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Fermenting directly in stainless steel, whether a dedicated fermenter like the Kegmenter or a repurposed corny keg, offers genuine advantages for closed fermentation, pressure capability, and elimination of oxygen pickup during transfer. I’ve fermented in both and the comparison reveals real practical differences that matter depending on how much you prioritize cleaning access versus transfer simplicity.
Kegmenter vs. corny keg fermenter: design comparison
Kegland Kegmenter: A purpose-built stainless steel fermenter designed specifically for homebrewing fermentation, sold in 19L and 35L versions. The Kegmenter is based on a ball-lock keg form factor but with a wide-mouth lid (approximately 10cm tri-clamp opening) instead of the corny keg’s narrow post-and-lid design. Key features: wide-mouth lid for easy cleaning access with a brush or hand; tri-clamp connections for dip tube, gas post, and spunding valve; pressure-rated to allow pressure fermentation and closed transfer; integrated pressure relief valve; clear floating dip tube for drawing from the top of the liquid without pulling yeast sediment. Price: approximately $150–200 USD for the 19L version. The Kegmenter represents Kegland’s purpose-designed approach to fermenter-in-keg form: the wide mouth makes it significantly easier to clean than a standard corny keg, while retaining all the pressure capability of a keg. Corny keg fermenter (repurposed Cornelius keg): Using a standard 19L (5-gallon) ball-lock or pin-lock corny keg as a fermenter, pitching directly into the keg, applying a spunding valve, and fermenting under pressure. Corny kegs are pressure-rated to 130 PSI (their standard use for carbonated serving at 10–14 PSI provides enormous safety headroom for fermentation). Cleaning limitation: the standard corny keg has a narrow opening (the liquid post and lid assembly), cleaning the interior thoroughly requires either a pressurized cleaning solution (PBW recirculation) or a specialized long-handled keg brush. The narrow opening makes it impossible to inspect the interior surface after cleaning without specialized keg inspection equipment. Gas and liquid posts must be removed and cleaned separately. Dry hopping in a corny keg requires either a larger mesh hop bag that fits through the post or post removal to add hops, neither is as convenient as the Kegmenter’s wide-mouth lid. Price: used corny kegs are available for $30–60 each, making them the lowest-cost stainless fermentation option. New kegs cost $80–120. Pressure ratings: Both are adequate for fermentation pressure. Corny kegs rated to 130 PSI have extreme safety margin over fermentation pressures (15–20 PSI). Kegmenter pressure rating is typically 35–45 PSI, still more than adequate for any fermentation pressure protocol.
Fermentation advantages of steel over plastic
Why ferment in stainless at all: Stainless steel offers non-porous surfaces that cannot harbor bacteria or Brettanomyces in micro-scratches the way plastic fermenters can, making decontamination after Brett or sour fermentation fully achievable. Oxygen impermeability, stainless provides a complete oxygen barrier; plastic PET and HDPE fermenters are slightly oxygen-permeable over extended conditioning periods, which matters for long-term aging. Durability, stainless lasts indefinitely with proper care; plastic fermenters become scratched and cloudy over years of use, increasing contamination harboring risk and making sanitation assessment difficult. Pressure fermentation capability, both the Kegmenter and corny keg handle fermentation pressure safely; most plastic fermenters do not. Closed transfer capability: Both the Kegmenter and corny keg enable fully closed CO2-pressure transfer to serving kegs, beer moves from fermenter to keg entirely under CO2 pressure with no air contact. This eliminates the primary oxygen pickup risk in homebrewing (the transfer step) and produces beers with dramatically better oxidation stability than open-transfer equivalents. This is arguably the most important practical benefit of fermenting in stainless keg-format vessels. Recommendation: For brewers new to stainless keg fermentation: repurposed corny keg at $40–60 is an excellent low-cost entry point. For brewers who want convenient wide-mouth cleaning access and purpose-built features: the Kegmenter at $150–200 is worth the premium.
Common Questions
How do you dry hop a corny keg fermenter?
Dry hopping in a corny keg fermenter requires a different approach than wide-mouth fermenters due to the keg’s narrow opening, but several workable techniques exist. The main options: (1) Hop bag through the liquid post opening: remove the liquid post and poppet, place hops in a fine mesh nylon bag, attach a length of stainless chain or wire to the bag, lower the bag into the keg through the liquid post opening, and replace the post. The bag hangs suspended in the beer during dry hop contact. This works for pellet hops in small quantities (up to 50g) but larger dry hop additions may not fit through the post tube. (2) Hop bag on a metal tie-down: before fermenting, place hops in a weighted mesh bag inside the keg at pitching, so hops are present from fermentation start. This is a “biotransformation dry hop” approach rather than post-fermentation, which changes the character (more biotransformation ester development, less late-addition aroma preservation). (3) Remove one post entirely: using a post removal tool, take off one post (liquid post), add hops through the open port, replace the post and reseal. This allows larger hop additions than the bag-through-post method. Re-sanitize the post and port before resealing. (4) Accept that corny keg fermenters are not ideal for large dry hop additions, use a Kegmenter or wide-mouth fermenter for heavily dry hopped styles and reserve the corny keg for clean ales, lagers, and styles with minimal dry hop requirements.
