The development of a simple paper-based device for the determination of benzoic acids

• Main Authors: Chen, Kuan-Lin, 陳冠霖
• Other Authors: Liu, Chan-Chiung
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/12870961563547390674

碩士 === 國立屏東科技大學 === 食品科學系所 === 104 === Food preservatives are a group of food additives aiming to detent food spoilage and deterioration, and hence to prolong its shelf life. Food preservatives could be classified to organic acids, inorganic acids, organic and inorganic salts, antibiotics, etc. Evidences show that benzoic acid and its salts are the most frequently abused preservatives in Taiwan. They are commonly used in jams and juices, pastry, margarine, and sauces, the content of preservative has been regulated as below 1.0 g/kg (as acid). Instrumental analyses could achieve more accurate results, yet subjected to higher cost and time consuming sample preparation steps. This lead to an increasing need for swifter and more economical assay methods. In order for effective and rapid detection of benzoic acid in foods, spectrophotometric concept was utilized to develop the paper-based device kit. Both spectrophotometric and paper-based detections are based on chemical color test. Paper-based device is a blooming analysis tool in recent years, owing to its characteristics such as easy-to-use, time shortening, easy-to-carry, etc. It is a detection method combing high yield, speed, convenience, simplicity, and low cost. This investigation employed the principle of Janovsky Reaction. Using filter paper pre-coated with 5N sodium hydroxide solution as substrate, benzoic acid would react with substrate and yield compound with red-purple color. hence could be quantified through its color development. Photos would be taken to record this color development, and analyzed via Vision Assistant software for the values of R (red), G (green), and B (blue), hence the benzoic acid content could be quantified through its color values. The results showed the optimized regression equation would be obtained with R+B value after 20 minutes of reaction, i.e. y =-0.0264x + 408.79, R2= 0.9953. Benzoic acid could be semi-quantified via R+B value on filter paper, with detection limit around 800 ppm. The paper-based device was also applied to assay benzoic acid in real food (dehydrated radish and soy sauce). The content was determined as 863 ppm in dehydrated radish with the above paper-based device, compared to the result of 1000 ppm carried out by accredited laboratory via standard method. Benzoic acids was intentionally spiked into soy sauce previously found without it, and was determined as 2984 ppm in spiked soy sauce with the above paper-based device, compared to the result of 3400 ppm carried out also by accredited laboratory via standard method. Similar results were obtained with spiking sodium benzoate into “cleaned” soy sauce (2454 vs. 2590 ppm). Paper-based device would be highly potential in applicability possibly for biomedical industry, because of low cost, fast speed, no sophisticated instruments involved, easy operation, and best of all, results could be visionally determined. It could be further applied in the development of detection kits aiming to be used at home by general public, for swift assay of foods and daily necessities.