Yeast particles (YPs) are 3−5 µm hollow and porous microspheres, a byproduct of some food grade yeast (Saccharomyces cerevisiae) extract manufacturing processes. Terpenes can be efficiently encapsulated inside YPs by passive diffusion through the porous cell walls. As previously published, this YP terpene encapsulation approach has been successfully implemented (1) to develop and commercialize fungicide and nematicide products for agricultural applications, (2) to co-load high potency agrochemical actives dissolved in terpenes or suitable solvents, and (3) to identify YP terpenes with broad-acting anthelmintic activity for potential pharmaceutical applications. These first-generation YP terpene materials were developed with a <2:1 terpene: YP weight ratio. Here we report methods to increase the terpene loading capacity in YPs up to 5:1 terpene: YP weight ratio. Hyper-loaded YP terpenes extend the kinetics of payload release up to three-fold compared to the commercialized YP terpene formulations. Hyper-loaded YP-terpene compositions were further optimized to achieve high terpene storage encapsulation stability from −20 °C to 54 °C. The development of hyper-loaded YP terpenes has a wide range of potential agricultural and pharmaceutical applications with terpenes and other compatible active substances that could benefit from a delivery system with a high payload loading capacity combined with increased payload stability and sustained release properties.
Keywords: biocide; controlled delivery; microencapsulation; terpenes; yeast particles.