Lignin and Lignosulfonate-Based Formulations To Protect Pyrethrins against Photodegradation and Volatilization

We evaluate the use of kraft-lignin and lignosulfonate to protect pyrethrins against photodegradation and volatilization. Copolymerization between kraft-lignin and sodium alginate and lignosulfonate spray drying encapsulation were developed as formulation methods, reaching encapsulation efficiency values higher than 77%. DT50 values obtained from photodegradation studies were 115 h for lignin-based formulation and 231 h for lignosulfonate-based formulation, these values being 7 and 14 times higher than that obtained for pyrethrum extract, respectively. These results showed that formulations based on lignin-derivates provided extended simulated sunlight protection, that prepared with lignosulfonate being the most photostable formulation. Volatilization experiments showed the potential of the prepared formulations in protecting pyrethrins against evaporation, thus improving their stability. The enhanced photoprotection of pyrethrins using ionotropic gelation and spray drying, as encapsulation techniques, could facilitate the application of this botanical insecticide as far as outdoors uses, such as agronomic practices.