/ RAW MATERIALS / Barley / Physiological Tests

R-110.37.600 [2016-03] Pre-germination in Barley – Copper Sulfate Method

Germinative capacity

Germinative capacity is the most important characteristic of malting barley. It measures the percentage of viable kernels in a barley sample, independent of whether they are still dormant or not.

Germinative energy

Germinative energy measures the percentage of kernels in a barley sample, which would germinate under normal malting conditions at the time of the analysis.

A high value for germinative energy indicates that the barley is in good condition and therefore can be successfully malted.

Pre-germination (number of kernels exhibiting pre-germination)

Moist weather during the final maturation stage can cause germination to occur prematurely, while the barley is still in the field. The acrospire and rootlet develop, enzymes are produced and therefore extract is consumed (extract loss) and during the necessary drying process, germinative capacity is diminished. Floating tests and sectioning provide a certain amount of information with regard to pre-germination; however, staining methods allow the degree of hidden pre-germination to be determined. Additionally, the percentage of non-germinated and unmalted barley in malt can be established as well.

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barley

pre-germination

copper sulfate

copper sulfate method

rootlet

acrospire

barley admixtures

Application/Purpose

This method describes how to monitor for visible and hidden pre-germination in barley. Kernels, which will not germinate (i.e., “lie-backs”), and admixtures of other barley varieties are also detected.

Scope of Application

Barley intended for the production of malt is evaluated with regard to pre-germination.

Principle

Visible pre-germination is evident at the rootlet and is therefore grounds for rejecting a barley lot. However, after the barley is cleaned and the rootlets are removed, the so-called “hidden pre-germination” can be made visible using the staining methods described below.

Kernels suspected of having pre-germinated are boiled for ½−1 min in a 20 % solution of copper sulfate, allowed to remain for 30 min in the hot solution and are subsequently rinsed with water. The acrospire is stained green, making it clearly visible.