Today, we’re talking MOLD. Yes, that kind of mold. We discuss causes of mold in cold brew and steps that you can take to help prevent mold in your cold brew. Once again, we talk about cleaning and sanitization and the importance of proper cleaning and sanitization of your cold brew systems.
Highlights & Takeaways
Mother Earth Brew Co – Cali Creamin’ Ale, Boo Koo Mosaic IPA
What causes mold? 3 contributing factors to mold
- Food source
- And a 4th contributor – Darkness
Proper cleaning and sanitization can help you prevent mold – don’t skimp on cleaning
Episode 17 Transcript
Brendan: Welcome back to the Drips & Draughts podcast, where we help you bring your craft to draught. From soda to beer and from coffee to Kombucha, we will discuss making your favorite craft beverage in small or large batches and how to best serve it on draught.
Hey there, and welcome back to the Drips & Draughts podcast. As always, I’m Brendan Hansen and I’ll be your host today. I’m pleased to announce that I am once again joined by my brother Cary, and today we’re going to be talking about mold. Yes, you heard me right, mold.
Some of you may have experienced mold with your cold brew coffee before. Hopefully not, but it is something that can happen if your brewing environment isn’t totally sanitary and clean, if the bottles or the kegs or the growlers that you’re putting your cold brew into, aren’t entirely clean and sanitized. So we’ll get into all that in the episode and we’ll also discuss ways to prevent that because let’s face it, the last thing you or anybody drinking your cold brew want is mold. You don’t want mold brew.
So before we get into today’s episode, I want to say thanks again to everybody who’s going over to iTunes and leaving us a review for this podcast. We’ve gotten a couple more since the episode- I think it was a couple episodes ago now, where we pretty much pleaded for reviews. So thanks to all of you who have taken the time and hopped on iTunes and left us a review. Actually I might start reading one of these each time.
In fact, yes, I am going to start reading one of these each episode, assuming we get enough to do that. I’m going to start with the most recent one here, is from July 16th. So this one is from @TooMuchT.V and the title is Cold Brew is Getting Hot. It says, “As a new commercial cold brewer, this is a great podcast to get information and to hear the experiences of other cold Brewers. I’m a pro beer brewer and expanding our business to cold brewing coffee has really opened up a whole new market for us. We have even been able to mix the two with great results. The podcast gives me another reason to look forward to Fridays.” Cheers @TooMuchTV, thanks for the review. And we will read another one next week. That was a Five Star review by the way. So thanks again @TooMuchTV.
Speaking of five star reviews, if you have any comments or suggestions or anything that you want us to talk about or anything you want to hear about or just maybe some criticism, go ahead and e-mail us at firstname.lastname@example.org. Let us know what you’d like to hear or you can let us know through social media. You can find our Drips & Draughts podcast social media profiles, by going to dripsanddraughts.com /facebook, /twitter or /instagram.
The last mention before we get into this episode. I just wanted to bring up our new e-book, The Definitive Guide to Draft Coffee. You may have read our first e-book, Ultimate Guide to Cold Brew Coffee and Serving Coffee on Draft. If you haven’t seen that already, you can download it by going to dripsanddraughts.com/ultimateguide. So our new e-book, The Definitive Guide to Draft Coffee is turning out to be just absolutely enormous, but not only that it’s becoming a work of art. Cary’s designing this one and he is putting a lot of time into it. His background is in Graphic Design, so this thing looks awesome. We’re going to release it as an e-book but the more I look at this thing, the more I want to actually get this printed and bound a hard cover version of this would be awesome.
So the book’s got eight chapters or eight sections, each section is pretty detailed, loaded with pictures, it looks amazing but it’s packed full of information. Everything you need to know about drafts systems and serving coffee on draft. So I’m excited to get that new book released and get that into your guys’ hands and see what you all think. Especially because of the fact that this one’s being professionally designed. I put the first one together, The Ultimate Guide to Cold Brew Coffee and I think Cary is planning on using that as a template for this new book but when he open the file, I think the first thing he said to me was, “Dude, you got like 80 fonts in here. 80 Different fonts.” So this one’s obviously going to have a lot more consistency throughout. I’m excited for it, I can’t wait to get that into your guys’ hands. If you want to be one of the first people to receive that book, make sure you join the forum, at forum.coldbrewavenue.com. All right that’s enough jibber jabber from me. Let’s get into today’s episode, talking about “Mold.”
Alright, welcome back to the Drips & Draughts podcast, as always I’m Brendan Hanson. And today I’ve got Cary back in the- [crosstalk]
Cary: I’m back.
Brendan: “Studio” with me. So welcome back.
