The "break" is a very important stage. This is where the tomatoes are heated very rapidly. Tomato paste can either be processed as hot break or cold break. Hot break tomato paste preserves viscosity or "thickness", but at a slight cost of flavor. Cold break paste preserves virtually all the flavor, but at the cost of viscosity. Why? it has to do with enzymes: polymethylesterase, polygalacturonase, and lipoxygenase. Polymethylesterase and polygalacturonase act to break down a chemical called pectin. Pectin is a naturally occurring compound that binds the cells of a tomato together. In the hot break process (hot break refers to heating the tomatoes to approximately 210 degrees F), these "pectic enzymes" are inactivated, inhibiting the breakdown of pectin, creating a more viscous product. However, the enzyme lipoxygenase (vital to flavor) is also inactivated in the hot break process. In cold break tomato paste (heated to approximately 150 degrees F), lipoxygenase "survives," while polymethylesterase and polygalacturonase are not inactivated--bad for viscosity, but good for flavor. Essentially, the "break" is a large cooker, where tomatoes are heated to a closely-monitored temperature.
Temperature is closely monitored.
Each of these pastes can be produced in a variety of configurations, based on concentration, measured in NTSS (Natural Tomato Soluble Solids). For example: 25 percent NTSS paste has 25 percent tomato product and nearly 75 percent water (a ripe tomato is approximately 6 percent tomato solids and nearly 94 percent water). Hot break paste can be produced to have anywhere from 21 percent NTSS up to 31 percent NTSS. Cold break paste is typically produced to 31 percent to 37 percent NTSS. Other measuring factors important to high quality include Bostwick levels (viscosity) and Brix (similar to NTSS, Brix is used more commonly in Europe and incorporates the very small constituent of salt content in its value). The hot / cold break stage, the finisher stage, and the evaporator stage are where Morning Star technicians calibrate the type of tomato paste produced.