PDF(Pubmed)
Abstract：
The quality of pasteurized milk is commonly assessed through microbiological analysis, with variations in storage conditions significantly impacting the suppression of bacterial growth throughout the milk\'s shelf life. This study investigated the dynamics of total bacterial counts (TBCs) and bacterial community shifts in milk that underwent pasteurization at 80 °C for 15 s. The milk was subsequently stored at 4 °C for varying intervals of 1, 4, 7, 10, 13, and 16 days. Culture-based testing revealed a significant TBC increase during the storage period spanning 1 to 16 days (up to -log10 4.2 CFU/mL at day 16). The TBC in pasteurized milk exhibited accelerated microbial growth from day 13 onwards, ultimately peaking on day 16. Bacillus was detected through 16S rRNA identification. Principal component analysis demonstrated a significant impact of storage time on bacterial communities in pasteurized milk. Analysis of bacterial diversity revealed a negative correlation between the Shannon index and the duration of pasteurized milk storage. Using high-throughput sequencing, Streptococcus and Acinetobacter were detected as prevalent bacterial genera, with Streptococcus dysgalactiae and Streptococcus uberis showing as dominant taxa. The presence of Streptococcus dysgalactiae and Streptococcus uberis in pasteurized milk might be attributed to the initial contamination from raw milk with mastitis. This study offers new evidence of the prevalence of bacterial community in pasteurized milk, thereby adding value to the enhancement of quality control and the development of strategies for reducing microbial risks.
摘要：
巴氏杀菌牛奶的质量通常通过微生物分析来评估，随着储存条件的变化，在整个牛奶的保质期内显着影响细菌生长的抑制。这项研究调查了在80°C下进行巴氏灭菌15s的牛奶中总细菌计数（TBC）和细菌群落变化的动态。随后将牛奶在4°C下储存1、4、7、10、13和16天的不同间隔。基于培养物的测试显示在1至16天的储存期间TBC显著增加(在第16天高达-log10±4.2CFU/mL)。从第13天开始，巴氏杀菌牛奶中的TBC表现出加速的微生物生长，最终在第16天达到峰值。通过16SrRNA鉴定检测芽孢杆菌。主成分分析表明，储存时间对巴氏杀菌牛奶中细菌群落的显着影响。细菌多样性分析表明，香农指数与巴氏杀菌奶的储存时间呈负相关。采用高通量测序,链球菌和不动杆菌被检测为流行的细菌属，表现为优势类群的无乳链球菌和乳房链球菌。巴氏杀菌牛奶中无乳链球菌和乳糜链球菌的存在可能归因于乳腺炎原奶的初始污染。这项研究提供了巴氏杀菌牛奶中细菌群落普遍存在的新证据，从而为加强质量控制和制定降低微生物风险的策略增加价值。
