TY - JOUR TI - Characterization and application of carrot antifreeze protein in keeping bacterial cell viability under low temperature DO - https://doi.org/doi:10.7282/T3ZW1NRV PY - 2015 AB - The ice-structuring protein (ISP) or antifreeze protein (AFP) has great potential applications in frozen food preservation. This study aims at developing a fast and economical method to prepare carrot (Daucus carota) AFP (DcAFP) and apply it in the preservation of bacterial cell. The carrot AFP (DcAFP) was cloned and transformed into the recombinant bacteria. The recombinant protein was purified and refolded, and its second structure, as determined by circular-dichroism (CD), was found to contain approximately 60% beta sheet structure, suggesting the potential binding plane for ice and liquid water. The inhibition of ice crystal formation by DcAFP was further demonstrated by the following three experiments: first, the recrystallization of ice crystals with the DcAFP solution was monitored by using video microscopy. By quantifying the crystal number and their average diameter, the ability of DcAFP to inhibit the recrystallization has been demonstrated. Second, bacterial cell viability under 0ºC was detected. With the addition of DcAFP, cell survival rate was 50% higher than that of the control sample. Finally, the addition of DcAFP in the lactobacillus without any other protective agent significantly increased cell viability under 0ºC. These results suggested the potential applications of DcAFP in the preservation of probiotic foods. KW - Food Science KW - Antifreeze proteins KW - Plants--Effect of cold on KW - Carrots LA - eng ER -