College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China.
Quality Inspection Department, Fuping County Inspection and Testing Center (Shaanxi Goat Milk Product Quality Supervision and Inspection Center), Fuping 711700, China.
Food Res Int. 2022 Sep;159:111607. doi: 10.1016/j.foodres.2022.111607. Epub 2022 Jul 3.
Dielectric barrier discharge cold plasma (DBD-CP) processing can be considered as a potential alternative to conventional pasteurization in ewe milk, which has previously been shown. However, residual microorganisms in ewe milk during DBD-CP processing have not yet been evaluated. This study investigated the microbiota present in ewe milk that was cold plasma-treated. Pasteurized ewe milk was used as a positive control. The bacterial community analysis demonstrated that 8 phyla and 16 genera were identified as dominant microbiota, and Proteobacteria and Pseudomonas were the predominant phyla and genera in cold plasma-treated milk samples. In addition, 23, 22, and 16 volatile flavor compounds (VFCs) were detected in raw milk, pasteurized milk, and cold plasma-treated milk samples, respectively. Fourteen different VFCs were produced according to the variable importance in the projection (VIP ≥ 1.0). The application of DBD-CP might lead to the absence of mutton odor produced by some carboxylic acids, further improving the characteristic flavor of ewe milk by facilitating lipid oxidation. Six bacterial genera, including Porphyromonas, Streptococcus, Fusobacterium, Prevotella, Treponema_2 and Leptotrichia, were highly negatively correlated (|ρ| > 0.5 and P < 0.05) with the flavor substances, according to Spearman correlation coefficient analysis. Overall, the systematic method employed in this study could identify core microbiota present and important VFCs in cold plasma-treated milk ewe milk. The study also provided a better understanding of the potential relationship between bacterial profiles and flavor compounds, which might be useful for further enhancing the quality of ewe milk products.
介质阻挡放电冷等离子体（DBD-CP）处理可被视为替代羊奶巴氏杀菌的潜在方法，这在以前已经得到了证明。然而，DBD-CP 处理过程中羊奶中的残留微生物尚未得到评估。本研究调查了冷等离子体处理羊奶中的微生物群。巴氏杀菌羊奶用作阳性对照。细菌群落分析表明，8 个门和 16 个属被鉴定为主要微生物群，变形菌门和假单胞菌属是冷等离子体处理奶样中的主要门和属。此外，在生奶、巴氏杀菌奶和冷等离子体处理奶样中分别检测到 23、22 和 16 种挥发性风味化合物（VFC）。根据投影变量重要性（VIP≥1.0），产生了 14 种不同的 VFC。DBD-CP 的应用可能导致某些羧酸产生的羊肉气味缺失，通过促进脂质氧化，进一步改善羊奶的特征风味。根据 Spearman 相关系数分析，六个细菌属，包括卟啉单胞菌属、链球菌属、梭杆菌属、普雷沃氏菌属、密螺旋体属和 Leptotrichia 属，与风味物质呈高度负相关（|ρ|>0.5 和 P<0.05）。总体而言，本研究中采用的系统方法可以鉴定冷等离子体处理羊奶中的核心微生物群和重要的 VFC。该研究还提供了对细菌谱和风味化合物之间潜在关系的更好理解，这可能有助于进一步提高羊奶产品的质量。
