__From_: gjfix@utamat.uta.edu_ (George J Fix) _Subject_: Malt Modification Continental lager malt is today far more modified than at any point in the past, yet its degree of modification is still well below what is found in malts from the UK and US. I always felt this was mainly because of tradition, however recent research have brought up entirely new issues. (Dr. Narziss has written an excellent survey on this subject, an English translation of which can be found in 1993 Brauwelt). In particular, it was found for both decoction and multiple temperature infusion mashes that foam stability decreased with increasing malt modification. More important is the finding that the definition and intensity of malt flavor also decreased with increasing modification. Lager beer made from highly modified malt gave malt flavors which were judged to be "dull", "unfocused", "lacking in fullness" in comparison with what was obtained with normal continental lager malts. In fact, Dr. Narziss implicitly implied that the trend to increasing modification in lager malt should be stopped, and perhaps reversed to some extent. This jives 100% with my own experiences, and may explain why many have found that their lagers come out best when imported Pils malts are used. I personally use highly modified malt for ales (both from domestic 2-row as well as malt from the UK). The above work suggests that if a multiple temperature mash is used then the starting point should be no lower than 60C (140F). This is also consistent with what I have been finding with my own brews, and I would be interested in what others have experienced. Cheers. George Fix __________________________________________________________________________ _Posting 13_: Extracted from file: 1484 _Date_: Fri, 22 Jul 94 14:00:39 -0500 __From_: gjfix@utamat.uta.edu_ (George J Fix) _Subject_: Malt Modification II I have gotten a number of questions about my post on modification, so perhaps some additional comments are in order. Terms like "overmodification" and "undermodification" are vague and potentially misleading. A large number of numerical indices have been proposed for malt modification, but the two most widely cited are Friability and the Kolbach Index. Friability is an easy one, and can be determined by chewing on the grain. A highly modified malt will chew like a marshmallow, while at the other extreme raw barley will have the texture of a ball bearing. The Kolbach Index strongly correlates with this, and is the % wort nitrogen to malt nitrogen (as measured in a laboratory mash). The following are normally used as guidelines: undermodified <35% moderate modification 35-37% highly modifiied >40% With this criteria the malt used at Pilsen (at least as of 1990) is undermodified, the Pils malts available here (DeWolf-Cosyns, Durst, and Irek) are moderately modified, while most UK and UK malts are highly modified. I personally feel that a protein rest should be used with the Pils malts, provided that the total time spent under 40C (140F) does not exceed 30-40 mins. In particular, I have found that lager beer made from the DeWolf- Cosyns Pils malt and a single temperature mash will tend to be thin and insipid compared to one made from a multiple temperature mash. It is not surprising that some brewers in the US and UK specializing in delicately flavored lagers prefer highly modified malt, specially those doing 8-10 brews a day. However, if ones idea of lager beer starts with something along the lines of Spaten's Maibock, then I can see how different conclusions can be drawn. What the research seems to be showing is that optimization of malt flavor in lager beer requires that the bulk of the protein breakdown take place under conditions found in a protein rest, as compared with a germination box. In addition, excessive protein breakdown is harmful to beer flavor and foam, and this is true for ales as well as lagers. This is undoubtly why Dr. Narziss is recommending that the mash start at 60-62C if highly modified malt is used. An alternative I have been looking at with ale malt is to start at 35C(95F) and then go to the rests over 40C. There is no proteolytic activity at 35C, but beta-glucanase is active and there is some evidence that alpha-amylase is active in assisting grain liquefaction. The hope is that this will give the benefits of a low temperature rest without excessive protein modification. George Fix _Posting 17_: Extracted from file: 1506 _Date_: Thu, 18 Aug 94 10:24:46 -0500 __From_: gjfix@utamat.uta.edu_ (George J Fix) _Subject_: Yield I have found that the two most important operational variables affecting yield are the mash pH and the time/temperature program used. For infusion mashes I have