Production of a recombinant carrot antifreeze protein by Pichia pastoris GS115 and its cryoprotective effects on frozen dough properties and bread quality

Carrot (Daucus carota) antifreeze protein (CaAFP) is reported to have strong ice recrystallization inhibition (IRI) activity and great potential in frozen dough. However, the low yield and high cost of extracting CaAFP from natural sources limit its wide applications. To overcome the paucity of CaAFP, in this study, recombinant carrot antifreeze protein (rCaAFP) was expressed and produced in Pichia pastoris GS115, and the cryoprotective effects of rCaAFP on frozen dough properties and bread quality were investigated. The rCaAFP production reached 379.47 mg/L in a 7 L fermentor, and the rCaAFP exhibited high thermal hysteresis activity (1.96 degrees C at 10 mg/mL) and strong IRI activity. The addition of rCaAFP to frozen dough lessened the increment of freezable water content during freeze-thawed cycles, weakened the damage of freeze-thawed cycles to fermentation capacity and microstructure of frozen dough, and consequently improved the specific volume and texture properties of bread. The rCaAFP produced by Pichia pastoris GS115 was proven to be an effective cryoprotectant for frozen dough. This study provides a feasible method for the production of recombinant plant antifreeze proteins. The availability of gram quantities of rCaAFP contributes to accelerating further application studies.