About My Blog

My name is Jason Rodriguez and I’m a post-doctoral fellow at Columbia University working in a lab that studies Retroviruses.  I work on trying to figure what human genes HIV uses to replicate and establish a spreading infection. I also work on XMRV, a novel human retrovirus discovered in prostate tumors and chronic fatigue syndrome patients.


The first beer that I ever brewed was in the lab!  A good labmate of mine did his Ph.D. in the UK and promptly educated me on the necessities of cask ale, or REAL ale. We endeavored to make our first beer in the lab so our co-workers could enjoy a fresh pint from time to time. I was quickly hooked on the hobby and began to brew beers routinely in the lab.  Because of time constraits, complaints, and the general idea that you shouldn’t be brewing beer at your place of work, I’ve moved my brewing to my apartment in NYC.

I soon realized that there is much science that goes on behind brewing and I have available to me all the equipment needed to study yeast.  I occasionally bring yeast into lab to analyze and prep starters.

This brew blog is all about my experiences in the science of brewing beer.

I hope you enjoy!


50 responses to “About My Blog

  1. Toby

    We here in Canada sometimes use small scale breweries called “U-Brews” to brew 50 litres of beer at a time. I want to add some chipotle chillies to a scotch ale. I was thinking of asking them to add them (2 peppers) to the boil phase inside a cheese cloth. Given your comments that you didn’t get enough heat, do you think I should also allow them to be part of the later aspects of brewing?

    • Hi Toby,

      Sorry I didn’t get your comments earlier, somehow I missed it.

      Better late than never however…

      Short answer, yes. 😉 I think you can increase the pepper amount and use more in the later stages of the brew process. Keep in mind adding chipotle peppers in secondary lets say, will add more smokiness rather than heat.



  2. bella

    Hi Jason

    I just wanted to thank you sincerely for your efforts to communicate your thoughts on what might be behind M.E. (termed CFS in the USA) on J D-J’s blog.
    I really did appreciate and trusted what you were trying to do, and was dismayed and disappointed at the response you got. I’m sure many people with M.E. (like myself) felt the same way.
    Just wanted to say thanks anyway, and best of luck with your beer, studies and daughter!


    • Thanks Bella and I hope you feel better in future.

      As for her blog, I admit I may have come on too strong. However, the whole affair really sickens me. I was honestly looking into a viral hypothesis based on what we know but her rants and attacks on me just pushed me the other way. I have so little time that it needs to be focused on my HIV project not on something that will ultimately get rejected and ridiculed by someone with an agenda.

      Cheers and best wishes,


  3. Brett Thompson

    My name is Brett Thompson and I am a producer for Beer Sessions Radio in Brooklyn (http://www.heritageradionetwork.com/programs/47-Beer-Sessions-Radio-TM-). Was wondering if you would like to be part of our upcoming show on yeast. Please email me at brett.thompson@gmail.com if you are interested.



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  5. This weekend I put the sediment from a Bruery Saison de Lente under the microscope. I saw a few objects I have not seen in any other beer. Some appear to be octahedron shaped and others are dark spheres both slightly larger than the average Saccharomyces cell. Any idea of what these may be? I first thought was diatomaceous earth that escaped a filter or some other fining agent, but they don’t look like other pics I have seen. The sediment settles out in a conical tube with a black layer on the bottom and beige yeast on top. I wonder if I may have stumbled across a QC issue.


    • So the octahedron shape is some sort of crystal that is clearly insoluble. What this crystal might be who knows. It could be fining agent, but I doubt it. I really have no idea.

      As for the brown blobs, hard to know as well. The images are a tad bit fuzzy, but if you see smaller circles within it, maybe greater than three, you could Saccharomyces spores.


      Or those might be mold spores too…

      Hard to know for sure though.

  6. I found an email address for Patrick Rue this morning. I am curious to see if he responds.

    The beer itself tasted smokey and phenolic like a Hoedergaarden, which is not how it is described on the BA reviews. Although, I am not sure mold would cause those flavors.