We recently got a question about moldy cold brew, somebody was having a problem, cold brewing their coffee, putting it into the fridge and I guess after about a week or less than a week, he was getting mold in the cold brew. So we figured we’d address this in a whole episode today. But before we get into that, as always Cary and I are splitting a beer here. So today, we’ve got- what do we got here?
Cary: Let’s see, we got Mother Earth Brewing Co, Boo Koo, India Pale Ale. It’s very good.
Brendan: I’ve had this one before.
Cary: Yes, this is a good beer. Mother Earth of- what is it? Vista California, I believe.
Brendan: It’s down in San Diego, right?
Brendan: What’s that they do that Cream Ale- Cali Creamin?
Cary: Cali Creamin, yes.
Brendan: -Mother Earth.
Cary: Yes. It’s got a lot of like vanilla flavor in there. Yes, good beers.
Brendan: Yes, this one’s good. This will definitely get me through this show.
Brendan: So anyways, moving back from beer to coffee. I guess this applies to anything that you might cold brew, whether it’s coffee or tea or Kombucha.
Cary: Yes, not even cold brew, even going back to beer when you ferment, not boiling temperatures, you’re-
Brendan: You could have a problem.
Brendan: So why are we talking about mold? Whether you’re cold brewing coffee, tea, Kombucha, whether you’re making beer, whether it’s for home or personal consumption or especially if you’re a shop that’s making any sort of beverage and you’re serving it to customers, one thing’s for certain and that’s you don’t want mold in your beverages.
So before we start talking about how to prevent mold and some of the best practices for cold brewing, let’s first talk about what causes mold and what type of environments and conditions that mold is going to thrive in.
I think everybody seen mold, probably in their kitchen a time or two.
Cary: Right, going back to your second grade experiments with-
Brendan: Loaves of bread.
Cary: Loaves of bread, yes.
Brendan: What causes mold? I had to do a little research for this, I’m not a scientist or anything, so if we give any false information today, don’t hold us accountable, send us an email and we will try to correct it in a future episode. So mold is caused by mold spores, they’re microscopic, they can’t be seen obviously and they can just be an ambient air, they can be outside, they can be inside. And mold spores don’t turn into or don’t grow into mold until the conditions are right.
What are the right conditions for mold to grow? I looked this up as well and it’s basically, mold needs three things, they need a food source or source of nutrients. So in this case, we’re talking about either coffee grounds or the cold brew itself. Those are both protein rich food sources for mold. They need moisture, so spent grounds could definitely turn into like a moldy, nastier thing. Cold brew itself could probably turn moldy, if mold spores got into the cold brew. And then they also need time, mold can grow and I guess a 24 to 48 hour window and obviously if you let it go beyond that it’s going to probably get much worse- [crosstalk]
Brendan: Cary and I ran a couple experiments after we got this email that we’ll talk about and yes, we got some mold for sure.
Brendan: [chuckles] And darkness can also accelerate mold growth. So I guess, we could probably start by talking about our batch that we did last week. We basically did at 12 gallon batch of cold brew and after we emptied the kettle, we dumped a majority of the grounds out, but we left some in the bottom of it and we just let it sit in the back of the warehouse for- it’s been there for about a week today, I finally took it home and hosed it out.
Cary: It was nasty.
Brendan: Yes, we came in on Monday and the first thing we thought was, “Oh shoot, we didn’t clean the kettle out.” But it made for a nice experiment because we opened it up and molds got a characteristic- apparently, they can be any number of colors from white to yellow to green to black but apparently all mold starts growing in a circle pattern, and this definitely did. We will put some pictures on with the show notes for this episode. Just mold patches growing all over the place on this stuff. Pretty nasty.
Cary: Yes. We had a fuzzy mold on top of the grounds right and then below, in the liquid, there was actually- I don’t even know what you would call that, but it was like a liquid mold just flowing around in there.
Brendan: Yes, it probably got sloshed around quite a bit, I don’t know what it looked like below that filter. But yes, when I got home, it was not pretty, it looked like zombie skin-
Brendan: Zombie melted in my [chuckles] cold brew kettle. So we did that experiment with the coffee grounds. And I hope to have somebody on in a future, pretty hopefully, very soon in upcoming episode to talk about ways to use spent grounds. I’ve heard a lot of people just dump them. But there’s a lot of companies out there that are trying to be sustainable with their spent grounds because cold brewing requires a lot of coffee grounds.
So what are some ways that you can prevent mold in your cold brew in your tea or in your Kombucha? First and foremost, this goes back to our brewing background, is just proper cleaning and sanitation, that’s always going to be your best defense.
Cary: Right. Yes. It’s not a fun topic to talk about. I know you already did an episode on it but you just got to get back to that every time.
