Development of a Handheld Fluorescence Meter foretermination of Umami and Astringency of Tea
Date Issued
2009
Date
2009
Author(s)
Chang, Kuang-Hua
Abstract
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.
Subjects
Handhold Fluorometer
System Development
Single Fluorometric
Light Emitting Diode
Astringency
Umami
Type
thesis
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