  7. On a slightly separate subject, do you know anything about hefeweizen strains? Every hefe I have viewed has large quantities of small particles that out number the regular yeast cells. When I saw the first two I figured it was just a byproduct of their brewing process, but after four different beers I am thinking it is a product of the yeast. My question is are the small particles “petite mutants” as described by Chris White in the book Yeast or something else?

    The four samples:


    • So a few things here.

      I think the images that you are showing have yeast but also some trub like particles. Could be protein aggregates and I really don’t think those are yeast. Also, what type of scope are you using? Your images seem to be out of phase, and maybe I can help you tog et better images.

      Now petite mutants don’t mean smaller cells. They are genetic mutations that result in the yeast being unable to grow poorly on non-fermentable carbohydrates, such as glycerol. They grow to very small colony size, hence the “petite”. These cells are deficient in there ability to undergo respiration, most often due to mitochondrial DNA mutation.

      However, what you have there is some healthy yeast and what one would expect looking at a hefeweizen slurry sample under a scope.

      • I am using an entry level iOptron ST-80. The scope is itself is not horrible, but the webcam for imaging is really bad. It has the basics like a metal frame and glass lenses (640x with eyepiece), but lacks
        fine focus knobs. I will go bigger if I go commercial in the future. The wife does not agree with me on how much I should spend on home lab equipment. Still need to convice her that I need an incubator, autoclave, precision pipettor, cell counting chamber, etc…


        Is there any chance the yeast is excreting anything that would cause the proteins to aggregate and not settle as opposed to other beers? The only other beer that I have seen with possibly as many floaties is Orval. Maybe it is just a coincidence about the hefes.

    • Bryan;
      The larger particles look like starch granules- you can confirm if you can observe the purple black color formed by starch and Iodine tincture (damn meth heads have made this hard to find at the local drugstore). Another interesting experiment is to take some Polaroid sunglass lenses and make a poor man polarizer- Starch granules are birefringent under crossed polarizers. Some inorganic crystals, also. Place one of the lenses on the light source, and use the other at your eyepiece- turn the eyepiece “lense’ through 90 degrees to max the darkness, anything that is polarized will be visible sometimes with neat interference fringes in rainbow colors.

  8. Anthony


    I was in your yeast class at Brooklyn HomeBrew back in February, so first of all, thanks for all the great information. I have a porter that I brewed back in February that I’ve left sitting with sour cherries in the carboy. I wanted to give it a good amount of time to infuse with the cherries. It was pitched with Wyeast English Ale II 1335 and I’ll be bottling it soon, but my worry is that there won’t be enough yeast left to carbonate the beer while it matures in the bottle. Is that a valid concern? If so what would you recommend to “fix” the situation?



    • Thanks Anthony!

      As for your porter. How much time has it been sitting on cherries? Keep in mind that longer the brew was in secondary, the longer it will take to carbonate. Unless a beer is filtered, there will always be some yeast cells in suspension. Even crystal clear beer will have yeast in suspension (unless it has been filtered). However, the longer you wait in secondary, the more yeast falls out of suspension and the longer it takes to carbonate. How long did you want it in the bottles? If this doesn’t matter, then bottle away, but it may take several months to carb. If you want the beer carbed in two weeks then you need to add yeast. Also, higher ABV beers (above 8-9% need extra yeast since alcohol itself poisons yeast.

      The amount of yeast that you add to the bottling bucket doesn’t really matter, just as long your priming sugar is right. I’ve heard people add a packet of dry yeast to their bottling buckets with good results.


      • Anthony

        It’s been on the cherries in a secondary for about 10wks, and I was going to let it sit for another 3-4 wks before I bottle. I was also going to give the carboy a walk to break up the sediment like you mentioned in class. I don’t mind waiting a month or so for carbonation to happen in the bottles. It’s not suppose to be a high ABV, but I’ll take that into consideration.

