Aloe Bitter sap or Aloe Yellow Sap or Ale Juice

The aloe bitter is the yellow exudate (also known as the bitter sap or acíbar in the spanish speaking countries), which drains from the outer green skin of the leaves when cut. Usually is called aloe juice (creating confusion with the aloe gel also called aloe juice) or aloe extract.

The aloe yellow sap is found on the aloe leaves, near the epidermis. There, the pericyclic cells contains the yellow juice. This aloe yellow sap or aloe bitter sap exudes when the leaf is cut.

Aloin is one of the element of the bitter juice of the aloe leaves. When the leaves are cut, the juice that flows out is usually collected and then treated to obtain aloins.

According to W. A. Shenstone, two classes of Aloins are to be recognized: (1) nataloins, which yield picric and oxalic acids with nitric acid, and do not give a red coloration with nitric acid; and (2) barbaloins, which yield aloetic acid (C₇H₂N₃O₅), chrysammic acid (C₇H₂N₂O₆), picric and oxalic acids with nitric acid, being reddened by the acid. This second group may be divided into a-barbaloins, obtained from Barbadoes aloes, and reddened in the cold, and b-barbaloins, obtained from Socotrine and Zanzibar aloes, reddened by ordinary nitric acid only when warmed or by fuming acid in the cold. Nataloin (2C₁₇H₁₃O₇·H₂O) forms bright yellow scales. Barbaloin (C₁₇H₁₈O₇) forms yellow prismatic crystals. Aloes also contain a trace of volatile oil, to which its odour is due.