Antioxidant Activity, Fiber, Acidity (pH), and Population of Lactic Acid Bacteria in Green Juice as Functional Beverages

Abstract

Bok choy ( Brassica rapa L) is a vegetable group of Brassicaceae which still a family with Chinese vegetables. It contains phytochemical substances such as carotenoids, β-carotene , and glucosinolates which are a source of antioxidant. Bok choy can be processed into juice. The purpose of this research is to determine the content of the antioxidant activity, fiber, acidity (pH) and population of lactic acid bacteria in each formulation. The other ingredients added in making this green juice are yogurt and honey made into 5 formulations. The analysis of this research was the analysis of antioxidant activity content using DPPH method (2.2, -diphenyl-1- picrylhydrazyl), crude fiber contents analysis using gravimetric method, pH analysis using pH meter and analysis of lactic acid bacteria using spread plate method. The result obtained is the highest content of the antioxidant activity was found in formulation 5 consist of 30 g yogurt, 15 g honey and 50 g bok choy with 35,198 ± 0,057%. The content of crude fiber ranged from (0,447 ± 0,046) g to (0,507 ± 0,058) g. The highest of acidity (pH) is in formulation 1 which consists of 10 g of yogurt, 15 g of honey and 50 g of bok choy at 5,50 ± 0,040. The highest population content of lactic acid bacteria in formulation 5 consists of 30 g yogurt, 15 g honey and 50 g bok choy at 2,8 x 106cfu/mL. Therefore, green juice can be used as functional drinks.