I should be able to type "Rosella Condensed Tomato Soup", and it finds the right product for me and tells me that it has:
Serving size 245.0g
Servings per package 4
... and I ate a whole can, meaning I ate 4 servings.
So, I set off looking around for things which already did this.
Update: Bigfoodlist is almost exactly what I want.
Apparently, you can get information from a bunch of sources, like Foodstandards.gov.au or the USDA; but after just a little bit of clicking my eyes bled from the web 1.0 of it all.
Finally, I find where I can get information in CSV form - by emailed request.
This work is copyright. You may download, display, print and reproduce this material in unaltered form only (retaining this notice) for your personal, non-commercial use or use within your organisation.
Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from Food Standards Australia New Zealand (FSANZ).
Requests and inquiries concerning reproduction and rights should be addressed to the Information Officer, FSANZ, PO Box 7186, Canberra BC, ACT 2610 or email firstname.lastname@example.org
I feel so very backwards that there isn't a simple, universal product database which stores this information.
This is the kind of thing I want from the semantic web - government data I can query so that I can control my calorie intake. Why is this idea so foreign to government? Why are all licenses by default set to "no".
We'll see how far I get with my can-I-have-information email, but past experience has led me to disappointment.
Update 2: Success! USDA SR21 is a bunch of data you can download and stick into a database. It would not be hard to RDFize this.