To achieve microbial stability in hot-filled foods, several barriers to growth can be used such as initial heating, low water activity, antimicrobials, low pH, etc.
A pH below 4 is effective in obviating sterilization. Acidic foods can be packed and sealed while hot enough to kill organisms that would survive that pH at lower temperatures during brief storage. To achieve this, a pH of 4.6 or lower and temperatures greater than 155 °F (68 °C) are required.
High levels of cross-linking are necessary due to the low pH and because the hot package is allowed to cool slowly. The need for high levels of crosslinking in acidic hot-filled products may require the use of specific types of starches that can provide the desired texture and stability.
Hot-filled products include tomato sauces, salad dressings, and fruit pie fillings. However, white sauces and cream pie fillings cannot be hot-filled because of their higher pH.