Whey Protein Isolate Based Aerogels with Improved Hydration Properties for Food Packaging Applications

Effraimopoulou, Eleni and Kalmár, József and Paul, Geo and Marchese, Leonardo and Ioannou, Dimosthenis and Paraskevopoulou, Patrina and Gurikov, Pavel (2024) Whey Protein Isolate Based Aerogels with Improved Hydration Properties for Food Packaging Applications. ACS APPLIED NANO MATERIALS, 7 (1). pp. 618-627. ISSN 2574-0970

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Abstract

In the present work tannin-modified whey protein isolate (WPI/tannin) aerogels were synthesized, and their hydration properties were evaluated. The materials were prepared by introducing two different tannins (one hydrolyzable and one condensed) in the protein matrix via thermal-induced gelation of neutral or alkaline aqueous solutions (pH 7, 9 or 11) at 80 °C. WPI and WPI/tannin aerogels are nanostructured porous materials with high BET surface areas (216- 353 m2 g –1 ). Subsequently, WPI and WPI/tannin aerogels were hydrophobized via silanization (with bis(trimethylsilyl)amine) in the gas phase (HWPI and HWPI/tannin aerogels). As a result of silanization, BET surface areas were reduced to 87-242 m2 g –1. The hydration properties of all aerogels were studied by measuring water uptake and water contact angles. Pristine WPI aerogels absorbed high amounts of water (up to 4794% w/w in 24 h), swelled and eventually disintegrated. WPI/tannin aerogels prepared with the condensed tannin absorbed more water (219-559% w/w) than those prepared with the hydrolyzable tannin (81-88% w/w). In any case, the water uptake was significantly lower compared to that of pristine WPI aerogels. After silanization, all aerogels absorbed much lower amounts of water (39-84% w/w). The reduced water uptake was in agreement with the water contact angles, which were in the range of 35-55° for WPI aerogels, 40- 60° for WPI/tannin aerogels, 80-86° for HWPI aerogels, and 100-116° for HWPI/tannin aerogels. These results clearly indicate that both the introduction of tannin in the protein matrix and the silanization of the solid network are necessary to obtain water-stable WPI-based aerogels. There is an immense need for replacing the existing plastic-based food packaging with bio-based and biodegradable materials. In this context, our results address the major disadvantage of most biobased materials (i.e., poor stability in aqueous environments) and render these new aerogels good candidates for food packaging applications.

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