Complex modification of whey protein profile as an approach to the creation of enriched protein ingredients

In the context of the persistent problem of deficiency of essential trace elements such as iodine (iodine deficiency is recorded in 68 % of the world’s population), an urgent task is the development of effective approaches to the creation of food ingredients and products with bioavailable forms of trace elements. In this regard, the work investigated the complex modification of protein profile of milk whey in order to create a protein ingredient enriched with iodine and zinc. Based on the results of a number of studies, the optimal parameters of protein profile modification by thermoselective fractionation in the presence of chelator (58 °C; pH 3.0; mass fraction of chelator 0.2 %; 120 minutes) were determined. The rational conditions of zinc chelation by whey proteins (40 °C; pH 8.0; 60 minutes) were established, providing the maximum concentration of organically bound trace element: 169.8±27.3 mg per 100 g of protein. The protease screening revealed that trypsin provides an increase in the number of functional sites capable of binding iodine, provided that the initial concentration of zinc bound to proteins is maintained. Optimal parameters of protein hydrolysis by trypsin (44 °C; pH 8.0; 180 min) are given. Effective modes of preliminary hydrolysis of zinc-enriched whey proteins (enzyme-substrate ratio 1/100 CPROT g/g; 44 °C; pH 8.0; 165 minutes) and substrate iodization (20 °C; pH 8.0; 12 h) were established, providing the concentration of organically bound iodine 2.5±0.4 g per 100 g of protein and preserving the initial concentration of organically bound zinc. Rational parameters of baromembrane purification of protein matrix from inorganic forms of iodine and zinc were determined for each stage of trace elements immobilization: 3-fold ultradiafiltration for the stage of zinc chelation and nanodiafiltration for the stage of iodination. The obtained results can be used in the development of new functional food products and technologies for deep processing of whey.