結合蜂蜜花粉分析與高效液相層析鑑定台灣荔枝蜜與龍眼蜜

Abstract

台灣的主要蜜源以荔枝（Litchi chinensis）和龍眼（Euphoria longan）最為重要，兩者亦為台灣單花蜜的主要來源。由於在分佈與花期上多有重疊，加上花粉形態的高度相似，至今對兩種蜂蜜的判別仍多仰賴蜂農的主觀經驗，未有標準化的檢定程序。本研究於2011年3到5月間蒐集採自台灣中南部各地的荔枝蜜43件、龍眼蜜94件、荔枝龍眼混合蜜10件、其他種類的本土蜜28件及外國蜜3件，以蜂蜜花粉分析研究花粉組成，再以固相萃取法對樣本中的待測物進行萃取，並透過高效液相層析連接紫外光偵測器（λ = 280nm）建立所有樣本的層析圖譜，旨在找出可靠的植物源標記。花粉分析鑑定出51科共98種花粉型，其中荔枝-龍眼型（litchi-longan type）之花粉頻率於荔枝蜜和龍眼蜜中普遍大於50％，可與其他種類的本土蜜區別。荔枝蜜和龍眼蜜之高效液相層析圖譜存在三道主訊號A、B、D峰，而分析結果顯示D峰積分面積相對A、B、D峰面積總和之比值於荔枝蜜中明顯較低，於龍眼蜜中明顯較高，於混合蜜中的數值範圍則介於荔枝蜜與和龍眼蜜之間。將蜂蜜花粉資料與高效液相層析圖譜資料進行比對，並以主成份分析對圖譜資料進行化學計量統計分析，結果支持A、B、D峰確實堪為判別台灣荔枝蜜和龍眼蜜的植物源化學標記，且其主要來源為荔枝與龍眼花蜜而非花粉。比對結果亦顯示蜂農欲標示台灣荔枝蜜或龍眼蜜者，其所含荔枝-龍眼型之花粉頻率至少要大於50％。

Litchi (Litchi chinensis) and longan (Euphoria longan) are two of most important nectariferous plants for monofloral honeys in Taiwan. Owing to high similarity in pollen morphology and overlapping of flowering time in some areas, it is difficult to distinguish either kind of honey. In order to set up a method for identifying them, we collected in this study 43 litchi honeys, 94 longan honeys, 10 mixtures of litchi- and longan-honeys, 28 other honeys from Taiwan and 3 foreign lhoneys from foreign country over the time from March to May, 2011. Melissopalynological analysis was applied to construct the pollen profiles. In addition, samples were extracted with solid-phase extraction, followed by high performance liquid chromatography (HPLC) detected at 280 nm to find out reliable botanical markers. In studied samples, there were 98 pollen types belonging to 51 families. The frequencies of the litchi-longan type pollen grains were generally above 50% in litch- and longan-honeys and were readily differentiated from other Taiwan honeys.. Both litchi- and longan-honeys displayed three characteristic peaks (A, B, D) in HPLC-chromatogram. Semi-quantitative analysis showed that the peak D was significantly lower for litchi honeys, whereas higher for longan honeys. The results of melissopalynological and HPLC analyses supported that A, B and D peaks originated mainly from litchi– and longan-nectars, and could be used as the botanical markers of ether type of honeys. It is suggested those labeled with typical litchi- or longan-honey should have pollen frequency higher than 50%, respectively.