This morning while making ketchup I grabbed the camera to take some pictures so you can see how it's done. I have this unique contraption called the "Sauce Master" which separates the skins and seeds from the pulp. (The kids "squished" 1 1/2 bushels of roma tomatoes and I got 20 quarts from them.) I divided up the pulp into 2 stock pots on the stove, one was a 8 quart and the other a 12 quart. Keep some pulp set aside for use later on in the recipe. Get your pulp boiling, you want it to boil for about 1 hour.
A word of caution when cooking tomato pulp: Before you have a nice rolling boil, ALWAYS have 1-2" of room left in your pan. DO NOT over fill!!!! I can't stress this enough!!! What happens when you cook the pulp is the heat pushes up the pulp while heating and you could end up with a really big mess!!! Once it gets to a rolling boil, you'll notice a "hole" in the pulp and steam coming out...this is good. Now the chances of it boiling over has decreased drastically. If using other tomatoes rather than romas, you'll need to boil a little longer and add some more pulp.
You'll notice that you are getting a little room in your stock pot to add some more ingredients...add 1/4 c. pickling spice, 2 T. cinnamon, 1 T. allspice and 1 T. cloves. I add the spices right to the pot...some recipes tell you to make a spice bag for the pickling spice. It's a matter of choice and later on you'll see how I "dissolve" the pickling spice. :) You'll also want to take 2 c. vinegar and put into your blender and add 3 large onions. Blend really well so no chunks are visible. If you are having some troubles you can add some of your reserved pulp so blending goes easier.
Pour this into your cooking pulp. Add 2 c. sugar also to your pulp. About now the kitchen smells really good. Cook for about another hour. Take your reserved pulp and put into your blender, add 1 c. clear jel or perma flo. I personally like clear jel but not the instant. This is also the thickener that manufacturers use. Perma flo is used more in pie fillings but it does work in ketchup. :) DO NOT use corn starch!!! Corn starch is for gravy not canning. If you've ever made gravy using corn starch you'll know what I'm talking about when you get the left overs out of the fridge it just doesn't look right anymore...you don't want that in your canning. Also, do not use flour! Same type of situation. Slowly add the clear jel mixture into the ketchup while stirring. If you see that you're ending up with "dumplings" grab a stick blender and start blending. If you don't have a stick blender your counter top blender will work but be careful of adding hot liquid to your blender. Also, blend if you see some spices or lumps that you aren't happy with. You'll need to boil a little while longer to get the clear jel to work, just remember...it will thicken as it cools. Now ladle into clean hot canning jars. Process in a hot water bath for 30 minutes for pints and 40 minutes for quarts.
Congratulations!!!! You just made the best ketchup for your family.
NOTE: the measurements used are for the 8 quart stock pot when adding the spices, vinegar and sugar. You'll need more for a 12 quart stock pot. I just had a bunch of tomatoes to do this morning so I had both going. So for the tomatoes you'll need a little more than a 1/2 bushel of romas for the 8 quart pot.
When reading ketchup recipes they vary a lot. I've seen some with more sugar and more vinegar, less spices...it really matters as to what your family likes and eats.