Whey protein-based hydrogels as phenylethyl isothiocyanate delivery systems

Phenylethyl isothiocyanate (PEITC), a glucosinolate hydrolysis product, is a bioactive compound present in some cruciferous vegetables, namely watercress, with interesting bioactivities such as anticancer, antioxidant and anti- inflammatory. Indeed, this phytochemical has been studied for its potential preventive and therapeutic effects on chronic diseases such as cancer1. Although PEITC is a promising health-promoting compound, its industrialisation has been complex due to its relative instability and reactivity. In this sense, the encapsulation of this agent can solve these limitations2. On the other hand, protein hydrogels have received considerable attention because of their common use in food matrices, but also as promising bioactive components and nutraceuticals delivery systems3. This study aims to develop a hydrogel based on animal protein, namely whey protein isolate (WPI). Protein hydrogel was fabricated from a heat-denatured protein solution and subsequent crosslinking by citric acid, resulting in cold- setting hydrogel4. Then, PEITC and microparticles (MP), previous developed using chitosan-olive oil-PEITC systems2, were added to the protein solution.
Fourier transform infrared spectroscopy (FTIR) results propose the formation of a band at ≈3290 cm-1 referring to the hydrogen-bonded N-H elongation. Also, in the FITR spectroscopy, bands were found referring to the loading of PEITC and MPs with PEITC in the gels. The WPI hydrogels showed a high water-holding capacity under the same conditions. Moreover, particle size was characterised by dynamic light scattering. Rheological studies were performed with the different gels and scanning electron microscopy (SEM) was used to analyse the microstructure of the hydrogels.
Therefore, protein hydrogel could be a new efficient delivery system to encapsulate and deliver PEITC with potential applications in functional foods.