The natural abundance, polymer stability, biodegradability, and natural antimicrobial properties of lignin open a wide range of potential applications aiming for sustainability. In this work, the effects of 1% (w/w) softwood kraft lignin nanoparticles (SLNPs) on the physicochemical properties of polybutylene succinate (PBS) composite films were investigated. Incorporation of SLNPs into neat PBS enhanced T_d from 354.1 °C to 364.7 °C, determined through TGA, whereas T_g increased from −39.1 °C to −35.7 °C while no significant change was observed in T_m and crystallinity, analyzed through DSC. The tensile strength of neat PBS increased, to 35.6 MPa, when SLNPs were added to it. Oxygen and water vapor permeabilities of PBS with SLNPs decreased equating to enhanced barrier properties. The good interactions among SLNPs, thymol, and PBS matrix, and the high homogeneity of the resultant PBS composite films, were determined through FTIR and FE-SEM analyses. This work revealed that, among the PBS composite films tested, PBS + 1% SLNPs + 10% thymol showed the strongest microbial growth inhibition against Colletotrichum gloeosporioides and Lasiodiplodia theobromae, both in vitro, through a diffusion method assay, and in actual testing on active packaging of mango fruit (cultivar “Nam Dok Mai Si Thong”). SLNPs could be an attractive replacement for synthetic substances for enhancing polymer properties without compromising the biodegradability of the resultant material, and for providing antimicrobial functions for active packaging applications.

Sea grapes (Caulerpa lentillifera) are highly perishable and deteriorate rapidly postharvest (within 3–5 d), leading to pronounced quality degradation and imposing considerable challenges for commercial distribution. This study addressed these limitations, based on investigating the effects of moderate electric field (MEF) treatments powered by varying the alternating current (1–2 V cm⁻¹) for 1–3 min, or by varying the low-intensity direct current electric field (DCEF) treatment (0.5–2 V cm⁻¹) for 1–5 min on the quality of sea grapes during preservation. The quality of the sea grapes was assessed using microbial analysis, physicochemical properties and physical appearance. Based on the results, the MEF using 2 V cm-1 for 2 min produced the lowest total aerobic microbial count (TAMC) of 5.83 log CFU g-1 after 14 d, while effectively controlling the pathogenic risks from Salmonella spp., Bacillus cereus, Staphylococcus aureus, and Clostridium perfringens. The MEF significantly (p<0.05) reduced weight loss, with samples exhibiting only 7.93% and color change of 2.42 by day 14. On the other hand, the DCEF treatment using 1 V cm-1 for 3 min had a TAMC of approximately 4.88 log CFU g-1 and incurred substantial moisture loss, reaching nearly 10.10% after 5 d. In conclusion, the MEF using 2 V cm-1 for 2 min was optimal, providing a shelf life up to 14 d, while effectively limiting physicochemical deterioration and offering superior preservation in sea grapes. These findings demonstrate the potential of MEF as a practical postharvest technology for preserving the quality and marketability of sea grapes.