Coatings Applied to the Optimization of Portulaca oleracea L. Seed Pellet Formulation Based on Mixture Design

Portulaca oleracea L. is an important herb with the same origin in medicine and food. To achieve the precise sowing of P. oleracea, this study employed a mixed experimental design to optimize the pellet formulation of the seeds. Fillers such as kaolin, bentonite, and talcum powder were used, along with binders including polyvinyl alcohol, sodium alginate, and sodium carboxymethyl cellulose. The physical characteristics and germination properties of the pelletized seeds were evaluated to determine the optimal formulation. The results indicated that, after pelletizing, the seeds exhibited a higher seed viability and vigor, germination rate, and germination index. Specifically, the seed singulation rate correlated positively with the kaolin content, the disintegration rate was proportional to the amount of talcum powder added, and the compression resistance was positively correlated with the bentonite ratio. Using response optimization, the optimal formulation of fillers used for pelletizing P. oleracea seeds was identified as 17% talcum powder, 16% kaolin, and 67% bentonite. Single-factor experiments showed that using PVP as a binder at a mass fraction of 10% resulted in improved pelletizing indices. This study not only optimized the pelletizing formulation of P. oleracea seeds based on physical and germination properties, but also expanded the application of pelletizing in the processing of the seeds of traditional Chinese herbs. It holds significant implications for the mechanized production of small, pelletized seeds of traditional Chinese herbs.