Evaluation of quality parameters and antioxidant activity of commercial melinjo (Gnetum gnemon) for functional food

Abstract

Functional foods are ingredients which provide health benefits. Gnetum gnemon Linn (melinjo) seeds contain bioactive compounds with extremely high antioxidant activity and are considered to have the potential to be used as raw materials for functional food. The utilization of melinjo seeds as functional food ingredients must consider the general and specific quality standards to ensure the generated products deliver the intended health benefits. The purpose of this study was to determine the specific and nonspecific quality parameters of commercial melinjo products in the form of extracts and flour as well as evaluate its antioxidant capacity as functional food raw materials. The nonspecific parameters evaluated include drying loss, microbial contamination, moisture, total ash, insoluble acid ash, extract yield, fat, and crude fiber. The specific parameters tested were phenolic and flavonoid content, water-and ethanol-soluble compounds, and marker compounds. The results showed that the nonspecific parameter values extract and flour of melinjo seed met the standard's provisions. Analysis of specific parameters showed that the extract was dark brown in the form of a thick paste, while flour was light brown powdery. Both have a distinctive odor with a slightly bitter taste. The phenolic and flavonoid content of the extract was higher than that of the flour. To the contrary, the water-and ethanol-soluble compounds of the extract were lower than that of the flour. Resveratrol, one of the marker compounds in melinjo seeds, was identified by TLC and HPLC. The melinjo seed extract was found to have strong antioxidant activity with IC50 value of 1.45 mg/ml. On the basis of the nonspecific and specific parameter values together with the antioxidant activity it was concluded that the melinjo seed extract has high potential to be used as a raw material for functional food.