Demonstration of anti-oxidant properties of mustard seed (Brassica juncea) protein isolate in orange juice

Previous research has shown that formulated and natural beverages containing mixtures of anti-oxidants can produce stable levels of hydrogen peroxide (H2O2). The aim of this study was to demonstrate the ultimate anti-oxidant effects of proteins for suppressing H2O2, using a protein extract from mustard seed (Brassica juncea). The mustard seed protein isolate (MPI) contained similar to 51% protein, and 6.4 mg GAe/g TS of total reducible substances, presumably representing secondary metabolites, including polyphenolics. Dose-dependent suppression of H2O2 (present at 110 mu M and 550 mu M), in fresh and thermally-processed orange juice was complete in the presence of 0.1 mg/mL MPI after 24 hr, with slightly higher anti-oxidant efficacy than the fruit juice-derived reference protein, thaumatin. The combination of thiol-rich amino acid (methionine and cysteine)-containing proteins and other anti-oxidant species in the MPI were highly effective for inhibiting autoxidation-mediated production of H2O2 in orange juice, and may be useful for other manufactured beverages.

Automated summary

This study aimed to demonstrate the ultimate antioxidant effects of protein extract from mustard seed in suppressing hydrogen peroxide (H2O2). The results showed that the mustard seed protein isolate (MPI) could completely suppress the production of H2O2 in orange juice, with slightly higher antioxidant efficacy than the reference protein thaumatin. The thiol-rich amino acid-containing proteins and other antioxidants in MPI were highly effective in inhibiting the autoxidation-mediated production of H2O2 in orange juice and could be useful for other manufactured beverages.