Effect of Fermentation on Cyanide and Ethyl Carbamate Contents in Cassava Flour and Evaluation of Their Mass Balance during Lab-Scale Continuous Distillation

When cassava is used for the production of distilled spirits through fermentation and distillation, toxic hydrogen cyanide (HCN) is released from linamarin and carcinogenic ethyl carbamate is produced. Herein, cyanide and ethyl carbamate contents were monitored during the fermentation and lab-scale continuous distillation processes. Thereafter, mass balance and the influence of copper chips were evaluated. Results showed that 81.5% of cyanide was removed after fermentation. Use of copper chips completely prevented the migration of cyanide into the distilled spirits, while 88.3% of cyanide migrated from the fermented liquid in the absence of copper chips. Formation of ethyl carbamate was significantly promoted during distillation. Most of the produced ethyl carbamate (73.2%) was transferred into the distilled spirits in the absence of copper chips, only 9.6% of the ethyl carbamate was transferred when copper chips were used. Thus, copper chips effectively prevented the migration of cyanide and ethyl carbamate into the distilled spirts during continuous distillation.

Vapor–liquid Equilibrium and Distillation of Mixtures Containing Formaldehdye and Poly(oxymethylene) Dimethyl Ethers

Poly(oxymethylene) dimethyl ethers (OME, H3C–O–(CH2O)n–CH3) are promising synthetic diesel fuels. Fordesigning OME production processes, a model for describing the vapor–liquid equilibrium (VLE) in mixtures of(formaldehyde + water + methanol + methylal + OME + trioxane) is needed. Building on previous work ofour group, a physico-chemical model for the VLE in these mixtures is developed in the present work. For thedevelopment and the testing of the model, experiments of different types were carried out: VLE measurements ina thin film evaporator, batch evaporation experiments in an open still, and continuous distillation experiments ina laboratory column. The model predicts the results of the distillation experiments well. It is shown that OMEwith n ≥ 3 can be separated as bottom product from mixtures of formaldehyde, water, methanol, methylal, andOME with n ≥ 2. This separation is a critical step in a novel OME production process that increases the sustainabilityof OME production.

Advance in the characterization of alambic cachaça: ethyl lactate

In the current methodology for the analysis of cachaça, the limit of 200 mg/100 mL ethanol established in Brazilian legislation for the totality of esters present in cachaça is measured exclusively by the dosage of ethyl acetate, the principal ester in cachaça produced on an industrial scale (continuous distillation), whose asepsis procedures applied to the broth are focused on combating the activity of bacteria. However, it is known that producers of alembic cachaça (batch distillation) ferment the fresh juice, which naturally incorporates lactic bacteria from the environment. A survey of the analysis records of 300 samples, corresponding to 110 cachaça brands, was performed. The analyses were performed using the recommended laboratory methods and gas chromatography. The extensive occurrence of ethyl lactate was found in varying proportions, but with the same order of magnitude as ethyl acetate. It was concluded that, in addition to the olfactory peculiarities related to the particular contents in each brand, the simple presence of ethyl lactate (above a level that can be referred to as traces) permits one to infer whether the cachaça originates from alembic or from industrial production.

Decrease of energy demand of semi-batch distillation policies

Batch distillation (BD) has much higher energy demand than continuous distillation (CD). Different semi-batch distillation (SBD) policies, by which one part of the feed is continuously fed into a batch column, are investigated and optimised to minimise the energy demand. SBD has the advantage, that contrary to the batch distillation (BD), the liquid volume in the reboiler, can be kept constant, even at its maximal value. Usually, continuous feeding is performed into the reboiler (SBD1), but by shaping a feed plate in the batch column, it has not only a rectifying but also a stripping section. Several SBD policies differing in feeding location are studied by dynamic simulation and compared based on the specific energy demand (SED) of production. The different policies and effects of the variation of feed composition are studied for the separation of the mixture dichloromethane-acetone. The lowest SED is obtained by SBD with feeding at a variable location of the column (SBD3). However, feeding at a fixed location (SBD2) is much simpler to realise and only slightly inferior. Further reduction of SED is reached by using two SBD2 or one SBD2 and one BD step with different reflux ratios. The separation of the mixture n-hexane-n-heptane-n-octane is also studied by SBD1 and SBD2 policies with both direct and indirect sequences. The energy demand of SBD2 in indirect sequence is lower than that of the direct sequence by 25%. By applying SBD2, SED was reduced by 38% and 39% for binary and ternary mixtures, respectively, compared to BD.

Innovation in Continuous Rectification for Tequila Production

In this study, a new process of continuous horizontal distillation at a pilot level is presented. It was applied for the first time to the rectification of an ordinario fraction obtained industrially. Continuous horizontal distillation is a new process whose design combines the benefits of both distillation columns, in terms of productivity and energy savings (50%), and distillation stills in batch, in terms of the aromatic complexity of the distillate obtained. The horizontal process of continuous distillation was carried out at the pilot level in a manual mode, obtaining five accumulated fractions of distillate that were characterized by gas chromatography (GC-FID). The tequila obtained from the rectification process in this new continuous horizontal distillation process complies with the content of methanol and higher alcohols regulated by the Official Mexican Standard (NOM-006-SCFI-2012). Continuous horizontal distillation of tequila has potential energy savings of 50% compared to the traditional process, besides allowing products with major volatile profiles within the maximum limits established by the regulation for this beverage to be obtained.