| Summary: | 碩士 === 輔仁大學 === 食品科學系 === 97 === The present study aimed to develop an ethanol biosensor equipped by bienzyme (alcohol oxidase–peroxidase) and coloring agent (2, 6-dichloroindophenol, DCIP) immobilized on polymer film for a non-destructive detection of ethanol in package. LDPE film, underwent surface modification using a UV/O3/TiO2 process, and then was coated with polyvinyl alcohol / polyvinyl pyrrolidone (PVA/PVP) blend which was then bound to cellulose for the biosensor basis. Characterizations of the polymer surface using Attenuated Total Reflectance-FTIR (ATR-FTIR), contact angle and toluidine blue O dye assay confirmed surface modification for 3 hr is effective to increase the polarity and affinity on LDPE surface. The optimal PVA/PVP ratio for coating on LDPE was found at 4:6 (w/w) determined by ATR-FTIR, and this copolymer incorporated with 25% cellulose was effective to reveal color change (ΔE) from the present immobilized biosensing components. The formula of enzyme reagents containing alcohol oxidase: peroxidase: DCIP = 1: 1: 1 in association with 1mM potassium ferrocyanide resulted an observable ΔE value with respect to 50 ppm ethanol vapor after 6 hr at 4oC, and color development reached saturation in 12hr when exposed to 200 ppm ethanol. The ethanol biosensor under air or low oxygen (1%) conditions was found to form significant color development. Fresh strawberries packed in air and MAP (O2/CO2/N2=1: 5: 94) were then used to determine the feasibility of ethanol biosensor. Both packages showed 30~40 ppm ethanol accumulation and the total airborne microbial count was 105 cfu/g after 2 days storage at 4oC, and color development reached saturation at the same time. Additionally, weight loss and discoloration on the skin of fruit were significantly after 9 d. Therefore, the present resutls show a close relation among ethanol production, color development rate on biosensor film and microbial growth, and this is beneficial to maintain packaged food quality and safety by this developed ethanol biosensor.
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