A comparison of extraction methods for preparation of glucosinolate-containing extracts from Brassica juncea antagonistic toward Ditylenchus dipsaci

Summary The stem and bulb nematode, a globally distributed pest, primarily affects onions and garlic, causing significant yield losses. Chemical treatments are a practical and effective method for controlling plant-parasitic nematodes to protect high-value crops. However, to minimise environmental damage, chemicals of natural origin need to be investigated. Brown mustard ( Brassica juncea ) plant is an annual plant in the Brassicaceae family, which is rich in bioactive compounds called glucosinolates. These bioactive compounds play a major role in the defence of Brassica plants against biotic stress factors in nature. Based on this point, efforts to develop plant protection products from the brown mustard plant are ongoing. In this study, the most suitable pre-extraction and extraction conditions were determined to ensure the maximum preservation of glucosinolate content and biological activity, to process brown mustard on an industrial scale. For this purpose, steam treatment was applied before extraction at 3 bar (=3 × 10 5 Pa) pressure for 1 and 3 min. Four different temperatures (room temperature, 40, 55 and 70°C) and two different methanol concentrations (70% and 80%) were tested to optimise glucosinolates extraction from brown mustard. It was found that sinigrin was the most abundant glucosinolate, with extraction yields 1184.4 ± 14.4 mg kg −1 at 55°C for 3 min, and 2624.2 ± 98.5 mg kg −1 at 70°C/70% MeOH for 1 min. However, nematode immobility was higher at 55°C/70% MeOH for 3 min. It was determined that the application of hot steam for 3 min at 3 bar pressure as a pre-extraction process provided optimal conditions for methanolic extraction. The results may contribute significantly to the development of potential plant protection products with further studies.