蜂蜜摻偽快速檢測法之開發

Abstract

天然的蜂蜜成本較為昂貴，因此常有不肖商人在市售蜂蜜中混摻成本較低之人工糖漿，冒充純正蜂蜜以賺取利潤的情形發生，使消費者與養蜂業者的權益受影響。現用的摻偽檢測方法多倚賴分析級儀器，檢測程序較為繁瑣且耗時，然而市售蜂蜜品牌眾多，大規模或高頻率地進行分析並不符合成本考量，因此，亟需發展出一套快速、可靠的檢測方法。本研究旨在利用電化學阻抗頻譜分析（Electrochemical Impedance Spectroscopy, EIS）做為基礎檢測技術，來建立一套蜂蜜摻偽快速檢測系統。實驗結果顯示，本檢測系統僅需對樣品進行簡單稀釋的前處理，即可透過阻抗圖譜奈氏圖（Nyquist plot）的觀察，區別出市售的純正蜂蜜、糖漿、及調和蜂蜜，並進一步得出三種類型樣品間差異最為顯著的是電荷轉移阻抗（Charge Transfer Resistance, Rct）之數值，同時藉由此阻抗值會與蜂蜜中混摻糖漿比例呈現正相關的特性，可將電荷轉移阻抗做為判斷蜂蜜摻假與否的潛力指標。當阻抗分析的掃引頻率介於101至105 Hz之間時，調和蜂蜜與純正蜂蜜間之阻抗值（LogZ）差異可達一個數量級，因此即便在對數維度下，透過阻抗波德圖（Bode plot）仍可輕易地將兩者區分開來。藉由本研究所訂定的鑑別條件，收集得來之10件調和蜂蜜可以完全地與34件純正蜂蜜樣品區分開來，因此摻假蜂蜜的鑑別成功率達100%。本檢測系統在具分辨性之頻率區間內針對單一樣品進行一次完整頻譜掃引只需花費3分鐘；若是在上述區間內擇一頻率進行定頻檢測，更可將檢測時間大幅縮短至數秒鐘。

Since the price of natural honey is much higher than any other sweeteners, producers tended to adulterate honey with less expensive substances such as high fructose corn syrup. However, recent methods for detecting adulteration rely on expensive instruments and the procedures are time-consuming, a fast, simple, and low-cost analytical method is therefore demanded. A rapid and simple detection method for honey adulteration was developed based on electrochemical impedance spectroscopy (EIS) with a detection chamber composed of a gold electrode pair. After a simple sample pretreatment of water dilution, the differences of Nyquist curves among pure honeys, syrups, and adulterated honeys could be easily observed. The simulated impedance data of equivalent circuit model revealed the honey adulteration ratio is most distinguishable from the values of charge transfer resistances (Rct), and an obvious positive correlation was shown between them. Furthermore, in the frequency region between 101 to 105 Hz (Bode plot), the impedance response consistently increased along with the increasing adulteration ratio, which indicated that the adulteration ratio can be estimated even by the logarithmic values of the impedances (LogZ) at any designated frequency in the mentioned region. Based on the proposed method, all the 10 commercial adulterated honey samples were successfully identified from all the 34 authentic pure honey samples whether judged by Rct or LogZ. The data acquisition time was about 3 min for a single frequency scan (1 to 106 Hz) while only few sec was required for the impedance data at a designated frequency.