## 3 Results and Discussion
### Volume of Bread  
The volume of the bread made from the fresh, RTP, and RTB doughs ranged from 156.2-235.2 mL, 153.9-233.2 mL, and 156.3-249.9 mL, respectively. Although [PERSON] et al. [25] reported that dough frozen after fermentation produced inferior quality bread than that produced by dough frozen without fermentation, no significant difference in the range of the bread volume among the three doughs in the present study was observed because of different formulations and processing conditions. The largest volume of the bread made from the RTP and RTB doughs was obtained using the processing conditions of 45 min for the first fermentation, 90 min for the second fermentation, a \(-45\)\({}^{\circ}\)C freezing temperature, and a 90 min freezing time and the processing conditions of a 45 min first fermentation, a 60 min second fermentation, a \(-35\)\({}^{\circ}\)C freezing temperature, and a 60 min freezing time, respectively. In contrast, the smallest volume of the bread from the RTP and RTB doughs was obtained using the processing conditions of a 15 min first fermentation, a 30 min second fermentation, a \(-45\)\({}^{\circ}\)C to \(-25\)\({}^{\circ}\)C freezing temperature, and a 30 min freezing time. The results indicate that the first and second fermentation times are critical for bread volume. A short fermentation time is insufficient for yeast growth, resulting in less carbon dioxide gas released by the yeast and thus a low bread volume. [PERSON] et al. [26] reported a dramatic effect of fermentation time on the freezing and thawing stability of pre-fermented lean wheat dough. A short pre-fermentation time (25 min) favored larger loaf volumes than a long pre-fermentation time (40 min) did. However, the results in the present study showed a different trend. The larger volume of the bread loaves after a longer pre-fermentation period could be due to the greater number of live yeast cells, which, in turn, could be related to the relatively higher sugar level (about 30% based on flour weight) of sweet bread. [PERSON] et al. [27] observed that much more living yeast cells remained in sweet dough than in the rye dough and explained that the yeast had more food in the sweet dough and that the sugar could protect the yeast. [PERSON] et al. [3] also showed that a higher expansion ratio before freezing resulted in a more fragile dough with higher porosity, resulting in the lowest bread volume with the lowest freezing rate and the highest pre-fermentation time. Additionally, the pre-fermentation time influenced a much greater extent than the freezer temperature did. When the bread prepared from each dough was compared, the processing conditions of a 45 min first fermentation, a 90 min second fermentation, a \(-45\)\({}^{\circ}\)C freezing temperature, and a 90 min freezing time for the RTP and RTB doughs resulted in similar bread volumes (233.2 and 244.1 mL, respectively) to that of the bread made with fresh dough (235.2 mL). The bread volume obtained under these processing conditions was also relatively higher than the other processing conditions, suggesting that a single potential set of processing conditions could be used to produce two types of frozen dough with good frozen stability.  
Among the four factors, the first and second fermentation times showed significant effects on the bread volume (Table 2). It was observed that there was a positive correlation between the first and second fermentation times and the bread volume from all three dough types. Sufficient fermentation time could help yeast cells metabolize more fermentable sugars and produce carbon dioxide, which increases the volume of bread [27].