      • Well keep in mind that “walking” the carboy is meant to squeeze the most out of fermentation. Specifically, the tail end when fermentation is slowing. If you shake the carboy you may get too much sediment when you rack to your bottling bucket. What I would do is make sure you grab some yeast from the bottom with your autosiphon to ensure carbonation. You don’t need alot, just plunk the autosiphon on the yeast cake for a second or two to pull up yeast.

  9. Anthony

    Thanks Jason, I appreciate the tips…and will let you know how it all ends up in a few months.

  10. John E

    Hi Jason,

    I’ve been reading your blog with interest for a few weeks now. I have to say I jealous that you are able to use some academic lab resources to further your homebrewing. I work in a GLP lab so they probably would look too kindly on my borrowing some space in a cryofreezer for my yeast bank.

    Anyway, I’m looking for some advice on a diacetyl issue I’m having with a pilsner. It was feremented a ~50F. We did a diacetyl rest for about 36-48h hours before racking to secondary. When we racked, we tasted almost no diacetyls – we were really excited with the taste of the pilsner. It lagered in the high 30s for about a month. We just bottled it and the same we tasted (prior to priming sugar addn) was very butterscotchy. The gravity had not changed much, so it is unlikely that any further fermentation had occurred.

    If the yeast had absorbed the diacetyl during the rest, why would they have release it during lagering? Is it likely that yeast activity during carbonation will clear some or all of the diacetyl? Would really appreciate your thoughts because a scientific explanation would help us avoid this in the future.



    • Hey John,

      Sorry for the delay. So the key thing to remember when dealing with diacetyl is you can’t detect diacetyl precursors by taste. Specifically, 2,3 pentadione has a slightly honey-like taste but can convert to diacetyl. Also, excessive pyruvate or acetaldehyde (leading to more alpha acetolactic acid) will turnover to diacetyl. So you might not have detected it before the beer was ready, but it was still there. These precursors are also called vicinal diketones (VDKs)

      Need some more information on your brew as well. What temperature was your diacetyl rest? Two days *should* be OK, but I have gone longer with good results (4-5 days). I usually ramp up slowly to 60F. This is key. taking the brew out of 50F to room temp is akin to a temperature shock for lager yeast. Better to go from 50-60F over the course of two days.

      Also, keep in mind that bacteria can produce diacetyl. Namely, pedio and lacto. Not saying your brew is contaminated, but just to keep an eye on it.

      The next time you are in the middle of your diacetyl rest do a VDK test to check the presence of diacetyl precursors. I’ve been meaning to write a post about it, but the jist is here:


      The best way to get rid of diacetyl? Fresh healthy yeast added to secondary. Simply adding carbonation sugar for bottle priming might not do the trick. I would add a very neutral yeast (WLP001 or wyeast 1056) from a starter. Make sure it is in exponential phase (12-16 hours) when you add the yeast. This should clean up any diacetyl. Cold crash, and lager some more and you should be good to go.


  11. Hi Jason, I was hoping to send you some information about how your site can become involved with the AHA. What is the best way to reach you?

    Steve Parr
    Business Coordinator
    American Homebrewers Association

  12. Guillermo

    Thanks a lot!. I appreciate the information that you share with us. I´m a engineer and homebrewer since 4 year ago and your tips are just that i need to improve the “scientific side” of mi hobbie. I´m from Chile and sorry if my english is not very good. I´d like to share ideas whit you in order to enrich own knowledge.


  13. Bryce

    Jason are you still interested in getting into Craft Beer? If so please contact me via email.

  14. Hi Jason,

    I just wanted to say congratulations on making our list of favorite beer blogs of 2012 over here at Homewetbar.com! You can find the full list of awards at http://www.homewetbar.com/blog/homewetbars-top-home-entertaining-blogs-of-2012-awards/ . Feel free to shoot me an email, and thanks for the great blog!

  15. Brian Graham

    Hi Jason,

    Do you have any of the CB1 or CB2 to offer interested parties?

