Canned Tomatoes and Thiamin

Spencer_007

I have been wondering
Every time that I load up canned tomatoes
I vacilate between simply canned and crushed
Whilst noticing curiously that the canned tomatoes listed have a really high Thiamin level
155% per cup
Anyone know why this is?
Canned crushed is just 15%

Karen_Cronometer

Hi Spencer_007,

I have looked into this before! Canned tomatoes are generally made from the whole tomato in juice, while crushed tomatoes are made from stewed tomatoes with concentrated tomato paste added. So there is more tomato and more heat treatment in crushed tomatoes.

The extra heat is the cause for the difference in thiamin content - it is degraded by heat.

Best,

Nony_Mouse

Hi Karen,

The canned tomato listing is wrong. While your explanation of heat degradation being the reason for there being less thiamin sounds good, the food would have to be high in thiamin to start with. Logically, a food that has only a small amount of thiamin (fresh tomato), is not going to increase exponentially due to canning.

No other food database (USDA, New Zealand Food Tables, for example) give canned tomatoes this crazy high reading. It is very obviously an error.

Karen_Cronometer

Hi there,

These values come from the USDA - I've contacted them to see if they can provide the reference for these values and let you know when I hear back.

Nony_Mouse

Thanks Karen, they'll give you the FDA's phone number, that's what they did to me.

Karen_Cronometer

Hi Nony_mouse,

They provided the data they have for canned tomatoes:
The sample size was 4 values with high variability ranging from 0.081 to 1.66mg/100g and a mean thiamin value of 0.575mg/100g.

So the thiamin value varied by a LOT between the 4 samples that were used. They also acknowledged there may be more recent data available in peer-reviewed literature. I haven't found anything yet; using NUTTAB might be a better source to use in this case.

Nony_Mouse

Thanks Karen

Still highly skeptical that 1 cup of canned tomatoes can have the thiamin level of 4kg of fresh! There's not a suitable alternative in Cronometer, so I'll just create a custom entry and use the value from the NZ Food Composition Tables.