Hulless barley for functional food

Abstract

Under-utilisation of barley as a human food in the UK is potentially a missed opportunity for public health as components of barley grain, especially beta-glucan soluble fibre, have the proven ability to ameliorate diet-related health problems, including obesity, type-2 diabetes and high cholesterol.

The development of a health food market for barley could also benefit UK barley growers. All current UK barley varieties have covered grain and the hull must be removed by pearling to render the grain edible. Pearling also removes the nutritious bran and germ. Naked barley grains thresh freely from the pales (that form the hull) so that the whole grain can be used without processing.

This project evaluated the agronomic and grain quality characteristics of a collection of exotic naked barley varieties under field conditions in Wales over two years, and compared them with those of UK hulled varieties. Spring and autumn sowing were compared and grain beta-glucan and amino acid content were measured.

As a test of the potential to breed UK-adapted naked barley, selected naked lines from a cross between a conventional UK hulled and exotic naked barley were assessed for agronomic properties.

Many of the exotic naked barley varieties had high levels of foliar disease and lodging and only a limited yield response to fungicide. Conversely naked grain lines with modern UK parentage had stiff straw and good resistance to disease.

The only agronomic problem specific to the naked grain trait was poorer crop establishment, due to the vulnerability of the exposed embryo to damage during harvesting, and to weaker coleoptile growth. Solutions for this are to ensure careful harvesting and handling of seed crops (e.g. reduce combine drum speed to 600-700rpm) and to delay sowing of spring varieties to ensure a warm seedbed.

However, some naked Himalayan varieties, and progeny from Himalayan x UK crosses, had excellent seedling vigour, indicating that careful crossing and selection for early vigour may resolve establishment problems in future. There was wide variation in beta-glucan concentration between genotypes (3.0 - 7.0g/100g DM), but also considerable variation between environments.