Concentration of sage (Salvia fruticosa Miller) extract by using integrated membrane process

•Dried sage leaves (Salvia fruticosa Miller) were infused by using hot water.•Integrated membrane process was applied on the extract to concentrate to 32.4w/w%.•Retention of total polyphenols, flavonoids and antioxidant activity were determined.•Phenolic composition of sage extract was identified with HPLC technique. The purpose of this study was to examine a recent integrated membrane process including microfiltration, reverse osmosis and osmotic distillation for producing concentrated sage (Salvia fruticosa Miller) extract. Critical and limiting conditions with respect to the flux and transmembrane pressure difference in case of the applied membrane filtration techniques were brought to the light. Regarding the valuable compound retention of the integrated process, total phenolic content, total flavonoid content and antioxidant activity using spectrophotometric assays were determined. Individual phenolic compounds of the initial and concentrated sage extracts and their retention using high-performance liquid chromatography were also determined. Individual phenolic compounds namely apigenin, rutin, hesperetin, luteolin, caffeic acid, p-coumaric, ferulic and rosmarinic acids were identified. The study concluded that sage extract can be successfully concentrated up to 32.4w/w% by using the suggested integrated membrane process, however, a remarkable valuable compounds loss (30–40%) can be observed during reverse osmosis process in the applied conditions. Contrast, osmotic distillation was able to retain more than 90% the total polyphenol content, total flavonoid content and antioxidant activity and also almost all of the determined individual polyphenols with more than 90% retention.