National Chiayi University

  As modern concerns about health have been increasing by the day, ensuring food safety not only safeguards our health but urges the upgrading of the food industry. Some bright-looking vegetables on the market may have chemicals added to them, which can unknowingly places a burden on the body if consumed in excess. To enhance the efficiency of food safety testing in Taiwan, NCYU Department of Electrical Engineering Prof. Cheng-Ta Chiang and Department of Food Science Assistant Prof. Jyh-Cheng Chen jointly supervised Shu-Huan Yang and Yi-Cheng Wu, both undergraduate students of the Department of Electrical Engineering, to conduct studies. They developed a groundbreaking “Detector for Measuring Sulfur Dioxide Concentration in Daylilies,” which can be used to measure the concentration of sulfur dioxide in daylilies via a titration method. The complete research design and results were published in the internationally renowned IEEE Sensors Journal.
   Prof. Cheng-Ta Chiang from the Department of Electrical Engineering, NCYU, said that this research was mainly motivated by his love for the daylily pork rib soup. This inspired him to discuss food safety issues related to “daylilies” with Assistant Prof. Jyh-Cheng Chen from the Department of Food Science. After in-depth studies, they discovered that sulfites have been excessively used by unscrupulous sellers as a bleaching agent for daylilies, which may be converted to sulfur dioxide during storage. Therefore, they began creating a detector by designing a conversion circuit to measure sulfur dioxide concentration in daylilies. According to the experimental results from research and development, this device can quickly determine the concentration of sulfur dioxide in daylilies. This is a much more time-efficient way for testing personnel to measure sulfur dioxide levels in the daylilies.
   Shu-Huan Yang and Yi-Cheng Wu, both students from NCYU's Department of Electrical Engineering, mentioned that there are a wide spectrum of methods to measure sulfur dioxide in food, such as voltammetry, colorimetry, high performance liquid chromatography (HPLC), and fluorescence. To determine the sulfur dioxide concentration in daylilies in a time-saving and convenient way, they opted for the "titration method," which is characterized by a shorter reaction time and lower requirements for equipment, and is more straightforward to operate. With the sulfur dioxide concentration detector, the solution obtained after soaking the daylilies is connected to the conversion chip, which creates resistance changes due to conductivity. The detector can be applied under various concentrations and used to determine the sulfur dioxide concentration in daylilies through the periodic output of the chip. The sulfur dioxide concentration detector distinguishes itself from the counterparts in that it is relatively cost- and time-effective.

  Assistant Prof. Jyh-Cheng Chen from the Department of Food Science indicated that, according to the "Standards for Specification, Scope, Application and Limitation of Food Additives," sulfites are legal food additives for sterilization, color restoration and bleaching, oxidation inhibition, and prevention of enzymatic and non-enzymatic browning reactions. The sulfites in the food, however, may be converted back to sulfur dioxide under certain storage conditions. The residual sulfur dioxide can trigger respiratory allergies in some individuals. Thus it is prerequisite to develop a simple and fast method to detect sulfur dioxide. In this collaboration with faculty and students from the Department of Electrical Engineering, they successfully developed the sulfur dioxide detection device by integrating the electrode system and complementary metal-oxide-semiconductor (CMOS). In the future, the device can be more easily applied to the detection of additives in daylilies and other processed foods.