What is ultra heat treatment primarily used for?

Ultra heat treatment (UHT) is primarily used for processing dairy and eggs. This method involves heating the products to a very high temperature for a short period of time, which effectively kills harmful bacteria and extends the shelf life of the products without the need for refrigeration until they are opened. UHT is particularly beneficial in dairy processing, as it allows products like milk and cream to be stored for extended periods without spoiling, thus ensuring safety and convenience for consumers.

In contrast, the other options do not align with the primary application of ultra heat treatment. Preserving raw vegetables typically involves methods such as blanching or pickling, while heating canned foods is associated with standard canning processes that may not require the ultra high temperatures used in UHT. Dehydrating fruits involves removing moisture to inhibit microbial growth, which is a different preservation method altogether. Therefore, ultra heat treatment's specific focus on dairy and egg processing highlights its effectiveness in ensuring safety and longevity in these products.