臺灣山胡椒(馬告)的香氣及抗氧化力-以乾燥模式、採收成熟度、產區為區別

Abstract

山胡椒Litsea cubeba (Lour.) Pers. 為臺灣泰雅族香料「馬告」，果實帶有檸檬、胡椒及薑香氣及辛辣味，多為乾燥加工品。乾燥處理對山胡椒果實之香氣及抗氧化成分影響尚未明確；果實成熟度及產地對臺灣山胡椒之揮發性化合物及機能性成分影響之研究亦不多。本研究針對乾燥方式、果實成熟度及產地，透過分析其香氣組成、總多元酚含量及抗氧化能力，期望能暸解其對山胡椒果實之影響，找出能保留特色並有效率之乾燥方法。乾燥條件包括-50℃冷凍乾燥、40℃、60℃、80℃熱風烘乾及日曬乾燥，山胡椒果實乾燥後的主要香氣化合物皆為檸檬醛。以-50℃冷凍乾燥可保留最多單萜類化合物、總酚及抗氧化能力，總酚含量達17.95±0.39 mg/g，DPPH及ABTS自由基清除能力分別為33.61±4.48%及71.36±2.21%。以熱風80℃烘乾則可有效乾燥，乾燥時間縮短至9小時，並適度保留香氣、總酚及抗氧化能力，總酚含量達14.44±0.30 mg/g，DPPH及ABTS自由基清除能力分別為20.97±2.94%及58.36±3.79%。山胡椒果實成熟前有較多帶清新氣味之單萜類化合物如檸檬烯，成熟後檸檬醛組成提高，總多元酚及抗氧化能力亦顯著增加，DPPH自由基清除能力分別從49.18±2.49%及53.36±0.47%增加到66.10±1.21%及64.97±1.74%。採自4個產區的9個山胡椒果實樣品共分析出13種共同芳香化合物。南投梅峰果實總多元酚含量最高，但以花蓮2號及烏來野生果實抗氧化能力最強，DPPH自由基清除能力為63.25±5.52%及66.22±0.36%，ABTS自由基清除能力為91.15±1.39%及92.20±0.44%。山胡椒葉片、枝條、果梗及花朵之總多元酚含量及抗氧化能力均比果實高，三單株果實DPPH自由基清除能力為43.71±1.52%至63.25±5.52%，葉片及枝條則高達75.56±0.95%至82.62±0.42%。果實兩倍稀釋萃取液的ABTS自由基清除能力從85.26±4.11%至91.15±1.39%，果梗及花朵萃取液稀釋32倍仍有57.32±2.98%至64.00±1.96%清除率。

Litsea cubeba (Lour.) Pers. is a traditional spice ‘Maqaw’ used by Taiwan aborigine Tayal, which the fruit is lemon, pepper and ginger scented. Fruit of L. cubeba usually preserved by drying but the effect of drying to its quality is not known. On the other hand, fruit maturity and its origin are also factors. This investigation analysed the quality of fruits with various drying treatments, fruit ripeness and origin, in order to estimate its most suitable drying method, harvest maturity and usage through their aromatic components, polyphenols content and antioxidative activities. Fruit of L. cubeba was dried by -50℃ freeze drying, 40℃, 60℃, 80℃ oven drying and sun drying. Main aroma component in all drying treatments is citral. Monoterpenoids, polyphenols and antioxidative activity are conserved most by -50℃ freeze drying, which total polyphenols content is 17.95±0.39 mg/g, DPPH and ABTS radical scavenging power are 33.61±4.48% and 71.36±2.21% repectively. Oven drying with 80℃shorten the drying time effectively to 9 hours and keeps the specific aroma, polyphenols and antioxdative activity. Its total polyphenols content is 14.44±0.30 mg/g, DPPH and ABTS radical scavenging power are 20.97±2.94% and 58.36±3.79% respectively. Unripe fruits contain more fresh scented monoterpenoids, but ripen fruits have higher polyphenols content, antioxidative activity, and the ratio of citral. The DPPH radical scavenging power raised from 49.18±2.49% and 53.36±0.47% to 66.10±1.21% and 64.97±1.74%. 9 fruits from 4 production areas have 13 same aroma compounds. Although total polyphenols content of fruits from Meifeng is the highest, Hualian no. 2 and Wulai wild fruit performed the highst antioxidative activities, which DPPH radical scavenging power are 63.25±5.52% and 66.22±0.36%, ABTS radical scavenging power are 91.15±1.39% and 92.20±0.44%, respectively. All parts from L. cubeba can be used. Total polyphenols content and antioxidative activities of leaf, stem, fruit pedicel and flowers are much higher than fruits. In three individual of L. cubeba trees, fruit extracts perform 43.71±1.52% to 63.25±5.52% DPPH scavenging power, leaf and stem are 75.56±0.95% to 82.62±0.42%. ABTS radical scavenging power of 2X diluted fruit extract are 85.26±4.11% to 91.15±1.39%, fruit pedicel and flower 32X extracts still have 57.32±2.98% to 64.00±1.96% scavenging powers.