The quality of stirred yogurt is determined by texture attributes like appearance, flow behavior, and mouthfeel. In dairy industry, machines like pumps used for the commercial production generate vibrations that can spread to the fermentation tanks. During acidification, such vibrations disturb the gelation of milk proteins by causing texture defects including lumpiness and syneresis. Removal of visible particles by mechanical post-processing will lead to structure losses and lower viscosities. To study the effect of vibrations on yogurt structure systematically, an experimental setup was developed consisting of a vibration exciter (shaker) to generate defined vibrational states and accelerometers for monitoring. Tactile and audible frequencies as occurring in dairies up to 5,000 Hz can be generated. A novel method based on image analysis was established to quantify large particles (d > 0.9 mm) and evaluate textures objectively. Skim milk (3.4% protein) was heated to 95°C for 5 min and fermented in containers (m = 900 g) until pH 4.6. During acidification, containers were put on a table mounted on the shaker and vibrated from pH 5.6 to 5.2 (approximately 20 min). At a frequency of 30 Hz, amplitudes were set to different vibration accelerations up to 25 m/s². After fermentation, set gels were examined first and then processed into stirred yogurt for further analyses. Vibration treatments resulted in set gels with increased whey separation and firmness (P < 0.001). Resultant stirred yogurts showed a positive correlation between amplitude and particle number. Vibrations increased particle numbers from 37 ± 3 (control) up to 144 ± 12 (25 m/s², P < 0.001) particles per 100 g. Yogurts exhibiting a high particle number showed an inhomogeneous texture and a reduced water-holding capacity. Furthermore, the presence of large particles resulted in reduced apparent viscosities (P < 0.001). We concluded that vibrations increase the collision probability of aggregating milk proteins entailing a coarser network structure and stirred products with unfavorable texture properties. Manufacturers should consider vibrations as a further cause for quality defects.