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1 hour ago, indyspirits said:

Hey @bluestar,  isn't Tailwinds up in the Chicagoland area a big agave spirits producer? Sure would be interested in how they do it.

Yes they are. And the owners are really nice people, so I would suggest reaching out directly to them if you want to get advice. I don't know if @Tailwinds follows the forum regularly, so they may not have posted yet because they haven't seen it, are too busy, or are just shy ;-)

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I know the thread is a few months old, but I wanted to jump in and give you all an insight into our experience with Agave (it is our first batch that we have worked on, we got a great deal on a tote of Agave Nectar and couldn't say no). We took recommendations and our notes from the Downslope distilling course and went to work (they had success with agave and similar to us, hadn't planned on making it but lucked into some). So the non-scientific version of what happens with Agave, as we have been told, is that the yeast are like a fat guy given a pizza, they gorge themselves and then lay around on the proverbial couch (not dead, just not eating). We knew this going in and decided to have a lot of nutrient on hand to get them refocused. Despite the yeast being a Blue Agave specific one (Safteq Blue Tequila yeast), the nutrient wasn't enough and after day 12, SG stopped dropping. pH was in the low 4s/high 3s, which is where Agave will end up, temps were good but SG went from 1.074 to 1.035 and stopped in its tracks, no visible signs of fermentation either (no carbon dioxide, no fizzing, completely still). We decided to pitch fresh yeast and we are now at day 20 and SG is down to 1.014!

So we still have about 4 batches left to make and we will now be pitching half the yeast at startup and half on day 7, keeping everything else the same and we think we can avoid the crash and cut the time back to 14 days or less. We also will try to go a little lower on our OG, maybe 1.065. It tastes amazing, great esters coming through, all around great profile. Let's hope we can get the distillation part of this dialed in and we might have something.

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Lower opening gravity will help.  I had bad information on opening gravity for my first run and it did exactly what yours did, but I could not restart it.  Also step feed the yeast with nutrients over the first 3 days.  Bsg recommends 3,2,2 as the latest advise.  I have not tried the second addition of yeast, but may do so as I am not finishing as well as I would like (1.01).     

 

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One producer of agave spirits I spoke to said he uses multiple yeast strains to full attenuate the syrup. He didn't share which strains since it took him a lot of trial and error to figure it out. Given @bluestar comment about the different sugar contents of bulk agave syrup, maybe using a couple of yeasts more suited to each sugar type would help avoid stuck ferments.

On 9/12/2017 at 7:17 AM, bluestar said:

We didn't experiment enough with it to know, so like Round Barn, we gave up. But keep in mind that one of the things that distinguishes agave is that it is like the fructose version of corn: corn starch is primarily converted to dextrin that gets converted to dextrose (glucose), which is most easily consumed by the yeast for conversion to alcohol; agave primarily contains inulin that gets converted to fructose (mild heat will do it). So, agave syrup or nectar is primarily fructose, with some glucose and maybe some residual inulin, depending on how the syrup was processed. Yeast will consume both glucose and fructose, but efficiency of conversion of fructose to alcohol varies depending on the yeast strain. And inulin needs conversion. There can be a lot of variation in the content of the agave syrups, so even if you processed the same way each time, supplier or batch can affect the result. Sufficient glucose in the syrup will get a yeast started that might initially consume glucose and eventually fructose. Too little glucose, and some yeast may never start up. We notice this with honeys, where there is wide variation in sugar content depending on the flower source. We see that reflected at times in the speed of fermentation, startup, or even stuck fermentations. So I suspect that could be another factor in difficulties with agave syrup. Round Barn is right, that V1116 is specifically intended as a yeast for wine fermentation in extreme conditions, including high residual fructose due to stuck fermentations. I don't know how that compares to something like SafTeq Blue or Silver, which are specifically formulated for use with agave.

 

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@bluefish_dist it is tough to go against that mindset of having something that theoretically could get you 12%-14% ABV, and instead go for 7%. We actually knew that going in, but messed up on our calculations and figured what the heck lets shoot for that 10%. In the end the time required doesn't make it worth it and so next time we will shoot for that lower OG. @EZdrinking if our plan of multiple yeast additions doesn't work then we may look into the yeast strain option. One of the issues with that might be temperature. This Safteq Blue yeast is straight from Jalisco and likes it hot, 89-90F, which is way warmer than what I have been used to with other yeasts. The other issue, from what I have heard is the high furfural content of agave is hard on most yeasts...i think that is some of the fun of starting this endeavor is the trial and error, figuring s*** out. I just wish it didn't cost so dang much.

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I heat my ferments and ran it between 89-90 deg.  I have heard from other sources that multiple yeasts can be the key to full fermentation.  

My question to anyone who successfully ferments agave, what is a good ending gravity?   Is it like rum where you have a decent amount of unfermentables left or should it ferment dry, i.e. Less than 1.  I would hate to put a lot of time into my process only to find out it will only get to 1.01.  

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Keep you posted on ours as far as FG goes. From BSG, the agave has:

80-84% Fructose

13-15% Dextrose

2-4% Sucrose

So not sure what other yeast would tolerate the high furfural environment, but maybe something that is better at the Dextrose and Sucrose?

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I believe there are yeast strains classified as high fructophillic - preferentially fermenting fructose.  I recall reading some studies on the genetics and identification of these strains.

Given the high fructose, this might be a reason why a dual strain strategy works better.

