ORIGINAL PAPER Effects of Pressurized Low Polarity Water Extraction Parameters on Antioxidant Properties and Composition of Cow Cockle Seed Extracts Özlem Güçlü-Üstündağ & G. Mazza Published online: 31 October 2008 # Her Majesty the Queen in Rights of Canada 2008 Abstract Antioxidant activity of pressurized low polarity water (PLPW) extracts of cow cockle seed and extraction residues were determined using DPPH, ABTS, and FRAP assays. The effect of extraction conditions (temperature (125, 150 and 175 °C) and time) on the antioxidant activity and the relationship amongst the antioxidant activity and extract composition (total phenolics and saponin content) were determined. The antioxidant activity of PLPW extracts increased with extraction temperature. Increasing activity with time was also observed at 175 °C. PLPW extraction residues had the highest activity suggesting antioxidant compounds were not completely extracted by PLPW. Anti- oxidant activity correlated well with total phenolics content of samples (R 2 ≥ 0.94), however no correlation was observed with the saponin content. A strong correlation was observed between the antioxidant activity values obtained using different methods (R 2 ≥ 0.94). These results point to the potential of PLPW extraction as a method to modify the activity of biological materials for the production of cus- tomized extracts. Keywords Vaccaria segetalis . Saponaria vaccaria . Cow cockle seed . Phenolics . Saponins . Subcritical water extraction . Antioxidant activity . DPPH . ABTS . FRAP Introduction Pressurized low polarity water (PLPW) extraction has emerged as an environmentally friendly technique for the processing of natural products and has been investigated for the extraction of bioactive compounds such as isoflavones [1], lignans [2], saponins [3], and anthocyanins [4]. It involves the use of high pressures which enables processing at temperatures above 100 °C, improving mass transfer rates and modifying the polarity/solvent power of water. Selective extraction of sample components with tempera- ture, which arises from the differences in the effects of temperature on their solubility behavior, can be used to modify the composition and hence the bioactivity of PLPW extracts [5]. The exposure of biological samples to high temperatures during PLPW extraction might have important implications for bioactivity of extracts. Heat treatment may affect the interaction of bioactive components with matrix compo- nents [6] and/or result in the degradation and/or formation of bioactive compounds [7]. The increase of antioxidant activity of citrus peel extracts and the corresponding increase in the total phenolics content due to heat treatment have been attributed to the liberation of phenolic com- pounds from their bound states [6]. The degradation of bioactive compounds such as anthocyanins has been observed during PLPW extraction of plant materials [4]. An increase in bioactivity due to the formation of new compounds upon heat treatment has also been reported [7, 8]. While heating sugar–lysine model systems resulted in the formation of Maillard reaction products with antioxi- dant activity [8], the increase in radical scavenging and endothelium-dependent relaxation activities of ginseng was Plant Foods Hum Nutr (2009) 64:32–38 DOI 10.1007/s11130-008-0093-9 Ö. Güçlü-Üstündağ : G. Mazza (*) Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, 4200 Highway 97, Summerland, BC, Canada V0H 1Z0 e-mail: MazzaG@agr.gc.ca