A colour indicator film based on bromothymol blue/poly‐L‐lactic acid/polyvinylpyrrolidone for detecting bacteria

The unintentional bacterial contamination in food seriously harms food quality and human health, so it is necessary to establish a real‐time bacterial detection method. Here, a colour indicator film was designed to detect bacterial by incorporating bromothymol blue (BTB) into degradable poly‐L‐lactic acid (PLLA) and polyvinylpyrrolidone (PVP). The colour indicator film was prepared into fibres by electrospinning technology. The colour indicator film showed colour responsiveness from yellow to green at different pH. The colour indicator film showed good colour stability at different temperature and humidity conditions. The colour indicator film was used for the detection of bacteria, and it was found that the colour indicator film could make a colour response visible to the naked eye according to different concentrations of bacteria, which showed the great potential of the colour indicator film in detecting bacteria.