found that it is highly advantageous to keep the mash pH at 5.4 or lower. Decoction mashes appear to be more forgiving in this regard. The negative effects of a high mash (and wort) pH are numerous, and I plan to treat this subject in great detail in my new book. It appears that yield (which is a measure of the extent we dissolve grain carbs.) is strongly influenced by the lower temperatures used, while the composition of the carbohydrates dissolved (i.e., % fermentability) is influenced by the higher temperatures. The following batch is typical of the results I have been getting with highly modified malt. Data brew size = 15.5 gals total water = 9.5 gals in mash + 9.5 gals for sparging grain bill : 24 lbs. D-C Pale Ale malt 2 lbs. D-C Caravienne 1 lb. D-C Aromatic Temperature Program 40C (104F) - 30 mins.- 24 lbs. base malt + 6.5 gals. water Transition 40 to 60C - add 3 gals. of boiling water - add adjunct malts at the end as a brake - less than 5 mins. is needed Note - I now feel (with Narziss) that the time spent in the range 45-55C should be keep below 15 mins. if highly modified malt is used. 60C (140F) - 30 mins. Transition 60 to 70C - external heat is needed and this can be done in 15 mins. 70C (158F) - 30 mins. Mash Data Vol = 9.5 gals. % extract = 22P (i.e., 22 grms extract per 100 grams mash) SG =1.092 Converting to wt/vol and US units the % extract comes out to 62.24 lbs/bbl. (~2 lbs/gal). This means that the mash has 62.24*9.5/31 = 19.1 lbs. extract. Yield in commercial units is 19.1 * 100/27 = 70.7%. Yield in homebrew units is 92 *9.5 /27 = 32.3 pts/(lbs/gal). The value of the rest at 40C can not be understated [George clearly means "overstated" here]. The rise in SG in this mash is almost 3 times faster than what I get when this rest is omitted. The final mash yield is ~20 % higher. Clearly there is a lot of favorable activity going on including preparation of the enzyme systems, beta glucanase activity, and highly favorable enzymatically assisted grain liquefaction. This wort clears up very quickly (for European malts), and after ~2 gals. of recirculation it will change from a milkly turbidity to a moderate see through clarity. The 1st wort is then run into the kettle until 1 inch of liquid covers the grain surface. At this point sparging is started with the inflow and outflow rates adjusted to ~1/3 gals/min. It is of course very important to maintain the liquid cover of the grain bed. After ~30 mins. the sparge water is depleted, and the outflow is increased to ~1 gal/min. The following is typical data at kettle full: Vol = 17 gals. % extract = 12.3 P SG = 1.050. Repeating the above calculations, this means that 18.3 lbs. of extract was carried over to the kettle. The losses in sparging were water = 19 -17 = 2 gals. extract = 19.1 -18.3 =.8 lbs. By using a slower runoff and a higher fraction of sparge water it is likely one could leach most of the residual extract out of the grains. I choose not to do this because this is not the way I brew. The finished wort in the fermenter typically cames out as follows: Vol = 15.5 gals. % extract = 13.3 P SG =1.053 This means that a final yield of 30.4 pts was obtained. With a single temperature mash (or 60-70 combo) this would have dropped into the 26-28 pts/(lbs/gal) range. The % fermentability as determined by a liter sized forced fermentation at 30C usually gives an ADF near 79% (RDF = 65%). This means that FG limit is 1.011. The ale strain that I am using does not completely ferment maltotriose, so I usually wind up a 1.012 to 1.013 in this context. The ADF is greatly influenced by the times spent at 60 and 70C. E.g., 15 mins. at 60 followed by 45 mins at 70 will typically drop the ADF into the low 70s. The reverse will increase it into the mid 80s. For my ale strain spending at least 15 mins. at 60C is crucial for it greatly increases the maltose/maltotriose ratio. I strongly prefer moderately modified malt for lager beer, and I have found that a protein rest at 50C (122F) has numerous advantages. I have done test brews with a 40-50-60-70 schedule, but little is gained in yield over a 50-60-70 program. I personally am going to stick with the latter since among other things half of the 3 gals of transition water can be used to go from 50 to 60, while the other half can be used to go from 60 to 70. Thus very little external heat need be applied to the mash. Another point I have noticed is that most lager yeast are insensitive to maltose/ maltotriose ratios. W-34/70 for example starts taking in maltotriose at the same time it takes in maltose, and metabolizes both sugars at approximately the same rate. Thus the rest at 60C can be used with such strains simply to adjust ADF. George Fix