Quality Of Distillates Research Articles

Comparison of fermentation results and quality of the agricultural distillates obtained by application of commercial amylolytic preparations and cereal malts

The objective of this study was to determine the efficiency of rye starch hydrolysis in mashing processes using either enzymatic preparations or cereal malts and their effect on the chemical composition of prepared mashes, fermentation results, as well as the composition of the obtained distillates. The raw materials used were unmalted rye grain and different malts (wheat, rye, and barley malts). The differences in the chemical composition of the distillery mashes, depending on the type and amount of malts used, were observed. The concentrations of reducing sugars were twice as high in mashes containing 30 % cereal malts as in the reference sample prepared with enzymatic preparations (56.2 ± 1.8) g glucose L−1 mash. An increase in the content of cereal malt in mashes from 30 to 50 % did not significantly improve the initial degree of starch saccharification. The highest ethanol content (8.40 ± 0.25) % vol. was found in the mash containing 50 % rye malt, but the fermentation efficiency in this case was the lowest among all fermentation trials and reached only (75.39 ± 1.88) % of the theoretical value. The highest efficiency of process (87.92 ± 2.19) %, comparable to that obtained from the rye mash digested with amylolytic preparations (86.60 ± 2.17) %, was found in the mash prepared with 50 % wheat malt. The fermentation of mash containing 50 % unmalted rye grain and 50 % barley malt gave the lowest ethanol concentration (6.60 ± 0.12) % vol. in the mash after fermentation. The distillates originating from mashes containing cereal malts were characterized by lower concentrations of undesirable acetaldehyde than the distillate obtained from unmalted rye alone.

Correlations among thermophysical properties, ignition quality, volatility, chemical composition, and kinematic viscosity of petroleum distillates

Thermophysical measurements and Raman spectroscopy were utilized to investigate 17 hydrocarbon distillates derived from Canadian oil sands in this work. Thermal lens and optical interferometer techniques were used to determine the thermal diffusivity (D) and temperature coefficient of the refractive index (dn/dT), respectively. It was found that D and dn/dT are closely correlated with the cetane numbers, distillation temperatures, monocyclic aromatics contents, and kinematic viscosities of the fuels. Raman spectra yielded information on the chemical compositions of the distillates, with aromatic contents proving to be particularly relevant. Multivariate analysis elucidated the relationships among the samples, their properties according to ASTM analyses, and the influence of composition on D and dn/dT.

Relationship between volatile aroma compounds and sensory quality of fresh grape marc distillates

To investigate possible relationships, the volatile aroma compound composition of 30 grape marc distillates obtained from six varieties was correlated with the sensory scores for basic properties (clearness, odour and taste) obtained by sensory testing using the hedonic German DLG model. High negative Pearson's correlation coefficients were determined between total concentrations of long-chain ethyl esters and the scores for the property clearness. Strong positive correlation of middle-chain fatty acids and their ethyl esters, and strong negative correlation of sesquiterpenes, diterpenes, methanol, C6-alcohols, acetic and short-chain fatty acids, long-chain ethyl esters, ethyl acetate, other acetate esters, acetaldehyde and furanic compounds with the properties odour and taste were found. Principal component analysis corroborated these results. Monoterpenes were confirmed to be responsible for a typical Muscat aroma, as well as for descriptors such as flowery, rose, citrus and spicy/menthol in distillates made from Muscat varieties. A significant degree of correlation was found between the concentration of C6-alcohols and the frequency of quotation of the descriptor vegetative/grass. Indications were found that vegetative odours of C6-alcohols may act as suppressants of Muscat aroma. A certain degree of congruence was noted between higher concentrations of medium-chain ethyl esters and acetaldehyde, and the occurrence of fruity and nutty odours, respectively. Copyright © 2012 The Institute of Brewing & Distilling

