Design of β-lactoglobulin nanostructures for encapsulation and controlled release of riboflavin in the gastrointestinal tract

Abstract

[Excerpt] Bovine β-lactoglobulin (β-Lg) is a globular protein from milk and the major component of whey proteins (ca. 50 % of its protein content). It is a food-grade and Generally Recognized As Safe (GRAS) material, that have a high nutritional value and important biological and functional properties, particularly the capacity to form gels, which allows the formation of nanostructures that can be used to encapsulate nutraceuticals [1]. Besides, β-Lg is stable at low pH, and highly resistant to proteolytic degradation in the stomach. Riboflavin is an essential vitamin for the normal function of human brain and nervous system. However, this vitamin is poorly soluble in water and highly susceptible to light degradation, thus its encapsulation may represent a suitable solution to its protection, overcoming these issues [2]. This study aims at evaluating the ability of β-Lg food-grade nanostructures to encapsulate and control the release of riboflavin during the gastrointestinal (GI) passage. In this study, aqueous dispersions of β-Lg (1%) were accordingly produced, and formation of stable βLg nanostructures was ascertained at pH 6.0, after heating at 80 ºC for 10 min. The nanostructures formed were characterized in terms of size, surface charge and stability, morphology and association efficiency (AE) of riboflavin. Riboflavin-loaded nanostructures were then submitted to an in vitro GI model system, simulating the conditions of human GI tract (i.e. stomach, duodenum, jejunum and ileum) and their condition (e.g. temperature, pH, mixing, transit time, enzymes and other constituents such as bile). The experiments were carried out for 5 h, and the nanostructures were structurally characterized after each stage of digestion. [...]