Electrostatic interactions regulate the physical properties of gelatin-cellulose nanocrystals nanocomposite films intended for biodegradable packaging

Author(s)

Leite, Liliane S. F. ^{[1, 2, 3]} ; Moreira, Francys K. V. ^[4] ; Mattoso, Luiz H. C. ^{[1, 2]} ; Bras, Julien ^{[5, 3]}

Affiliation

^[1] Univ Fed Sao Carlos, Grad Program Mat Sci & Engn PPGCEM, BR-13565905 Sao Carlos - Brazil

^[2] Embrapa Instrumentacao, Natl Nanotechnol Lab Agribusiness, XV Novembro St 1452, BR-13560979 Sao Carlos - Brazil

^[3] Univ Grenoble Alpes, CNRS, Grenoble INP LGP2, F-38400 Grenoble - France

^[4] Univ Fed Sao Carlos, Dept Mat Engn, Rod Washington Luis Km 235, BR-13565905 Sao Carlos - Brazil

^[5] Nestle Res Ctr, CH-1000 Lausanne - Switzerland

• Document type: Journal article
• Source: FOOD HYDROCOLLOIDS; v. 113, APR 2021.
• Web of Science Citations: 2

Abstract

Cellulose nanocrystals (CNCs)-reinforced gelatin (Gel) films are appealing candidates for biodegradable packaging. However, tailoring the physical properties of Gel/CNCs films by control of pH and film-forming drying temperature continues unstudied. Here, we described the influence of pH on the physical properties of Gel/CNCs films covering different CNCs contents. The interactions between CNCs and Gel were studied by assessing the zeta-potential of Gel/CNCs suspensions under acidic (pH 3), Gel isoelectric point (pI, pH 6) and alkaline (pH 8) conditions. pH 3 promotes the electrostatic attraction, while pH 8 favors the electrostatic repulsion in the Gel-CNCs pair, increasing the suspension viscosity in both cases. The addition of 0.5 wt% CNCs decreased the water vapor permeability (WVP) of the Gel/CNCs films by 68% under electrostatic attractive forces and by 39% at the gelatin pI. The addition of 5 wt% CNCs at pH 3 resulted in the formation of complex coacervates, which decreased the mechanical properties and increased the WVP of Gel/CNCs films. Increasing pH above the Gel pI remarkedly increased the gelatin renaturation as triple helices, which was found to be key for increasing by 152% and 56% the Young's modulus and tensile strength, respectively, of the Gel/CNCs films with 0.5 wt% CNCsFilm-forming drying temperatures had an inverse effect on the triple helix content, and, consequently, on the physical properties of the Gel/CNCs films. These findings denote that modulating pH, CNCs amount, and drying temperature is a suitable strategy for tailoring the properties of nanocellulose-reinforced gelatin films for an extended range of food packaging applications. (AU)

• FAPESP's process: 18/00278-2 - Functionalization, characterization and properties evaluation of cellulose nanocrystals and their bionanocomposites based on protein
• Grantee: Liliane Samara Ferreira Leite
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate