Studying the Halochromic Behavior of Cellulose Acetate Films Incorporated with Bromothymol Blue Indicator

Microbial growth in food products decreases the food shelf life and increases the risk of foodborne diseases. There are various methods for monitoring the microbial growth and consequently the incidence of food spoilage; e.g. food spoilage monitoring sensors. In this research we aim to investigate the feasibility of producing the cellulose acetate (CA) film incorporated with bromothymol blue (BTB), as a kind of halochromic sensor. The 4% (w/w) cellulose acetate solution with 0.5, 1 and 1.5% bromothymol blue (wdye/wpolymer) and 0.5% glycerol (as plasticizer) was used to produce the pH sensitive films. The halochromic behavior of sensors in pH 5-9 buffer solutions were studied through the L*, a*, b*, and total color difference (ΔE*) measurements. The reaction of the produced films and the leakage of the dye at different pH values were also studied. The results showed the significant effect of dye and pH (P