Search: octyl acetate

Volatile aroma compounds are driven out of the sample through steam distillation. The ethanolic distillate is saturated with NaCl. Potassium hydrogen sulfite is added to separate carbonyl groups that might interfere with the analysis. The extraction of the aroma compounds is performed by shaking out with dichloromethane and the phases separated by centrifuging.

Higher alcohols and esters in beer are determined by gas chromatography using the headspace method, e.g., the volatile compounds are transferred from the gas space in the sample vial to the GC system for analysis. The method is suitable for beer brewed to any original gravity or to any alcohol content.

The gas chromatography headspace method is used to determine the higher alcohols and esters present in beer, i.e., the volatile compounds are transferred from the headspace in the sample vial into the GC system for analysis. The following substances are measured in this analysis:

Acetaldehyde

Propanol-1

Ethyl acetate

2-Methylpropanol

3-Methylbutanol

2-Methylbutanol

2-Methylpropylacetate

Butyric acid ethyl ester

3-Methylbutyl acetate

2-Methylbutyl acetate

Hexanoic acid ethyl ester

Volatile compounds in beer are concentrated through distillation and the distillate is quantitatively determined by direct injection into a gas chromatograph. The linearity of the detector and the determination of the concentrations of analytes in the sample are achieved by using multiple concentration levels within the relevant range and through evaluation of the relative area under the peaks.

This method is suitable for beers exhibiting all ranges of original gravity and alcohol concentrations.

Inductively coupled plasma optical emission spectroscopy (ICP-OES) is a fast and reliable method for the laboratory analysis of metals. Inductively coupled plasma (ICP), a high frequency field of ionized gas, serves as a medium for atomizing and exciting the substances found in samples. Liquid, dissolved or aerosol samples are injected into the ionized gas stream. In emission spectroscopy, ICP can be used in conjunction with a number of optical and electronic systems either simultaneously or sequentially in multi-element spectrometers. In the plasma, the atoms and ions are excited to a higher energy state bringing about the emission of electromagnetic radiation (light), primarily in the ultraviolet and visible region of the spectrum. Metals ordinarily occur as ions in the temperature range typical for ICP of 6000 to 10000 K; however, non-metals and metalloids are only partially ionized.

ICP-OES operates within a very wide range. This usually encompasses six orders of magnitude in concentrations smaller than μg/l up to g/l, depending upon the element and the concentrations used for the set of analysis data. With ICP-OES, beer and wort can also be analyzed without prior processing of the samples, in contrast to AAS. Methods for determining the following in beer and wort will be described below: Al, B, Ba, Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Na, P, Si, Sr, Sn and Zn.

Volatile aroma compounds are driven out of the sample through steam distillation. The ethanol distillate is adjusted to be alkaline and saturated with NaCl. The extraction of the aroma compounds is performed by shaking out with dichloromethane and the phases separated by centrifuging. The organic phase is further concentrated in a stream of nitrogen gas. An ammonia solution is added to remove the acids, because the acids would co-elute, thus preventing quantification of the target substances.