Dry Soylent Mix: How Can You Tell If It's Spoiled?


My question is about how to determine whether a bag of the dry mix of Soylent is bad in some fashion. Let me explain.

I ordered a 2 1/2 month supply of Soylent and have been really enjoying it. I love the flavor, love the texture, and love the ease of use. It’s everything I’ve wanted in this product and it meets all of my needs.

However, in the past week I opened a bag to mix and noticed it didn’t have the typical “vanilla” smell. Rather it smelled rather “metallic” or even “fishy” (like raw choline bitrate smells). I didn’t think much of it and mixed the batch and it still had that “funky” smell rather than the vanilla cake batter smell I’m used to. When I tasted it, it had the same texture but the taste was completely wrong. So I threw it out.

The next three bags I opened all smelled the same. I mixed another of the opened bags and it too had the same funky smell and the same bad taste.

Can you please advise on what’s going on? How can I tell if the batch is bad, contaminated, or spoiled? And if I have spoiled or contaminated mix, is there a process to obtain replacements? And will I have to open all of my sealed bags to inspect each one to request a replacement quantity if that is offered?

Lee in Oregon


Hey Lee,

Can you open up a bag from a different box and see if you find the same results?

Can you reseal a bag of bad soylent (in a ziploc bag or something and mail it to us? DM me for more details

Also, can you provide the code that is imprinted on the top of the bag (the part you tear off) for those spoiled bags?

When making a decision about a spoiled product, it’s always best to use your intuition. I will work to get you an answer and all of the above will help the investigation.

Thank you!



Hi, Matt:

I have opened 7 different bags from different locations in my pantry and they all have the same weird smell. I didn’t leave them in the boxes they arrived in; when the Soylent arrived I simply unpacked everything and put them in my cabinets and on my kitchen countertop.

I’ve also noticed that after mixing the Soylent that has this smell it develops a foam on the top that never goes away. Normally, when I’ve blended my Soylent it naturally foams at the top and once refridgerated for about 30 minutes the foam bubbles just vanish. This is the first time that after several hours the foam not only doesn’t go away it’s like an algae layer on the top of the mix. I photographed it and can email those to you if you wish.

It appears as though the rest of my Soylent is of this “kind.” Do you want me to keep opening bags?

I can provide you with a bag of the Soylent (several if you wish). How do I direct message you to do this?

At this point, I don’t wish to risk consuming anymore of this but I’m extremely bummed about it. I had made this my exclusive dietary intake. Not sure how I’ll proceed.



This is not the first question about Soylent being a little bit off. Not being part of Rosa Labs or its contractor all I can do is speculate. However, my educated guess is that the bag was not mixed right. I have no knowledge about how they mix and pack, but I imagine they mix big batches and portion it out. If the big batch is not mixed evenly, maybe a particular bag has more of one ingredient than another that causes the issue you have seen.

This is an issue I would raise with Rosa Labs and provide as much information as possible. I noticed the bags do not have lot numbers (this really needs to be added), but maybe your ship date or the lot number from the oil containers would help?

Lot Numbers Location on Soylent Packages?

They do have lot numbers, it’s stamped in the thermal seal on the bag. When you tear off the flap to open the bag, you’re tearing off the lot number.


Actually, they do. The lot number and manufacture date is embossed along the top portion of the bag, the part that you rip off to open the bag. It’s not easy to read, some bags are easier than others though, and really easy to miss if you don’t know where to look.

Edit: @j8048188 is a ninja. :slight_smile:

Lot Numbers Location on Soylent Packages?

Wow, that is sneaky. You are correct: the lot numbers are stamped there, not printed. I had to look closely but under the right light the numbers were visible.


Soylent and Matt Cauble have been very quick to respond to this issue. I have sent them four pouches via FedEx of the suspect powder. I’m anxious to hear what they discover.

I would, however, note that I’m not convinced its a mixing problem. Why would all of my bags up until a certain date be fine and then one day all of the successive bags be bad? As I noted, I didn’t unpack all of my Soylent in order. I opened all of my boxes and simply put them in cabinets for storage; so the lots were all mixed together.

My total speculation on this is that something chemically changed in the powder and fouled it.


I saw this post when it was created, and was’t having the issue, but thank you @lcdlex for reporting your experience. I believe I have just run in to the same issue. The last bag I made was definite off flavored and I couldn’t finish it. And it was characterized by a thick foam at the top.

I always let my soylent sit in the fridge overnight and have never had the foam remain. I do use a blender to mix my soylent.

