Pengaruh Waktu Pemasakan dan Konsentrasi Terhadap Aktivitas Antioksidan dan Kadar Fenolik Total Brokoli (Brassica oleracea L. var. italica)

Abstract

There are many plants that can be used as alternative medicine. One of them is broccoli which is known as vegetable that contain antioxidant, such as phenolic compounds. Antioxidant is capable to inhibit free radicals in human tuJy. This research was aimed to measure the effect of cooking time and concentration of broccoli on antioxidants activity tested by DPPH (1,I-diphenyl-2-pycrilhydrazil) method and total phenolic content. Butylated hydroxytoluene (BHT) was used as positive control with various concentrations, 2, 4, 6, and 8 ppm. Some samples were cooked by conventional boiling treatment for 10, 20, and 30 minutes, and then were extracted with methanol. The extracts were separated by flash chromatography with toluene:ethyl acetate (11:9) as mobile phase. The number of fractions were determined with bioautography thin layer chromatography that were sprayed with DPPH 0.004% to get the active fraction. The methanol extracts and the active fractions were diluted to various concentrations, 10, 30, 50, and 70 ppm and then were determined for their antioxidant activity and the total phenolic content. The results showed that cooking time of broccoli from 10 to 30 minutes were significantly decreased antioxidant activity of extracts while increasing concentration of extract and active fraction from 10 to 70 ppm increase antioxidant activity of both of them. The ICso value of methanol extracts and active fraction were 226.94 and 221.78 ~g/mL, respectively. The ICso value of BHT was 6.46 ~g/mL. The total phenolic content active fraction for raw vegetable, 10, 20, and 30 minutes cooking time were 764.91, 495.96, 441.19, dan 304.66 mg/lOOg, respectively. Total phenolic content of broccoli were significantly decreased during the cooking.