By: Mike Dixon firstname.lastname@example.org
In a recent discussion about recipe formulation, I disagreed with a fellow brewer about whether or not you could just steep base malts, namely Munich malt. My position was that it must be mashed for conversion and proper utilization and his was that just placing in steeping water in a grain bag would convert the grain and base malts could be used in extract brewing by that method. This experiment was a result of those discussions. (To see those discussions, look at this rec.crafts.brewing archive thread)
Two pots each with approximately 2 gallons of untreated tap water were heated to 150-155║F and then 1 lb of crushed Munich malt was added. To one pot, the malt was added loose, to the other it was added in a grain bag. The respective pots were then stirred and the temperature regulated to 150║F and held for 45 minutes. Data was taken during that time period.
Straining Bag Loose Malt
After 45 minutes, the grain bag was allowed to drain for 10 minutes and the loose grain strained and allowed to drain for 10 minutes. After this time period, the final data was obtained.
Straining Bag and Loose Malt
Several data points were utilized, temperature, pH, starch test, specific gravity, and volume. Taste/Flavor was also noted along the way to see if any changed occurred.
Note: My inexperience with the pH meter may mean that the pH data prior to the last data point is slightly skewed. I inadvertently took it completely out of adjustment prior to the test, and before the test had a reasonable calibration.
Generally a starch test is not a great indication of the enzyme activity due to the fact that the test can be easily skewed by grain husks or particles. I have used it with my own brewing at times, and generally find it unnecessary, but I have always been able to get a negative test by carefully taking the sample to avoid grain husks. The other party who sparked this experiment indicated that he had been able to obtain a negative starch test in steeping base grains using the methods we have laid out. I decided for that reason to use a starch test with Tincture of Iodine during the test. Following are pictures of the starch tests at intervals of 10 minutes into the experiment, 20 min, and at the conclusion of both the liquid draining from the malts and the total liquid stirring and allowing any particles to settle.
Starch test at 10 minutes. Note the straining bag sample is to the left, and the loose malt is to the right. Both samples gave a positive starch test at 10 minutes. The tincture immediately turned the liquid samples black although the picture may not clearly indicate that.
Starch test at 20 minutes. Note the straining bag sample is to the left, and the loose malt is to the right. Both samples gave a positive starch test at 20 minutes. The tincture immediately turned the liquid samples black, again, the picture may not clearly indicate that.
Starch test of drained liquid from grain at end of trial. Note the straining bag sample is to the left, and the loose malt is to the right. Both samples gave a positive starch test. The tincture immediately turned the liquid samples black, again, the picture may not clearly indicate that. Neither the grain bag, nor the loose grain was squeezed, only the liquid that freely dripped was collected.
Starch test at end of trial. Note the straining bag sample is to the left, and the loose malt is to the right. Both samples gave a positive starch test in the liquid after 45 minutes and after allowing some time for the top liquid, which was stirred, to settle. The tincture immediately turned the liquid samples black, again, the picture may not clearly indicate that.
The pH of the liquid was taken of the untreated tap water, at 10 min, 20 min, and at the end of the experiment. The results are as follows:
pH of Straining bag pot pH of Loose Malt pot
Untreated Tap Water 7.5 7.5
10 min 5.9 5.9
20 min 6.2 5.7
End (45 min)* 5.7 5.7
*pH meter was recalibrated before last measurement obtained
The volumes were measured using a 1000ml plastic beaker, after the trial. That value was then converted to gallons. Some liquid, a small amount, was lost due to absorption into the grain and small pH samples. The original volume is not known, but was close to 2 gallons in each pot.
Straining bag pot liquid volume: 1.94 gallons
Loose Malt pot liquid volume: 1.96 gallons
The gravity* of the liquid after straining was measured.
Straining bag pot liquid gravity: 1.013
Loose Malt pot liquid gravity: 1.015
*This is an indication of how the malt steeping changed the gravity of the water, but should not be assumed to be the sugars in the wort
Taste/Flavor and Color assessment:
Every time a liquid sample was taken, the liquid was tasted to see how it might change over the course of the experiment. Also, the spent grain was tasted. Below are the notes of that and of the noted color differences that may, or may not be apparent in the pictures above.
Taste of both samples was completely awful. Both were huge with tannins and astringency. Both also had sour flavors. The color of the loose malt was noticeably darker than that of the straining bag.
Both samples still tasted bad with tannins and astringency. The loose malt had a very slight sweet flavor in the background, but nothing that could ever be mistaken for anything good. The loose malt still has a noticeably darker color.
Both have grainy, husky, tannin flavors. Neither tastes like watered down wort. Both were much better than the 10 min and 20 min observations, but still fairly awful. The loose malt sample has only a slightly darker color than that of the straining bag.
The spent grain had a flavor that reminded me of oatmeal, with chewy husks flavor. Oddly enough, there was no real astringency to note in the grain itself.
Comments and Conclusions:
The reader should always be encouraged to come to his or her own conclusions of the experiment, but from a starch test and flavor standpoint, my position was substantiated. Base malt should/must be mashed and not simply steeped. The harsh astringent flavors from steeping base malt in a large quantity of water whether in a straining bag or loose would follow thorough into the final product post boil.
From a pH basis, and keeping in mind the limitations of my pH calibration, the end pH is higher than most accepted values of a mash pH. A mash pH should be in the range of 5.2-5.6 at saccharification and this experiment never got close to that.
The Munich malt for this experiment was Weissheimer Munich malt and should theoretically yield about 37 p/p/g (points per pound per gallon). I obtained 1.94 and 1.96 gallons of wort and the gravities were 1.013 and 1.015 respectively for the straining bag and loose malt liquids. Quickly running through the math yields and extract for the straining bag of 25.22 points and for the loose malt as 29.4 points. That would lead one to calculate efficiencies of 68% and 79%. These figures could be misleading mainly because they are not an indication of the sugars in our case, but an indication of the solids and starches as indicated by the positive starch tests throughout the trial. Below is a picture of the respective worts after an additional hour of settling.
Note the sediment near the bottom of the glasses. The loose malt (right) had much more sediment, almost double the amount of the malt in the grainbag.
My position remains unchanged as a result of this experiment. Base malt must be mashed in order to achieve recommended pH levels, and to convert starches without tannins and astringency in that marvelous liquid we all call beerů.