Avoiding surprises and solving scaling headaches in fermentation, distillation, and botanical extraction WRITTEN AND PHOTOGRAPHED BY JOHNNY JEFFERY, M.S.
S K C U S G N I SCAL (But You Can Do It)
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caling from a benchtop to a production line rarely works the way you hope it will. Unfortunately, linear scaling isn’t really a thing, as all the cats and dogs do what they please once you push into higher volume equipment. Everything from fluid dynamics in a fermentation, to differences in reflux in a lab still versus a production still, to botanicals extracting differently at production volume can contribute to discrepancies that are impossible to anticipate. That said, we can absolutely work our way up and correct for things or meticulously run test modifications if we see quality drift.
Fermentation and Distillation Test runs on a benchtop for fermentation are some of the easiest to scale. The factors we control for (pitch rate, grain-to-volume ratio, yeast type, fermentation temperature, fermentation time) are relatively simple to scale and if the control (temperature, agitation) you’re exercising on the bench mimic what you’re capable of at production, those should run up linearly. Two factors that are often overlooked are fermenter geometry and agitation rates. A cylindro-conical fermenter with a deep-angled cone at the bottom or a tall narrow fermenter can result in more pressure at the bottom of the fermenter that forces CO2 to solubilize as carbonic acid, acidifying the wash at a production scale more than you would find in a bench scale vessel. While this is something that is ideally controlled g isn’t really Linear scalin for in facility design, if these are the vessels ts ca e th you’ve got, then understanding the difference ll a s a thing, a can explain sensory shifts when scaling up. at they h w o d s g o d d It's often the case that stirrers on a benchtop an to in sh u p give you more rapid agitation, better temperau o y please once ture control, and better dispersion of solids in equipment. e m lu o v er h the broth than you would see at greater volume. hig 58
Adequate agitation at the production scale is worth your attention, as hot pockets and uneven distribution of solids can lead to issues; however, when scaling up, it’s most important to mimic your conditions. It can also be tempting to overdose ingredients like enzymes, yeast, and nutrients at the bench, or be more attentive to yeast hydration in a way that’s dissimilar to how it would be handled on the production floor, but the dose rates and process should exactly mimic your scaleup so the fermentation rate, conversion rate, and yeast condition is parallel. Lab stills for this kind of R&D should closely mimic the shape, style, heat-rate, and cooling of the production still if possible. Glass doesn’t interact with sulfur in the same way copper does in distillation, and reflux ratios and temperature of condensed spirit have great effects on the character of the finished product. Data collection and doing your best to mimic conditions is your best bet for accurately scaling from one to the other. A glass still with a lab condenser that cools well below what you are capable of at scale will skew the product qualities in ways that will be difficult to correct if you don’t have accurate information about how the lab still treated the spirit. From glass to copper, you’ll probably see improvements, but if your expectations are set by the glass still, you’ll need to anticipate the differences and do your best to keep conditions consistent. (Example: If your 2L still is putting out 100mL/hour during R&D, your 5,000L still should put out 250L/hour in your scale-up, i.e. both running at five percent still volume as output/hour.) W W W . ARTISANSPIRITMAG . C O M