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Understanding key factors for the use of bioactive lipid nanoparticles to modulate the functionality of complex food systems

Periodic Reporting for period 1 - NANOLIPID (Understanding key factors for the use of bioactive lipid nanoparticles to modulate the functionality of complex food systems)

Reporting period: 2015-10-01 to 2017-09-30

The use of lipid nanoparticles as carriers of lipophilic functional compounds is emerging as a promising way to efficiently deliver food ingredients. Recent studies report that the unique properties of loading bioactive compounds within lipid nanoparticles would involve an enhancement of their functional properties after digestion due to their small particle size, increasing their nutritional value in the human gut. However, the incorporation of active nanosized ingredients in foods remains a challenge for the food sector. Lipid nanoparticles may interact with the food matrix components causing destabilization phenomena or binding, which in turn might decrease their biological activity. Moreover, food processing operations used after the incorporation of the active lipid nanoparticles may have an impact on their properties. In this context, NANOLIPID, aims to contribute to the design, characterization and application of active lipid nanoparticles into real food systems towards a more rational and optimal use of food ingredients. For that purpose, the major goal of the current proposal is to obtain stable lipid nanoparticles loaded with carotenoids, incorporate them in complex food systems and assess their digestibility and nutritional value under simulated digestion conditions. Thus, NANOLIPID aims at identifying the key aspects for lipid nanoparticle formulation and at elucidating the interaction between nanoparticles and food matrix components that may compromise their fate during digestion. NANOLIPID is a multidisciplinary project covering the formulation of lipid nanoparticles and use of state of the art techniques for nanomaterial characterization, food processing, and analysis of simulated digestion protocols.
During the realization of the project, the main key aspects for the production and stabilization of lipid nanoparticles loaded with carotenoids were systematically studied, being the particle size, surfactant type and concentration, lipid state (solid or liquid) and oil saturation degree. The implications of the formulation characteristics of lipid nanoparticles on the lipid digestion rate and extent (kinetics) and the subsequent formation of lipid digestion products was studied under simulated digestive conditions. Overall, the oil droplet size and surfactant type were found as the most determining factors affecting lipid digestion rate during the simulation of small intestine conditions. The smaller the particle size the faster the lipid digestion due to a higher surface active area for lipid digestion enzymes to adsorb. Moreover, the surfactant type determined the emulsion stability during digestion conditions. In this regard, stable small oil droplets after simulated gastric conditions were obtained by small-molecule non-ionic surfactants, and those were more efficiently digested during intestinal conditions.
Moreover, as a second phase of the project, the interactions between lipid nanoparticles and food components from vegetable origin, mainly pectin, were evaluated and their implications on the lipid digestibility were studied. It was observed that pectin from carrot or broccoli purées did not significantly affect lipid digestion. Also when emulsions were produced within vegetable purées, lipid digestion kinetics was not significantly affected in comparison to their respective model emulsion systems. However, a lower incorporation of lipid digestion products into mixed micelles was observed in emulsions formed within complex food matrices, which suggests that interaction between food components and lipid digestion products occurred.
Ultimately, it was consistently observed along the realization of the present project that there is a direct relationship between the lipolysis degree, micelle formation and the carotenoid bioaccessibility. It was identified that emulsion digestion kinetics is the rate limiting step for both releasing the carotenoids from the oil core and generating lipid digestion species that will contribute to increase the solubilisation capacity of mixed micelles. These two processes are crucial in the carotenoid bioaccessibility kinetics under intestinal conditions and are determined by emulsion characteristics and the presence of other food components.
NANOLIPID contributed in elucidating the key aspects that determine lipolysis rate and extent during digestion of lipid nanoparticles that can act as carriers of lipophilic bioactive compounds, such as carotenoids. Moreover, the relationship between lipid digestion, micelle formation and carotenoid micellarization was unraveled. The effect of lipid droplets-food matrix interactions with special focus of plant-origin biopolymers and its implications on lipolysis kinetics has been explained. This will contribute to consumers’ awareness of the potential nutritional value of formulated food products from plant origin, but also to increase the information available for food producers in order to develop foods with optimal digestibility and functionality.