Effects of modification of encapsulant materials on the susceptibility of fish oil microcapsules to lipolysis

The aim of the study was to assess the effects of modification of encapsulant materials before emulsion formation on the viscosity and interfacial properties of the emulsions and their influence on the susceptibility of emulsions to in vitro lipolysis. Emulsions (oil/protein ratio 2:1) were prepared by homogenizing mixtures containing fish oil and non-heated or heated (100 degrees C/120 min) dispersions comprising (a) sodium caseinate (NaCas), (b) mixtures of NaCas and a high amylose-resistant starch (Hylon VII; 1:1 mass ratio), and (c) mixtures of NaCas and previously modified resistant starch (heat/microfluidized [MF] Hylon VII; 1:1 mass ratio), followed by freeze drying. Reconstituted emulsion containing heated mixture of NaCas and heat/MF Hylon VII was the most viscous. The extent of lipolysis was the same in all emulsions stabilized by non-heated NaCas or non-heated mixtures of NaCas with resistant starch. Heat treatment of NaCas increased lipolysis of emulsions stabilized with protein alone, but heating NaCas with Hylon VII or heat/MF Hylon VII before emulsion formation reduced lipolysis. The emulsion stabilized with the heated NaCas-heat/MF Hylon VII mixture was the most resistant to lipolysis. Overall, the resistance to lipolysis was considered to be primarily dependent on the interfacial properties of the microcapsules. These findings of in vitro lipolysis of NaCas-resistant starch formulated oil powders may be relevant to an understanding of in vivo digestibility of the oil powders. The insights may be used as a guide to formulate oil systems for altering the susceptibility to lipolysis of ingested oil emulsions.