Estimation of folic acid bioavailability in egg white nanocarriers by a microbiological model

CAROLINA ARZENI; OSCAR E PÉREZ; JEAN G. J. LEBLANC; ANA MR PILOSOF

Foz do Iguaçu

Congreso; Bioavailability 2014 - Understanding the bioavailability of micronutrients and bioactive compounds so as to improve public health.; 2014

SBAN - Sociedad Brasileña de Alimentación y Nutrición

Egg white (EW) is widely used in the food industry due to its excellent gelling, emulsifying and foaming properties. High intensity ultrasound (HIUS) is known to induce modifications in biopolymers, and this could be used to control particle size and generate nanocarriers. On the other hand, folic acid (FA), an important B vitamin, participates in many metabolic pathways, such as DNA and RNA biosynthesis and amino acid interconversions. FA is unstable to heat and light exposure, especially at acid pHs. Thus, its complexation with proteins could enhance its stability to manufacturing processes but its biological activity in the nanocomplexes must be guaranteed. The aim of this work was to develop FA nanocomplexes with EW nanoparticles and evaluate the biological activity of FA after the nanocomplexes were subjected to an in vitro digestion process. The nanoparticles were generated by applying HIUS to 5% EW solutions at pH 3 and 7, with (thermosonication) or without simultaneous heating. Then, FA was added to the nanoparticles and their interaction was evaluated by measuring the fluorescent quenching and the degree of binding by ultrafiltration. Stability to dehydration was also evaluated by dynamic light scattering. Samples were subjected to changes in pH involved in the digestion process. Then particle size and degree of FA binding was reassessed. Finally, a digestion of the nanocarriers was achieved by applying an in vitro digestion protocol and the biological activity of FA on the digested samples was determined with a microbiological assay (MA). At pH 3, a population of particles of about 70 nm of diameter was obtained after thermosonication at 85 °C for 20 min; using sonication without heating a monomodal population of about 200 nm was yielded. After the binding with FA a reduction of the nanoparticles fluorescence intensity was detected; this proved the interaction with FA. The percentage of binding was approximately 80% for both systems. Only a few aggregates were formed after drying the nanocomplexes. The nanocarriers were stable up to pH 4, then they aggregated and FA was partially released. The results of the MA showed that bound FA presented a higher biological activity in comparison to the free form of the vitamin. EW nanocarriers proved to be suitable for the preservation of FA biological activity and its transport across the gastrointestinal tract. EW nanoparticles might be used as a potential carrier for fortification of food products with FA.