    It would be great to purchase one or both strains.


    • Hi Brian,

      As of right now I have no intention to sell them, but I’m open to sharing with specific agreements. Whether I sell them depends on how much work I have done to characterize them.


      • Brian

        Hi Jason,

        Any chance you could share some of the sample with me?

      • Hi Brian,

        Definitely don’t mind sharing these strains. However, I need to grow them up first and actually brew a batch of beer with them. I’ll be brewing this Monday (4/29/13) and will have more yeast after then.



  16. Brian Graham

    Sharing is good. What are the agreements? Let me know how you have done this in the past. Cheers, Brian

  17. Brian Graham

    I saw you on the Mad Fermentationist blog. Good stuff. Glad there are guys like you sharing what you do. It really helps move homebrewing forward and keeps things interesting.

  18. Brian Graham

    Hi Jason,
    I am starting a couple small 8 gallon soleras and would love to use the CB1 and CB2 in them. Let me know the best way to get the samples. Cheers, Brian

  19. Jason we are working on a homebrew documentary and would like to chat with you. Several folks have mentioned your name in the homebrewing circles.

  20. Brian Graham

    Hey Jason Brian Graham again. Are you willing to share some of the CB1 and CB2? I am excited about starting my soleras and these would be great.


  21. Bob Teichmann

    Jason, as a beginning home brewer and chemist, I’m really enjoying your blog. I wish you were in N. Jersey to come to our brew club. Thanks for sharing!


  22. Brian Graham

    Thanks Jason. Good luck with your brewing day! Let me know when you have them to ship. I can give you more details on address and things like that.


  23. Hi Jason,

    I wanted to ask you to see if you have any interest in doing some guest posting for a homebrewing site I manage, but I can’t seem to find your contact information.

    If this is something you might be interested in, please let me know.



  24. Dan

    Hey Jason,
    I am also a scientist that happens to be into homebrewing! I’m a medicinal chemistry post-doc at the University of Kansas. I have enjoyed your blog for a bit now. Keep up the good work. I only hope my small fledgling blog could ever be this good.


  25. Hey Jason,

    Love your blog. Looking forward to incorporating some of your recipes.
    I’m in NYC and would love to connect. Can you shoot me an email?

  26. Andy

    Hi Jason,
    I have a plan to harvest wild yeast and isolate them from various orchards around town. Anyway this can be done on a poor mans budget? I have a scope, dishes, and agar. However I don’t have access to antibiotics or anything like that. What can I do to increase my chances of finding some Brett and keeping out the stuff I don’t want.

    • Hi Andy,

      Sorry about not getting back to you sooner – I’ve been away for vacation.

      If you have a scope, dishes and agar, you are set in my opinion. That is all you need.

      The key to isolating Brett away from fast growing bacteria is dilution. That is you need to dilute the sample enough to allow the Brett to grow separately from the bacteria and other wild microbes.

      For example, lets say you have a grape from a vineyard. I would take the grape and let is soak in some sterile for a while. I would then take out the grape and make a serial 1:10 dilution of that liquid. So set up several tubes with 9 mls of sterile water in them. Then take 1 ml from the original tube (neat) and mix it with a 9 ml tube with water (1:10 dilution). Then repeat this with another tube (1:100, 1:1000, etc…). Finally, take a few drops from each tune and spread it around on the agar plate.

      You will get lots of stuff growing in neat sample, but less in the diluted sample. Colonies of bacteria and yeast look very different. Bacteria are usually smaller and more glossy, while yeast is white.

      Pick the white ones and let them grow in sample wort. Check for overall funkiness and you’re on your way.

      Also, check out BKyeast, he has some interesting DIY selective media.



  27. Jack

    Jason, there is a discussion in the BA homebrewing forum and conducting a study on yeast die off rates (viability and vitality):http://beeradvocate.com/community/threads/yeast-in-storage-viability-and-vitality.149989/
    Do you have any thoughts about the setup of the experiment?

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