Changes in components of aqueous and non-aqueous extracts from sea buckthorn seed residues through solid state fermentation of Monascus purpureus

Abstract

The feasibility of solid-state fermentation was studied for sea buckthorn seed residues (SBSR). Effects of different fermentation parameters were evaluated regarding the levels of biomass and compounds in aqueous and non-aqueous extracts. In the latent and logarithmic phases of fermentation, the total phenols and flavonoids were increased. The microbes’ decomposition on fibrous matter allowed the active components to be fully extracted. The changes of total sugar levels had a contrary trend with the changes of total phenol and flavonoid contents. The monosaccharide and polypeptide contents decreased dramatically and then kept steady along with the fermentation. Unsuitable environments led to weak growth of the fungi, limited enzyme contents, low enzyme activity, and a poor degradation of the substrates. The active compounds considered in the study were protected, and the contents reached a maximum under conditions that were usually not suitable for the fungal growth. The chemical structure was another important factor influencing the content and stability of the compounds. The content of procyanidins decreased dramatically because of its sensitivity to heat and alkaline environments. Antioxidant abilities of SBSR extracts, both aqueous and non-aqueous, increased after fermentation. These results reflected a possibility to recycle SBSR for further use in the food industry.