Effect of molecular weight on the emulsion properties of microfluidized gelatin hydrolysates

Microfluidized gelatin hydrolysates (MGH) with decreasing molecular weight from MGH-A to MGH-E were prepared, and their emulsion properties were investigated. The molecular weight, particle size, and emulsifying activity of MGH decreased as gelatin degraded by enzymatic hydrolysis with neutral protease increased. Dramatic decreases in the surface hydrophobicity and emulsifying stability of MGH were observed as the content of peptide fractions of 18 and 23 kDa increased. The average droplet sizes of emulsions based on MGH-A, MGH-B, MGH-C, and MGH-D were 622.1, 558.8, 389.7, and 1058.9 nm, respectively, and the MGH-E-based emulsion exhibited creaming. While the flow index of the MGH-A-based emulsion was greater than 1, those of the other emulsions were less than 1. Optical and confocal laser scanning microscopic images showed fine and uniform droplet distributions without flocculation or coalescence in the MGH-A-, MGH-B-, and MGH-C-based emulsions. The encapsulation efficiency (EE) of co-enzyme Q 10 (CoQ 10 ) in the spray-dried encapsulation prepared from MGH-B was 84.3%, and EE generally decreased with increasing or decreasing degradation degree of MGH. No obvious differences were observed among the surface images of encapsulations prepared using MGH-A, MGH-B, and MGH-C, and aggregated distributions were found in the MGH-D- and MGH-E-based encapsulations. The storage stability and in vitro bioaccessibility of CoQ 10 encapsulated by MGH-E were poorer than those of CoQ 10 encapsulated by the other wall materials. The results of the current study indicate that molecular weight and particle size have significant effects on the emulsion and encapsulation properties of MGH.