Physicochemical characterisation and cell viability of riboflavin loaded WPI nanostructures towards foods fortification

• Author(s): Araújo, João Miguel Fernandes ; Martins, Joana T. ; Vicente, A. A. ; Pinheiro, A. C.
• Date: 2021
• Persistent ID: https://hdl.handle.net/1822/76938
• Origin: RepositóriUM - Universidade do Minho
• Document Type: Other
• Language: English
• Contributor(s): Universidade do Minho

Description

The innovative approach of fortifying foods by incorporating nanostructures encapsulating bioactive compounds enables the development of specifically tailored foods with high bioactive compounds bioavailability. However, nanostructures biological fate during digestion/absorption once incorporated in foods are still inconclusive regarding their risk assessment. Through thermal gelation method, a whey protein isolate (WPI) nanostructure was developed to associate riboflavin (Rb) as hydrophilic model compound, aiming at its incorporation in foods. The association efficiency and loading capacity of WPI nanostructures were determined, and lyophilised nanostructures were produced by freeze-drying, in order to extent storage stability and to favour the application in food matrices. A physicochemical characterisation was performed by analysing WPI-Rb nanostructures particle size and polydispersity index (PDI) by dynamic light scattering, and by evaluating structural behaviour by fluorescence spectroscopy. Cell viability was assessed by evaluating nanostructures toxicity using a Caco-2 cell model. WPI-Rb nanostructures with a particle size of ca. 130 nm and a PDI of ca. 0.2, were obtained at 5 mg/mL1 of WPI and at pH 6, after thermal treatment at 80 °C for 15 minutes. Lyophilised WPI-Rb nanostructures showed similar results in terms of size (ca. 105 nm) and PDI (ca. 0.3). This system was able to associate Rb at 0.1 mg/mL with an efficiency of ca. 67% and a loading capacity of ca. 2%. Furthermore, fluorescence measurements revealed that thermal gelation led WPI proteins to unfold (red shift from 328 to 332 nm; increased maximum intensity peak) and confirmed their interactions with Rb through the observation of energy transfer between WPI and Rb molecules. Finally, Caco-2 cell viability was not affected up to 0.1 mg/mL1 of Rb in WPI nanostructures. Physicochemical characterisation and cell viability results provided relevant information on the potential use of WPI-Rb nanostructures for food fortification, allowing to proceed towards the development of nanostructures with increased bioaccessibility