Facile one-step recovery of stable lignin nanoparticles from sugarcane bagasse black liquor and their application in bioactive food packaging.

Lignin nanoparticles (LNPs) were recovered by one-step acidification of the black liquor from sugarcane bagasse treatment, substituting the conventional two-step practice. For the first time, the effect of extra stirring time on the stability of LNPs was investigated. Having been precipitated from 10 to 25 folds diluted black liquor to pH values of 1.0-3.0 for extra stirring time (0-180 min), LNPs had sizes ranging from 150 to 250 nm, polydispersity indexes of 0.27-0.44 and high negative zeta potentials of (-38.4)-(-72.5) mV. Antimicrobial analysis through broth dilution revealed that LNPs exhibited better activity against Staphylococcus aureus than against Escherichia coli, and poor performance against Candida albicans. LNPs showed strong antioxidation property, demonstrated through 1,1-diphenyl-2-picryl-hydrazyl radical scavenging assay (IC50 = 147 ppm), and a total phenolic content of 93.66 mg gallic acid equivalent/g, and promising UV shielding activity. The practicality of LNPs in food preservation was analyzed by incorporating them with different concentrations (0-0.2 wt/vol%) into bio-packaging. A reduction in water solubility from 51.2 % at 0.025 wt/vol% to 31.4 % at 0.2 wt/vol% and alterations to the water vapor permeability (4.2-6.0 × 10-10 g.m-1.Pa-1.s-1) were recorded. Bio-packaging with LNPs showed resistance against Staphylococcus aureus (97 %) and Escherichia coli (30 %), along with complete UVB and 80 % UVA shielding. This study is a milestone in the ongoing exploration of LNPs potential with a focus on sustainable fabrication.