Milk and milk products have been utilized by humans for many thousands of years. With the advent of metagenomic studies, our knowledge on the microbiota of milk and milk products, especially as affected by the environment, production, and storage parameters, has increased. Milk quality depends on chemical parameters (fat and protein content and absence of inhibitory substances), as well as microbial and somatic cells counts, and affects the price of milk. The effects of hygiene and effective cooling on the spoilage microbiota have shown that proteolytic and lipolytic bacteria such as Pseudomonas or Acinetobacter spp. predominate the spoilage bacterial populations. These bacteria can produce heat‐stable proteases and lipases, which remain active after pasteurization and thus can spoil the milk during prolonged storage. Additionally, milk can become contaminated after pasteurization and therefore there is still a high demand on developing better cleaning and sanitation regimes and equipment, as well as test systems to (quantitatively) detect relevant pathogenic or spoilage microorganisms. Raw milk and raw milk cheese consumption is also increasing worldwide with the growing demand of minimally processed, sustainable, healthy, and local foods. In this context, emerging and re‐emerging pathogens once again represent a major food safety challenge. As a result of global warming, it is conceivable that not only microbiological risks but also chemical risks relating to presence of mycotoxins or plant toxins in milk will increase. Herein, we provide an overview of the major microbial hazards occurring in the 21st century.

中文翻译：

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21世纪乳及乳制品的微生物质量与安全

数千年来，人类一直使用牛奶和奶制品。随着宏基因组研究的出现，我们对牛奶和奶制品微生物群的了解有所增加，特别是受环境、生产和储存参数的影响。牛奶质量取决于化学参数（脂肪和蛋白质含量以及抑制物质的缺乏），以及微生物和体细胞数量，并影响牛奶的价格。卫生和有效冷却对腐败微生物群的影响表明，蛋白水解和脂肪分解细菌，如假单胞菌或不动杆菌属 以腐败菌群为主。这些细菌可以产生热稳定的蛋白酶和脂肪酶，这些蛋白酶和脂肪酶在巴氏杀菌后仍保持活性，因此在长期储存期间会损坏牛奶。此外，牛奶在巴氏杀菌后可能会受到污染，因此仍然需要开发更好的清洁和卫生制度和设备，以及（定量）检测相关致病或腐败微生物的测试系统。随着对最低限度加工、可持续、健康和当地食品的需求不断增长，原奶和原奶奶酪的消费量也在全球范围内增加。在这种情况下，新出现和重新出现的病原体再次代表了重大的食品安全挑战。由于全球变暖，可以想象，不仅微生物风险会增加，与牛奶中存在的霉菌毒素或植物毒素相关的化学风险也会增加。在此，我们概述了 21 世纪发生的主要微生物危害。