Barley quality and grain size homogeneity for malting

Abstract

JOINT ABSTRACT of Volumes I and II

Homogeneity, a measure of grain uniformity, is important for malting and brewing performance and is of increasing interest to maltsters who have to produce a homogeneous malt. The aim of this project was to investigate how barley and malt homogeneity are affected and could be improved by, agronomic management and malting process.

The work was conducted at two sites over three years.

Field trials (Volume I of Project Report No. 120)

The influences of barley variety, nitrogen application, seed rate, fungicide treatment and sowing date on barley properties were examined by ADAS.

Malting trials (Volume II of Project Report No. 120)

The grain produced in the field trials was passed to Brewing Research International for malting. The influence of the malting process (both commercial and laboratory) on malt homogeneity was then examined.

Reducing plant density significantly increased grain size and, possibly, grain size distribution. Grain size has a large influence on the homogeneity of a sample of barley. Seed rate may therefore be a practical way of agronomically influencing homogeneity. Grain nitrogen also increased at reduced plant densities. This effect was greater than that of variety and should be taken into consideration to achieve malting specification.

Fertiliser nitrogen rate and fungicide programme affected grain size by altering crop canopy size and duration and also influenced homogeneity. Nitrogen rate effects on grain nitrogen and thus endosperm structure are a major influence on homogeneity. There is a need to balance use of these agronomic treatments for homogeneity whilst aiming to optimise yield.

The main factors influencing the homogeneity of the malt were damage to grain, endosperm structure of the grain and the corn size distribution. Commercial malting plants did not have a major effect of malt homogeneity.

The main factor influencing the homogeneity of malt was the quality of the barley and the way it was treated in the field. The three key results found when malting grain obtained from the field trials were:

a significant influence of the seed rate on the corn size distribution (mentioned above),
a significant influence of nitrogen application on the endosperm structure of the grain (by LTm),
a significant influence of variety on endosperm structure, corn size distribution and on homogeneity.
Treatments in the commercial malting plant had much less influence than did agronomic factors. This suggests that there are opportunities to grow malting barley under agronomic management to increase homogeneity. However, as such management regimes may not necessarily optimise output for the grower, premiums would have to be set to encourage their adoption.