减菌处理对鸭蛋壳内外菌群组成及功能的影响

Effects of Sterilization Treatments on the Compositions and Functions of Microflora on Duck Eggshell Inner and Outer Surfaces

摘要:

该文探索了减菌处理对鸭蛋壳内外菌落组成及咸蛋黑黄率的影响。对鸭蛋使用不同熏蒸清洗剂进行熏蒸、清洗及不同温度下临储，比较减菌前后鸭蛋壳内外菌落总数变化，基于16S rRNA基因测序和PICRUSt基因功能预测研究减菌处理对鸭蛋壳外菌群的影响，在35 ℃下泥包法腌制咸蛋，统计咸蛋黑黄率。结果表明，熏蒸处理可以显著抑制壳外菌落向壳内迁移，有效控制壳内菌落总数，熏蒸两次效果优于一次；清洗处理可将壳外菌落总数降低至检测限以下；低温储藏可在7 d内控制壳内外菌落总数增殖。联合熏蒸-清洗-低温的减菌处理可以显著降低壳内外菌落总数，抑制其迁移，控制壳内菌落总数。16S rRNA基因测序发现减菌处理可以显著减少壳外变形菌门和嗜冷杆菌属比例，PICRUSt基因功能预测发现减菌处理后微生物在脂质氧化通路、氨基酸转运和代谢通路上的活跃度显著降低。减菌后咸蛋蛋黄黑化率显著降低，证明了减菌处理能有效减少壳外菌群数以及抑制蛋黄黑黄的发生，表明鸭蛋加工前减菌的重要性和必要性。

Abstract:

The effects of sterilization treatments on the microbial compositions on both the inner and outer surfaces of duck eggshells and the ratio of black to yellow salted egg yolks were investigated in this study. Duck eggs were fumigated and cleaned with different fumigants and cleaning agents, and then stored at different temperatures. Changes in the total number of bacteria on duck eggshell inner and outer surfaces before and after treatments were subsequently compared. The effects of sterilization on the microflora on duck eggshell outer surfaces were evaluated using 16S rRNA gene sequencing and PICRUSt gene function prediction. Salted duck eggs were prepared using the mud-packing method at 35 ℃, and the ratio of black to yellow salted egg yolks was calculated. The results show that fumigation significantly inhibits the migration of bacterial colonies from the outer to inner surfaces of the eggshells, effectively controlling the total number of bacteria inside the shell. Two fumigation treatments increase efficacy relative to one. Total bacteria on the outer surface can be reduced to below the detection limit by cleaning. Low-temperature storage can limit bacterial proliferation on both inner and outer eggshell surfaces over 7 days. Total bacteria numbers on both inner and outer surfaces can be significantly reduced by combining fumigation, cleaning, and low-temperature storage. These processes also inhibit bacterial migration, tightly controlling the total bacteria inside the eggshell. 16S rRNA gene sequencing demonstrates a notable reduction in the proportion of Proteobacteria and Psychrobacter on the outer surface of the shell following sterilization treatments. Additionally, PICRUSt gene function prediction indicates a significant decrease in microbial activity within pathways associated with lipid oxidation, amino acid transport, and metabolism after sterilization treatments. Sterilization also significantly reduces the ratio of black to yellow salted egg yolks. These studies illustrate that sterilization treatment effectively decreases total bacteria count on the outer surfaces of duck eggshells and inhibits the occurrence of black salted egg yolks. These findings demonstrate the importance and necessity of sterilization before duck egg processing.