Introduction. Methods

Transcription

1 Introduction Many unique strains of Belgian- style ale yeast are available through commercial yeast suppliers. Many are mainstays in the product lineup and some are limited, seasonal offerings. With so many strains available, how do you know which strain to pick for your perfect Belgian- style beer? Is one more beneficial for competition beers? Do these strains really produce different beers? If so, how do these beers differ in perceived characteristics like spiciness, fruitiness, maltiness and hops, as well as more objective measurements like krausen height, percent attenuation and flocculation behavior. We selected 6 different Belgian- style yeast strains to determine how much the different strains affect the flavor of the resulting beer. Methods A Belgian tripel recipe (slightly reduced in gravity) using Belgian pilsner malt, Belgian aromatic malt, table sugar and styrian goldings hops was used to make a common wort that was evenly divided between 6 individual fermentors. One vial of each yeast strain was pitched into a unique fermentor containing the common wort. The different strains were from White Labs and include WLP500, WLP510, WLP530, WLP540, WLP550 and WLP570. Based on the original gravity and wort volume, one vial of commercial yeast in each fermentor resulted in an appropriate cell count for ensuring proper pitching rate. Based on data from the book Brew Like a Monk, 68% of Belgian and 10 of the Trappist breweries raise the temperature over the course of the ferment. So for this experiment, the fermentation was also increased over time within the range that Belgian breweries use. Fermentors were held at 68 F for 48 hours, then raised 1 F every 12 hours until 80 F was reached. Temperature was held for 24 hours, then reduced 1 F every 12 hours until the temperature returned to 70 F. Temperature was held at 70 F for an additional 48 hours, then temperatures were allowed to naturally fall to 66 F. Fermenters were crash cooled to 36 F after 24 days in the primary fermenter. Beers remained at 36 F for 14 days to cold age and improve clarity. Beers were transferred in a closed system using CO2 to push the beer from the fermentor to a corny keg. Forced carbonation was used until the beers equilibrated at F or approximately 3.5 volumes of CO2. Krausen height and attenuation were recorded during and after fermentation. After carbonating, a tasting panel of 4 BJCP judges initially sampled the beers to evaluate the beers according to BJCP guidelines. This information was used to construct a form to be used to help evaluate the beers. Afterwards the beers and judges comments were presented to the LAGERS homebrew club to discuss differences in flavors, perceptions and measurable statistics, and to use the form to evaluate any differences between the 6 strains of yeast with a large group of tasters.

2 I: Belgian Experiment Basics Grain Bill Ingredient Amount % Wt MCU When Belgian Pilsen Malt 12lb 0oz 85.7 % 3.2 In Mash/Steeped Belgian Aromatic Malt 8.00 oz 3.6 % 1.6 In Mash/Steeped Sugar - White Sugar/Sucrose 1lb 8oz 10.7 % 0.0 End Of Boil Hop Schedule Variety Alpha Amount IBU Form When Slovenian Styrian Goldings 2.6 % 128 g 31.6 Loose Pellet Hops 60 Min From End II: Analytical Data Results Krausen Height with Increasing Temperature Krausen Height (inches) Temperature WLP500 WLP510 WLP530 WLP540 WLP550 WLP570 Krausen Height Data 9/25/11 9/26/11 9/27/11 9/28/11 9/29/11 9/30/11 10/1/11 Brewery* Temperature Chimay WLP Orval WLP Westmalle WLP Rochefort WLP Achouffe WLP Duvel WLP * according to online sources at Mr.Malty.com

3 Attenuation Data Brewery* Strain OG FG % Attenuation Chimay WLP % Orval WLP % Westmalle WLP % Rochefort WLP % Achouffe WLP % Duvel WLP % * according to online sources at Mr.Malty.com III: Sensory Data Results Sensory data are the analysis of 30 data forms from 30 unique tasters. Graphical data below are constructed from the number of a particular descriptor within a category divided by the total number of data points within the whole category. It is not simply the number of people who tasted a descriptor divided by the total number of tasters, as a taster could check off multiple flavors for each beer within a category, or none at all. For example, if we select apple as a descriptor example, the data represents the number of times apple was checked divided by the total number of descriptor data points and not the number of people who tasted apple. So, if there were 30 tasters, 100 unique data points for fruity esters and 10 for apple, the graph would show 0.10 (10/100) rather than 0.3 (10/30). Overall Impression of the Strain Favorite Spicy Fruity Hoppy Malty The most preferred strain was the WLP550. WLP500 and WLP510 were dominated by fruity esters, while WLP530 and WLP550 were dominated by spicy phenolics. WLP570 was balanced between spice and hops, and WLP540 was malt dominant.

4 Broad category of Descriptors: Hop Character Malt Character Yeast Character With all strains, the yeast characters dominated the flavor of the beer. While malt and hop characters were perceived, the yeast provided the beer with the basic essence or character that is indicative of the Belgian- style ales. Narrow Category of Descriptors: Hops Dried Fruits Melanoidins Spicy Fruity The yeast flavors of WLP500, WLP510 and WLP540 are characterized more by fruity esters than spicy phenolics, whereas WLP530, WLP550 and WLP570 are characterized more by spicy phenolics than fruity esters. With all strains, melanoidin characters dominated dried fruit characters.

