Saltiness Enhancement Through the Synergism of Pyroglutamyl Peptides and Organic Acids

Excess sodium consumption has been linked to various health risks. The use of taste modulators may be a promising strategy to reduce the salt content in low-sodium foods yet maintain salty perception. Previous research has confirmed the subthreshold synergistic effect among pyroglutamyl dipeptides on saltiness enhancement; however, no studies have been published on the subthreshold synergistic effect of mixture of pyroglutamyl peptides and organic acids. This study aimed to explore the subthreshold synergistic effect of pyroglutamyl peptides and organic acids on saltiness perception. Specifically, pyroglutamyl dipeptides (pgluE and pgluV), pyroglutamyl tripeptides (pgluVL and pgluVC), and organic acids (malic acid and succinic acid) were explored in model system and subsequently in a commercial brown onion sauce. First, the detection threshold of pyroglutamyl peptides (pgluE, pgluV, pgluVL, pgluVC) were determined to be 646 μmol/L (167 ppm), 77 μmol/L (18 ppm), 273 μmol/L (93 ppm), and 221 μmol/L (73.2 ppm) respectively. Next, the subthreshold synergistic effect of the pyroglutamyl tripeptides and organic acids was determined using the isobologram method. One of the eight combinations of pyroglutamyl tripeptides with pyroglutamyl dipeptide (pgluV) showed subthreshold synergistic effect, whereas four combinations of pyroglutamyl tripeptides with malic acid and one combination of pyroglutamyl tripeptides with succinic acid exhibited subthreshold synergistic effect. Later, we conducted a triangle test to determine the maximum achievable salt reduction in a commercial brown onion sauce, accomplishing a notable 20% reduction in salt without the introduction of any supplementary ingredients. Subsequently, we achieved an additional salt reduction in the brown onion sauce by 5% and 10%, through the synergistic combinations of pyroglutamyl tripeptides with malic acid and succinic acid, respectively, resulting in an overall salt reduction of 25% and 30% respectively. This research lays the foundation for future investigations into the potential of combinations of pyroglutamyl peptides and organic acids for saltiness enhancement in low-sodium foods.