The salt is just for flavoring in this case. You can leave it out.

As to the amount of tomatoes - unless someone has actually weighed a cup of crushed tomatoes and knows its weight you will need a scale to weigh your tomatoes (the loss of the skin weight is negligible). Even a bath scale or postal scale will work.

Some will claim 2 cups (16oz) will equal a pound - the old "a pint's a pound the world around" saying. But that isn't really accurate. A cup is a unit of volume and an pound is a unit of weight. You'd need to know the specific density of what you're measuring to make an accurate conversion and the density of crushed tomatoes is much higher than that of water.

If you simply can't weigh them anyway then I suggest this compromise form of measuring: because of the additional liquid your thawed frozen tomatoes will have in them, drain them first (otherwise it means much more cooking down time) and use roughly 1 1/2 cups of them to equal 1 lb. It won't be a really accurate conversion - may be a bit heavy-on-the-tomatoes side but since the seasonings in ketchup are to taste anyway, it should be close. Taste frequently as you cook it down and have a couple of extra jars ready to go too.

Dave

This is why it is considered unsafe to use precanned or prefrozen tomatoes. It would have been OK if you had weighed them before freezing. Now it would just be a guess as to how many to use.
Elizabeth Andress at the Univ.of Georgia, who wrote the USDA guidelines is who I got this information from.

Thanks, Dave...I think I can manage weighing them. I wish recipes were consistent...some of the recipes call for "cups" of tomatoes; now that I can handle.

And it's really good news about the salt! We go through a lot of ketchup/barbecue sauce so this was definitely an issue when we found out about the low salt diet.

I wish recipes were consistent...

Don't we all. :) But Linda Lou is right about potential safety issues when one gets into guessing at amounts. It isn't so much an issue with the ketchup because it is well acidified with all the vinegar.

But for future reference a kitchen scale is a great item to have and relatively inexpensive. If you are going to freeze them be sure to measure the cups in the container and weigh it too and mark the containers. That way all the bases are covered. ;)

Dave

You can get a 11 pound 5000 gram digital kitchen scale accurate to 1 gram for $6.24 including shipping. Great scale. on Ebay. also linked at the bottom

http://shop.ebay.com/i.html?_trkparms=65%253A12%257C66%253A2%257C39%253A1%257C72%253A4026&rt=nc&_nkw=digital+scale+5000&_sticky=1&_trksid=p3286.c0.m14&_sop=15&_sc=1

A pound of tomatoes before freezing is the same pound after freezing and will be the same pound after thawing out.

Saying you had to weigh them ahead of time is ridiculous on its face. the weight does not change. It does cook down as it loses water but so what. the 24 pounds is just an approximation anyway. The idea is simply to make the ketchup as thick as you like it. If you like it thicker then make it thicker with more tomatoes or tomato paste. it does not matter one bit.

If you cook away half the water then the weight goes down to half. if you estimate you cooked it to 60% then use that figure. math is simple. 60% of 24 lbs is 14.4 lbs.

water weight is 8.5 lbs/gallon thus most watery food is about the same. meaning tomato juice will be about the same. so 16 liquid oz will be 8.5/8= 1.06 pounds if the tomatoes are thick maybe figure 1.1 lb/pint or 16 oz. close but not too bad for some estimates. would be way off on dry solids like salt. but ok on watery stuff like milk. For salt the weight of the pint would be much higher and way off.

I never add salt to anything. It is never needed. It does not preserve. Acid vinegar preserves. Salt simply is poison.

Stop being a slave to recipes. All tomatoes are different so all recipes must be different. but since they are the same the recipe is wrong. Just make ketchup and add a little vinegar and enjoy. make it as thick as you want. the easy way to make tomatoes thick is to add tomato paste. instant thicker tomatoes.

Also consider adding a little lemon or lime juice for acid instead of in addition to the vinegar.

I have never in 40 years of canning ever added salt to anything and all my canning has been perfectly fine. I also never follow any recipes and it all works just fine for me because I use common sense.

Here is a link that might be useful: digital scale

Hi, I posted back to you last night but "message rejected", said I had to change subject line. (???) Here goes again!

Thank you for the "heads up." Now I will know to do things differently this summer when putting up the tomatoes; will weigh them before freezing!

I have read many of your posts & really appreciate you taking the time to help us inexperienced canners!

Yes I think we will invest in a kitchen scale; sounds like a good idea.

Safety is the #1 issue for me because I just got started canning last summer & there is so much to learn. With all the work involved, from seed starting to transplanting to growing to harvest, it just isn't worth taking chances. I've seen posts on here where people had to throw out their canned goods...I would cry inconsolably I am sure!!

