acid, CGA) 不但是咖啡生豆中重要的機能性成分，且會影響咖啡風味。本試驗分析147件「民國105年國產精品咖啡評鑑」生豆之綠原酸組成，並比較其與處理法、栽培海拔和杯測得分之相關性。生豆中的CGA以5-caffeoylquinic acids (5-CQA) 和3,5-dicaffeoylquinic acids (3,5-diCQA) 為主。處理法影響CGA組成，水洗處理之生豆CGA濃度為58.32 mg·g-1 dw，低於日曬的62.51 mg·g-1 dw。相較於進入決選的咖啡，初選的咖啡有較高的3,4-dicaffeoylquinic (3,4-diCQA) 濃度2.06 mg·g-1 dw與較低的5-CQA濃度37.11 mg·g-1 dw。海拔與多個CGA組成有顯著相關，日曬處理之5-CQA濃度與海拔高度正相關 (r = 0.76, P ≤ 0.001)。杯測總分與栽培海拔高度正相關 ( r = 0.43, P ≤ 0.001)，與總CGA雖無顯著相關性，但與5-CQA和3,4-diCQA分別高度正相關 ( r = 0.36, P ≤ 0.001)與高度負相關 (r = -0.39, P ≤ 0.001)。逐步正向迴歸結果顯示個別CGA對杯測總分的貢獻，依序為3,4-diCQA、5-CQA與3,5-diCQA，分別有負向、正向、負向的貢獻，合計模型解釋力R2 = 0.331。5-CQA與多個杯測項目正相關，以香氣最為顯著 ( r = 0.44, P ≤ 0.001)。生豆5-CQA和3,4-diCQA比總CGA更可作為杯測品質指標。

Chlorogenic acids (CGA) are important bioactive compounds in green coffee beans and affect cup quality. This research examined chlorogenic acid composition of 147 green coffee samples from 2016 Taiwan Specialty Coffee Evaluation and performed correlation analysis between their processing, cultivation altitude, and cupping scores. In green coffee, 5-caffeoylquinic acid (5-CQA) and 3,5-dicaffeoylquinic acid (3,5-diCQA) account for the majority of CGA. Washed coffee displayed a lower 5-CQA concentration at 58.32 mg·g-1 dw in comparison to natural coffee's concentration of 62.51 mg·g-1 dw. Coffee eliminated in the first round of the evaluation showed a higher 3,4-diCQA concentration at 2.06 mg·g-1 dw and a lower 5-CQA concentration at 37.11 mg·g-1 dw. Cultivation altitude correlated with several CGA groups. In natural coffee, 5-CQA concentration showed a high positive correlation with (r=0.76, P ≤ 0.001) altitude. Cupping scores also showed high positive correlations (r=0.43, P ≤ 0.001) to cultivation altitudes. Although cupping scores were not correlated to total CGA concentrations, 5-CQA and 3,4-diCQA were highly positively correlated (r=0.36, P ≤ 0.001) and highly negatively correlated (r=-0.39, P ≤ 0.001) to cupping scores respectively. By stepwise forward regression analysis, 3,4-diCQA,5-CQA and 3,5-diCQA had been included in the cupping score model. These variables were negatively, positively and negatively correlated to cupping score, respectively, and gave a combined model R2 of 0.331. Concentration of 5-CQA was positively correlated to several attributes during cupping. The most significant one was fragrance (r=0.44, P ≤ 0.001). As such, concentrations of 5-CQA and 3,4-diCQA were better cup quality indicators than total CGA concentration