Abstract Rikkert Berendsen
Commercial extracts rich in polyphenols are extensively used to formulate foods. Nevertheless, their effectiveness depends on preserving the stability and bioavailability of the active ingredients. Encapsulation is a strategy to meet these requirements. We have investigated two encapsulation systems to entrap a procyanidin-rich extract: water-in-oil-in-water (W1/O/W2) emulsions and solid microcapsules (spray dried W1/O/W2 emulsions). While premix membrane emulsification (ME) was used to produce these emulsions, we focused on how the interfacial layer (O?W2) affected emulsion stability and procyanidin release.
Premix ME enabled to produce single and double emulsions stabilized with whey protein isolate (WPI), and WPI?Carboxymethyl cellulose (WPI?CMC), WPI?Gum Arabic (WPI?GA) and WPI?Chitosan (WPI?Chi) complexes. Adsorption measurements showed that WPI?polysaccharides interfaces form thicker but less dense layers than only WPI.
n O/W emulsions, different interfacial structures made of WPI and CMC led to large differences in lipid oxidation. The negatively charged droplets of the emulsions stabilized with WPI?MC would attract positively charged transition metals, promoting lipid oxidation.
Procyanidin-loaded W1/O/W2 emulsions stabilized by WPI?CMC, WPI?GA, or WPI?Chi complexes retained at least 70% of the initial procyanidins at the end of premix ME. Emulsion stability depended on the interfacial layer and the pH of the W2 phase. The release rate of procyanidins was correlated to the interfacial thickness of the WPI?polysaccharide layer: thicker layers lowered the release rate.
All the W1/O/W2 emulsions were able to produce procyanidin-loaded microcapsules after spray drying and could all recover their W1/O/W2 emulsion structure upon rehydration. The interfacial composition affected particle size of W1/O/W2 emulsions after microcapsule rehydration. Particularly, WPI?CMC complex was able to truly stabilize the W1/O droplets during the different stages of microcapsule production although it moderately retained the migration of procyanidins through the O?W2 interface.
For each type of encapsulation system, a tailor-made hydrophilic emulsifier is required to comply with the type of protection needed, the addenda used and the delivery conditions.
Download: