Self-assembled colloidal complexes of polyphenol–gelatin and their stabilizing effects on emulsions

Abstract

This research studies the in-depth characteristics including the binding interactions and morphological structure of tannic acid (TA)/grape seed proanthocyanidins (GSP) and gelatin (GLT) colloidal complexes, and evaluated the stability and lipid oxidation of emulsions formed by the colloidal complexes. Polyphenol and GLT (1.2 wt%) self-assembled complexes were fabricated by varying the mass ratio (1 : 16, 1 : 8 and 1 : 4) and pH in the range of 3-7. TA and GSP can form stable colloidal complexes with GLT at the nanoscale at pH 6, as shown by the particle size results, and the complexes exhibited a spherical morphology as seen by transmission electron microscopy. Hydrogen bonding was the main binding force for the interaction between polyphenols and GLT. The antioxidant activity of GLT was greatly improved after complexing with polyphenols. The oil/water emulsion formed by the complexes had a smaller droplet size and higher lipid oxidation stability during storage. This was largely due to the physical barrier formed by polyphenol-GLT colloidal complexes at the oil-water interface, which can prevent the pro-oxidant from penetrating into oil. These results clarified the structural, morphological and antioxidant properties of polyphenol-gelatin non-covalent complexes, which is of great value for their application in food solutions as well as in emulsion systems.

Fabrication and Characterization of Oleogel Stabilized by Gelatin-Polyphenol-Polysaccharides Nanocomplexes

“…Colloidal complexes solutions were prepared according to the process as described in our previous paper. 18 GLT and TA stock solutions were prepared by dissolving GLT and TA in distilled water, and the pH of the solution was adjusted to 6.0 with 1 M HCl or NaOH. Colloidal complexes were then fabricated by adding TA solutions to GLT solution with mass ratios of 1:16, 1:8, and 1:4, respectively, and stirring for 1 h to form complexes.…”

“…Recently, we reported the assembly mechanism of GLT with TA and the effect of their interaction on the emulsion properties. 18 The colloidal complexes were mainly assembled by hydrogen bonds and could effectively inhibit lipid oxidation in emulsion. Therefore, the colloidal complexes are promising to construct oleogel by forming interfacial rigid film with antioxidant activity, which would efficiently prevent the unsaturated fatty acids in the oleogel from oxidization.…”

Emulsion structure design for improving the oxidative stability of polyunsaturated fatty acids

“…(Lee et al, 2007;Phoon et al, 2014) Noncovalent interaction WPI-gum Arabic, Tannic acid-cuttlefish skin gelatin, Gliadin-proanthocyanidins ⋅Electrostatic interaction ⋅Antisolvent technology Be able to prepare Pickering particles; Compact interfacial layer; More antioxidative emulsifiers; Higher oxidative stability of PUFAs in emulsions. (Aewsiri et al, 2010;Huang et al, 2017;Yao et al, 2016) Fibrillation Innovative approach. (Chang et al, 2018;Mohammadian & Madadlou, 2016;Serfert et al, 2014) PUFAs, polyunsaturated fatty acids; WPI, whey protein isolate.…”

“…Physical complexation of biopolymers occurs through electrostatic interactions, hydrophobic interactions, and hydrogen bonds. These noncovalent complexes can be formed after or before emulsion preparation, and do help in inhibiting PUFAs oxidation in emulsions (Huang, Li, Qiu, Teng, & Wang, 2017). The former is fabricated mainly through electrostatic deposition, which is widely used in preparation of multilayer emulsions (Sivapratha & Sarkar, 2016).…”

“…However, the concentration of TBARS in menhaden oil emulsions stabilized with the complexes was reduced compared with that stabilized with tannic acid or gelatin during the storage. The complexes formed between gelatin and tannic acid‐grape seed proanthocyanins were effective in preventing PUFAs from oxidation (Huang et al., 2017). The polyphenols are vulnerable to degradation and hard to adsorb at the interface so that it exhibits limited protection of PUFAs in emulsions.…”