Abstract
The effect of boiling on antioxidant activity, total phenolic content (TPC) and total flavonoid content (TFC) in the ethanol extracts from Plectranthus amboinicus leaves were studied. The dried leaves were boiled in water for 0 (control), 30, 60, 90 and 120 minutes, then extracted with ethanol to produce ethanol extracts. The ethanol extracts were subjected to three antioxidant assays, i.e., 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and ferric reducing antioxidant power (FRAP). TPC and TFC in extracts were determined by Folin-Ciocalteu assay and aluminium chloride colorimetric assay, respectively. The results of DPPH, ABTS and FRAP assays indicated that the antioxidant of extracts were significantly (p < 0.05) more potent than the control and also increased when the boiling time was increased. Furthermore, TPC and TFC in extracts from boiled samples were significantly (p < 0.05) higher than the control and correlated with antioxidant activity. This study revealed that boiling of P. amboinicus leaves were increased its antioxidant activity, TPC and TFC as determine in ethanol extracts, and suggested that boiling can be used as a method for enhancing antioxidant activity of P. amboinicus.
Highlights
Fats and oils are important substances during food processing and use as ingredients in a variety of foods
The yield of extract for boiled samples at 30, 60, 90 and 120 minutes were increased significantly (p < 0.05) compared to control at 78 %, 83%, 87 % and 131 %, respectively. These results indicated that longer boiling time was increase the yield of extract
The first is due to an inactivation the polyphenol oxidase enzymes leading to inhibition of polyphenolics degradation [25, 41], and the second is the cause of a Maillard reaction occur during thermal treatment that decompose a phenolic substances and produce new products with more potent antioxidant activity [40]
Summary
Fats and oils are important substances during food processing and use as ingredients in a variety of foods. Plectranthus amboinicus (Lamiaceae) or Indian borage is a soft-stem plant with a strong oregano-like minty aroma and flavor mainly cultivated and used in traditional medicine or culinary purposes by in tropical and subtropical regions such as India, Southeast Asian (Malaysia, Indonesia, Thailand), China, Taiwan, West Asia (Egypt) and United States of America (Hawaii) [10]. This plant is propagated by stem cutting and grows well in drained soil with enough water. This studied was conducted to determine the effect of thermal treatment on antioxidant in leaves of P. amboinicus
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