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By way of an update, for those that are interested, we ended up with a 24-day ferment down to 1.002, which would have been awesome had it not taken so long. We felt we learned some things about nutrient additions and adding more yeast so we tried again with our new found knowledge. We started batch #2 on march 1 and went with roughly the same OG, feeling that the correct nutrient and yeast addition regimen would overcome...we were wrong. We started batch #3 on March 7 at a lower OG of 1.065 and followed the  same yeast and nutrient regimen. They are both down to 1.03, but batch #3 has done it in half the time. That being said both have had issues of stalling and we are in the strong belief it has to do with pH. At one point the pH of batch #2 got down to 2.5. We have been working to keep the pH of both around 3.5 and the fermentation is visibly more active and the SG drops about 4 points a day instead of 1-2. So batch 4 is going to be the charm, with an OG around 1.065 and monitoring pH daily. Thanks again for all of your input and i hope our experience is helpful to someone else.

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Thanks for sharing.  Can I ask when and how much yeast you pitched on the second addition?   Generalities of amount are ok, i.e. Same as first pitch or half first pitch.  

I try to hold ph between 3.8 and 4.   I also get slow fermentation times 3-4 weeks.  Next batch will be addition of a second yeast to see if I can get another .01 of attenuation.  

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@bluefish_dist based on our records things start to slow down around day 5-7 so that's when we have planned to do our addition. If we really monitor the pH I think we can get it to take off after this point (maybe we wont need the second yeast addition if we can keep pH up...batch 4 will let us know). So this time around we did about half the original pitch on day 7.

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Sorry guys I dont spend much time on here anymore but came on here to see if the ad for selling our Vendome Still had been approved yet. I can only speak from our experiences with agave as we have been making an agave spirit since we opened in 2012. @bluestar is right in that you will get a lot of variation of not only the sugar content but the types of sugars as well. We used one firm who was adding HFCS to their agave. As you could imagine it fermented easily but tasted terrible. Unlike molasses, there is not a high amount of solids in agave syrup so there is no buffer for wild ph drops. We have used many types of yeasts and agave from many different sources and have only had one batch that would not ferment completely. Three practices that have helped us with consistency: Dont be greedy - keep your washes below 1.060 to start. We will usually see a finish below 1.009. As you become more comfortable with your ferements and what works for you then start stepping up the starting Sg. Be patient -we have never been able to break 7 days on fermentation time. The sugars are more complex and take longer to break down. Use this after fermentation as well- distill it slow. It is very easy to smear heads hearts and tails together though I cant find any scientific reasoning behind  it other than the agave doesn't like to be rushed in anyway. :) Lastly as before mentioned control the ph like a helicopter parent. When we started we used open fermentations which made it easier to constanly bring the ph back up until got good at starting the batch adding buffer. I would recommend PH of around 5.0. Best explained is that yeast spends a lot of energy trying to maintain internal body ph in stressful environments and agave is very stressful on microorganisms (think honey) as is so keeping ph in check will keep your little guys working efficiently. I dont do much of our distilling anymore but our guys have made vast improvements on the information I have started them off with. I pass this along to you because I would love to see American Agave spirits become a more recognized category. It helps us all out. However I must caution,  good fermentable pure agave syrups are expensive (about 3 times more than what we pay for molasses until we started bringing agave across the border by the truck load) so just dabbling in it can blow cash very quickly. Good luck!

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I just finished a run which started at 1.056 and finished at .997.  Took about 2 weeks to fully ferment and clear.  I did a second yeast addition at 48 hrs.   Turned out well and now I am running another batch starting at 1.065 to see how it compares.  From talking with a master tequila distiller he recommended a 6-8% potential abv.  

 

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This sounds about correct.  Nice work.  

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@Tailwinds and @bluefish_dist thanks for the input. So far we we have been average 15 days. pH seems to be the thing that has the biggest affect on fermentation time, from our records. Keeping the temp at 90-95 seems to help too. We have a regimen of yeast at day 0, and again at day 7. We also do nutrients the same day as the yeast and 48hr after. Trying to get my partner to understand its not about higher yield, but getting it done sooner (our OG have all been 1.07, with only 1 at 1.063), but he is a bigger is better guy, so hoping all the data I am collecting will go to prove that SG point. We are still getting to 1.002 at day 14-15 , so not bad. To keep pH up we have been using sodium bicarbonate, because its cheap and I can get it from the store when I need it. I have had a couple of chances to add calcium carbonate as well, but not as consistently or with the same volume as the sodium. Using the sodium bicarbonate I can get the pH to go up by .10 with 200g in 240gal  and stay there for about 2 days. You guys have better luck with any pH adjustment methods...I would love to keep it at 5.0. but right now its a struggle to keep it at 3.8.

Agree 100% on the slow distillation, we use a pot and 4-plate column and eek it out. Good flavor, it actually resembles tequila and not just semi-sweet vodka. 3 batches left to complete our first run of the 270gal tote we bought then going blend it all bottle most of it and age some.

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I use calcium carbonate for ph adjusting.  1/2 lb at a time on a 110 gal ferment.  Raises it about .2 ph and that lasts for a day or so.  I aim to hold ph from 3.8-4.0.  that is the bottom end for the yeast, but it finished well.   I also heat to 90 deg.   After the second yeast addition I drop about .05 per day on the sg.   

I have never used baking soda except in vodka low wines, but I would be concerned in adding too much sodium.  Cc is available in 50lb sacks for cheap.   

I would rather finish better and use all the sugar.   Especially on one that costs so much.  

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Anyone find a benefit or negative to letting an agave ferment sit for a few days after the ferment completes?

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