Here’s the numbers stamped into the last bag that did this: C14121P01.05.15
We received our order on: 06/03/2014

I had ordered enough for my wife and I to have a steady 2.5 month supply thinking there would be more issues with resupply than with initial supply. So we’ve gone through our first month, and started on our second.

I’m about to mix up another bag, going to go spelunking through my supply, for one with different batch numbers. I’ll report back. I am not going to change anything else besides the batch number.

UPDATE: All of my bags are in that same batch coding reported above.
So I will be trying a bag from a different months supply sometime today and I’ll update.


BJoshman: I’m glad I’m not the only one experiencing this. Without any evidence but my own experience at this point, I believe something is happening to the Soylent as it ages in the bag. Since there is a small amount of air in the bag, it seems reasonable to assume a bacterium may be metabolizing some of the sugars OR some ingredients when exposed to the air are going inert. But that’s just my brain trying to figure out what’s up.

But there definitely is a taste and smell change and I’ll bet you find that all of your bags are the same way from each lot. All of mine have changed.

Four bags were sent to Matt Cauble via FedEx and he let me know that they have my samples in the lab for testing. He indicated they may have results for me by the end of the week. I’m very curious to find what they discover and what the fix will be. I hope its an easy fix, because I was really enjoying the Soylent and the ease of it. I want them to succeed so I can use this all the time.



This morning I felt massively lethargic, waaaaaaaaay more than normal which seems strange as we’re now on our third week.

I still haven’t been adding the extra salt though so I can’t really safely say it was the Soylent until I’ve done a solid week of extra salt.


Tiredness can be a symptom of hyponatremia. I don’t know if three weeks of low-salt Soylent would get you there. You might try an electrolyte drink (something Gatorade-y).


UPDATE: Please see my post made 07/08/2014 in this thread - the bad taste turned out to be an undisclosed rare side effect of a medication I had been on for a while before this side effect started. I am preserving the content for continuity.

@MattCauble - i would definitely be interested in the results you find from @lcdlex’s supply. And wondering fi you would like some from mine for testing?

The metallic mediciney taste in it now is making it impossible to consume. My wife Is flavoring hers with extracts and hasn’t noticed it. So her next batch she makes tonight or tomorrow morning, I am going to ask her to make it plain.

I am going to take a break for a couple days and try making a batch for Sunday.


I have bags with the same stamp on them, and have not had any issues (fingers crossed)
Just an FYI.


If the findings end up showing that nothing is wrong with the Soylent… It could be the increased sense of smell and taste that others have mentioned?


The last case I opened was the same lot as well. Thankfully I haven’t noticed any taste/smell problems either.


Uh oh… I’m getting slightly concerned. I just broke open the last 2 weeks of our most recent reorder from last month, and noticed something is decidedly “off” about this one. Can’t really describe it… it’s just not normal. Checked the stamp and it’s exactly the same as that being discussed in this thread.

I’ll be mixing up another pouch tomorrow and will pay close attention to it as I do so in case I notice anything out of the ordinary.


I’m having a bitch of a time reading the stamps, so I have no clue which lot #'s I have in use right now. They seem fine. They’re from an end-of-May shipment.

I’ll be starting on the early June shipment soon. I’ll go look through those boxes, and with the help of glasses and a handsome codebreaker, I’ll see if I have any matching #'s to the one listed here. If so, I’ll open one to see if it smells off.


Even with having had my eyes Lasik’d a couple years ago, I still had to bust out a magnifying glass and a reading lamp to be able to make out the numbers.

I’m not sure what was off about our last batch, but this next one seems ok. Something is different, but I’m actually thinking it may be the canola oil, since this time I didn’t go with Wesson, instead buying the store brand. Wouldn’t have thought there would be any discernible taste difference but I’m thinking there is.


I may also be in this boat. The few packages I’ve opened recently haven’t had the slight vanilla smell to it the first few had, though it doesn’t have the ‘metallic’ smell Icdlex mentions.

I’ve also noticed I’m getting a lot more separation now even without adding the oil when mixing though perhaps that’s just the oats and other things absorbing so much water that it sinks?

My batch is labeled M14139P01 I think. Something close to that. @MattCauble, @JulioMiles or @rob is there any more info on this?

Edit to add: The Soylent itself doesn’t taste any different as far as I can tell. There’s a slight change since I started waiting to add the oil but I figured that was just because it hasn’t had as long for the oil to mix.