In vitro digestion and stability assessment of β-lactoglobulin/riboflavin nanostructures

Abstract

RiboflavinIn vitro gastrointestinal system Food simulant a b s t r a c t b-Lactoglobulin (b-Lg) is the major protein fraction of bovine whey serum and a primary gelling agent. b-Lg has a high nutritional value, is stable at low pH being highly resistant to proteolytic degradation in the stomach, besides, it has the ability of acting as an encapsulating agent. This study aims at assessing the ability of b-Lg nanostructures to associate a nutraceutical -i.e. riboflavin -and release it in a controlled manner throughout an in vitro gastrointestinal (GI) system. For this reason b-Lg nanostructures loaded with riboflavin were critically characterized in terms of their morphology (i.e. size, polydispersity, zpotential and shape) by dynamic light scattering (DLS) and transmission electron microscopy (TEM), and efficiency to associate to riboflavin through spectrofluorimetry. Furthermore, these nanocomplexes were evaluated in an in vitro GI model, simulating the physiological conditions. Stable b-Lg nanostructures were obtained at pH 6, of spherical shape, characterized by particle size of 172±1 nm, low polydispersity (i.e. PDI of 0.06±0.02), z-potential of À32±3 mV and association efficiency (AE) of 26±1 %. b-Lg nanostructures showed to be stable upon their passage throughout stomach (i.e. particle size, PDI and z potential of 248±10 nm, 0.18±0.03 and 18±3 mV, respectively). Concerning their passage throughout the intestine, such nanostructures were mostly degraded in the duodenum. Regarding riboflavin, a release of about 11 % was observed after their passage through stomach, while 35 %, 38 % and 5 % were the released percentages of the total riboflavin associated observed after passage through duodenum, jejunum and ileum, respectively. Hence, b-Lg nanostructures showed to be suitable carriers for riboflavin until the intestine, where their degradation occurs. b-Lg also showed to be structurally stable, under food simulant conditions (yoghurt simulant, composed of 3 % acetic acid), over 14 days, with a protective effect upon riboflavin activity, releasing it in a 7 day period.

Design of β-lactoglobulin micro- and nanostructures by controlling gelation through physical variables

“…Both purified and commercial β-Lg samples were characterized by the presence of two high molecular weight bands. The higher molecular weight band with molecular mass between 30 and 40 kDa indicates the presence of β-Lg in dimer form, whereas the lower molecular weight band with molecular mass between 15 and 20 kDa corresponds to β-Lg in monomer form, in agreement with previous research on β-Lg (Halder, Chakraborty, Das, & Bose, 2012;Madalena et al, 2016).…”

“…PDI emerged from cumulants analysis of the measurements and describes the width or the relative variance of the particle diameter distribution. The ζ-potential determines the charge at the surface of the structure and was performed with an angle of 17° (Madalena et al, 2016). Samples (1.5 mL) were poured into disposable sizing cuvettes with a path length of 10 mm for particle size and PDI analyses, and into a folded capillary cell for ζ-potential measurements.…”

“…50 % of its protein content), widely used as functional and nutritional ingredient in food, cosmetic and pharmaceutical industry Rodrigues et al, 2015). Whey proteins are obtained from whey, which is a byproduct of cheese production, relatively inexpensive and classified as a GRAS (generally regarded as safe) material (Madalena et al, 2016).…”

Protein-Based Structures for Food Applications: From Macro to Nanoscale

“…Moreover, 11% riboflavin was release in the stomach, whereas 35, 38, and 5% riboflavin was released in the duodenum, jejunum and ileum, respectively. The authors conclude that β-Lg nanostructures are appropriate riboflavin vehicles until their degradation in the intestine (Madalena et al, 2016). Similar results were obtained by other authors, when encapsulating EGCG in heat-denatured β-Lg nanohydrogels.…”

Towards the understanding of the behavior of bio-based nanostructures during in vitro digestion

“…Centrifugation [31,32,33] and sample dilution [33] are often used as a pre-treatment, prior to sample analysis regarding spectrometry (i.e. spectrophotometry, spectrofluorimetry), chromatography (i.e.…”