Lesson 4 - Wort and Beer Analysis
This lesson looks at how to analyse the composition of wort and beer. It covers the current methods for each analysis, outlining the basics of how they are undertaken. It then explains the methods and standards used to ensure that analysis is both precise and accurate. Finally, it discusses how laboratories collaborate so that proficiency levels can be determined.
Point of Reflection – Reconvene
Welcome back. So, what were your thoughts?
We learned earlier that there are variations in results for all methods, even when undertaken by the same person in the best possible lab. So, there is no exactly ‘right’ answer. Having the results of all labs used to produce proficiency data will take into account the variation within the R95 for the analysis method. Having a spread of data from all the labs also makes the peer comparison possible.
Each brewery also receives a z-score for each analysis. This is calculated as above but from the median in place of the mean and using a standard deviation calculated from the median of absolute differences. A z-score of less than 2 is said to be satisfactory and a z-score of 3 and above unsatisfactory.
Another scheme is the ASBC Lab Proficiency Program. In this scheme, labs can sign up to receive samples of beer, hops, malted barley, and mycotoxins. Samples are sent on a quarterly basis with results published in a similar way to BAPS. In the ASBC scheme the assigned value is the mean of participant results after the data have been analysed for Grubbs’ outliers. A z-score for each laboratory per analysis is also published.