The 3D printer, that marvel of modern
science that makes it possible to fabricate solid objects such as a piece of jewelry or computer part seemingly from thin air, looks like something out of science fiction. I recently saw one in action at Hive, a science and education co-working space in Philadelphia, and watching three dimensional forms emerge line by line reminds me of the way a sketch artist builds depth in an image from lines and hatchmarks.
The 3D printer “draws” objects from digital models; the printouts can take just about any form that can be created in three dimensions, and can be made with just about any material that can be extruded or pushed through a syringe—even the good stuff: sugar and chocolate.
The development of the extruder on this machine disproves the proverb about too many cooks spoiling the broth: in the robot kitchen, many minds collaborated in the creation of these little chocolate boxes. Four years ago, when bioengineer Jordan Miller became a founding member of Hive76, it was possible to print edible materials, but primarily in two dimensions: with a syringe and air pressure, a machine could sketch out wonderfully precise images in frosting or jelly, but these materials are too soft to build up much bulk. But with fellow Hive founders Chris Thompson and Robert Vlacich, along with a printer adapted from an open source model (RepRap.org, which makes its designs freely available), Jordan was able to modify an extruder that would temper sugar and chocolate, or control their crystallization in the way confectioners do when molding and shaping sweets. (You can see this in the embedded video: the chocolate emerges molten, and cools into a hard, shiny layer.)
“Sugar is like a glass,” Jordan explained. Table sugar is its crystal form, but it passes through several stages and textures as it is heated higher and longer: it melts, becomes gummy, and eventually hardens into a clear, hard, and brittle candy. Jordan’s challenge was to develop both an extruder that would heat up the sugar to the clear liquid stage and a sugar formula that could withstand the pressure it takes to extrude it as a filament through a syringe. (Early experiments with applying pressure resulted in a clogged nozzle and a sticky white powder that is not described in any confectioner’s sugar stage tables.) But from the growing field of food science and molecular gastronomy, the Hive engineers knew that adding glucose would make the sugar thicker and somewhat less brittle. Their current sugar formula is as versatile as the plastic filaments—it can build up a human vascular system, a sculptural bust of Cory Doctorow, or a mathematical knot—and it is far stronger than the delicate, translucent sugar threads would seem.
Chocolate presents a slightly different set of challenges for the extruder. Like sugar, chocolate has half a dozen stages of melting and crystallization—although we are most used to the firm, shiny tempered form, as softer and crumblier stages of crystallization are considered less desirable in chocolate. Further, chocolate is a more complex material than sugar. If sugar is like glass, Chris Thompson suggests, then chocolate is like steel: it’s an alloy, in a manner of speaking. The mixture of components present more possibilities for inconsistency in texture or crystallization, like the white bloom that appears on under-tempered chocolate or the potential for burning chocolate at lower cacao percentages. (The darker the chocolate, the less likely it is to burn.) If properly annealed, however, the chocolate sculptures have the potential to be solid and strong—and, yes, delicious. “Taste is all about surface area,” Jordan says, which is why he and his collaborators are experimenting with three-dimensional designs that maximize surface with intricate textures or shapes. A chocolate sculpture composed of folds like an accordion would be unique—you couldn’t mold a shape like that—but it would also have more snap, more taste, more aroma than your average kitchen chocolate.
At this stage of experimentation, the field is wide open for potential applications of this technology, and Jordan and his colleagues have an open door for potential collaborators. The 3D printer was built for limitless customization and modification; Jordan’s particular model of extruder is open source and available for the tech-savvy to build at home for individual use. In a more commercial vein, sugar and chocolate printing would seem to be natural companions for molecular gastronomy and mixology, which depend on playful design and unusual tastes and textures. Chocolate in particular is a luxury good and chocolate-making is an artisan craft; the ability to create personalized or artistic chocolate sculpture may well be a remunerative application. The Hive members are considering several fundraising models to help finance their techsploits.
But the sweet sculptures already benefit Jordan’s original intent in sugar printing: he recently published a scientific paper on his 3D-printed sugar vasculature, a cornerstone in his research team’s ongoing efforts to “grow” replacement organs. The printed sugar vascular systems create a delicate (and dissolvable) armature on which researchers can build up—layer by layer—the sensitive tissues that comprise these organs. Meanwhile, the playful printing of chocolate boxes and sugar trees explores the limits and abilities of the technology, fine-tunes the machinery, and works toward a better understanding of how the printed sugar’s uses in bioengineering.
As a layperson, watching the printer circle its 3D sketch and listening to the background buzz of advice and instruction during Open House, I’m impressed by the science but affected by how much it resembles art-making—and cooking, too. The 3D printing is a result of collaborative creativity; it depends on innovation but also the free play of ideas and information. Jordan suggests that there’s always a design aesthetic at play in technology; his example is the geometric patterns of circuit boards. But the chocolate printing in particular embodies science as art. “It has the snap of chocolate, the smell and the taste, the texture—and we make it visually appealing,” Jordan says. “It’s technology that engages the five senses.”
Photos and videos by Jordan Miller.