Monday, 17 February 2014

Science Lesson in the Kitchen

Sorry - I confess to a Google image

There are times when I wish I had taken Science as a subject at school for a little longer than age 13. Witness my odd experience with my Kenwood Chef last week.  I was making cup cakes for Book Club and for the second time recently noticed that my hands were covered in sooty-looking stuff after I had set up my machine. I assumed it was something to do with the oily parts at the top,  but was puzzled nevertheless. When I tipped out the cake mixture I noticed it looked a bit of a greyish color but still didn't think much of it. Maybe the flour was different this month?  We duly had Book Club and the cakes all disappeared but when I came to wash the dishes the next morning I was horrified to find that when I picked up the K-beater my hands were immediately black again.  On closer examination I found  the beater was the culprit. And the stuff was quite hard to remove.  I asked my husband about it later that day, when big son was visiting and the two of them shared an 'aha' moment, when I admitted to having placed the item in my new dishwasher.  "SALT!"  the said in unison, explaining that the beater was made of pewter and the surface was oxidising while being washed by my new, super-efficient, salt-filled dishwasher.  After much scrubbing and a return of its previous color, my husband pronounced it still fit to use.  No-one at Book Club got sick, but that may be because I had parsimoniously made only 9 cupcakes for the meeting, having run out of eggs, hoping that as usual, perhaps three members would be absent.  Murphy's law:  everyone pitched up that night so we were twelve and it was a question of the loaves and the fish and my miscalculation was exposed.  In the end, I cut them all in half. Perhaps that was for the best, health-wise.  I should mention that our Book Club is all about the books: we usually only have tea or coffee unless someone feels like taking something to eat. So it was only cup cakes that night.  I wonder what the oxidised substance was? Carbon?  (Sextant?)


  1. Will you tell this story at your next book club meeting or just keep the whole thing to yourself?

    1. This is Top Secret! (NB. No-one here reads my blog)

  2. Funny story!
    Thankfully, our bodies are created to handle many of the non-food, foreign substances that enter it on occasion. I've given up trying to convince my germaphobe husband of this. I used to remind him that when you eat at restaurants, you never know what little added gray matter you're also getting. :)
    Once again, your post relates a little to mine. It's about books. Stop by if you have a minute or two.

  3. Well a quick google search revealed this:

    Now I find it hard to believe that expensive mixers would use anything other than stainless steel beaters. My wife has a cheap hand held mixer older than my son and the beaters appear to be chrome plated carbon steel. They don't oxidize but we don't have a dish wash either (well we do, it is a general purpose Sextant model).

    I doubt very much they would be pewter which is a softer metal used in decorative applications. I would think it not suitable for mechanical action...although I suppose they could be, or perhaps language may be more of an issue than materials--my father talked about things being made of pot metal--sort of a junky catchall term for junky castings using a lot of zinc and a cornucopia of other crap. You wouldn't want a pot made of pot metal...the heat would ruin it.

    It sounds from your description that the beater is made of aluminum and indeed aluminum can oxidize into grey or black coating. If they are aluminum they should feel light, less dense than say your silver ware. If they are pewter, I am not sure which component would oxidize, tin is used to plate other metals to prevent oxidation. However you are talking about this occurring in a dish washer. I am not familiar with salt in a dish washer but I suspect that it is a demineralizing agent to keep your dishes from water spotting. Some car washes use demineralized water to prevent spotting. Demineralized water in it self can create some interesting chemical problems, which more than once proved a head ache during my working life. Can't say that I miss that at all. The purity of it can cause certain metals to dissolve rapidly and there is something about hydrogen ions making it seem acidic. So good luck on trying to figure out the nature of the oxidation.

    This is a very long answer saying basically, it beats the hell out of me. I would try to getting new stainless steel beaters and don't put them in the dishwasher.

    One thing I would not recommend is using car wheel cleaners to remove oxidation from food utensils as was presented in the third comment in the link above. You don't know what secondary compounds such cleaners are generating and depositing in the surface, to be later liberated in your food, especially in applications that use heat such as pans. Stick to cleaners meant for contact with food utensils.

    One thing you might try if the beaters are oxidizing during use is to coat them with vegetable oil or shortening or spray them with non-stick stuff...Pam in the US.

    1. Thanks, Sextant (thorough as always). I get lazy when I know I can rely on you to look things up for me. Just to say I've had the mixer for 36 years - never a problem before. I just thought it was maybe old? It might be aluminium, although it's always had a darker color than that typical of that. What I'm going to do next is bake another cake....keep you posted. Fancy you not having a dishwasher (other than your good self!) I thought ALL Americans had them - de riguer.