the effect of different deheating processes on residual myrosinase activity, antimicrobial properties and total phenolic contents of yellow mustard (sinapis alba)

abstract: mustard is a natural multi-functional additive with strong hot flavor. in this research, powdered yellow mustard (sinapis alba) was heated by 21 different thermal processes, statistically designed by response surface methodology to evaluate the effects of combinations of heating media (hot air, hot water and steam) and heating time (0-20 min) on residual myrosinase activity, the minimum inhibitory concentration (mic), color characteristic and also the major phenolic constituents of each treated sample. the optimum process, for the desirable function was 5 min of heating by hot air. under optimal conditions, myrosinase activity was reduced by 44%, mic and lightness (l*) were approximately unchanged, redness (a*) and yellowness (b*) were increased as compared to the control. in spite of the fact that the  total phenolic content were reduced severely (>90%) due to deheating processes, but the chromatography spectrum indicated that some compound (caffeic acid) were newly formed or existed in higher concentration (sinapine) particularary in steam treated samples.