Development of food analytical systems based on the use of immobilized biocatalysts

Abstract

A convenient and rapid analytical system for food components responsible for food quality was developed based on the use of immobilized enzymes and microorganisms. First, an analytical system for superoxide dismutase (SOD) activity was constructed using the combination of an immobilized enzyme with flow-injection analysis (FIA). In this system, the immobilized xanthine oxidase played the role of a generator of superoxide anion; the sampling frequency was about 30 samples/h. Next, a novel analytical format was proposed involving a combination of immobilized enzymes with a 96-well microtiter plate. An alternate and repeated deposition of avidin and biotinylated enzyme was useful for enzyme immobilization with high activity and stability. Immobilized glucose oxidase under the optimized conditions was applicable to glucose determination, and the acitivity was retained during storage for 6 months and 50 successive determinations. The ability of microorganisms to recognize a given group of substances is useful for exploiting novel analytes. An example was indicated by the development of a rapid and convenient analytical system for short-chain fatty acids using immobilized Arthrobacter nicotiana-FIA. A sample throughput of 20 samples/h was achieved, and the obtained response showed a linear correlation with the total concentration of C4 0 to C12 - 0. The response was also partly related to the somatic cell count in raw-milk samples (n = 150), suggesting that the system should be applicable to detecting mastitis milk. The application of immobilized Psuedomonas putida to the determination of organic acids in wine is also described, in which the relationship between the specificity and the carbon sources used in the growth medium was investigated.