Instead, there is a two-phase region of 11 + 0 in the oil-rich region. With increasing oil content, a fraction of the surfactant monomer is dissolved in oil and the solubility of a short EO-chain lipophilic surfactant (C12E03) is much larger than that of a hydrophilic one (C12E08) . Then, the fraction of hydrophilic surfactant at the interface of aggregates dominates and hence the structures are characterized by the hydrophilic surfactant. Consequently, although the 11 phase is not observed in the oil-poor region, the 11 + 0 twophase region appears (Fig. 15) as a gel in an oil-rich region. The presence of the 11 + 0 region is confirmed and discussed elsewhere in details [44]. Consequently, the 0/11 highly concentrated emulsion corresponds to a gel in the D-phase emulsification although a single 11 phase is not observed in commercial surfactant system.