DescriptionAccording to the global health risks report(2009), insufficient intake of fruit and vegetables was estimated to cause around 14% of gastrointestinal cancer deaths, about 11% of ischemic heart disease deaths and about 9% of stroke deaths worldwide (Mathers, Stevens et al. 2009). Anthocyanins, a major type of phytonutrient in berry, are considered to be able to provide the positive effect on health and it has been drawn great attention by institution and food industry. Thereby, it is significant to concentrate the anthocyanins into food matrix by an efficient method. This study covers the adsorption process of the cranberry juice anthocyanins by soy protein isolate (SPI). Provided results indicate that the soy protein isolate can effectively adsorb the anthocyanins and can be used for successful extraction of it from the low acid juice matrix. The adsorption capabilities of the SPI are tested at various temperature and pH values. It is found that the optimal processing condition for the adsorption is with 45℃ at pH 7. Particle size and zeta potential of the SPI are investigated, and the results of conformational changes in soy protein as the processing conditions vary describe the mechanism of adsorption. Chemical changes in vibrational spectra of soy protein and anthocyanins are monitored. Mathematical modeling of the adsorption equilibrium reveals that both Langmuir and Dubinin–Radushkevich isotherms well describe the adsorption equilibrium of anthocyanins onto soy protein isolate, and process kinetics follows the pseudo-first order. The mean free energy of adsorption per molecule of adsorbate (i.e. anthocyanins) is equal to 1.96 kJ/mol, which corresponds to an electrostatic physicosorption nature of anthocyanins–soy protein interaction. Proposed processing method for the extraction of health-promoting phytonutrients from cranberry juice by plant protein matrix can be applied for wide range of juices and extracts and used for development of new high value food products.