Brendan: Yes. It was Episode 12, I’ll have to look, I’ll put a link in the show notes for sure but we talked about cleaning and sanitizing with Matt Johnson from Trident Coffee. That is the number one defense, make sure everything is cleaned. Obviously your cold brew never gets boiled, never gets heated, so it doesn’t necessarily get pasteurized and if it’s not getting pasteurized, neither is the equipment that it’s in necessarily. So it stands a chance to become rancid or become moldy. So make sure all your equipment is clean.
If you’re going to steep your product in, the product or the equipment the you’re going to steep your grounds in, as well as the packaging, whether you’re going to put it into a growler or into a keg or a bottle, make sure those are all cleaned as well. And once you clean up, don’t just let them sit out in the open. Especially, if you’ve got doors or windows open.
Cary: Right, you want them covered.
Brendan: Yes, cover them or make sure that you’re cleaning and dipping them into a rinsing agent right before you fill them. So minimize the chance for something from the outside to get in.
What else? Keep the equipment away from doors and windows, I just mention that. Mold spores are going to be more concentrated outdoors, especially if you have trees around, plants. That’s actually something that home brewers do, is they set out petri dishes and they try to harvest a wild yeast. So if you go wild yeast into your cold brew, I imagine that would cause the same problems, whether it’s mold or not, I don’t know, but you would definitely notice something funky starting to happen with the coffee.
And then once you transfer your cold brew or your tea or your Kombucha into its final vessel, whether that’s a keg or a bottle, limit the exposure to the outside air. So once it’s in there, put the lid on right away. And something you definitely don’t want to overlook is make sure that you clean and sanitize the lids for these things as well. Because if you spend a bunch of time cleaning a bunch of bottles and you bottle all your cold brew and then you just throw dirty lids on all these things, you could have a huge problem on your hands.
Cary: Another thing that will help too, is purging the oxygen out of these things, because a lot of molds and bacterias can’t grow in certain gas environments, they need- are basically living air in order to grow. If you’re in a keg, put some nitrogen in there, purge out all of the regular oxygen. And with smaller bottles, this is a little more difficult to do but I think there are still ways of doing that kind of flushing out the air.
Brendan: Yes, I’ve seen a lot of breweries lately, when they feel growlers, they’ll put a CO2 dip tube down to the bottom of the growler and they’ll start releasing CO2 into the growler. And this is all prior to them filling it with beer, they’ll just try to push out all ambient air and then they’ll fill it with beer from there. The thought being that CO2 is heavier than oxygen and air. So that’s basically filling up the growler from the bottom up. But yes, that’s a great point as well, get rid of the oxygen, suffocate it.
What else? Going back to the container that you’re putting it in, we experimented at your house with a batch of cold brew we had done. We finished a keg and then you made another one right.
Cary: Right. And instead of cleaning that keg out, we just figured, this keg is already sanitized, it hasn’t been exposed to any outside air, so we just remove the literal quick, refilled the keg without washing, sanitizing it. Closed it back up, purge the oxygen and about a week later, I was noticing, it wasn’t tasting quite right and I stopped drinking it for a week. Come two weeks down the road, I just decided to empty it, make a new batch, take the lid off the find, just floating zombie skin as you called it before.
Cary: Pretty gross stuff, but it’s just the thought of actually ingesting that the week prior, really grossed me out. I have been a lot more careful with this stuff now.
Brendan: So in that instance, obviously our process was bad. We took the lid off, didn’t rinse the keg out, I didn’t clean anything, didn’t sanitize anything, no cleaning agents were involved. When the lid was off, it was probably just sitting on the table where we normally set stuff when we’re brewing.
Cary: Right. And we were outside who knows how much stuff fell into the keg at the time.
Brendan: Yes, and just to give you a little background, when we home brewing, when we do all this stuff, we do a lot of this testing in Cary’s backyard, we homebrew in his backyard, that’s where our brewing set up is. Its cold brew set up outback, there’s trees around the backyard. So if the lids just sitting out there, yes, it probably got some mold spores on it or maybe they blew directly into the keg itself. So our process was terrible in that and it went to- just prove the point that, you need to have good cleaning and sanitization processes.
Cary: Yes, that was good learning lesson for sure, clean your kegs after every batch, it doesn’t matter if you think it’s clean because you just finished it. You’re opening it up, you’re exposing it to everything.
Brendan: And the same goes for- not just your kegs but your brewing equipment. We had left those coffee grounds in over the weekend. So they were in there for just over 48 hours and it was a giant science experiment in there, gone wrong, when we got back on Monday.
If you think you’re running out of time and you’re not going to be able to clean something, maybe at least just fill it with water to help break that up, so it’s more wet than just damp, or hot water and soap, just let it soak. I’ll tell you why, this thing’s a mess and it’s going to be a lot of work cleaning it, you have to get the pressure washer out, probably going to boil it and yes, a lot of work’s going to go into this.