5 Fruity Yeast Characters: Strawberry Raspberry Plum Pear Orange Lemon Grapefruit Grape Bubblegum Blackberry Banana Apple All strains produced considerable apple, banana, grape and pear flavors, but they varied in the balance between these flavors to give different overall impressions. WLP510 had a significant amount of orange (pith) character and WLP540 was more complex and dominated by berry characters. The WLP540 strain had difficulty fermenting at higher temps, and differences in these characters might be a result of heat stress on the yeast. Spicy Yeast Characters Vanilla Start anise Pepper Oak GOP Cumin Coriander Clove Cinnamon All strains had strong notes of clove, coriander and pepper. WLP510 and WLP530 had the least clove character. Other notable differences between strains are the cinnamon, coriander, oak and pepper balance.

6 Melanoidin Malt Characters: Toffee Toast Dough Cracker Caramel Bread crust Bread Biscuit Cracker and bread notes were tasted across all strains. All strains appeared to accent malt characters fairly evenly. Dried Fruit Malt Characters: Licorice Fig Date Prune Currant Raisin Dark fruit characters were accented by all yeast strains. Raisins and currants were most common. WLP500 and WLP540 appeared to accent fig flavors.

7 Hop Characters: Earthy Soapy Perfumy Citrusy Spicy The yeast accented different hop characters. WLP550 and WLP570 were both spicy and perfumy. WLP500 and WLP510 were relatively balanced across all descriptors. WLP530 was spicy and earthy, while WLP540 was mostly earthy. Summary and Conclusions All strains produced beers that were noticeably different. WLP550 was the favored yeast and the one most people readily identified from commercial examples as that classic Belgian character. If choosing a yeast solely for entering competitions, this profile may be favored or more easily recognized by judges. The Rochefort strain, WLP540, lost its krausen as temperatures rose and the beer did not completely attenuate. The beer had noticeable berry characters that were largely missing from all other strains, and may have resulted from heat stress on the yeast. Overall, this strain produced a maltier and fruitier beer, which may better complement the complex malts and dark fruit characters in Belgian dubbels or Belgian dark strong ales. The Orval strain, WLP510, had a strong orange and orange pith character that was not noticed in any other strain. Given these orange characters, this yeast might serve well for making Belgian witbiers. Acknowledgments Thank you to the LAGERS homebrew club for facilitating this experiment as part of the membership learning series. Thanks to My Old Kentucky Homebrew for assistance with sourcing and supplying ingredients and equipment for the experiment. A special thanks goes to Chuck, Leah and Paul for assisting with the initial tastings and development of the evaluation form.

8 Yeast Number: (check all boxes that apply) Overall, is the Beer profile is: o Malty o Hoppy o Yeasty o Fruity Yeast profile: o Estery-Fruity o Apple o Banana o Blackberry o Grape o Grapefruit o Lemon o Orange o Pear o Plum o Raspberry o Strawberry o Cinnamon o Clove o Coriander o Cumin o Grains of paradise o Oak o Pepper o Start anise o Vanilla Malt profile: o Biscuit o Bread o Bread crust o Caramel o Cracker o Dough o Dried fruits o Raisin o Currants o Prune o Date o Fig o Licorice o Toast o Toffee Hop profile: o Citrusy o Perfumy o Soapy o Earthy o Other: Yeast Number: (check all boxes that apply) Overall, is the Beer profile is: o Malty o Hoppy o Yeasty o Fruity Yeast profile: o Estery-Fruity o Apple o Banana o Blackberry o Grape o Grapefruit o Lemon o Orange o Pear o Plum o Raspberry o Strawberry o Cinnamon o Clove o Coriander o Cumin o Grains of paradise o Oak o Pepper o Start anise o Vanilla Malt profile: o Biscuit o Bread o Bread crust o Caramel o Cracker o Dough o Dried fruits o Raisin o Currants o Prune o Date o Fig o Licorice o Toast o Toffee Hop profile: o Citrusy o Perfumy o Soapy o Earthy o Other: Yeast Number: (check all boxes that apply) Overall, is the Beer profile is: o Malty o Hoppy o Yeasty o Fruity Yeast profile: o Estery-Fruity o Apple o Banana o Blackberry o Grape o Grapefruit o Lemon o Orange o Pear o Plum o Raspberry o Strawberry o Cinnamon o Clove o Coriander o Cumin o Grains of paradise o Oak o Pepper o Start anise o Vanilla Malt profile: o Biscuit o Bread o Bread crust o Caramel o Cracker o Dough o Dried fruits o Raisin o Currants o Prune o Date o Fig o Licorice o Toast o Toffee Hop profile: o Citrusy o Perfumy o Soapy o Earthy o Other: