Saliva and taste are connected because saliva secretions are needed to carry food molecules to the corresponding receptors in the taste buds. Normal saliva softens food so that it can be swallowed easily. It also breaks down the structures of different foods and releases these molecules. The tongue contains clusters of taste buds that pick up salty, sweet, bitter, and sour flavors. When a flavor molecule binds to a taste bud receptor, signals that identify each different flavor are sent to the brain.
The majority of healthy human saliva is made up of water, but it also contains important enzymes that dissolve the complex chemical structures of various foods. Saliva and taste both have key roles in the ability to identify various food textures such as grainy or smooth textures. An enzyme called salivary amylase helps break down starches from foods such as breads and rice, and scientific studies have shown that different people have varying levels of this enzyme in their saliva. One person with higher levels of salivary amylase will often have one perception of a certain food's taste and texture. Someone else with lower levels of this enzyme can possibly have quite different taste and texture perceptions of the same food.
An interaction of saliva and taste is also connected to the burning sensations that people feel in their mouths when eating very spicy foods such as peppers or certain sauces such as horseradish or wasabi. These kinds of foods register as hot and even painful because saliva acts as a catalyst between pain receptors throughout the mouth and molecules from food chemicals such as capsaicin found in chilli peppers. This catalytic action also makes the release of endorphins possible in the brains of people who like to eat these types of spicy foods. Sensitivities to these spicy tastes are usually considered hereditary.
Saliva and taste are linked to the nervous system as well as the sense of smell in order to register specific tastes whenever someone eats any type of food. A common sign of illness or injury affecting the ability to taste and smell is abnormal saliva production or thickness. Salivary glands can sometimes develop cysts from injuries to the sides of the face where the glands are located. Frequent respiratory infections and the development of benign nasal growths called polyps can also contribute to losses of taste even when saliva secretion is normal.