應於海鮮與肉類腐壞檢測之酸鹼值感測系統

A pH Sensing System for Detecting Spoilage in Seafood and Meat

本論文提出一種應用於海鮮與肉類腐壞檢測的免校正酸鹼值感測系統。隨著存放時間的增加，海鮮和肉類開始腐壞，微生物會分解其中的蛋白質、脂肪和糖類，並產生有機酸和氨等物質，這些產物會改變物體的氣味與顏色，進而導致腐壞。海鮮與肉類在死亡後，隨著糖解反應的進行，pH值會逐漸下降，隨後在腐敗過程中，pH值會逐漸上升，變得更鹼性。透過本免校正酸鹼值感測系統來測量海鮮與肉類的pH值，可以準確得知海鮮與肉類的腐敗變質時間。
在系統設計上，本系統採用基於ARM Cortex-M3架構的Silicon Labs EFM32作為控制核心，並搭配液體pH試片，該試片為超極生技開發的免校正酸鹼電極（Humming Probe UH1）。該試片會將檢測檢體的pH值轉換成電壓信號，經由EFM32的類比數位轉換（ADC）處理，再透過EFM32的通用非同步收發傳輸器（UART），將數據傳送至PC端的LabVIEW人機介面，並即時顯示酸鹼值量測結果。
在系統驗證方面，我們使用市售的pH校準液來建立本酸鹼值感測系統的校正曲線，並將結果與商用酸鹼檢測儀器進行比較。實驗顯示，本論文設計的系統能夠與商用酸鹼檢測儀具有相同的趨勢。利用本系統進行海鮮與肉類腐壞檢測實驗，其實驗結果顯示，海鮮的pH值約在五小時左右會出現明顯變化，而肉類則會在十一小時半至十四小時之間出現較大的變化，利用這個pH值的明顯變化可以來判斷海鮮與肉類腐壞時間。
本論文提出的免校正酸鹼值感測系統能有效監控食物的腐敗過程，透過監控pH變化，進而預防食品腐壞，實時追蹤和控制食品品質，保證食品安全，並有助於預防食源性疾病的發生。

In this paper, we propose a calibration-free pH sensing system for detecting spoilage in seafood and meat. As storage time increases, seafood and meat begin to spoil due to microbial decomposition of proteins, fats, and carbohydrates, producing organic acids and ammonia. These byproducts alter the odor and color of the food, leading to spoilage. After death, seafood and meat undergo glycolysis, causing the pH to initially decrease. However, during the spoilage process, the pH gradually rises, becoming more alkaline. By measuring the pH of seafood and meat using the proposed calibration-free pH sensing system, the spoilage time can be accurately determined.
For system design, this study employs the Silicon Labs EFM32 microcontroller, based on the ARM Cortex-M3 architecture, as the control core. It is paired with a liquid pH test strip, the Humming Probe UH1, developed by SuperExtreme Biotech. This test strip converts the pH value of the sample into a voltage signal, which is processed by the analog-to-digital converter (ADC) of the EFM32 microcontroller. The data is then transmitted via the EFM32’s universal asynchronous receiver-transmitter (UART) to a PC-based LabVIEW human-machine interface (HMI) for real-time pH measurement display.
For system validation, commercially available pH calibration solutions were used to establish the calibration curve of the pH sensing system, and the results were compared with those obtained from commercial pH meters. Experimental results indicate that the proposed system exhibits the same trend as commercial pH meters. When applied to seafood and meat spoilage detection, the system demonstrated that the pH of seafood changes significantly after approximately five hours, while meat exhibits noticeable changes between eleven and fourteen hours. These distinct pH variations can be used to determine the spoilage time of seafood and meat.
The proposed calibration-free pH sensing system effectively monitors food spoilage by tracking pH changes, thereby preventing food deterioration, ensuring real-time food quality control, and enhancing food safety. Additionally, it contributes to the prevention of foodborne illnesses.