it is the amount of dried solids in tomato paste. Generally it is between 28-30 percent of dry solids. For the consumer aspect it means about 6 kg. of fresh tomato is used for 1 kg. of tomato paste.
The viscosity of tomato paste is called Bostwick. The type of tomato used and the process defines the Bostwick value.
There is natural salt (sodium) in tomato around 0.8 %.
The colour of tomato comes from the caratenoids. The proccess type and the quality of tomato is also important for the colour quality of tomato paste.