| Summary: | 碩士 === 輔仁大學 === 食品科學系 === 100 === Functional food is one of the most predominant categories in food market currently. Typically, functional food products are sold in multi-serving containers, once the container is open, oxygen enters and leads to degradation of active ingredient. The aim of this study was to develop an oxygen sensing biosensor for real-time monitoring the quality life of oxidation sensitive functional foods. The biosensor was made of oxygen sensitive enzymes (glucose oxidase) and food grade coloring agent (betalain) immobilized on a surface modified LDPE film. To optimize the biosensor, response surface methodology (RSM) was used for the formulation, and the biosensor was then applied to monitor the quality life of lutein. The color development (ΔE) on biosensor exposed to air changed from purple to beige, and the maximum of ΔE on the biosensor was determined 50. From the RSM results, the optimal formula for monitoring active ingredients in one month storage (a simulation of 30 pills in a package) was 150 mM betalain, 320 mM glucose and 0.02g glucose oxidase, and this formula led to a significant visual difference in 28 days at 25oC due to 92.52% of max ΔE on biosensor. An kinetic equation derived from regressive analysis of RSM results was obtained as ΔE = e(0.01 t + 3.57) (t: time in days), and degradation of pigment was found to be first-order reaction. Encapsulation of bioreagents was also prepared to prevent an early color change from oxidation of betalain alone, and this modified biosensor was then used to monitor the degradation of lutein at 5, 25 and 45oC for 4 weeks. Results showed that the encapsulation effectively delayed oxidation of betalainA biosensor for monitoring lutein was formulated by 30 mM betalain, 150 mM glucose and 0.02g glucose oxidase, and the Ea of biosensor color change and lutein degradation were 12.39 and 11.38 KJ/mol, respectively. The color change on biosensor provides a significant visual difference with the degradation of lutein, therefore, that is beneficial to directly determine the quality of product.
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