開發掌上型螢光檢測器用以評估 茶水中之甘味與澀味

Development of a Handheld Fluorescence Meter for Determination of Umami and Astringency of Tea

張光華(Kuang-Hua Chang)

指導教授 ： 鄭宗記

國立臺灣大學/生物資源暨農學院/生物產業機電工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.00808

摘要

本研究開發一掌上型螢光檢測器，以檢測茶水中胺基酸與茶單寧含量，評估其甘澀味程度。檢測原理為鄰苯二甲醛(o-phthalaldehyde, OPA)和胺類之螢光反應，以及茶單寧對3-aminophthalate 螢光團之螢光消光特性。由於上述二螢光反應具相近之激發波長與發射波長，因此可使用單一螢光法，將二者整合於同一檢測系統(λex= 340 nm / λem= 425nm)。
研究中使用UVLED與Photodiode Array作為螢光檢測之光學元件，並搭配半導體晶片與程式語言，達到穩定光源、截取訊號、資料傳輸與人機介面等功能。依照光學路徑需求，研究中利用電腦輔助設計軟體(CAD)進行機構設計，並使用快速成型機進行製造與加工。
文中探討掌上型螢光檢測器之訊噪比、靈敏度、檢量範圍等系統性能，並藉由更改光學路徑以達改善與提升。本研究採用實驗室級螢光檢測儀與本檢測器進行標準品實驗之系統比對，結果顯示兩系統於二項檢測之相關係數均高於0.9950。本螢光檢測器對茶胺酸與單寧酸之檢量範圍分別為0.2-10 μg mL-1及1-20 μg mL-1，CV值小於6％(n=3)，所需樣品量為10μL，檢測速度約為每個樣品15秒。本研究尚針對四種不同價格之台灣烏龍茶進行檢測，並初步討論其甘澀味與價格之相關性。
本研究開發之掌上型螢光檢測器輕便可攜、成本相對低廉、檢測快速，且能即時檢測茶水中之茶單寧與胺基酸，有助於客觀評估茶品之甘澀味，進而評比茶葉之良莠。

關鍵字

掌上型螢光檢測器 ； 系統開發 ； 單一螢光法 ； 發光二極體 ； 茶品甘澀味

並列摘要

The design and developing of a compact fluorometry system for determining tannin and amino acid in tea was presented. The sensing principles are based on quenching the fluorescence of 3-aminophthalate by tannin, and the fluorogenic reaction of o-phthalaldehyde (OPA) with amino acids. Both reactions were measured by a single fluorescence sensing system with same excitation and emission wavelengths (340/425 nm). An ultraviolet light emitting diode (UVLED) and a photodiode array (PD array) was utilized to compose the handhold fluorometer. The photodiode array with frequency signal output was used for easily converted to digital signal and integrated into microprocessor-based electronics. The cuvette holder and the light path were designed by mechanism manufacture. The relation coefficients of system comparison with commercial fluorescence meter were both higher than 0.9959 in the determination of tannin acid and theanine. Dynamic ranges of the final handhold fluorometer for tannic acid and theanine were 1–20 μg mL-1 and 0.2–10 μg mL-1 (CV＜5％, n=3), and the measurement speed is about 15 seconds per sample. The dimension and the weight of fluorometer were 120 × 60 × 65 mm3 and under 150g. The miniaturization of fluorometry system provides a convenient, low-cost, fast measurement, and portable way to estimate tannin and amino acid in tea. This system is potentially applicable to quality monitoring and classification in tea beverage industry.

並列關鍵字

Handhold Fluorometer ； System Development ； Single Fluorometric ； Light Emitting Diode ； Astringency ； Umami

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