27 Analysis of Raw Materials
This methodology can also be utilised to characterise the raw materials used in the production of beer. The resulting data could be utilised to assess what components will provide the desired flavour of the finished product. By monitoring the compounds in the raw materials ‘up front’, and not at the end of the fermentation process, it can save the brewer a significant amount of time and expense by increasing the chances of producing a consistent beer with the desirable flavour and aroma characteristics.
This is exemplified in Figure 8, which displays the results of a study comparing the VOC components of two different types of hops in order to understand and improve their characteristic bitterness on the flavour of the brew. Additionally, some beers use adjuncts to produce unique flavours, such as coffee, honey and fruits. Therefore, the same approach may be used to characterise these compounds. Figure 9 displays the results of a comparison between orange peel from different suppliers for use in Belgian style beers.
Figure 4: Comparison of flavour compounds between five different fermentation trials of the same beer type (data courtesy of the Long Trail Brewing Company, Bridgewater Corners, VT)
Figure 5: Specific gravity profile for the experimental beer, showing that the fermentation process was completed in about 100 hours
Figure 6: Concentration profile of diacetyl for the experimental beer during the fermentation process
Figure 8: VOC profiles of two different types of hops (data courtesy of the Long Trail Brewing Company, Bridgewater Corners, VT)
Figure 7: Concentration profile of dimethyl sulphide for the experimental beer during the fermentation process
Aging Studies
Beer is a very complex matrix, which ages over time due to chemical and biological activity. For that reason, storage conditions are critical to its quality. Exposure to air promotes the formation of aldehydes, acetic acid and other undesirable compounds that can impair the flavour of a beer.
For example, one flavour concern is that bittering components, such as
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