Diesel quality and molecular structure of bitumen-derived middle distillates

Six to seven narrow fractions from each of six light gas oils obtained from various upgrading processes of Athabasca oilsands bitumen were evaluated as diesel fuels. The relationships among the boiling range, cetane number (CN), and aromatics content were investigated. The correlation between CN and aromatic content of narrow-cut fractions showed three trends; i.e. (1) CN increases as aromatics increase; (2) CN decreases as aromatics increase; and (3) a mixed trend of both. In order to investigate such trends, the narrow-cut samples were separated into saturate and aromatic fractions using HPLC, and analyses of type distribution and average molecular structures were carried out. CN of narrow cuts was estimated from the type distribution and CN data for pure compounds. From the H/C atomic ratio, each narrow-cut sample was represented by six types of compounds, i.e. alkanes, mono- and dicycloalkanes, alkyl and naphthenic benzenes, and diaromatics. The average molecular structures for those types had 4–5 branches. The CN trend of the narrow-cuts were reproducible at a certain assumption from the CN of the average molecule structure by type estimated from the CNs of pure compounds. It was found that for the prediction of CN, not only aromatic content but also hydrocarbon types of saturates are important.

Quality of Distillates from Repeated Recycle of Residue

The yields of gas, liquid, and coke from the coking of Athabasca vacuum residue were determined as a function of conversion of the residue. High conversion was achieved by subjecting the unconverted residue to repeated coking steps. The cumulative yield of liquid increased by 12% from stage 1 of coking, where 80% residue conversion was obtained, to stage 3 where over 97% cumulative residue conversion was obtained. The quality of the distillates obtained at each stage deteriorated based on the concentrations of nitrogen and polyaromatic hydrocarbons. Although coking reactions resulted in a significant decrease in the number of paraffinic chains, the average chain length remained constant. A mass balance showed that the aromatic carbon increased in the first coking step, then remained constant.

Influência do dióxido de enxofre e cultivares de videira na formação de alguns compostos voláteis e na qualidade sensorial do destilado de vinho

With the aim of studying the influence of SO2 and grape varieties - Herbemont, Couderc 13, Trebbiano and Isabella, on the chemical composition and sensory quality of wine distillates, some microvinification and posterior distillation of wines were made, at the harvest of 1996. The analyses of volatile components were made through gas chromatography and the sensory evaluation of distillates was accomplished by the sensory group of EMBRAPA Uva e Vinho. The results showed that the sulfur dioxide helped the formation of ethanal in the grape varieties studied. It was also observed an increase in the fusel oil fraction due to the sulfur dioxide, except for the distillate of the Isabel grape variety. It was showed also that the Isabel’s distillated had a higher fraction of methanol and lower of 1-propanol, possibly due to the vinification process. The Isabel distillate together with the Couderc 13 distillate, showed a lower fraction of 2-methyl-1-propanol and a lower fraction of 3-methyl-1-butanol and the fusel oil fraction as compared with the other distillates. The distillate of Trebbiano presented a higher fraction of 2-methyl-1-propanol and together with the Herbemont distillate a higher fraction of 1-propanol, 2-methyl-1-butanol and fusel oil. The sensory evaluation showed that the SO2 had an influence in the aroma, taste and in the general quality of the Herbemont and Trebbiano distillates. The Herbemont distillate was characterized by presenting a lower aroma, taste and general quality. It presented, also, negativelly the highest score for undesirable aroma and taste.

Increasing the quality of oil distillates

Increasing the quality of oil distillates

Intermediate irrigation of complex rectification columns

1. The use of “blind” trays in complex columns is not advantageous since, in this case, the connection of the sections with respect to the liquid flow is made difficult, and there is a lowering of the operating flexibility of the unit, with regulation of different industrial indices (removal and quality of distillates, degree of heating of the raw material, etc.). The investigations show that in industrial columns in atmospheric—vacuum pipe stills equipped with “blind” trays, there is, in many cases, overflow of hot irrigation reflux into the sections lying below. 2. A more rational scheme for irrigation of a complex column is one in which the irrigation is done in the upper section (sharp irrigation) and in two lower-lying sections (ICI-1 and ICI-2). The number of condensation trays for intermediate irrigation in these sections is determined by calculation of the heat removed from 1 m2 of bubbling area; this is 0.5–0.75 million kcal/h · m2 for atmospheric columns, and 0.05–0.1 million kcal/m2 · h for vacuum columns.