Varietal dependence of chemoprotective substances in fresh and frozen spinach (Spinacia oleracea, L.)

Spinach (Spinacia oleracea L.) is an important source of bioactive compounds. It is commonly consumed fresh or frozen products. Spinach is rich sources of polyphenols, it is a good source of vitamin C and has potential beneficial properties for human health. This study provides some knowledge about content of total polyphenols, and antioxidant activity in selected varieties of fresh and frozen spinach samples. Four spinach cultivars (̓Boa ̓, ̓ Hudson ̓, ̓Chica ̓, ̓Trombone ̓) were analysed. The content of the total polyphenols (TPC) was determined by the Folin-Ciocalteu reagent (FCR). Antioxidant activity (AA) was measured using a compound DPPH (2,2-diphenyl-1-picrylhydrazyl). The content of total polyhenols in fresh samples of spinach ranged from 975 ±97.15 mg.kg-1 to 1493 ±50.42 mg.kg-1 and values of antioxidant activity were in interval from 77.55 ±0.34% to 82.57 ±0.83%. The highest level of TP content in fresh spinach was recorded in variety Hudson (1493 mg.kg-1) and the lowest in variety Chica (975 mg.kg-1). Between these varieties statistically significant difference in the content of total polyphenols was found. The highest value of antioxidant activity in fresh spinach was recorded in variety Trombone (82.57%) and the lowest in variety Boa (78.59%). This difference was also statistically significant. The highest level of TP content in frozen spinach samples was found in variety Hudson (1749 mg.kg-1) and the lowest in variety Chica (855 mg.kg-1). The values of antioxidant activity in frozen spinach samples were in range from 45.86 ±7.84%to 79.67 ±0.88%. The highest value of antioxidant activity in frozen spinach was found in variety Hudson (79.67%) and the lowest in variety Chica (45.86%).