20.500.12556/DKUM-96748 Osmolality and tonicity of isotonic beverages This study aimed to measure and compare the osmolality and tonicity of isotonic beverages that can be bought on the Slovenian market. The main goal was to examine how good is the agreement between the measured osmolalities of the beverages and the requirements for isotonic beverages set up by EFSA. Osmolalities were measured with an osmometer using the freezing point depression method. Afterwards, two complementary methods for the observation of tonicity were developed. Erythrocytes were exposed to standard NaCl solutions of different osmolalities to observe their influence on the volume and shape of cells following the turbidity of the solution and the morphology of erythrocytes. These two methods enabled us to determine whether standard solutions were hypo-, iso-, or hypertonic. In this way, we found that the osmolality of 12 out of the 18 investigated isotonic beverages was in the range of 270–330 mOsm/kg, as required by EFSA. However, six samples did not meet this criterion and should therefore not have the label “isotonic” or be described as such. The measurements of turbidity of solutions indicated that most isotonic beverages exhibit a lower tonicity than standard NaCl solutions of identical osmolality. However, examination of the erythrocytes in isotonic beverages showed that the measurements were additionally complicated by the low pH values of these beverages. Finally, by demonstrating how different components of isotonic beverages pass through the erythrocyte membranes, we found that even isoosmolal beverages are often not isotonic, as the concentration of actively transported sugars in these beverages is relatively high. hydration osmolality tonicity isotonic beverages erythrocytes hidracija izotonični napitki eritrociti true false true MDPI Angleški jezik Slovenski jezik https://www.mdpi.com/journal/foods © 2024 by the authors Članek v reviji 2026-01-27 11:29:20 2026-01-27 11:29:24 2026-01-28 03:13:08 0000-00-00 00:00:00 2024 0 0 15 str. iss. 10, [article no.] 1483 Vol. 13 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 2024-04-10 2024-05-07 2024-05-10 544.352.4 195130883 10.3390/foods13101483 2304-8158 foods-13-01483-v2.pdf foods-13-01483-v2.pdf 1 A33E405AAE7988D26B4FABBE58313B34 d24b0ebbd47586f662b30fc2663e2c4bdf88a5ca92274a77186aaaaaf3463e76 c4c6519a-fb6b-11f0-9c79-00155d00018d https://dk.um.si/Dokument.php?lang=slv&id=202615 https://www.mdpi.com/2304-8158/13/10/1483 1 0e8a9e11-fb6b-11f0-9c79-00155d00018d https://dk.um.si/Dokument.php?lang=slv&id=202614 Fakulteta za kemijo in kemijsko tehnologijo Medicinska fakulteta 0 0 0