This 2013 article, ScienceShot: A Shot of Coffee That Gets You Drunk | Science | AAAS talks about how used coffee grounds are being tested as a base for fermentation, but doesn't give specific details.
Has anyone here had success doing this?
(I'd especially be interested in knowing if it can be done without significant addition of sugar, with the coffee being the primary source for the fermentation and not simply there to add flavour.)
Per the original paper (Armando Sampaio, Giuliano Dragone, Mar Vilanova, José M. Oliveira, José A. Teixeira, Solange I. Mussatto, Production, chemical characterization, and sensory profile of a novel spirit elaborated from spent coffee ground, LWT - Food Science and Technology, Volume 54, Issue 2, 2013, Pages 557-563)
A hydrothermal process was initially performed aiming to extract aroma compounds from SCG [spent coffee grounds]. Solid-liquid extraction conditions consisted in using water and SCG in the ratio of 1 g/10 mL, at 163 °C during 45 min. At the end of the reaction, the residual solid material was separated by centrifugation (5000 g, 15 min) and the liquid fraction (SCG extract) was stored at 4 °C. To be used as fermentation medium, SCG extract was supplemented with 180 g/L sucrose and 175 mg/L potassium metabisulfite. Then, the pH of the fermentation medium was adjusted to 5 by addition of calcium carbonate, and the remaining solid residue was removed by centrifugation (5000 g, 15 min).
[...]3.5 L of fermentation medium (180 g/L sucrose) inoculated with [ Saccharomyces cerevisiae (RL-11) at] an initial cell concentration of 1 g/L. Fermentations were maintained at 30 °C and 150 rpm. Samples were periodically withdrawn to determine the total sugars concentration in order to determine the fermentation end. At the end of the fermentation, the fermented broth was centrifuged (5000 g, 10 °C, 15 min) to separate the biomass, and the liquid phase was stored at 4 °C for further distillation. The fermentation runs were performed in triplicate.
The free-biomass fermented broth was distilled in a system comprising a vigreux column of 36 cm of length, a condenser, and a 4 L flask filled with 2–2.5 L of fermented broth. During the fermented broth distillation, samples of approximately 20 mL were recovered and the ethanol content in each one of them was determined. Then, the samples were blended in order to obtain three fractions according to their ethanol content: the foreshot or “head” (>70 mL/100 mL), the middle cut or “heart” (70–40 mL/100 mL), and the feints or “tail” (<40 mL/100 mL). The fraction corresponding to the heart had the ethanol concentration corrected to 40 mL/100 mL by adding ultrapure water, and was stored in glass bottles with caps and plastic coverings at room temperature for later sampling, chemical and sensory analyses.
