Chain Length-Dependent Reverse Micelle Extraction of Prolamins From Baijiu Jiuzao: Synergistic Effects of Ethanol, Ionic Strength, and Chaotropic Agent.

This study investigated the chain length-dependent extraction efficiency of two cationic surfactants-dodecyltrimethylammonium bromide (C12, 12-carbon chain) and cetyltrimethylammonium bromide (C16, 16-carbon chain)-for reverse micelle extraction of prolamins from Baijiu Jiuzao (Chinese Baijiu distillers' grains). Although pH variations (4.0-9.0) had negligible effects, ethanol, ionic strength, and chaotropic agent demonstrated distinct chain length-dependent behaviors: ethanol increased C12's forward extraction efficiency by 10.6% (absolute) while enhancing C16's backward efficiency by 8.7%. Potassium chloride enhanced C16's forward efficiency by 4.7%, while potassium bromide significantly improved C12's backward efficiency by 15.9%. Guanidine hydrochloride consistently promoted C16 in both extraction phases. Dynamic light scattering demonstrated significant differences (p < 0.05) in reverse micelle sizes: C12 formed smaller empty reverse micelles (1.5 ± 0.2 nm) compared to C16 (2.5 ± 0.5 nm). During forward extraction, reverse micelles expanded significantly to 217.9 ± 6.3 nm (C12) and 311.2 ± 43.2 nm (C16). Backward extraction released prolamin particles of 449.0 ± 16.2 nm (C12) and 650.4 ± 29.7 nm (C16), confirming the size-exclusion-driven release mechanism. The more compact C12 reverse micelles correlated with lower total prolamin yield (26.6 ± 0.1% vs. 32.2 ± 0.1% for C16, p < 0.01) and substantially diminished bovine serum albumin recovery (5.2 ± 0.2% vs. 45.3 ± 2.5%, p < 0.01). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis corroborated these findings, further demonstrating that reverse micelle-extracted prolamins formed thermally stable dimers resistant to reductive cleavage. Combined with dynamic light scattering data (particle size range: 400-700 nm in the backward-extraction aqueous phase), these findings demonstrate that prolamin aggregates after reverse micelle extraction. These findings demonstrate that surfactant chain length as a key parameter for optimizing reverse micellar systems, where shorter-chain surfactants facilitate selective extraction, whereas longer chains enhance yields.