油炸油品質快速檢測平台

Abstract

油炸在我們日常食物中是個簡單、快速且普遍的烹調手法，然而油炸油歷經連續反覆高溫烹煮食物的過程中，會發生水解、氧化與熱反應，形成許多對人體有害的物質，使得油炸油品質逐漸劣化。因此快速檢測油炸油何時該丟棄是一個具有挑戰性的任務，目前尚未有個令人滿意於現地分析的方法。本研究透過電化學阻抗頻譜分析法，來觀察油炸油品質隨油炸時間產生劣化之阻抗頻譜變化趨勢，希望藉此評估開發一個新型態油炸油品質快速檢測平台之可行性並探究其阻抗頻譜變化之理論基礎。電化學阻抗頻譜搭配疏水性碳電極組，以100 mV之正弦訊號從10-2掃引至103 Hz，無偏壓且控溫於30 ℃之實驗結果顯示，本檢測系統不需要對樣品進行前處理，能輕易地於Nyquist圖譜中觀測出電荷轉移阻抗（Charge Transfer Resistance；RCT）下降趨勢，經過等效電路模擬後可得知油炸油歷經20小時油炸模擬試驗後，RCT從新鮮油炸油之57.85±1.45 GΩ大幅下降為8.43±1.12 GΩ，而官方油炸油劣化指標之總極性物質（Total Polar Compounds；TPC）含量百分比亦相對應地從新鮮油炸油之5.5 %增加為23.5 %，且RCT與TPC含量百分比呈現高度負相關，因此RCT可視為判斷油炸油品質的潛力指標。藉本研究結果證實，電化學阻抗頻譜分析法搭配疏水性碳電極組之實驗設計的確具有被開發成為油炸油品質快速檢測平台之可行性。

Deep-frying is a simple, rapid and popular cooking method in our daily foods. There are several chemical reactions occurring during repetitive and continuous deep-frying process, which gives rise to the formation of considerable number of harmful compounds that significantly deteriorate the quality of deep-frying oil. To determine the point at which the deep-frying oil should be discarded rapidly is thus a challenging task, and no satisfactory method for real-time field analysis is available to date. Our work was to study the electrochemical impedance spectroscopic (EIS) behavior of deep-frying oil during heating, as well as assess the feasibility of developing an EIS platform for the quality of deep-frying oil. EIS measurement was scanned from 10-2 Hz to 103 Hz at 30 °C with an unbiased 100 mV sinusoidal signal through a pair of screen-printed carbon electrodes. The result showed that the sample didn’t need any pretreatment and the charge transfer resistance (RCT) in Nyquist plot decreased with increasing the frying cycles. The resulted EIS spectrum was fit to the Randles equivalent circuit for further data interpretation. RCT was gradually decreased from 57.85±1.45 GΩ (fresh frying oil) to 8.43±1.12 GΩ (oil sample after 20 hours frying simulation test), and total polar compounds (TPC) content also increased from 5.5 % to 23.5 %. Since RCT showed obvious negative correlation with the content of TPC, it would be a potential index for the quality of deep-frying oil. Electrochemical impedance spectroscopic has been proved that it has potential to develop a rapid sensing platform for deep-frying oil quality through a pair of screen printed carbon paste electrodes.