The presence of which microorganism can significantly affect milk flavor?

Lactic acid bacteria are a crucial factor in determining milk flavor due to their metabolic activities, particularly the fermentation of lactose. These bacteria produce lactic acid, which not only lowers the pH of the milk but can also contribute to a range of flavor profiles depending on the strain and conditions during the fermentation process. The presence of specific strains can lead to desirable flavors in products like yogurt and cheese, enhancing the overall sensory qualities.

In contrast, while yeasts, coliforms, and filamentous fungi can have effects on milk, their impact is often related to spoilage rather than flavor enhancement. Yeasts can lead to fermentation and produce off-flavors if they proliferate in milk, coliforms are generally indicative of poor hygiene and can spoil milk without contributing positively to flavor, and filamentous fungi can also cause spoilage, often producing undesirable tastes and odors. Therefore, lactic acid bacteria are synonymous with the desirable flavor development in fermented dairy products.