EMULSION-BASED ENCAPSULATION SYSTEMS STABILIZED WITH INSECT PROTEINS: PRODUCTION WITH PREMIX MICROPOROUS EMULSIFICATION
The focus of the thesis is to produce emulsion-based encapsulation systems using both sustainable ingredients and technologies. Specifically, valorisation of an agri-food by product (carob pulp polyphenol) was proved feasible coupling forward osmosis for concentration and membrane emulsification for encapsulation. Insect powder defatting by solvent extraction was investigated using green solvents (ethanol, isopropanol, and 2-methyltetrahydrofuran), paying special attention to defatting yield and the techno-functional properties of the resulting protein fractions, particularly emulsifying ability. Single and double emulsions stabilised with sustainable protein sources from insects, black soldier fly (Hermetia illucens) and lesser mealworm (Alphitobius diaperinus) larvae, have been successfully produced for the first time by a low-energy high-throughput emulsification technology based on dynamic membranes of tunable pore size (DMTS). H. illucens protein concentrate showed superior ability to stabilize higher lemon oil fraction (40 wt%) compared to whey protein isolate. A commercial polyphenol extract was encapsulated in W1/O/W2 emulsions stabilised with A. diaperinus protein concentrate. These emulsions displayed a comparable stability under freeze-thaw cycles, storage conditions, acidic, and alkaline conditions than the ones stabilized with WPI, and better than the ones stabilized with pea protein. However, they were less able to withstand osmotic pressure differences compared to whey protein. Insect protein stabilized W1/O/W2 emulsions showed less changes in droplet size distribution at the highest temperature tested (90ºC) than the ones stabilized with whey or pea protein, pointing out the benefit of using insect proteins in emulsions that need to undergo heat treatment. Solid microcapsules were successfully produced from refined polyphenol loaded W1/O/W2 emulsions stabilized with insect protein by spray drying or freeze drying. The results demonstrate the insect protein concentrates assessed are a promising sustainable ingredient to replace diary and plant proteins in the emulsion-based encapsulation systems.
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