The culinary products readiness is largely determined by organoleptic characteristics. Culinary processing can both improve and degrade the quality of products. Prolonged cooking increases the weight loss and nutritional value of the product. These losses are less while using the sous-vide technology, however, there are limitations in its use, which determines the relevance of the research, including morphological ones. The analysis of morphometric changes was carried out at two temperatures: 70 and 100 ⁰С. Samples of beef meat were removed out of the cooking medium every 15 minutes and the structure of muscle fibers was studied by microscopy. Visible transverse slit-like disturbances and fragmentation of the muscle fiber were observed sous-vide meat cooked, 25-30 minutes later than in meat at 100 ⁰С. The work noted that the sarcoplasm of the muscle fiber is more susceptible to high temperatures. Its decrease was observed, while cooking, which affects the volume of muscle fiber, lower their hydrophilicity and, as a result, increases the rigidity of the finished product. The following meat structure softening and the increase in organoleptic parameters is associated with the destruction of the muscle fiber, its fragmentation. Sous-vide meat is less of destruction, which helps the meat retain moisture - thus keeping it juicy. Analysis of the muscle fiber destruction at 100 °C showed the presence of numerous breaks, defragmentation and graininess and, as a result, more loss of sarcoplasm after 3 hours of cooking, which was not observed in the sous vide samples during the same time. This fact provides a partial explanation for the preservation of meat juiciness during long-term vacuum cooking at 70 °C.