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

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 m 2 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 m 2 g −1 . The hydration properties of all aerogels were studied by measuring the 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 with that of pristine WPI aerogels. After silanization, all aerogels absorbed much smaller amounts of water (39−84% w/w). The reduced water uptake was in agreement with the water contact angles, which were in the ranges 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 biobased 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.

Nanostructured Gelatin Aerogel for Selective Recovery of Aqueous Pd(II) Based on Coordination to the Peptide Backbone

“…As a reference, the SEM image of a pure gelatin aerogel is also shown. The pristine gelatin aerogel (G) has a well-defined fibrillar structure, which is similar to that of whey protein aerogels. , However, the primary fibrils are entangled and interwoven due to the strong secondary interactions among the molecules of this structural protein. Chemically cross-linking the biopolymer highly influences the nanoscale morphology, resulting in a dense network of thick cylindrical bundles that are not characteristic of the pure gelatin aerogel.…”

Hydrophobic Modification of Pectin Aerogels via Chemical Vapor Deposition

“…It was shown that in some cases, they can exhibit the characteristics of conventional aerogels such as low density and high specific surface area, as well as mesoporosity, and also possess the characteristics specific to bio-based polymers such as biodegradability and often biocompatibility. A wide range of bio-aerogels were obtained based on polysaccharides such as cellulose [ 11 , 12 , 13 ], chitosan [ 14 ], starch [ 15 , 16 ], alginate [ 17 , 18 ], pectin [ 19 , 20 , 21 ], proteins [ 22 , 23 ], or other polymers extracted from biomass [ 24 ]. Bio-aerogels are very attractive materials for a very wide variety of applications.…”

“…Bio-aerogels are very attractive materials for a very wide variety of applications. These include thermal insulators [ 25 ], acoustic insulators [ 26 ], batteries’ electrodes [ 27 ], supercapacitors [ 28 ], piezoelectric transducers [ 29 ], CO 2 captures [ 30 ], absorbents [ 31 ], drug carriers [ 32 ], catalyst supports [ 33 ], and food packaging [ 22 ]. Several bio-aerogels were studied for their thermal insulation properties, and materials based on nanocellulose, starch, and pectin were shown to fall in the superinsulating area [ 16 , 21 , 34 , 35 ].…”