Malting Behaviour of Barleys Grown in Canada and Spain as Related to Hordein and Enzyme Content

Abstract

To continue our effort to analyse the genetic (varietal) and environmental (sites and years) effects on malting quality of barley, we have field‐tested four barley varieties, two‐ and six‐rowed, European and North American, in Spain and Canada in 1998 and 1999. The Spanish trials were autumn‐sown whereas the Canadian ones were spring‐sown. Barley grain was analysed for total protein and hordein contents and micromalted. Canadian‐grown barleys had significantly lower contents of grain protein and all‐three hordein fractions than the Spanish ones. They also had lower malt respiratory losses, wort β‐glucan and viscosity but lower fine‐ and coarse‐ground malt extract yield, friability, free amino nitrogen, Kolbach index, α‐amylase and diastatic power. In other words, the Canadian‐grown barleys, despite showing lower protein and hordein contents, produced malt of inferior quality than their Spanish counterparts, which, overall, produced higher quantities of degrading enzymes (amylolytic, proteolytic and cytolytic) during germination, thus being able to attain higher extract yield levels.

Endosperm Structure Affects the Malting Quality of Barley (Hordeum vulgare L.)

“…The weight loss during the malting process showed that even though the steelier samples had a higher respiration rate and a higher total malting loss, the growth of their rootlets was lower than in the mealy samples. Recently, low respiratory losses have been linked to a low grain protein content (26), but our results suggest that endosperm structure may also affect respiratory losses. Apparently the high respiration rate of steelier barley was not related to the growth of the embryo but possibly to an increased requirement of energy for endosperm degradation caused by the tight structure of endosperm.…”

A model of the genetic differences in malting quality between European and North American barley cultivars based on a QTL study of the cross Triumph × Morex

“…1993), which could have affected six‐row types, particularly the lateral florets, to a greater extent, as even six‐row progeny had high levels of protein compared with all lines at the other sites. The malting quality of Spanish‐grown barley can be comparable to, or better than, that of N. European or Canadian barley, despite higher protein levels (Molina‐Cano et al. 2004).…”

Grain hordein content and malt quality as affected by foliar nitrogen fertilisation at heading

“…Further, Veliz et al ( 21 ) observed an increase in the expression of hordein C (poor in sulphur) due to the effect of nitrogen fertilisation. In contrast, Molina Cano et al ( 14 ) , in a series of field trials in Spain and Canada, together with Savin et al ( 22 ) in a container experiment observed no change in the proportion of the different hordeins due to nitrogen fertilisation.…”

“…The two most abundant fractions are B (rich in sulphur) and C (poor in sulphur), while the two less abundant fractions are D (intermediate sulphur content) and gamma (sulphur rich, high molecular weight) ( 11 ) . When different cultivars ( 12 ) or grains of the same cultivar grown in different geographical regions were compared ( 13, 14 ) , malt extract was positively related to the ratio of B‐hordein to C‐hordein. However, this relationship has not always been corroborated ( 15 ) .…”