Effect of part-baking time, freezing rate and storage time on part-baked bread quality

Abstract In the baking industry, different processes and methods of freezing have been used for breadmaking to preserve a quality comparable to that of fresh bread. In this study, the effect of part-baking time, freezing rate, and frozen storage time on part-baked French bread quality was determined. The bread was part-baked for 0, 3 and 6 min, frozen at slow (0.15 °C/min) and fast (1.75 °C/min) freezing rates, stored under freezing conditions for up to 56 days and thawed every 14 days. Part-baked bread was rebaked, and the SV and firmness at 2, 24 and 48 h were obtained. An experiment with a factorial design of 3×2×5 (3 part-baking time, 2 freezing rates and 5 frozen storage times) with analysis of variance (ANOVA) at a confidence level of 95% was carried out. The highest SV was obtained at 6 min of part-baking at a slow freezing rate and decreased as the frozen storage time increased. In contrast, TPA showed that bread firmness increases when the specific volume decreases, and the highest firmness is at 0 min of part-baked time. Relatively long part-baking times allow for firm crumb formation with limited damage to the structure and therefore bread with optimal quality.

**摘要**：在烘焙工业中，行业已在面包制作中应用多种冷冻工艺与方法，以维持面包品质接近新鲜面包水平。本研究探究了预烘烤时长、冷冻速率及冷冻贮藏时长对半烤法式面包品质的影响。实验中将面包分别进行0、3、6分钟的预烘烤，以慢速（0.15 ℃/min）与快速（1.75 ℃/min）两种速率冷冻，随后在冷冻条件下贮藏最长56天，并每14天进行一次解冻。将预烘烤后的面包进行复烤，并测定其在2、24、48小时三个时间点的比容（Specific Volume, SV）与硬度。本实验采用3×2×5的析因设计（包含3种预烘烤时长、2种冷冻速率与5种冷冻贮藏时长），并以95%置信水平开展方差分析（Analysis of Variance, ANOVA）。结果显示，在慢速冷冻条件下预烘烤6分钟时，面包比容达到最高值，且比容随冷冻贮藏时长的增加而下降。与之相对，质地剖面分析（Texture Profile Analysis, TPA）结果表明，面包硬度随比容降低而升高，且预烘烤0分钟时面包硬度最高。较长的预烘烤时长可使面包瓤形成紧实结构且结构损伤有限，最终获得品质最优的面包。