1994 Volume 41 Issue 11 Pages 803-809
The steam injection type direct heating sterilizing method is a typical method among sterilizing operations for liquid foods, together with the plate type indirect heating method. In addition, sterilization is a vital operation for food production and a research on the certainty of this sterilizing method has been required. Despite those facts, however, the phenomena that steam injected at high speed into liquid foods abruptly mixes followed by condensation, and that heating to the sterilizing temperature and holding for the required time are performed in a holding tube, have been rarely studied. Accordingly, the sterilizing efficiency resulted from these phenomena can hardly be determined beforehand. Therefore, a steam injection type sterilizing machine for experiment was assembled using a single nozzle which has been used typically. The details of uneven temperature distribution in the holding tube were measured with multi-points and real-time measuring method as well as velocity variations. In this way, the negative effect of these factors on the sterilization was examined. Moreover, similar measurements were carried out on a practical machine, and reproducibility and variation of the sterilizing effect due to the machine size were investigated.
