Impact of gum Arabic on the partition and stability of resveratrol in sunflower oil emulsions

Food proteins exhibit excellent properties such as emulsification and interact with low-molecular-weight ligands and polysaccharides, thus explaining their extensive use as carrier materials for encapsulation and protection of bioactive components. Consequently, they exert compact and random coil structures as well as disperse in the form of colloidal particles that are desirable for protein-stabilized O/W emulsions. Considering that non-polar and amphiphilic antioxidants guarantee better protection of oxidation-labile substances in oil-in-water emulsions, it is necessary to improve the content of interfacial antioxidants for both oxidative stability of oil-in-water emulsions and co-encapsulation of bioactive components in the single emulsion.

In a recently published literature, resveratrol, a naturally occurring polyphenol with antioxidant, anti-inflammatory among other effects, has been used in encapsulating protein-based nano- and micro-particles. However, the major challenge is the absorption of the resveratrol bound by whey protein at the interface of oil-in-water emulsions of sunflower oil. Up to now, several approaches such as the addition of calcium before emulsification have been adopted for improving the polyphenol content of the surfaces. However, the addition of calcium decreased the storage stability of resveratrol in sunflower oil emulsions. Additionally, complexation of proteins with polysaccharides like gum Arabic has exhibited great potential in improving the functional properties of individual polymers. Unfortunately, little is known about the effects of gum Arabic on the encapsulation of resveratrol in emulsions.

To this effect, a group of Jiangnan University researchers: Haixia Zhang, Qi Fan, Di Li, Dr. Xing Chen, and led by Professor Li Liang investigated the effects of gum Arabic on the partition and stability of the resveratrol in sunflower oil emulsions with and without calcium chloride. The sunflower oil emulsions were produced using whey protein isolate and characterized in terms of interfacial protein content, size distribution, and electric potential. The oxidative stability of the oil phase was measured both in the presence and absence of resveratrol. The work is published in the journal, Colloids and Surfaces B: Biointerfaces.

The authors observed that the gum Arabic increased the resveratrol and protein contents at the oil-water interface as well as the resveratrol stability. This was higher in the presence of calcium chloride. Specifically, the presence of the resveratrol increased the oxidative stability of the sunflower oil. Particles in emulsions stabilized by whey protein isolate and gum Arabic were generally smaller while on the other hand, higher gum Arabic concentrations produce larger particles relative to those in emulsions stabilized by whey protein isolate alone.

In summary, Professor Li Liang and her colleagues presented an excellent study on the impact of gum Arabic on the partition and stability of resveratrol in whey protein isolate-stabilized sunflower oil emulsions. Based on the presented results, the oxidative stability of the oils and co-encapsulated components in single emulsions can be obtained. Thus, whey protein isolate-calcium-gum Arabic emulsions can be used as effective carriers for co-encapsulation of both functional oils and polyphenols.