Sustainable Smart Packaging from Protein Nanofibrils

Abstract

Smart packaging technologies are revolutionizing the food industry by extending shelf life and enhancing quality monitoring through environmental responsiveness. Here, a novel smart packaging concept is presented, based on amyloid fibrils (AM) and red radish anthocyanins (RRA), to effectively monitor food spoilage by color change. A protein nanofibrils biofilm is developed from whey protein, which is functionalized with RRA to endow the resulting films with advanced monitoring capabilities. A comprehensive characterization, including pH responsiveness, water vapor permeability, thermal and mechanical testing, and colorimetric responses, demonstrates the superiority of AM/RRA films compared to control films based on whey monomer building blocks. The findings indicate that the AM/RRA films can effectively monitor, for example, shrimp freshness, showing visible changes within one day at room temperature and significant alterations in color after two days. Furthermore, these films exhibit high antibacterial and antioxidant activities, reinforcing their suitability for efficient food packaging. By integrating bio-based materials from whey and natural anthocyanins, this research presents a biodegradable, sustainable, and cost-effective smart packaging solution, contributing to eco-friendly innovations in food preservation.

Keywords: amyloid fibrils; bioplastics; food sidestreams; protein nanofibrils; smart packaging.

Figure 1

Schematic of the process followed for the fabrication of dye extract from radish peels, the biofilm based on whey nanofibrils, and its functionalization into smart packaging films.

Figure 2

a) pH‐series of RRA extract (the extract had a dry mass of 62 ± 1 wt.%, thus a concentration of 1 mg mL⁻¹, or 1 g L⁻¹ has a dry mass of 620 mg L⁻¹); b) AFM of pure AM (i), and AM with anthocyanin (ii); c) Thermal degradation of RRA in water vs in AM solution (both at pH 2) at 40 and 90 °C (data are represented as means ± SD, where n = 3 and ^* p < 0.05); d) RRA degradation in water (left) vs in AM solution of 2 wt.% (right) both at pH 2, e) FT‐IR of AM vs AM/RRA (AM specific region (i) and phenol specific region (ii)).

Figure 3

a) Visual appearance of biofilms; b) Thickness of films (data are represented as means ±  SD, where n = 8); c) Water vapor permeability (data are represented as means ± SD, where n = 4); d) Light transmittance by UV–vis of films. Mechanical properties: e) Maximum stress (data are represented as means ± SD, where n = 3, ^* p < 0.05, ^** p < 0.005); f) Maximum strain(data are represented as means ± SD, where n = 3, ^* p < 0.05, ^** p < 0.005, ^*** p < 0.001); g) Young's modulus of biofilms (data are represented as means ± SD, where n = 3).

Figure 4

a) Smart sensor with colored added before drying (i) and after drying (ii); b) Smart sensor attached to larger biofilm; c) Smart sensor exposed to 0.1 M NaOH and subsequent change in color at the beginning (i), after 5 min (ii) and 10 min (iii); d) response to different vapor compositions: pH 2 acetic acid (i), pH 10 1:10 NH₃ (ii), pH 12 NH₃ (iii); e) reaction to ammonia gas before (i) and after (ii) exposure; f) Reversibility in pH‐change of smart sensor from vapor over 4 cycles; Changes in color values of the monomer‐ and AM‐based films at various pH‐values in g) Brightness; h) Redness; i) Yellowness and j) Overall change (all data are represented as means ± SD, where n = 3).

Figure 5

a) Smart sensor changes over time in a Petri dish in the presence of a shrimp at 4 °C and room temperature (RT); Antioxidant assay measured by: b) scavenging rate as the linear change in absorbance before and after the addition of DPPH; and c) scavenged DPPH radicals according to the Beer‐Lamber‐Bouguer Law (Antioxidant test data are represented as means ± D, where n = 3, ^*** p < 0.001). D) Antibacterial assay of films in 4.6 × 10¹⁰ CFU mL⁻¹ of E. coli after 96 h (the diameter of the Petri dish is 94 mm). e) diameter in mm after 96 h in 4.6 × 10¹⁰ CFU mL⁻¹ of E. coli colony (Antibacterial test data are represented as means ± SD, where n = 3, ^*** p < 0.001).