Structure Steviol glycoside

molecular structure of steviol, showing substituted hydrogens on carboxyl group (bottom) , hydroxyl group (top)

these compounds glycosides of steviol, diterpene compound. specifically, molecules can viewed steviol molecule, carboxyl hydrogen atom replaced glucose molecule form ester, , hydroxyl hydrogen combinations of glucose , rhamnose form acetal.

the steviol glycosides found in s. rebaudiana leaves, , weight percentage, include:

stevioside (5–10%)
rebaudioside (2–4%)
rebaudioside c (1–2%)
dulcoside (0.5–1%)
rebaudioside b
rebaudioside d
rebaudioside e

the last 3 present in minute quantities, , rebaudioside b has been claimed byproduct of isolation technique. commercial steviol glycoside mixture extracted plant found have 80% stevioside, 8% rebaudioside a, , 0.6% rebaudioside c.

the chinese plant rubus chingii produces rubusoside, steviol glycoside not found in stevia.

stevioside , rebaudioside first isolated in 1931 french chemists, bridel , lavielle. both compounds have glucose subgroups: stevioside has 2 linked glucose molecules @ hydroxyl site, whereas rebaudioside has three, middle glucose of triplet connected central steviol structure.

early sensory tests led claims rebaudioside 150 320 times sweeter sucrose, stevioside 10 270 times sweeter, rebaudioside c 40 60 times sweeter, , dulcoside 30 times sweeter. however, more recent evaluation found rebaudoside 240 times sweeter, , stevioside 140 times. rebaudioside had least bitterness , aftertaste. relative sweetness seems vary concentration: mix of steviol glycosides in natural proportions found 150 times sweeter sucrose when matching 3% sucrose solution, 100 times sweeter when matching 10% sucrose solution.