Some clarification on the history of air rests in malting

I thought I’d have to dig through a bunch of old texts to find out when the inclusion of air rests in steeps started. The only mention of it in any old text that I had read so far was in Henry Stopes Malts and Malting An Historical, Scientific and Practical Treatise 1885. On page 332 he describes the newly adopted practice in Bohemia of Steeping for 24 hours followed by a 24 air rest and then a shorter steep of 8-10 hours (the date on the citation for this is 1874) He also describes the use of spray steeping on the continent.

As it turns out I didn’t have to look much further than this article by D.E. Briggs: Accelerating Malting: A Review of Some Lessons of the Past from the United Kingdom. 1986. In this paper Briggs describes the many methods used in the past and present to accelerate germination rates. Listed are methods such as abrasion to light crushing, low moisture squeezing as well as warm steeping and using additives like hydrogen peroxide and giberellic acid.

Any summary I could write about this article wouldn’t do it justice so I won’t try, but here are just a few interesting points  in a very, very brief summary form.

Briggs does confirm that air rests were adopted by maltsters in Germany in 1875 but also mentions the traditional Norwegian practice of steeping  barley in sacks submerged in streams and taking them out at intervals to drain and rest. Check out this old footage of traditional brewers in Norway from this awesome blog Larsblog shared by my friends at Spowtmalt.com  I’m not sure what they’re saying but it’s fascinating to watch.

Interestingly Briggs notes that the practice of air resting fell out of use in the U.K. in the early 1900’s but was re-introduced in the 1950’s  when it was recognized that an air rest after the grain had reached a water content of 35-37% overcame water-sensitivity and the grain could then be steeped again to a final moisture content between 41-46%

There is also a great description of how early chitting in the grain, which occurs with spray steeping and to a certain extent with air rests can affect the water uptake due to the more rapid absorption of water from the embryo over the starchy endosperm once the grain chitts. This can leave the inside of the endosperm dry even while the overall target moisture content is reached which can be detrimental to modification.

Briggs concludes by stating that despite all the new techniques and methods utilized in modern malting that each new batch of barley brings it’s own problems in production. He suggests that malt could be made more rapidly if there were a better understanding of various aspects of immaturity and vigor or dormancy. Also that further studies need to be done to improve methods that characterize the degree of maturity in grains. As well it would be advantageous to find methods other than prolonged storage to hasten grain maturation.

This article is well worth reading and sheds a lot of light on the recent history of the steeping process.

 

 

 

Un-aerated steeping Part 1

Ok, mind blown, and I don’t know how I’ve missed this key piece of information. Sometimes I feel like the world of malting is shrouded in so much mystery that you have to be a detective to figure it out. The data in the Scotch Bigg Report provided the biggest piece of the puzzle that was missing for me: that long germination times are only possible with un-aerated steeps. The report gives us actual recorded steep times, which are shockingly long 40-118 hours. What may be even more important was the observation in the report that some maltsters only changed their steep water once or twice and some not at all. But how is this possible? Most texts I’ve read state that the grain will die if submerged for over 24 hours, I’ve told people this myself (my apologies). In fact, I believe it’s only been in the last 150 years that aeration has been used in the steeping process – but I’ll have to do some further investigating to confirm this. In part one of this project, I do a side by side comparison of malt steeped with air rests and malt steeped for 72 hours without. Results in a nutshell: the un-aerated tastes better, but I haven’t brewed with them yet, that’s part two. One factor that may skew the comparison is that I malted these barley samples at the same temperature, which was lower than I would normally malt aerated barley – this may have affected the flavour of the aerated malt. This will be addressed in part three – how does historically malted barley compare with modern malt (malted at warmer temperatures – 15C, 59F)

 

The Barley and Scotch Bigg Report of 1806 Notes

My last post was all about the Barley and Scotch Bigg report of 1806 by Thomas, Coventry and Hope and evidence for the link between un-aerated steeps and long germination times, and while I highly recommend reading the report, the type is faded in places and changing all those “f”‘s to “s’s can really slow you down. So here are some condensed notes that I gleaned from the sections on malting and brewing in point form.

Malting:

• Steeped in square chamber for 40-118 hours pg 20, until grain could be crushed end to end between fingers. Avg. moisture content 42.5 %
• Scottish maltsters often steeped longer than English
• Some changed the water once or twice, others not at all
• Drained and rinsed (if warm) to wash off slime.
• Couch – 16″ deep for 26 hours pg 23
• Flooring – Spread gradually over time to a depth of 3-4″
• Turned 2,3,4, or more times per day depending on conditions
• Always kept level thickness to keep temperature even throughout
• Sweating – 96 hours (4 days)  after casting a rise of 8-12 degrees F occurs
• During sweating grain becomes wet again for a day or two
• Temperature must be kept in check by turning.
• Temperature of malt at casting 40-50F. (4.4-10C) Temp of barn 40-50F
• Temperature of malt at sweat 50-60. (10-15.5C) Temp. of barn 40-50
• Chitting usually occurs at sweating
• A day after chitting the acrospires appear and grow rapidly
• Acrospires on 8th day after casting will be half the length of grain, growth slows pg 28
• Grown till acrospires almost reach the end 12-20 days
• Avg. temp. of malt 52-60F (11-15.5C) Scottish avg. 56F (13.3) English avg. 59F (15C)
• Kiln depth 3-6 inches. pg 33
• Kilning starts at body temperature (98.6F  37C)
• Kiln temperatures recorded ranged from 140-160-170. highest observed- 186F
• Suspected some maltsters to kiln up to just below boiling for some malts like brown.
• 40-80 hours on kiln
• Pg 33 “Malt may be made brown at a lower temperature for it is not so much the temperature, as the suddenness with which it raised, while the malt is still moist, which alters the colour.”

Brewing:

• Malt mashed 3 hours then drained to underback
• More hot water poured for second mashing
• May even be repeated for a third time
• 8 1/2 gallons to the bushel of malt at 180F

I believe a different sized gallon was used at this time which held 282 cubic inches (instead of 231) which would make the infusion 10.38 u.s. gallons which with 37.5 lbs per bushel of malt, makes the mash thickness 1.11 qt/lb. If the malt temperature was 45 F and the strike water 180F the mash temperature would be 159.5. Rather high, however, we’re dealing with a lot of averages here and I could be wrong about the gallon size. As well the strike water would have lost a few degrees when it was transferred to the mash tun. If the gallons back then are the same as today then our mash temperature would be 156F but our mash thickness would be .91 qt/lb. As you can see below there is quite a variance between brewers as the runnings are from 160 to 140F.

• Sparge water also 180 F pg 46.
• Temperatures from runnings from first sparge ranged from 160-140F
• The quantity drawn off depends upon the strength which the ale is required to possess but is never less than the initial infusion amount
• The quantity of the second wort varies according to the choice of the brewer
• Boiled for an hour or two till it is reduced to the wished for quantity and strength
• Hops 2/3 to 1 lb. added per bushel (37.5 lb) of malt
• Cooled in large shallow square vessel only a few inches deep.
• Cooled to 52 F in Winter and 46 F is Summer
• Drained to fermenting tun
• 1 gallon of yeast added for every 3 barrels of wort “hence fermentation is slow and imperfect”
• Some temperature fluctuations observed during fermentation 44-71F , 55-82F (highest) 52-53F (lowest fluctuation).
• Ready to rack to a hogshead (54 gal. barrel) on 9th or 10th day and allowed more time to clarify

The beers in the table below have an average alcohol content of 10-11% a.b.v.

Table showing gravities of beers produced.

 

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

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 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!