Quantitative Analysis of Perceived Saltiness through Combination of Sensory Evaluation and Electronic Tongue and its Method Validation

A quantitative analysis of perceived saltiness was established by combining sensory perceived NaCl concentration with electronic tongue salty response. Saltiness index (SI) was defined as the ratio of perceived NaCl concentration to the actual NaCl concentration, and was proposed to evaluate the saltiness enchantment. Method validation of the saltiness sensor included assessments of linearity, repeatability, reproducibility, limit of detection, limit of quantitation, and recovery yield. A desirable linear relationship between the logarithm of perceived NaCl concentration and saltiness was observed at NaCl concentration ranging from 45 to 90 mM with a determination coefficient exceeding 0.99. A low relative standard deviation of less than 1% was achieved in the repeatability test. Through visual evaluation, the detection and quantitation limits of the saltiness sensor for NaCl solutions were determined to be 0.01 mM and 0.1 mM, respectively. A high recovery yield (97.6–108.3%) was obtained from the spike recovery test. Optional test solvents, including ultrapure water, distilled water, and pure water, were employed without interference. Upon adding 20–35 g/100 g potassium chloride, the salty response of the salt solution increased, while the linearity of NaCl solution remained unaffected. Saltiness enhancements of 37.20 ± 0.00% and 18.17 ± 0.18% were observed for the potassium-containing salt (30%, w/w) and oyster mushroom (Pleurotus ostreatus) peptides (0.3%, w/w), respectively. This evaluation method provided an effective and quantitative approach to advancing the development of salt reduction ingredients.