Question Why does chocolate melt in your hand?
Because the melting point of chocolate is lower than the temperature of the human body.
The melting point of chocolate falls between 86°F and 90°F. This is significantly lower than the average temperature of the human body, which is 98.6°F so the heat from your hand raises the temperature of the chocolate and causes it to melt. How fast it melts depends on several factors, including the amount of milk fat and other additives such as lecithin, as well as the amount and composition of the cocoa butter in your piece of chocolate. Recent findings have shown that the average human body temperature may be cooling down to 97.9°F, which is still higher than the melting point of chocolate so it will make a mess in your hands for the foreseeable future.
Chocolate comes from the pods of the cacao tree, an understory tropical tree native to the Amazon basin. Pods from the cacao tree contain the beans that are fermented, roasted, milled and otherwise processed into chocolate. The finished chocolate usually includes various amounts of cocoa solids and cocoa butter, as well as added ingredients, such as sugar, lecithin and milk powder.
The beans from the cacao tree contain about 50 percent cocoa butter, which is a main raw ingredient for chocolate manufacturing. Cocoa butter is solid at room temperature, but starts to melt at about 93 degrees F. — below the average human body temperature.
It is made up of three fats in almost equal amounts: palmitic acid, stearic acid and oleic acid. The exact composition strongly influences cocoa butter’s melting temperature, and chocolate makers sometimes adjust the ratio of these fats in order to fine-tune that melting point.
Researchers have identified the genetic component in cocoa butter that determines its melting point, a discovery which may lead to more new ways of adjusting melting points.
Most of the chocolate we buy in stores has been tempered. Tempering stabilizes chocolate and gives it a glossy appearance and a pleasing snap when broken. The tempering process involves carefully controlled heating of chocolate to exact temperatures followed by gradual cooling. In addition to making chocolate shiny and firm, tempering helps to control its melting qualities.
Cocoa butter, the main part of chocolate that melts in your mouth–or your hand–is made up of six types of crystal forms or structures. When chocolate is tempered the crystals it contains are rearranged or re-established in the most desirable form. These forms are reached at different temperatures:
- (63 degrees F) Form I: soft, crumbly
- (70 degrees F)Form II: crumbly, melts easily
- (78 degrees F) Form III: firm but melts easily
- (82 degrees F) Form IV: firm but melts easily
- (94 degrees F)Form V: best – melts near body temperature, ideal for that glossy, crisp finish
- (97 degrees F) Form VI: too firm
Published: 6/5/2020. Author: Science Reference Section, Library of Congress