Optimized Fermentation and Freezing Conditions for Ready-to-Proof and Ready-to-Bake Frozen Dough of Sweet Bread

The processing conditions for ready-to-proof (RTP) and ready-to-bake (RTB) frozen sweet bread doughs were optimized using response surface methodology. A central composite design determined four factors and the tested range for each factor: a first fermentation time of 15~45 min, a second fermentation time of 30~90 min, a freezing temperature of −45~−25 °C, and a freezing time of 30~90 min. Sweet bread produced with these doughs was evaluated by bread weight, moisture content, crust color, height, volume, and firmness. Both the RTP and RTB doughs resulted in equal bread volume and height to the fresh dough, indicating excellent frozen stability. The first and second fermentation times were the significant processing factors for the RTP and RTB doughs influencing representative bread quality attributes based on quadratic models and ANOVA. Fermentation steps appeared to more significantly contribute to the quality of sweet bread made of frozen dough than freezing steps. The optimized RTP and RTB sweet bread dough processing conditions were the long first and second fermentation times for the dough based on a multiple response method and desirability. The optimum processing conditions for the RTP and RTB doughs were 44.7 min for the first fermentation time, 86.3 min for the second fermentation time, a −32.8 °C freezing temperature, and an 85.5 min freezing time.