Stability and in vitro release behaviour of encapsulated omega fatty acid-rich oils in lentil protein isolate-based microcapsules.

The objective of this study was to investigate the use of a lentil protein isolate-based microcapsule design as a platform for entrapping different types of omega fatty acid-rich oil (e.g. canola, fish and flaxseed oils) and to characterise differences in the physical properties (e.g. moisture content, water activity, colour, wettability, particle size, surface oil and entrapment efficiency), storage stability and in vitro release behaviour of the entrapped oils. All microcapsules displayed similar physical properties regardless of the core material. Free fatty acid content, peroxide value, 2-thiobarbituric acid reactive substances and accelerated oxidation test were investigated between the free and encapsulated oils to determine protective effects from microencapsulation and found the wall material provided the greatest protective effect to the fish oils relative to the others. Based on an in vitro release assay, it was proposed that different intrinsic properties of fatty acids (e.g. polarity, conformation, chain length and number of double bonds) led to different release properties under simulated conditions. For instance, more encapsulated canola oil (∼8.9%) was released within simulated gastric fluid, whereas more encapsulated fish oil (∼73.4%) was released within simulated gastrointestinal fluids. Overall, the capsule design used in this study could be potentially used as a universal platform to deliver more healthy oils.

Microencapsulation of canola oil by lentil protein isolate-based wall materials.

The overall goal was to encapsulate canola oil using a mixture of lentil protein isolate and maltodextrin with/without lecithin and/or sodium alginate by spray drying. Initially, emulsion and microcapsule properties as a function of oil (20%-30%), protein (2%-8%) and maltodextrin concentration (9.5%-18%) were characterized by emulsion stability, droplet size, viscosity, surface oil and entrapment efficiency. Microcapsules with 20% oil, 2% protein and 18% maltodextrin were shown to have the highest entrapment efficiency, and selected for further re-design using different preparation conditions and wall ingredients (lentil protein isolate, maltodextrin, lecithin and/or sodium alginate). The combination of the lentil protein, maltodextrin and sodium alginate represented the best wall material to produce microcapsules with the highest entrapment efficiency (∼88%). The lentil protein-maltodextrin-alginate microcapsules showed better oxidative stability and had a stronger wall structure than the lentil protein-maltodextrin microcapsules.