In North America, Swiss cheese is a name given to any variety of cheese that resembles Emmental cheese, a yellow, medium-hard cheese that originated in the area around Emmental, Switzerland. It is classified as a Swiss-type or Alpine cheese. Some types of Swiss cheese have a distinctive appearance, as the blocks or rounds of the cheese are riddled with holes known as "eyes". Swiss cheese without eyes is known as "blind". Swiss cheese is now manufactured in many countries, including the United States, Finland, Estonia, and Ireland. It is sometimes made with pasteurized or part-skim milk, unlike the original from Switzerland made with raw milk. The United States Department of Agriculture uses the terms Swiss cheese and Emmentaler cheese interchangeably. In Australia, both terms are used, along with Swiss-style cheese, in some cases differentiating the two. The term Swiss cheese is sometimes used in India, although it is also often referred to as Emmental, which is the more common name in Europe. Production Three types of bacteria are used in the production of Swiss cheese: Streptococcus thermophilus, Lactobacillus (L. helveticus or L. delbrueckii subsp. bulgaricus), and Propionibacterium (Propionibacterium freudenreichii subsp. shermani). In a late stage of cheese production, the propionibacteria consume the lactic acid excreted by the other bacteria and release acetate, propionic acid, and carbon dioxide gas. The carbon dioxide slowly forms the bubbles that develop the "eyes". The acetate and propionic acid give Swiss its nutty and sweet flavor. A hypothesis proposed by Swiss researchers in 2015 notes that particulate matter may also play a role in the holes' development and that modern sanitation eliminated debris such as hay dust in the milk played a role in reduced hole size in Swiss cheeses, or even "blind cheese". Historically, the holes were seen as a sign of imperfection and cheese makers originally tried to avoid them by pressing during production -the holes only became an identifier of the cheese in modern times. In general, the larger the eyes in a Swiss cheese, the more pronounced its flavor because a longer fermentation period gives the bacteria more time to act. This poses a problem, because cheese with large eyes does not slice well and comes apart in mechanical slicers. As a result, U.S. industry regulators have reduced the minimum eye size with which Swiss cheese can receive the Grade A stamp. In 2014, 297.8 million pounds of Swiss cheese was