Research for Development of Food Quality Estimation System Using Oxygen Sensor

本研究旨在开发一种基于氧传感器的化学食品质量检测系统.采用氧传感器水封反应池测定溶解氧（DO）减少量的方法，利用抗坏血酸氧化酶（ASOD）氧化抗坏血酸的酶促反应，快速测定果蔬的新鲜度指数。测定了温度、pH值和缓冲液浓度对溶解氧摄取（DO降低）的影响，用测定DO降低的方法测定了SH还原剂还原的脱氢抗坏血酸（DHA）和葡萄糖氧化酶（GOD）氧化的葡萄糖。用同样的方法监测绿豆芽贮藏过程中还原型阿萨、总阿萨和葡萄糖含量的变化。监测成分的减少与感官新鲜度有较好的相关性.为了节省测定K值（鱼或肉的新鲜度指标）时酶的使用（酶非常昂贵），将核苷酸氧化酶（NP）和黄嘌呤氧化酶（XO）共固定在多孔尼龙膜上。所制备的酶电极可用于肉类新鲜度的重复性酶测定.提出了一种基于氧传感器过氧化氢酶法快速测定食品微生物活菌数的方法。对酵母菌和E.大肠杆菌细胞悬液中过氧化氢酶活性与细胞数在10 - 10个/ml范围内呈高度相关。建立了一个便于食品微生物检验的全自动计算机辅助系统。该系统不仅可用于新鲜度指标的测定，还可用于其他化学食品的分析。测量溶解氧增加的方法也用于检查牛奶、“味噌”和“纳豆”中的细胞计数。

This research was done to develop chemical food quality estimation system using oxygen sensor.1. Freshness index of fruits and vegetables was determined rapidly by enzymatic oxidation reaction of ascorbic acid using ascorbate oxidase (ASOD), following the method for measorement of the decrease in dissolved oxygen (DO) in a water sealed reaction cell of the oxygen sensor. The effect of temperature, pH and buffer concentration of the reaction mixture on the DO uptake (DO decrease) were determined.Dehydroascorbic acid (DHA, oxidized vitamin C) chemically reduced to ASA using SH reducing agent and glucose, oxidized by glucose oxidase (GOD) were determined by the method for measuring the decrease in DO. Changes in reduced ASA, total ASA and glucose content of stored mungbean sprouts were monitored using the same method mentioned above. Decrease of monitored components showed good correlation with sensory freshness.2. In order to save the use of enzymes (enzymes are very expensive) for the determination of K-value (freshness index of fish or meat), co-immobilization of nucleotide oxidase (NP) and xanthine oxidase (XO) on porous nylon membrane was carried out. The resulting enzyme electrode was useful for a repeated enzyme assay of meat freshness.3. A rapid method for estimating viable cell count of food microbes based on catalase assay using oxygen sensor was proposed. Results of the experiments on yeast and E. Coli cell suspension showed a high correlation between catalase activity and cell count ranging from 10 -10 cells/ml. A fully antomated computer-aided system, convenient for microbial test of foods was constructed. Future development of the system was expected not only for freshness index determination but also for other chemical food analysis. The method for measuring the increase in dissolved oxygen was also applied to check cell count in milk, "miso" and "natto".