With Heinrich Escher, in 1910, lycopene was isolated from tomatoes and shown to be an isomer of carotene. Later work by Escher also differentiated the luteal pigments in egg yolk from that of the carotenes in cow corpus luteum. Dietary sources
The following foods contain carotenes in notable  amounts:

Absorption from these foods is enhanced if eaten with fats, as carotenes are fat soluble, and if the food is cooked for a few minutes until the plant cell wall splits and the color is released into any liquid. 12 μg of dietary β-carotene supplies the equivalent of 1 μg of retinol, and 24 µg of α-carotene or β-cryptoxanthin provides the equivalent of 1 µg of retinol. Forms of carotene
The two primary isomers of carotene, α-carotene and β-carotene, differ in the position of a double bond (and thus a hydrogen) in the cyclic group at one end (the right end in the diagram at right). β-Carotene is the more common form and can be found in yellow, orange, and green leafy fruits and vegetables. As a rule of thumb, the greater the intensity of the orange colour of the fruit or vegetable, the more β-carotene it contains. Carotene protects plant cells against the destructive effects of ultraviolet light so β-Carotene is an antioxidant.
A higher than normal concentration may reflect any of several medical conditions, including acute inflammation of the pancreas (it may be measured concurrently with the more specific lipase), perforated peptic ulcer, torsion of an ovarian cyst, strangulation, ileus, mesenteric ischemia, macroamylasemia and mumps. Amylase may be measured in other body fluids, including urine and peritoneal fluid. A January 2007 study from Washington University in St. Louis suggests that saliva tests of the enzyme could be used to indicate sleep deficits, as the enzyme increases its activity in correlation with the length of time a subject has been deprived of sleep. History
In 1831, Erhard Friedrich Leuchs (1800–1837) described the hydrolysis of starch by saliva, due to the presence of an enzyme in saliva, "ptyalin", an amylase. it was named after the Ancient Greek name for saliva: πτύαλον - ptyalon. The modern history of enzymes began in 1833, when French chemists Anselme Payen and Jean-François Persoz isolated an amylase complex from germinating barley and named it "diastase". It is from this term that all subsequent enzyme names tend to end in the suffix -ase. In 1862, Alexander Jakulowitsch Danilewsky (1838–1923) separated pancreatic amylase from trypsin. Evolution
Salivary amylase
Saccharides are a food source rich in energy. Large polymers such as starch are partially hydrolyzed in the mouth by the enzyme amylase before being cleaved further into sugars. Many mammals have seen great expansions in the copy number of the amylase gene.