Abstract

Kelakai (Stenochlaena palustris) is an available natural herb with an excellent source of dietary fiber and antioxidant. It’s commonly used as vegetable in daily cuisine. In order to increase its economic value, it can be converted into pickle via lactic fermentation. This research was conducted during 2020 at STNanotech laboratory, Vietnam to evaluate the impact of pickling of Kelakai creeping fern on the phenolic composition and antioxidant ability of the pickled product. The total phenolic content was determined by the Folin-Cicalteau method. Aluminum chloride colorimetric method was used for quantification of total flavonoid content. DPPH free radical scavenging activity and ABTS radical scavenging activity was examined by using 2,2-diphenyl-2-picrylhydrazyl and 2,2'- azinobis (3-ethylbenzothiazoline-6-sulfonic acid) assays. Results showed that pickling at ambient temperature for 7 days in solution consisting of 10% salt, 4% sugar, 0.1 % L. plantarum culture (6 log CFU/mL) greatly improved the total phenolic content (450.3±0.9 mg GAE/100 g), flavonoid content (305.1±0.4 mg QE/100 g), DPPH free radical scavenging (149.1±0.9 μg/mL), ABTS radical scavenging activity (2.05±0.01 mM TE/g) of the pickled in kelakai (Stenochlaena palustris) creeping fern compared to the total phenolic content (367.5±1.6 mg GAE/100 g), flavonoid content (194.2±0.7 mg QE/100 g), DPPH free radical scavenging (201.2±0.5 μg/mL), ABTS radical scavenging activity (1.75±0.02 mM TE/g) of the raw material. This research demonstrated that lactic fermentation strongly enhanced the phytochemical composition and antioxidant property of kelakai (Stenochlaena palustris) creeping fern. Utilization of pickled kelakai (Stenochlaena palustris) creeping fern would be more beneficial than the fresh one.