Studies regarding the myrosinase enzymatic activity from black mustard (Brassica nigra) seeds

Author: Daniela Stoin ^*, Paul Pirsan, Florina Radu, Mariana-Atena Poiana, Ersilia Alexa and Diana Dogaru

Received 12 October 2008, accepted 5 December 2008.

Abstract

The aim of this study consists in the presentation of a simple and fast method for myrosinase activity quantification towards sinigrin from the aqueous extracts obtained from black mustard (Brassica nigra) seeds as raw material (SM) or crushed down (CM). The myrosinase activity was determined under different pH (5-8.5), temperature (T = 25-85°C) and reaction time (τ = 30-390 minutes) conditions, according to the spectrophotometric method and was expressed depending on the concentration of the glucose resulted from enzymatic reaction. The optimum parameters corresponding to the maximum myrosinase activity in the aqueous extracts of black mustard were the following: pH 7, T 55°C and τ 210 minutes for the crushed down mustard samples and τ 240 minutes for the mustard seeds samples. The myrosinase activity is significantly influenced by the physical state of the vegetable material (raw or crushed down), this values being of 116.3510 µg glucose/g.min for CM in comparison to the 85.0660 µg glucose/g.min for SM. The enzymatic hydrolysis reaction of the sinigrin takes place with heat releasing.

Key words: Brassica nigra, glucosionolates (GLS), sinigrin (SIN), myrosinase (MYR), enzymatic activity.