HVG Germany: Hopfen

 

 

Evaluating the methods

 

Unfortunately the methods described do not produce identical results when several analyses of a sample are made. In judging the methods Dr. Adrian Forster says in his publication "Wie analysiert man Hopfen" ("How to analyse hops")(1993):

How do you evaluate the methods?

A whole number of criteria can be applied here somewhat like the following:

1st Group: Accuracy, reproducibility, strength of evidence. These points embrace the quality of a method. How accurately can the desired substance be analysed? Do several assistants In a laboratory obtain the same result on different days or do they vary? How do the results vary if several laboratories examine the same types of samples? These points all come under the term "Reproducibility", by which it can be ascertained by statistical formulas what deviations must be expected when using a certain method.

By strength of evidence this means what information is obtained overall. There are methods which not only produce one value but several. Thus the complete Wšllmer analysis can produce the total content of bitter compounds (=total resin) and the aging degree (hard resin content) as well as the alpha-acids. The ASBC-method provides an aging index as well as the alpha-acids. The HPLC is the most informative method as characteristics of the specific variety can even be ascertained as well as alpha- and beta-acids and an indication on aging.

2nd Group: Apparatus required, time needed, capacity, use of solvents, other expenses. Last of all this group encompasses points which are included in the costs for an analysis. How expensive is the equipment? How long does it take until the result is available? Of course in processing hops it is important to reach a result quickly. If several analyses can be carried out simultaneously, how many analyses does a person/a team make per day? In other words: What use is the best analysis if only very few results are produced per employee and per day? Furthermore it is interesting to know how high the consumption of solvents and other material is. Finally it is also important what qualification the analyst must possess in order to cope with handling the equipment. Therefore all questions concerning the cost of an analysis are contained in this point.

3rd Group: Safety, health risks, environmental compatibility. Understandably this group has played an increasingly important role in recent years. Is a solvent which is required for the analysis explosive, similar to e.g. petrol? Are there any risks for human beings in handling it? Is a solvent harmful to health? Generally it must be said that all the solvents required for hop analytics are subject to certain reservations, anyway it is important to make sure that the laboratory is well ventilated.