During a welcome, but sadly brief, lull in my workload I was able to go through most of the piles of paper that had built up on my desk. There at the bottom of one of them was a gem I'd mined from the JIB archive* and then forgotten about: the malting qualities of Spring barley varieties from 1880 to 1980:
They've used some peculiar foreign system for the Hot Water Extract, but fortunately give it in litre degrees per kilogram too. Similarly they have the Kolbach Index not the Soluble Nitrogen Ratio but they're both pretty similar anyway.
In the century 1880 - 1980 plant breeders have made a 40% genetic improvement in grain yield, but how much have they managed to improve malting qualities? Yield is one thing but for malting we want plump and bold grains, rapid and even germination so there is rapid and even modification, as well as low concentrations of cell wall material and protein.
In the experiment described in the paper 15 varieties of barley from 1880 to 1980, all of which were considered suitable for malting at the time were grown at Cambridge and Warminster in 1980.
Improvement in extract yield per hectare (i.e. a factor of grain yield and extract improvement) was 0.012 and 0.015 tonne/ha/year at Cambridge and Warminster respectively. Post 1953 when the variety Proctor was introduced the rate increased from the 100 year average: tripling at Cambridge and doubling at Warminster.
A previous study found little difference in extract between new and old varieties grown in a greenhouse, it allowed up to nine days for malting though. However, this study with the barley grown under field conditions and using modern shorter malting times did find significant differences. The mean extract yield of post-1953 varieties was 48.7% higher than that of earlier varieties.
The Cambridge barley has nitrogen levels unacceptably high for commercial malting so data from Warminster was used to determine the relationship between nitrogen content and hot water extract
The genetic gain in yield was about 0.4% per year over the 100 year period, and 0.8% per year between 1953 and 1980.
Looking at the malt analysis figures its striking that though steady improvements have been made they are nowhere near as much as the improvements in the grain yield. It also looks to me that if you manage to get hold of a heritage variety it should be OK to brew with.
* THE MALTING QUALITY OF SOME SPRING BARLEY VARIETIES GROWN IN ENGLAND AND WALES BETWEEN 1880 AND 1980
Journal of the Institute of Brewing, Volume 89, Issue 5, September-October 1983, Pages: 344–348, P. G. Gothard, T. J. Riggs and D. B. Smith