Table 1.

Overview of the direct approaches to assess taste loss in participants.

				Taste Quality Measured
Test	Article	Test Method	Test Objective	Salty	Sweet	Sour	Bitter	Umami
Four-solution test	Vaira et al., 2020a–2020f Petrocelli et al., 2020A	1 mL of each solution, plus deionized water as control, placed on the participant’s tongue via cotton swab. Quarantined patients prepared their own solutions.	Identification	☑	☑	☑	☑	⨆
Four-solution test & Taste Strips	Altin et al., 2020 Salcan et al., 2021	Participants swallowed and identified the solution. Next, paper strips dipped into each solution and placed on the participant’s tongue.	Identification Duration	☑	☑	☑	☑	☑
Two-solution test (1)	Bidkar et al., 2020	Two drops (2 mL) of each solution placed on the participant’s tongue via pipette.	Identification	☑	☑	⨆	⨆	⨆
Two-solution test (2)	Mazzatenta et al., 2020	200 μl of each solution dropped onto participant’s tongue.	Detection	☑	☑	⨆	⨆	☑
Taste Strips by BMGB	Hintschich et al., 2020 Singer-Cornelius et al., 2021 Le Bon et al., 2021 Niklassen et al., 2021C	Taste strips (provided by Burghart Messtechnik GmbH) placed on the participant’s tongue.	Identification and threshold concentration	☑	☑	☑	☑	⨅
Taste sprays	Niklassen et al., 2021C	Each solution sprayed onto participant’s tongue.	Identification	☑	☑	☑	☑	⨆
Tastant capsules	Adamczyk et al., 2020	Each of ten 0.33 mL gelatin capsules (one tasteless and nine with tastant) dissolved on participant’s tongue.	Description	☑	☑	☑	☑	⨆
Brief Self-Administered Waterless Empirical Taste Test (SA-WETT)B	Cao et al., 2021	27 disposable plastic strips that contain dried solutions of each taste (and some tasteless strips) self-placed on participant’s tongue.	Identification	☑	☑	☑	☑	☑
Chemosensory Test by India Protocol	Ramteke et al., 2020	Authors used coconut oil, chocolates, and flavored milk to test smell and taste function. No further details are provided.	N/A	N/A

^AThese studies used a sweet solution concentration that is double what was used in the other four-solution tests.

^BValidated test.

^CNiklassen et al. (2021) used both Taste Strips and taste sprays with participants.