The present disclosure provides a sophorolipid composition that can be used for inducing protein expression in a fermentation host. The sophorolipid composition described herein can be prepared from a natural sophorolipid mixture. Acid treatment of the natural sophorolipid mixture results in a mixture of monoacetylated, deacetylated, and/or diacetylated sophorolipids. The chemically modified sophorolipid composition, or isolated components of the chemically modified sophorolipid composition, can be used as inducers for protein production in filamentous fungi.