Preliminary study on time-temperature indicator system based on tyrosinase

A new type of time-temperature indicators ( TTIs) based on enzymatic browning of tyrosinase had been developed.The absorbance curves and degrees of browning in liquid systems were determined at different temperatures. In addition, a preliminary study was conducted to analyze color changes when immobilized tyrosinase onto a solid phase carrier. The results showed that at 0℃ and 5℃, the color of the time temperature indicator system could shift from colorless to brown during 48 hours and finally turned into obvious black ( the end point of indication 42.05 ± 2.00) in the end. The whole process spent 48 h. However, at the condition of 35℃, only4 hours were needed for the whole process.The preliminary study which was conducted on a mixed sodium alginate-sodium carboxymethyl cellulose film manifested that there was a significant color change when reacted with tyrosine.All the results indicated that this kind of TTIs had a good prospect for development.It will provide another method in monitoring the flow of fresh food in China and it will offer a new option for consumers in choosing fresh food with reasonable price.