Beer Fermentation Control Using Ion Mobility Spectrometry - Results of a Pilot Study

Abstract

Beer fermentation -a time consuming part of the production process -is typically terminated based on the degradation of diacetyl and 2,3-pentanedione below the odour threshold. Presently no on-line control of both analytes is available. As a consequence, fermentation is often carried out longer than necessary, thus decreasing productivity. In this pilot study, an ion mobility spectrometer using a UV-lamp as an ionisation source and a GC column (30°C constant) for pre-separation were used for the rapid determination of both analytes from the headspace of beer wort, during and after fermentation. Samples were heated to 60°C. Results from such analyses were available after a few minutes without further sample treatment or pre-concentration. Detection limits were below the odour threshold (ng/L range in the gas phase corresponding to the µg/L range in the liquid phase). Results were validated by comparison with the brewery's standard GC-MS method. When applied on-line and in-situ, as a routine test in a brewery, it will help to ensure low levels of diacetyl and 2,3-pentanedione in the product on the one hand and will increase productivity by saving time during fermentation on the other (up to one day in large breweries and even more than one day in smaller ones) by obtaining on-line data of the relevant analytes. After optimisation of the method, further odour or taste relevant analytes could be determined simultaneously.

Empirical prediction of reduced ion mobilities of secondary alcohols

“…However, in recent years, ion mobility spectrometers are increasingly in demand for new applications specifically on biological samples (cells, fungi, bacteria) [3][4][5][6][7][8][9][10][11][12], in medicine (diagnosis, therapy and medication control e.g. from breath analysis) [3,4,13,14] and process control [15][16][17][18][19][20][21][22]. For such applications, IMS measurements faces challenges such as humid and rather complex samples, requirement of a specific sampling procedure adapted to the application, fast pre-separation techniques like multi-capillary columns and most importantly, suitable data processing techniques which include databases of relevant analytes for automatic characterisation of the signals detected in an IMS chromatogram [23][24][25][26][27][28], and different data pre-processing steps [29][30][31][32].…”

Exemplar application of multi-capillary column ion mobility spectrometry for biological and medical purpose

“…The detected five signals of the bacteria respectively the four signals of the fungi should enable their identification in the breath of an affected patient and the can be used for a pathogen specific diagnosis. In general, characteristic peak pattern of microorganisms can not only be used for medical purpose but also for the identification of microbial contamination in bioprocesses [22,24,26].…”

“…Only few investigations were published on other applications such as biological samples [15][16][17][18]. At ISAS-Institute for Analytical Sciences, Dortmund, Germany, ion mobility spectrometry with fast pre-separation techniques was applied for the sensitive detection (lower ppb v down to ppt v range) of metabolites in human breath [19,20] but also for process control and food quality and safety [21][22][23][24]. By help of representative examples, the potential of the method for the identification and quantification of metabolic markers of bacteria, cells, fungi and in human breath-including diagnosis, therapy and medication control-will be illustrated.…”

An implementable approach to obtain reproducible reduced ion mobility

“…In recent years, especially by employing additional pre-separation techniques, new fields have been opened such as medical applications including early diagnosis, medication and therapy control by analyses of human breath [4][5][6][7][8][9] as well as identification and quantification of the metabolites of cells, bacteria and fungi [10][11][12][13][14][15][16]. Furthermore, ion mobility spectrometry is expected to have high potential for its applicability in the field of process control [17][18][19][20] and of food quality and safety including storage and packaging [21][22][23][24][25][26][27]. A broad overview about the related literature is given in [28].…”