Soylent, the food replacement from former engineer Rob Rhinehart, has hit one of its final milestones before release: the formula has been finalized and frozen, and large-scale manufacturing and packing is underway. Just after Thanksgiving, Rhinehart posted a blog entry discussing the changes in "Soylent 1.0" versus the beta 0.89 version we consumed for a week back at the end of summer.

At the time, the Soylent folks estimated that backers of the company's wildly successful crowdfunding effort would be receiving their initial shipments of Soylent in December; this estimate has now been revised to January. The main reason for the delay has been due to the small Soylent team having to find ways to cope with the realities of mass-producing their product. The beta packages of Soylent sent out to the small list of testers were all hand-stuffed, whereas the actual production version is being mixed and packaged on an industrial scale by a specialist company called a "co-packer."

Macro mix

Going by the blog post, there are a number of substantial changes to the Soylent formula from the beta we slurped down. One is that the carbohydrate mixture has been nailed: one 500g bag of Soylent will contain 210g of oat flour and 132g of maltodextrin. The protein mix has also shifted—our beta Soylent contained a mix of rice and pea protein, but production Soylent will contain 102g of brown rice protein isolate.

"We found a brown rice isolate supplier that we really like and are now using only rice for protein," explained Rhinehart via e-mail. "This is important since the pea crop has been spotty lately. It's fascinating how insulated consumers are from the chaos of weather, disease, and agriculture. Food security is great!"

The mix of soluble and insoluble fibers has also been tweaked slightly. The majority of Soylent's fiber comes straight from the oat fiber, but there is additional fiber in the form of xanthan gum and gum acacia. Rhinehart said that this is to round out the recommended daily fiber requirement and to make Soylent more gut-friendly.

Speaking of guts—one of the more memorable things that happened to me during my week-long Soylent binge was... well, to put it gently, I suffered a small bit of gas. This made me rather unpleasant to be around for a couple of days before my body started to adapt (and it also allowed me to sneak phrases like "horse-killing farts" onto the Ars Technica front page! Look, I did it again!). Rhinehart assured Ars that the gas has been tamed in Soylent 1.0 by "modifying the fiber balance and sulfur content."

Another big change is with the oils used. Soylent is a dry mix and needs to have a certain amount of oils mixed in to provide fat content and to make it nutritionally complete. For the beta, two kinds of oil were provided: a small vial of grapeseed oil and individual fish oil capsules. You'd pop a fish oil capsule in the morning, then pour the grapeseed oil into your Soylent pitcher at the ratio of one vial to one whole Soylent packet.

This has been simplified, with the main oil switching from grapeseed to canola. Also, the separate fish oil capsules have been nixed. Rhinehart noted that the change over to canola oil was nutritionally motivated: "Grapeseed oil is cheap since it is a byproduct of winemaking. However, Canola has even lower saturated fat and much higher ALA content making it a superior fatty acid source. The EPA / DHA fatty acids from fish oil are incorporated directly into the oil blend now."

By far my biggest complaint was with Soylent's overly chalky texture—its "mouthfeel," in the jargon. The particular version I consumed was one of the first vegan Soylent mixes and was one of the first to use rice powder for protein; that powder was responsible for the sticky "riverbed silt" feel of Soylent on the tongue and throat. Rhinehart said that the texture has been substantially altered through finer milling of the protein powders, and production Soylent should lack the beta's chalkiness.

There is also good news on portioning and mixing. One 500g bag of Soylent contains about 2,400 kilocalories for the male-specific mix and 1,800 for the female mix; we mistakenly assumed, based on the available documentation, that an entire bag had to be consumed within a day's time in order to get all of the macro and micronutrients that a body needs to function. This led us to stuffing ourselves with Soylent—which was extremely unpleasant. Rhinehart told Ars that the shipping product will have more explicit instructions on how much Soylent one should consume, but that the guidelines from the beta will hold for production: eat as much as you want until you feel full.

This was a little difficult with the hand-mixed beta Soylent, since the product's powders arrived somewhat stratified in the bag. Here, though, the industrial packing process comes to the rescue: shipping Soylent powder will be completely homogenized, allowing customers to scoop out as much or as little as needed without having to first blend the powders together.

Is there a doctor in the house?

Soylent draws tremendous fire from Internet commenters wherever it's mentioned, because a lot of folks believe the product is harmful—or, at least, that it can't be healthy. To that end, Soylent has retained the services of Dr F. Xavier Pi-Sunyer, a professor of medicine at Columbia University College of Physicians and Surgeons and senior attending physician at St Luke's-Roosevelt Hospital and the New York-Presbyterian Hospital.

Pi-Sunyer has been advising Rhinehart and his team on Soylent's nutritional content, including driving the team to hit a carb/fat/protein ratio of 50/30/20 with the shipping product. "As a doctor Pi-Sunyer quickly saw the value in the product," explained Rhinehart. "Mostly he was surprised we were able to hit our price point and had a few tweaks and suggestions for us. As an adviser we consult him for specific questions like projecting how specific glycosidic bond types affect glycemic index. He is also an expert in metabolic disorders which we like to keep in mind throughout the design."

A very Soylent New Year

Crowdfunding backers could choose to pre-purchase days, weeks, or months of Soylent, and Rhinehart wanted to ensure that if supply was exhausted, customers could immediately get more product.

This is one of the biggest reasons behind the continual delivery delay. As of this writing, Rhinehart estimates that Soylent should be arriving in the hands of paying customers in January. The long run-up in production times will ensure enough inventory to meet the initial huge surge of orders, while also giving them the production capacity to handle reorders.

We're awaiting our own supply of production Soylent—way back in early August, I put down my own dollars for a month's supply of the stuff, and I'm looking forward to working it into my diet when I need to eat something fast. As long as it doesn't give me chemical warfare gas, it will be money well spent.