Physicochemical and Microstructural Characterization of Whey Protein Films Formed with Oxidized Ferulic/Tannic Acids.

Yaosong Wang,Youling L Xiong

doi:10.3390/foods10071599

Abstract

Protein-based biodegradable packaging films are of environmental significance. The effect of oxidized ferulic acid (OFA)/tannic acid (OTA) on the crosslinking and film-forming properties of whey protein isolate (WPI) was investigated. Both of the oxidized acids induced protein oxidation and promoted WPI crosslinking through the actions of quinone carbonyl and protein sulfhydryl, and amino groups. OTA enhanced the tensile strength (from 4.5 MPa to max 6.7 MPa) and stiffness (from 215 MPa to max 376 MPa) of the WPI film, whereas OFA significantly increased the elongation at break. The water absorption capability and heat resistance of the films were greatly improved by the addition of OTA. Due to the original color of OTA, the incorporation of OTA significantly reduced light transmittance of the WPI film (λ 200–600 nm) as well as the transparency, whereas no significant changes were induced by the OFA treatment. Higher concentrations of OTA reduced the in vitro digestibility of the WPI film, while the addition of OFA had no significant effect. Overall, these two oxidized polyphenols promoted the crosslinking of WPI and modified the film properties, with OTA showing an overall stronger efficacy than OFA due to more functional groups available.

Highlights

Biodegradable packaging materials are being developed as a part of “future food” to partially replace traditional nondegradable materials, to reduce environmental pollution [1]
While oxidized ferulic acid (OFA) did not affect protein surface hydrophobicity, oxidized tannic acid (OTA) significantly decreased the value, due to the induction of protein aggregation, which was evinced by the marked increase in protein particle size (Table 1)
The stronger efficacy of OTA was attributed to the polygalloyl structure (10 phenol groups) of tannic acid compared with only one phenol in ferulic acid; the potential of generating highly reactive polycarbonyls when oxidized

Summary

Introduction

Biodegradable packaging materials are being developed as a part of “future food” to partially replace traditional nondegradable materials, to reduce environmental pollution [1]. Suitable crosslinkers include a variety of natural compounds that prove to be safe and present minimal risk Phenolics, one of such compounds that are widely available, are a large class of non-toxic, antioxidative, and edible natural products, of which many exhibit health benefits [9]. Previous studies have shown that ferulic and tannic acids, two widely distributed natural phenols, have antimicrobial and antioxidant activity [11,12] Both have the potential to improve the mechanical properties and decrease the water vapor permeability of collagen- or gelatin-based films [13,14]. Ferulic acid is capable of decreasing the oxygen permeability of whey protein films [4], while tannic acid is able to crosslink caseins [16] and β-lactoglobulin (βLg) [17], leading to significantly improved overall physicochemical properties of such edible film products

Methods

Results

Conclusion