Toward the Upgrading Quality of Drinking Water from Flavor Evaluation: Taste, Feeling, and Retronasal Odor Issues

Sensory property (taste and odor, T&O) has become an essential factor in the assessment and selection of drinking water. In addition to odor issues, the taste of drinking water has also drawn consumers' attentions for causing a lot of misunderstanding and damage to the impression of the public water supply. In fact, the general concept of taste refers to the involved sensations in the tasting process, including taste, feeling, and retronasal odor (jointly called flavor). As an integral part of the drinking water sensory issues, the flavor issues that relate to both volatile and nonvolatile components have received inadequate attention due to the underperformance of a tasting panel and stricter ethical principles for tasting tests; even the flavor threshold for certain substances is lower than the odor threshold. To motivate research that can overcome these challenges, this paper provides an in-depth clarification of relevant concepts and an overview of the predominant and potential substances affecting flavor, as well as a modified wheel for the tasting test. Additionally, considering the current reliance on sensory panels, recent advances in evaluation methodologies have been critically evaluated, with particular emphasis on in vitro approaches. At last, this review proposes future prospects in four major aspects, with upgrading strategies for drinking water quality. It is hoped that this review both illustrates the current state of this field and stimulates further research.