不同水分含量鲜腐竹冷藏过程中品质变化研究

Study on the quality changes of fresh yuba during cold storage with different moisture content

中文关键词:  鲜腐竹  品质变化  4℃冷藏  初始水分含量

英文关键词:fresh yuba  quality changes  4℃ storage  initial moisture content

中文摘要:

      目的 探究不同初始水分含量下鲜腐竹冷藏过程中品质的变化规律, 确定适宜鲜腐竹冷藏的初始水分含量。方法 将鲜腐竹干燥至水分含量分别为50%、45%、40%后, 4℃冷藏。利用色差计、质构仪(texture profile analysis, TPA)、扫描电镜(scanning electron microscope, SEM)、低场核磁共振(low-field nuclear magnetic resonance, LF-NMR)测定鲜腐竹的色泽、质构特性、微观结构和水分分布状态; 采用化学分析手段测定鲜腐竹的可溶性肽含量、过氧化值、蒸煮损失率, 并对鲜腐竹进行感官评分和菌落总数测定, 探究冷藏过程中鲜腐竹的品质变化规律以及水分含量对鲜腐竹冷藏品质的影响机制。结果 随着冷藏时间的延长, 鲜腐竹的L*呈下降趋势, a*、b*呈增加趋势, 鲜腐竹感官品质劣变, 蒸煮损失率、可溶性肽含量、菌落总数增加。初始水分含量下降, 腐竹色泽L*降低, a*增加; 40%和45%水分含量的腐竹, 冷藏过程中的硬度、胶黏性、咀嚼性较高, 45%水分的腐竹弹性最大, 且质构特性更为稳定; 冷藏过程中, 鲜腐竹感官品质劣变, 降低水分含量至45%和40%时, 可使鲜腐竹在第8 d时感官评分在60分以上, 其对感官品质中的质地和气味改善最大; 40%的初始水分含量, 腐竹的蒸煮损失率最低, 但与45%的水分含量不具有显著性差异(P<0.05); 降低水分含量, 可延缓鲜腐竹最大过氧化值出现的时间, 降低蛋白质网络结构的破坏程度。冷藏过程中存在明显的水分迁移现象, 鲜腐竹的硬度、咀嚼性、弹性、胶黏性受可溶性肽含量影响最大, 与其呈极显著负相关(P<0.01)。结论 初始水分含量显著影响鲜腐竹的冷藏品质, 降低水分含量对于延长鲜腐竹保质期具有重要意义。

英文摘要:

      Objective To investigate the quality change rules of fresh yuba with different initial moisture content during cold storage, and get the appropriate initial moisture content. Methods The moisture content of fresh yuba was 50%, 45% and 40% after drying, and then refrigerated at 4℃. The color, textural characteristics, microstructure and water distribution of fresh yuba were determined by chromometer, texture profile analysis (TPA) , scanning electron microscope (SEM) and low-field nuclear magnetic resonance (LF-NMR). The changes of soluble peptide content, peroxide value and cooking loss rate of fresh yuba were determined by chemical analysis. The sensory quality and total number of bacteria were also determined. The change rule and the influence mechanism of moisture content on the quality of fresh yuba during cold storage were studied. Results With the increase of storage time, L* decreased, a* and b* of fresh yuba increased. The sensory quality deteriorated. The cooking loss rate, soluble peptide content, total number of bacteria increased. With the initial moisture content decreased, L* decreased and a* increased during cold storage. The hardness, cohesiveness and chewiness of yuba with 40% and 45% water content were higher during cold storage. The springiness of yuba with 45% water content was the highest and texture properties were more stable. When the initial moisture content was reduced to 45% and 40%, the sensory score of fresh yuba was above 60 on 8th day, the texture and odor of fresh yuba were improved the most. When the initial water content was 40%, the cooking loss rate of yuba was the lowest, but there was no significant difference between 40% and 45% water content (P<0.05). Reducing water content could delay the time of maximum peroxide value and reduce the damage degree of protein network structure. There was obvious water migration in fresh yuba during cold storage. The hardness, chewiness, springiness and cohesiveness of fresh yuba were most affected by the content of soluble peptide. Which had a significant negative correlation with the content of soluble peptide (P<0.01). Conclusion The quality of fresh yuba during cold storage is affected by the initial moisture content significantly. Reducing the moisture content is important for extending the shelf life of fresh yuba.