SYNTHESIS AND SURFACE-PROPERTIES OF AMINO-ACID SURFACTANTS FROM INDUSTRIAL-WASTE PROTEINS

N-Acyl amino acid surfactants (AAS) were chemically derived from indus trial waste protein hydrolysates [cottonseed (CSD), silk residue (SR), and silk chrysalis (SC)] according to two methods: (1) reacting hydro lysates with alkyl acyl chloride, followed by purification and neutral ization with alcoholic sodium hydroxide; (2) reacting hydrolysate with fatty alcohols in organic solvents followed by purification. The yiel d of purified mixed AAS (sodium salt) was similar to 60-75%; amino aci d ester from glutamic acid was considerably higher (85-92%) than the s odium salt derivatives. Results indicate that as acyl chain length (i. e., C-12-C-18) increased, surface tension of AAS increased, critical m icelle concentration (cmc) decreased, and Krafft point increased. The emulsifying power of AAS in O/W emulsion was better with n-decanol as an oil phase than Liquid paraffin. The C-12 derivatives of all the mix ed AAS showed high foaming power. Mixed AAS from CSD exhibited the bes t lime soap dispersing requirement (5.7-6.5 g/100 g). The diameter of micelle increased for glutamic acid AAS (GA-AAS) and CSD-AAS as the ac yl chain length increased (i.e, C-12-C-18). The hydrodynamic diameter of AAS followed the order SC > CSD > GA. Generally, AAS with C-12 prod uced good surface properties.