In the manufacturing process of long shelf-life yogurt, there are many factors that may affect its quality, including pasteurization temperature and time, the homogenization degree of stirred mixtures, and filling temperature. The shelf life of yogurt can be extended by choosing a proper pasteurization temperature and time taking the product quality into account, and its texture can be improved by selecting a suitable homogenization approach, which is also beneficial to more uniformly heating yoghurt during sterilization, avoiding the collapse of the system. The recovery of yogurt viscosity can be affected by filling temperature. A proper filling temperature should be selected to reach the requirements of quality design during the manufacturing of yogurt.

This study researched the effect of homogenization and post-sterilization of shelf-stable yoghurt the morphology of modified starch granules as one of its ingredients. It was demonstrated that with increasing either homogenization temperature or pressure, more starch granules were broken down. The optimal homogenization temperature was between 60 and 63 ℃ and the optimal pressure was in the range of 15–20 MPa. The starch granules further swelled under line pressure during ultra high temperature (UHT) processing, and they gradually enlarged or even cracked with an increase in either line pressure (up to 7 bar) or reflux cycles. Increased temperature up to 80 ℃ during UHT processing resulted in breakdown of more starch granules.

This study investigated the gelatinization properties of three types of modified starch and their application in long shelf-life yogurt. The three types of modified starch were physically modified starch (PMS), acetylated distarch phosphate (ADSP), hydroxypropyl distarch phosphate (HDSP). The results showed that the granular structure of the three kinds of starch remained intact after gelatinization. They all had strong shear resistance, and ADSP and HDSP showed stronger shear resistance and higher gelatinization temperature than PMS. Adding 2% (m/m) modified starch in long shelf-life yogurt increased its apparent viscosity, water holding capacity, viscoelasticity, yield stress, and storage stability. ADSP was better to improve the quality of long shelf-life yogurt than HDSP and PMS.