Erythrulose is a key active ingredient for natural self-tanners, most often combined with Dihydroxyacetone. Like Dihydroxyacetone, it reacts with the amino acids in the keratin protein on the outer layer of skin. The nontoxic reaction creates a colour change in the skin. Being considerably more expensive than DHA, Erythrulose only tends to be found in the more expensive tanning products. It takes longer to develop a tan than DHA but tends to produce a more authentic (not orange!) outcome and is less likely to produce streaking.
Better tanning lotions combine DHA and Erythrulose achieve a fast developing and more authentic tan
Can be added to formulas as is, usual concentration: 1-3 % (if used with 3- 5% DHA), 3-5% (if used alone).
Add to formulations at below 40C.
More info here