Effects of conventional cooking methods on the glucosinolate content and the antioxidant activity of alugbati (Basella rubra) and saluyot (Corchorus olitorius)

• Main Authors: Medelo, Althea Mae T., Toriaga, Jude Wenz P.
• Format: text
• Language: English
• Published: Animo Repository 2022
• Subjects: Glucosinolates; Basellaceae; Tossa jute; Biochemistry
• Online Access: https://animorepository.dlsu.edu.ph/etdb_chem/14; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=1016&context=etdb_chem
• Institution: De La Salle University

Glucosinolates (GSLs) and one of their hydrolysis products, isothiocyanates (ITCs), are thoroughly researched for their biological activities. In this study, the effects of conventional cooking methods – steaming, blanching, boiling, microwaving, and stir-frying – on the total GSL and ITC content and on the antioxidant activity of alugbati (Basella rubra) and saluyot (Corchorus olitorius), two non-Brassica vegetables, were investigated. HPLC showed that both species had detectable amounts of GSL. Among B. rubra samples, the raw sample had the highest GSL content (80.26 ± 7.04 µmol/g), and among C. olitorius samples, the microwaved sample had the highest GSL content (127.02 ± 23.26 µmol/g). Stir-frying was the least favorable method as it retained only 40.29% and 24.31% of the total GSL compared to the raw samples of B. rubra and C. olitorius. Overall, conventional cooking methods caused significant decreases or increases in total GSL content, depending on the method used. The isothiocyanate analysis via the cyclocondensation assay yielded inconclusive results as GC-MS suggested the presence of thieno[2,3-b]thiophene, 2-methyl instead of the expected product. By using the DPPH assay to determine antioxidant activity, extracts of raw C. olitorius displayed strong antioxidant activity (IC50 = 43.5 ppm), while raw B. rubra displayed weak antioxidant activity (IC50 = 773 ppm). Moreover, antioxidant activity decreased with the application of conventional cooking methods but based on the % scavenging activity of each sample, they had no significant influence on antioxidant activity.