Yes, to answer your question about moldy cold brew, if it’s growing in your keg or in your bottle, after less than a week, there’s something wrong with the process.
Brendan: Look at the way you’re handling your equipment, both your brewing equipment and your vessels that you’re going to store the cold brew in and just make sure you’re doing a better job cleaning. Clean, rinse, then sanitize prior to putting it in either a keg or a bottle or growler. Anything else?
Cary: Well, why don’t you tell them about your successful experiment over here that we still have sitting?
Brendan: Oh. Let me grab that. [laughs]
Cary: So we did a batch of cold brew on May 20th and bottled it or kegged it on May 21st and Bren pulled off, a small amount of this and just put it in a water bottle about how full with air, it’s just been sitting on our desk here for- what is it now?
Brendan: This is two months.
Cary: It’s going to be months tomorrow. There are no signs of mold in this thing, completely clean. We know our process of brewing this time was completely sanitary, we didn’t have the lid off at all, we just kept it, covered in clean. Yes, we’re just going to continue to let this bottle sit, see if anything ever develops, but so far it looks great.
Brendan: Yes. And this was just put into a water bottle. We basically emptied a water bottle into our cold brew kettle, put the lid back on and then when we were harvesting our cold brew, we filled one of these up. I left some air space in there just to see if the air would contribute to making it turn funky. But so far, this is totally clean two months later. Not that I would recommend this at all, but we’ve got pretty good cleaning and sanitizing processes from our brewing background. I’ve had a keg of cold brew in my kegerator at home for over three months before and drank from it the whole time.
Did I check it at any point to make sure it’s still clean? Yes, I opened the lid but I’ve got another one in there now, that’s been in there for a couple weeks. If your processors are good, there’s no reason your cold brew can’t last beyond two weeks, but if you’re serving in a commercial environment, you probably want to put a timestamp on, when to drink by, when to consume by. But at the end of the day, make sure your processes are good. You want to make cold brew, not mold brew.
Cary: Did we talk about- I know we opened that keg of cold brew, it was that vanilla nut, oily coffee. And we opened the keg because we needed one of our kegs, so we just had to ditch some of this cold brew we had in the keg and we opened it up and it looked as if there was mold floating on the top. And as the keg warmed up, it started to disappear and we realized, its oil basically, solidifying on the top of the keg. We thought it was mold at first but realized it wasn’t.
Brendan: Right. When I started doing a little research for this episode, looking up mold and causes of mold, I found a couple articles about people writing about moldy cold brew. And it turned out that finding oils on the top of the cold brew is pretty common. Just because some coffees are a lot more oily, obviously flavored coffees have a lot more additives in there. So you may get oils that start to solidify and form on the top. And going back to what I said earlier about mold generally being circular, that’s how you can typically tell whether it’s mold or not. If it’s got a circular shape, if you don’t know, close the lid, give it another couple days, if it’s mold, those circles will get bigger. If its oil, it’ll typically just stay the same size once it’s reached the surface.
So all good stuff, yes, clean your stuff, clean your equipment that is the most important thing. Make sure it’s clean, make sure it’s sanitized.
I think we’re good.
Brendan: Alright. Let’s finish this Boo Koo and we will see you guys next week.
Brendan: Alright. Thank you all for joining us for another week of the Drips & Draughts podcast. Kind of a disgusting episode when you think about it, hopefully our zombie skin mold brew discussion didn’t scare any of you guys away from cold brewing. But it’s obviously something that can happen and something that you need to take steps to prevent. If there’s anything that we missed or if you have questions about anything, feel free to email us, email@example.com or hit us up on Twitter. You can get us on Twitter at Drips Draughts @ColdBrewAvenue or even at Keg Outlet, any of those will work. So let us know if you have any questions or comments. Or hey, if we said something wrong in today’s episode, let us know, we’re not scientists.
One additional thing I’d like to mention as a source for potential mold and mold spores, is green coffee beans. I just read this after we recorded the episode. But apparently if coffee beans aren’t dried out completely, they can be a source that harvests mold and mold spores.
We’re not roasters, so if there’s any roasters out there who want to maybe come on the show with us and discuss the proper drying of beans, storage of those unroasted beans, maybe even talk about the roasting process in an after the roasting process, the packaging process, because there’s obviously a lot of contamination that can happen after the beans are roasted. So if your roaster and have any interest in being on a future episode of the show, let us know. Reach out firstname.lastname@example.org or you can go to dripsanddraughts.com/guest.
Alright. I think that’s going to do it for today. If you’re looking for show notes for this episode, you can find those at dripsanddraughts.com/17. Thanks for joining us today, we’ll see you again next week on the Drips & Draughts podcast.
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Thank you to everyone who has contributed questions and you for tuning in, thank you for listening. That does it for this week but looking forward to seeing you again for the next episode of Drips & Draughts.