Milk sugar, also known as lactose, is a disaccharide sugar present in milk. Its chemical formula is C12H22O11, and its molecular weight is 342.3 gmol−1. The IPA phonetic transcription of "milk sugar" is /mɪlk ˈʃʊɡər/. The "milk" is pronounced with the m sound, followed by the short i, and the k sound. The "sugar" is pronounced with the sh sound, followed by the short u, and the g sound. When written, it is spelled as "m-i-l-k s-u-g-a-r."
Milk sugar, also known by its scientific name lactose, is a natural carbohydrate found exclusively in the milk produced by mammals. It is classified as a disaccharide, meaning it consists of two sugar molecules joined together. Specifically, lactose consists of one molecule of glucose and one molecule of galactose linked through a beta-glycosidic bond.
Milk sugar is an important source of energy for infants and young animals, including human babies. It plays a crucial role in the nutrition of young mammals, especially during the early stages of life when their digestive systems are still developing. Although milk sugar is primarily found in milk, it can also be extracted from milk products such as cheese and yogurt.
For some individuals, properly digesting milk sugar may be challenging due to a deficiency or absence of the enzyme lactase, which is responsible for breaking down lactose into its constituent sugars. In these cases, consuming products containing milk sugar can lead to lactose intolerance, which is characterized by digestive issues such as abdominal discomfort, bloating, and diarrhea. To address this, lactose-free or lactose-reduced dairy products are available, where the milk sugar is broken down prior to consumption.
Lactose.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "milk sugar" is not a standalone term in English. However, "milk sugar" refers to a specific type of sugar known as lactose, which is naturally present in milk. The etymology of the term "lactose" can be traced back to the Latin word "lac" meaning "milk" and the suffix "-ose", which is commonly used to indicate sugars. Thus, "lactose" essentially means milk sugar because it is the type of sugar found in milk.