Application of organic solvent nanofiltration for concentration of antioxidant extracts of rosemary (Rosmarinus officiallis L.)

The present investigation revealed the potential benefits of nanofiltration application in herbal extracts processing. Nanofiltrations of modelling solution of caffeic and rosmarinic acid in ethanol and ethanolic rosemary extract were carried out in a laboratory cross-flow system. Duramem™ 200 nanofiltration membrane was selected based on screening experiments. The experimental data and model predictions demonstrated the efficacy of a semi-batch cross-flow diafiltration process for concentration of fresh rosemary extracts. The observed absence of significant loss of antioxidant capacity in the retentate during the process and the degree of extract concentration achieved may allow retentate direct application as preservative and functional ingredient in the foods, cosmetics, neutraceuticals and medicines. The capability of the selected membrane to separate monophenolic acids from higher molecular weight antioxidant compounds in the extracts was also discussed. The dry solids content in the permeate was found sufficiently low as to permit its direct re-use in the extraction process thus bringing additional economical benefits.