Abstract: The effects of ten bitterness inhibitors, namely zinc lactate, neohesperidin dihydrochalcone (NHDC), γ-aminobutyric acid (GABA), sodium caseinate, fat milk, ferulic acid, polydextrose, sucrose, neodiosmin and AMP on the bitterness, delayed bitterness, sweetness, delayed sweetness, astringency and flavor of bitter melon powder suspended in water were studied systematically by the general labeled magnitude scale (gLMS). The synergistic effects of three selected inhibitors on the bitterness and delayed bitterness were also explored. The results indicated that all ten inhibitors had an inhibitory effect on the bitterness, delayed bitterness and astringency of bitter melon. NHDC was more effective than were other inhibitors in inhibiting the bitterness and delayed bitterness, followed by zinc lactate for delayed bitterness and GABA for bitterness. Sodium caseinate was the best inhibitor for the astringency. Sucrose, polydextrose, sodium caseinate and milk could increase the sweetness and delayed sweetness of the whole system. The results of orthogonal array design showed that zinc lactate could affect the bitterness significantly. By adding NHDC, GABA and zinc lactate at 0.60, 3.98 and 4.46 mg/g of bitter melon powder, respectively, the bitterness and delayed bitterness were effectively decreased to almost no perception while maintaining the characteristic flavor of bitter melon without off-flavor.

Key words: bitterness, inhibitor, Momordica charantia, sensory evaluation