I believe it is due to the vacuum created inside the can as the paste cools down.
yes The best-before or use-by date will be printed on the container. The expiry date changes when the container is opened and it becomes necessary to refrigerate the tomato paste and use it within a specific time frame. The refrigerated life of the product will be given on the label.
According to the folks at Contadina...Tomato products can be kept in the refrigerator for 2 to 3 days. Remove the balance of the product from the opened can and place it in a container equal in size to the amount of product. Seal tightly. This reduces the amount of air in contact with the tomato product. Air causes oxidation and the product will turn black. But a little olive oil will also keep the air out.
You should keep foods out of the danger zone to prevent bacteria from forming on foods. Bacteria can form on foods in the danger zone after just an hour. The danger zone is under 145 degrees and over 45 degrees.
An heirloom tomato is an open-pollinated (non-hybrid) heirloom cultivar of tomato.
Yes fungi can be found in canned food that is left open for sometime.
If it's a canned yell, don't open it.
The 'Roma' tomato is not an heirloom. It is however an open pollinated, so it is somewhat like an heirloom, just not old enough to fit the category. 'Roma' is a very good tomato for sauces as is the 'Amish Paste' heirloom tomato. Both of them have very little seed and meaty flesh which is what you want for doing up tomato sauces and salsa.
to open a canned good ;)
use your hands to take a knife and chop the tomato into halves.
Tomato seeds, can be found inside the tomato, when you cut it open. or you could buy them at the store!
open it
canned food dose not give Cancer but if it stays in the can to long after you open it you may get sick