At present, the magnetic treatment of microorganisms in the food industry is gaining more popularity. The aim of this work lies in the design and construction of a magnetic device, which consists of a magnetic system, formed by permanent magnets of rectangular shape, which are distributed and confined in a non-ferromagnetic, annular structure; that contributes: to the growth of lactic acid bacteria (LAB), the pH, the acidity, the morphology of the cells, the symbiotic relationship with an increase in the cell concentration and viability of the yogurt culture to 96%, maintaining the parameters quality of the final product.