The presence of antioxidants in bioliquids contributes to the preservation of its taste properties and technological qualities, prevents its spoilage for a longer time, which is important at all stages of production and storage. Timely receipt of key data on the «antioxidant activity» (AOA) of bioliquids (e.g. in milk) is very important, therefore, it causes interest in methods for assessing AOA. The general principles for determining the integral AOA are based on "red-ox reactions" and can be implemented by red-ox titration, various biochemical and physico-chemical methods: spectral, electrochemical, coulometric, voltammetric, potentiometric, amperometric and others. Unfortunately, the classification of methods for determining the AOA of milk differs significantly in various sources. Based on a review of the main methods for determining the AOА in biological fluids, the author concludes that the most simple and informative is the measurement of the «total amount of water-soluble antioxidants» (TAWSA) of milk. This is confirmed by numerous publications of Russian scientists, including the team led by the author, regarding the TAWSA A in biological fluids and the data presented in this review on all antioxidant indicators of milk. It is proposed to recommend the definition of such an integral indicator as TAWSA in biological fluids for inclusion in both «current and new technical conditions and recommendations for assessing the quality of the corresponding food products».

Dr. Zaitsev has completed his PhD at the age of 21 years from Moscow State University and postdoctoral studies from Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry (Russia). He is the leading scientist in L.K. Ernst Federal Research Center for Animal Husbandry (Russia). He has 920 publications (2428 citations), including 15 monographs, 12 patents, etc., supervises 22 Ph.D.-students, 100 Magister-students. Selected publications (Q1): 1. Animals 2023, v.13, 852. https://doi.org/10.3390/ani13050852 2. Molecules 2022, v.27, 2278. https://doi.org/10.3390/molecules27072278 3. Animals, 2021, v.11, 2400. https://doi.org/10.3390/ani11082400. Dr. Zaitsev is a member of the Russian Ministry Board of Experts and in various Russian Science Foundations.