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The Barley and Scotch Bigg Report of 1806 and the influence of a long un-aerated steep on germination time

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Thomas Thomson

I recently came across a significant study about brewing and malting that was written in 1806 and it is fascinating. It’s entitled: Report of the Experiments made, by the Direction of the Honourable Board of Excise in Scotland to ascertain the relative Qualities of Malt made from Barley and Scotch Bigg.  You can read it here on page 9 (press “preview book”) I am not a beer historian but I believe this is one of the first large-scale surveys conducted for the brewing industry using scientific methods in England.  In 1806 Thomas Thomson, along with authors Hope and Coventry conducted a series of experiments comparing the qualities of Barley to that of Scottish Bigg in order to reduce the tax on Bigg since it was thought to make a lower quality malt for brewing and distilling. Bigg is another name for Bere or Bear, an old variety of six-row barley believed to have been introduced to Britain by the Vikings in the 8th or 9th century. It grows faster than barley so it can be sown later and harvested earlier and is ideal for climates with a short growing season. Their findings were published in a report presented to the House of Commons. They concluded that Bigg was 8-14% less productive than English Barley (depending on which author you asked) and proposed that the tax on Brigg should be reduced by one-third. Their survey was very comprehensive collecting the data from malting, brewing and distilling about 36,000 lbs. of English barley, 41,000 lbs. of Scottish barley and 55,500 lbs. of Scottish Bigg. This became a publication that would be referred to for years to come. You can find sections of the report quoted directly 40 years later in The Scottish Ale Brewer and Practical Maltster pg.208  by W.H. Roberts in 1846. By the way, it was Thomas Thomson who devised an accurate hydrometer for this study which was specific for brewing and distilling called the  Allan’s Saccharometer.

Of course what I found the most interesting is the section on malting. This is the earliest accurate written survey (in English) that I’m aware of with steep times, moisture content, germination temperature, kilning times and malt temperatures in actual malthouses. I must say the numbers are pretty surprising, like the 20 day germination times and the rather low kilning temperatures. By having this data we’re getting an insight into the brewing and malting methods of the time. For example, the practice described in the report for judging if barley has been steeped enough was to squeeze a grain end to end, if it was soft enough to be crushed then it was deemed to have enough moisture for germination. (This method is also described in the London and Country Brewer of 1736.) But the report also details the weight increase after steeping of each sample (pg 23) and using these numbers we can figure out the moisture contents which, low and behold, were the same ranges of moisture contents used today, 39%-46%. That’s a pretty good “rule of thumb”.  We don’t know the initial moisture content of all the barley used in the report but one sample was dried out and according to the weights given had a moisture content of 12.5 %. This is the figure I used in the calculation since any barley that’s properly dried and meant to last in storage would have had a moisture content under 14% so it’s likely a good average number. I think I’ll try this method on my next batch of malt and compare it to my calculated moisture contents.

2-row barley and 6-row Bere

2-row barley and 6-row Bere or Bigg

Even though moisture contents were the same, steep times were very long ranging from 44 hours to 116 hours with the averages being 81 hours for English barley, 76 hours for Scottish barley and 71.5 hours for Bigg. Maltsters were actually required to steep not less than 40 hours by law otherwise they would be fined. The report does mention water changes occurring on pg 20. “Some Maltmen change the water once or twice, while the grain is in the steep, others not at all”  I was curious to know what effects such a long steep has on germination and how this does not kill the grain? I found my answer in Malting and Brewing Science pg 48 (Hough, Briggs,Stevens 1971) ” The traditional English practice of long steeps without aeration tends to stifle the grain, and is said to hold back “bolters” so producing more even germination on the floor. As already noted prolonged steeping induces in barley a condition similar to water sensitivity.”  Water sensitivity is a condition where the barley will not germinate while there is a surface film of moisture on the grain. This explains why with this method chitting occurs so late, after 4 days according to the report ! When using air rests in the steep regimen chitting often begins before steeping is finished leading to a rapid uptake of water. In describing highly aerated steeping Hough, Briggs, and Stevens state ” Such extreme aeration is probably too costly to use as a routine measure. Particularaly in floor malting, the vigorous growth, with the production of heat, is liable to get out of control, leading to high malting losses…”

Since the germination starts so late with the traditional method it’s safe to assume that the grain will be drier while it is growing thus slowing things down even more. I always wondered why I could not replicate these long germination times using commercial steeping schedules. Every time I tried, my barley would be on the verge of bolting on day 7. As to the wide ranges of times in the report, a major factor in the rate of absorption of water is temperature as well as variety and quality of barley. Also the fact that these samples were carried out by different maltsters could explain some of the variance as well, according to Thomson “They seem to be regulated not so much by any determinate plan, as by custom, or perhaps, in some cases, by caprice.”

On Germination: The times from when the barley was cast onto the floor from the steep tank to the time it was deemed ready ranged from 12 days to 20 for brewing. Shorter times of 8 and 10 days were for distillation. The average for brewing was 14 days for the good quality barley. As mentioned the growth of the acrospire described in the report and in other historical texts was much slower. On page 30 there is a description of acrospires usually reaching only half the length of the grain on days 7-9. It has been my experience that acrospires are at this length after 3-4 days, this makes sense given the extra 4 days required to chit. One way malt is judged to be modified is when the starch turns into a smooth chalky paste, which today happens on day 5-8 (for a pale malt) depending on temperature and barley variety. The same is true for traditional malt and usually occurs when the acrospire is 4/5ths the length of the grain. There is a good description of determining the modification of traditional malt in the 1854 Encyclopaedia Brittanica on Brewing pg 322  which describes the malt undergoing two stages of apparent modification, the “first free” occuring on day 9 – 10 where the grain will feel chalky. At this stage the malt will produce “tolerable” beer. Then the grain hardens once again for another few days until the acrospire has reached 4/5ths the length of the grain usually happening on day 14. It also mentions English germination times averaging 14 days at 62 F and in Scotland 16-20 days at 55 F.

Another highlight of this report are the kiln temperatures, but I’ll save that one for another post.

Have fun reading these links and jumping down this rabbit hole!

 

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Posted by on January 20, 2017 in History

 

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