Emulsifying Properties of Oxidatively Stressed Myofibrillar Protein Emulsion Gels Prepared with (−)-Epigallocatechin-3-gallate and NaCl

Abstract

The dose-dependent effects of (-)-epigallocatechin-3-gallate (EGCG; 0, 100, or 1000 ppm) on the textural properties and stability of a myofibrillar protein (MP) emulsion gel were investigated. Addition of EGCG significantly inhibited formation of carbonyl but promoted the loss of both thiol and free amine groups. Addition of EGCG, particularly at 1000 ppm, initiated irreversible protein modifications, as evidenced by surface hydrophobicity changes, patterns in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and differential scanning calorimetry. These results indicated that MP was modified by additive reactions between the quinone of EGCG and thiols and free amines of proteins. These adducts increased cooking loss and destabilized the texture, especially with a large EGCG dose. Confocal laser scanning microscopy and scanning electron microscopy images clearly indicated the damage to the emulsifying properties and the collapse of the internal structure when the MP emulsion gel was treated with a large EGCG dose. A high concentration of NaCl (0.6 M) improved modification of MP and increased the rate of deterioration of the internal structure, especially with the large EGCG dose (1000 ppm), resulting in an MP emulsion gel with extremely unstable emulsifying properties.

Antioxidant and Antimicrobial Activities of (‐)‐Epigallocatechin‐3‐gallate (EGCG) and its Potential to Preserve the Quality and Safety of Foods

“…However, Feng et al. () showed that EGCG at a high dose (1000 mg/g) led to irreversibly protein modification, probably due to interactions between the quinone of EGCG and the sulfhydryl groups and free amines of the proteins. This resulted in high cooking loss and a weakened emulsion structure.…”

Effects of NaCl content and drying temperature on lipid oxidation, protein oxidation, and physical properties of dry‐cured chicken

“…After treatment with β‐ME (Figure 5B), polymers at the top of the stacking gel decreased and most bands of the MHC, tropomyosin, and actin bands were recovered. This finding indicated that the polymers were primarily formed by disulfide bonds (Feng et al., 2017). In fact, polymers can be formed by intra‐ and intermolecular cross‐links of proteins, and by the cross‐links of lipid oxidation byproducts with proteins (e.g., MDA react with proteins to form bis‐Schiff base diimine) (Requena et al., 1996).…”

Protective effects of epicatechin on the oxidation and N-nitrosamine formation of oxidatively stressed myofibrillar protein

“…This study was in accordance with those previous reports in which phenolic compounds inhibited protein carbonyl content, such as quercetin [27] ，rosmarinic acid [28] and EGCG. [29,30] Total and free sulfydryl groups MP is rich in sulfydryl groups, which are susceptible to attack by reactive oxygen species and can then convert to intra-and intermolecular disulfide bond linkages. [10] As shown in Table 1, the total sulfydryl group content of control MP was 109.63 nmol/mg protein.…”

“…This study was consistent with other previous reports which indicate that phenolic compounds inhibit the surface hydrophobicity. [29] It is also shown that phenolic compounds can protect protein side-chain groups.…”