Thank you for all your hard work on this forum; I've been reading your posts for over a year now & you deserve many thanks!

Great tasting recipe make it all the time
Dave's idea will work fine every recipe is an approximation no mater how some people interpret them for example your yield is 6 or 7 pints cook down to half or until its thick enough etc as long as your working within the general parameters a cup of tomatoes isn't going to mater with all that vinegar although it would defiantly help to premeasure before freezing

Catsup takes quite a while to boil down I like to use a crockpot so it can simmer all day

Thank you so much for the link to the kitchen scales; I had no idea they were so inexpensive!

Hi Jonas, thank you for letting me know that it is a good recipe; will be trying it soon!

Question: (probably a stupid question but...) when you use the crockpot to cook down, do you cover it like normal or leave it uncovered? tia

Hi,
Another good way to do tomato things is in the oven, uncovered. If you cover things they will steam and not reduce down as quickly as you will want.
I prefer a digital kitchen scale. I got my Salter one at Bed Bath and Beyond. Here I get coupons for 20 % off and use them for items such as the scales. I got one for my daughter, too. I like how compact mine is, thin and nice.
So, you can buy the $7 one or spend more and get a different type. It is up to you.
I would not suggest doing as someone else said and basically make up your own recipes.. density and ph are both really important in canning. Salt is only needed if you are fermenting or making jerky. Otherwise you can leave it out.
Glad you are learning to can at home. Do you also dehydrate, etc. ?
So much to do, so little time !! Have fun !

Yes, do please ignore comments like:

If you like it thicker then make it thicker with more tomatoes or tomato paste. it does not matter one bit.

I never add salt to anything. It is never needed. It does not preserve. Acid vinegar preserves. Salt simply is poison.

Stop being a slave to recipes. All tomatoes are different so all recipes must be different. but since they are the same the recipe is wrong. Just make ketchup and add a little vinegar and enjoy. make it as thick as you want.

I have never in 40 years of canning ever added salt to anything and all my canning has been perfectly fine. I also never follow any recipes and it all works just fine for me because I use common sense.

They are terribly misleading and potentially unsafe.

Dave

Hmm, common sense ? Ok, whatever you do, it is your decision, but we sure want to teach especially new people to do things 100 % safe.

Cover off with the crockpot and yes oven is a good idea too I bring the crockpot out to the shop and keep an eye on it while I work

Agree on the oven, Linda, I cooked down tons of tomatoes in the oven this past summer, before freezing.
I will do some research on the kitchen scales before buying, for sure.

Question: what about when canning (bwb) pickles? Those recipes, for the most part, seem to call for a lot of salt. My husband loves pickled okra; hate for him to have to give that up!

Funny you asked about dehydrating: I asked for & received a dehydrator for my birthday back in Sept.! But it is still in the box; has been too much going on to figure out how to use it. But before this summer's harvest, I have to figure it out! My SIL uses her dehydrator all the time; loves it.

I would love to take canning classes; will have to check & see if any are offered around here. I remember when I was growing up, in the summertime they would open up the school cafeteria kitchen for people to come in and can. (Those days are long gone, though...)

Only when you ferment pickles do you have to use salt. Otherwise it can be left out.
You can download a nice drying publication from Univ. of Idaho. I cannot send the link as it is a PDF file and it won't let me !
If you search online for the Univ. Of Idaho drying fruits and vegetables you should easily find it. Same publication we sell and also use in our training classes here. Very nice publication.
If you want to dry meat, the only safe way is to use a current recipe and method. No eggs, seafood, hamburger, etc. are safe to dry. I know a few people who do dry hamburger and a few that do shrimp, but it is dangerous.
Why would someone take risks like that ? I have never figured out why people try canning and drying things that are deemed unsafe. You should hear some of the stories I have heard over the years !
Someone tried canning mayonnaise, even ! They showed me a picture of the results. A terrible oily, seperated mess !
I tried to tell them..

Hi, Yes I have already learned enough here to disregard some comments. To each his own, for sure, and yes this is a message board, but when it comes to food safety I don't think one can be too careful. Just because it "always worked" doesn't mean it is safe. IMO

As an example: at holiday meals at my grandmother's house, turkey and fresh ham & dressing were always served. We would have our meal at noon, and all that food would be covered after we were finished, and would sit on the counters or in the pie safe till that evening, when we'd eat again. I don't remember anyone ever getting sick in all those years.

But would I do that today? Would you? Would anyone? I don't think so! At least I hope not!

I totally believe in keeping traditions & in learning from our elders, but at the same time, continuing to educate ourselves, in my opinion, is just "common sense."