Water‐annealing treatment for edible silk fibroin coatings from fibrous waste

Abstract

Silk fibroin (SF) is an engineered biopolymer with properties that are desirable for the development of food preservation materials, such as edible coatings or packaging. In this study, SF from fibrous waste was assessed for the first time as an edible coating for strawberries. Relationships were established between the structural properties of SF thin films obtained from silk waste, both untreated (SFW) and water annealed (WA‐SFW) and their morphology and performance as edible strawberry coatings. According to the results obtained, the water‐annealing treatment led to a structural modification in SF films. The strawberries coated with WA‐SFW exhibited better performance during storage by reducing weight loss and preserving its visual appearance. The analysis of metal contaminants showed that SFs obtained from fibrous waste are relatively nontoxic. Therefore, using this raw material for the development of edible coatings in perishable fruits is considered promising. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48505.

Plasma‐Assisted Deposition of Silk Fibroin on Different Surfaces

“…Silk fibroin is a natural biopolymer that has been successfully proposed as a biomaterial in tissue engineering, biosensing, and more generally, in biomedical applications due to its unique mechanical and structural properties, and its positive interaction with biological environments. [ 1–3 ] The mechanical properties of fibroin can be easily tuned by controlling its crystalline structure (specifically, β‐sheet content), which also has a direct impact on its degradation rate. The combination of these properties, together with its high thermal stability and processability by diverse fabrication techniques, make silk fibroin suitable for the production of biocompatible shapes and forms.…”

Effects of Chemical Post-treatments on Structural and Physicochemical Properties of Silk Fibroin Films Obtained From Silk Fibrous Waste

“…The crystallinity index of the SFW films was calculated using the ratio of the area of the crystalline regions to the total diffraction area ( Amiraliyan et al, 2010 ; Jaramillo-Quiceno and Restrepo-Osorio, 2019 ) and the results are present in Figure 4 . According to the literature, the enrichment of crystalline structures was achieved through post-treatments, resulting in a greater effect on those samples treated with MeOH.…”

“…Silk fibroin was extracted from fibrous wastes, provided by CORSEDA, following previously published procedures ( Rockwood et al, 2011 ; Jaramillo-Quiceno et al, 2017 ; Jaramillo-Quiceno and Restrepo-Osorio, 2019 ). Briefly, the fibrous waste was degummed twice in a 0.5% w/w aqueous solution of Na 2 CO 3 (MERK, Germany) at boiling point for 30 min.…”

“…64 scans and a resolution of 4 cm –1 were recorded in a range of the absorption spectrum between 4,000 and 400 cm –1 . OMNIC software was used to deconvolute the spectra in the region of amide I (1,700–1,600 cm –1 ) as detailed in previous work ( Jaramillo-Quiceno and Restrepo-Osorio, 2019 ). This spectral region was selected as it is the most sensitive to changes in the secondary structures of the protein which originate from the C = O stretch vibration of the amide groups together with the phase flexion of the N-H bond and C-N bond stretch ( Yang et al, 2015 ).…”

“…Such is the case of the Corporation for the Development of Sericulture of Cauca (CORSEDA), which produces about 20 tons/year of cocoons. It is estimated that the amount of fibrous by-products of silk can reach up to 30% by weight of the cocoons produced, in which SF is the predominant protein (Babu, 2013;Jaramillo-Quiceno and Restrepo-Osorio, 2019). The development of new value-added products from waste streams, such as the manufacture of materials from SF for medical applications, may represent an alternative solution for increasing the sustainability of the sericulture chain.…”