Friday, 24 April 2015

09:00 – It seems that Google stopped indexing WordPress blog comments sometime earlier this year. Thanks to a reader’s suggestion, I found a WP plug-in called Search Everything. I installed it yesterday, and it seems to work. The search box at the upper right now searches comments as well as posts.

Remind me never to order sodium hydroxide in a 12 kilo pail again. I used to order USP/FCC/NF/reagent-grade sodium hydroxide in 2.5 kilo jars, but this time I ordered a 12-kilo pail because it costs literally half as much per kilo in the larger container. But I typically use about one kilo at a time, and the stuff sucks water out of the air, so I need to repackage it in smaller containers. The time it takes to do that, not to mention the hassle and risk of dealing with so much of this caustic chemical at a time, obviates the cost advantage.

Most of my time this week was devoted to working on science kit stuff, but here’s what I did to prep this week:

  • I confirmed something about which I was already pretty certain. Eight years ago, while I was writing Illustrated Guide to Home Chemistry Experiments, I pulled two of those small cans of mixed fruit off the pantry shelf. Both were the same lot number and had the same best-by date. I opened one, ran an iodometric titration on the liquid to determine vitamin C quantitatively, wrote the result on the bottom of the other can, and ate the fruit. This week, I opened the other can, which had “expired” six years ago. I ran an iodometric titration on the liquid to determine vitamin C quantitatively, and ate the fruit. The result, no surprise to me, was that the concentration of vitamin C in the old can was identical within experimental error to the concentration in the can I’d tested eight years ago.

The common belief is that canned food loses nutrients as it ages. Vitamin C is a pretty good proxy for nutrients in general, because vitamin C is among the most fugitive of nutrients. Exposing a vitamin C solution to air will eventually oxidize most or all of the substance that was originally present. But of course in a sealed can it’s not exposed to oxygen, just as none of the other nutrients are. Now, vitamin C is in fact an unstable molecule, so it wouldn’t surprise me if there was at least some loss in canned goods that were 20, 30, or more years old. But as far as I’m concerned, this test pretty definitely refutes the idea that canned goods stored for a long period lose significant nutritional value. Oh, by the way, that fruit that “expired” six years ago tasted just like the newly-canned stuff does.

So, what precisely did you do to prepare this week? Tell me about it in the comments.