Category Archives: Air

Soluble Fiber

I was just stuffing my face with a crunchy granola bar for a mid-morning blood sugar bump. I noticed that the Nutrition Facts label has an entry for Soluble Fiber. It’s half the total for the Fiber category. That got me thinking. What difference does that make? Are the soluble fibers going to be digested and absorbed as carbs while the others will pass undigested as roughage?

Next I wondered whether chewing had any effect on solubility. I don’t guess so. Chewing won’t cause many changes at the molecular level. Compared to what goes on in the gut, that is.

Finally I wondered at the crunchiness of the granola bar. They also make a chewy variety. It’s amazing to me that these textures can be so important to the experience of eating. I could have pulverized the granola bar and then combined it with my drink to make a paste before eating it. Digestion would have proceeded regardless.

Or would it? Doesn’t the appetizing crunch assist digestion more than merely slurping down a less palatable paste?

Eating is wonderful when you take the time to experience it. Here’s to more of that.

Make Wanted: Cake Printer

You may have heard of 3D printing and rapid prototyping. Have you seen videos of concrete printers? We aren’t yet building apartments this way, or even backyard sheds, but the idea has been picked up and its development is now funded by very large companies.

I was thinking about this while spooning up a dish of Ben & Jerry’s 30th anniversary celebratory ice cream flavor, Cake Batter. I wondered what machinery had achieved the perfect swirling of ice cream flavors and gooey frosting. I have toured their factory in Waterbury, Vermont, and I even stood nearby while it was being built, but I’ve never seen up close the twirling, swirling nozzles. I wondered about their capabilities.

We had a 9-pin dot matrix printer when I was a kid. Eventually we got a 24-pin model that printed nicer-looking fonts, followed by a laser printer and a color bubble jet. I disassembled each one to see how it worked, or I read about it if the mechanism was too small. I found that if you ran a page enough times through any printer, the ink would build up on the paper until eventually the printer jammed. 3D printing is easy to imagine but not so easy to do.

Now if Ben & Jerry’s ice cream swirls could be created in a pint of ice cream by moving a rod having individually-controlled swirl ports, you might be able to print messages inside the pint, to be successively revealed by spooning away layers from the top. This has the obvious difficulty of the effect of the rod moving through the ice cream, swirling into oblivion whatever was deposited before.

It would be better to squirt the ice creams and swirls simultaneously into the pint to form one layer at a time. Having on its pint-wide print head a grid of nozzles arranged horizontally, the machine would print while moving the head vertically through the length of the pint. If it had the ability to control the nozzles to squirt different ingredients, the machine would be a 3D ice cream printer and my dream come true.

All of the forgoing occurred to me between bites of Cake Batter ice cream. These thoughts occupied a small part of my mind through the day until I began to think back on older printing technologies. Most interestingly, all of the laser printers I had seen contained a heating element called a fuser which baked the toner that had been deposited on the paper. What if you could automatically deposit cake batter and bake it by layers? You could extrude a fully-baked cake with a different birthday wish in every slice.

One mechanism appeared to me: tiny, retractable, non-stick heating elements would extend into the printed batter at the rate of print head advance, effectively staying put in the batter until it has finished baking and then retracting into the print head to be deployed again. Another idea involved inflating tiny balloons with hot liquid to bake the batter and then deflating them, mimicking the natural consistency of cake with the voids left behind.

I imagined that the resolution of such printing would be directly limited by the composition of the cake. Air bubbles are transparent holes that transmit color from the solid parts at their boundaries. Higher resolution would depend on smaller bubbles. Up to this point I was thinking primarily in the visual field. Bakeries and consumers already have access to frosting printers, which are simply Canon bubble jet printers with edible sheets of “paper” and edible inks, but this is 2D printing and not what I wanted to think about. Continuing on the 3D track, I thought separately about flavor printing and structure printing.

Flavor printing can be imagined very simply in one dimension by equipping a sausage mill with computer-controlled nozzles, each one adding a different ingredient to the filler and being turned on and off to create a pattern of flavors that the eater would experience in a sequence of bites. It is easy to expand the concept mechanically into two and three dimensions, printing out multi-flavored cakes or gelatin molds. I don’t know what consumer need this would fill. Still, I’d like to see it done.

Structure printing (creating, say, a frosted yellow cake in the form of the Statue of Liberty) brings up an important consideration: the physical properties of the food. Where are the compression strain diagrams of yellow cake? What is the tensile strength of frosting with and without coconut? How best to anneal the chocolate rebar?

If you know any mechanical engineering grad students who secretly wanted to major in home economics, or vice versa, please send them a link to this post. I would love to consult on any project that stems from these ideas.

Hotels are funny

When Zoe heard that I’d be in San Francisco on business for a couple of days she wanted to join me. I decided to stay over the weekend so we could spend time here together. My flights and weeknights are a company expense but the weekend stay comes out of my pocket.

Automattic rides in style. Maya put me up at the Westin on Market. This is a four-star hotel, or “the bomb” in urban parlance, just one star short of “bling bling”. Thus they command six times the nightly rate of the hotels I usually book for myself. I learned this when I checked in.

I’m neither cheap nor, despite Mom’s best efforts, congenitally frugal, but like a boxer to a muffler I wasn’t going to pay a lot for a hotel room. I checked for something closer to my range and found the same room in the same hotel available for about 45% less than the hotel’s quoted rate.

With several hours before the cancellation deadline for the weekend stay, I called the front desk to offer them the opportunity to take my money. I told them about the quote and asked them to match it. The agent checked with her manager and then advised me to book it online and cancel the existing reservation.

That’s crazy, right? I offered to pay the hotel the full price quoted by, saving them a commission and thus increasing their profit and they refused. Book it online, they said. So I went back to

Right about then, the hotel internet connection died. Perfect. Challenge me to book it online and cut my internet connection? Not really. The connection came back in a few minutes. I booked it and called the front desk to finally cancel the original weekend reservation and note that I’d keep the room for the new reservation.

Fifteen minutes of my time yielded a very big savings. It’s too bad the hotel will pay that commission. It’s a funny business. Use