Biocatalytic Enrichment of Dioleoylglycerol from Camellia japonica Seed Oil Through Lipase-Catalyzed Hydrolysis and Evaluation of Its Skin Hydration Properties

Camellia japonica seed oil (CJO), which is generally characterized by a high proportion of oleic acid in its fatty acid composition, represents a renewable lipid substrate for producing value-added glycerides. This study aimed to enrich dioleoylglycerol (DOG) in CJO through controlled lipase-catalyzed hydrolysis and evaluate the skin hydration properties of the resulting DOG-rich hydrolyzed CJO. Seven lipases were screened, and a lipase preparation from Thermomyces lanuginosus was selected. Key reaction variables were identified by factorial screening and subsequently optimized using a Box–Behnken design and response surface methodology. Temperature, enzyme concentration, and reaction time were identified as the major factors affecting DOG content. The quadratic model was significant (p < 0.0001; R2 = 0.9936) and predicted optimal conditions of 52.56 °C, 0.357 wt% enzyme, and 7.22 h, corresponding to 0.3006 mg DOG/mg oil. Validation at 53 °C, 0.36 wt% enzyme, and 7 h yielded 0.2976 ± 0.0040 mg DOG/mg oil. In an exploratory skin hydration assessment involving five participants, a formulation containing 20 wt% DOG-rich hydrolyzed CJO showed a 34.82% descriptive increase in hydration relative to baseline at 4 h and retained 89.29% of the immediate post-application hydration level. These findings demonstrate an effective biocatalytic strategy for producing DOG-rich CJO and support its potential as a functional lipid ingredient for topical applications.