13,700
edits
Changes
first pass at "Malt Inoculated Wort"
===Mash and Wort===
During mashing, the population of microbes diminishes greatly due to near pasteurization temperatures. However, thermotolerant microbes do survive. These are usually homofermentative LAB <ref name="Bamforth">[http://mmbr.asm.org/content/77/2/157.full#ref-199 The Microbiology of Malting and Brewing. Nicholas A. Bokulicha, and Charles W. Bamforth. June 2013.]</ref>. These microbes can have both positive and negative impact on wort production. Mash acidification by thermotolerant ''L. amylovorus'' has shown to improve enzymatic conversion of starches to sugars, increased extract and fermentability, increased TSN and FAN, and even improved head retention and increased shelf stability <ref>[http://www.asbcnet.org/publications/journal/vol/abstracts/ASBCJ-63-0096.htm Biological Acidification of a Mash Containing 20% Barley Using Lactobacillus amylovorus FST 1.1: Its Effects on Wort and Beer Quality. Deirdre P. Lowe and Helge M. Ulmer. 2005.]</ref>. Bacterial growth during mashing can also have a negative impact. For example, the thermotolerant Gram-positive and facultative anaerobe ''Bacillus coagulans'' can cause the mash to go sour and has been shown to form nitrosamines in wort that was supplemented with nitrate. ''B. coagulans'' forms nitrosamines without oxygen between the temperatures of 86°F/30°C and 154°F/68°C, and can withstand a pH of 4.0 or higher <ref>[http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1992.tb01124.x/pdf THE ROLE OF BACILLUS spp. IN N-NITROSAMINE FORMATION DURING WORT PRODUCTION N. A. Smith and P. Smith. 1992.]</ref>. ''Clostridium'', which probably does not necessarily originate from the malt itself (so far studies have shown very little to no ''Clostridium'' is present on malt), can create [[Butyric Acid|butyric acid]] off flavors during the mash or during kettle souring <ref>[http://www.asbcnet.org/publications/journal/vol/abstracts/49-02.htm Butyric Acid Off-Flavors in Beer: Origins and Control. D. B. Hawthorne, R. D. Shaw, D. F. Davine, and T. E. Kavanagh, Carlton. 1991.]</ref>. High bacterial growth can cause lautering issues, probably due to the production of dextrans by the bacteria <ref name="Bamforth"></ref>.
====Malt Inoculated Wort====
In 2016 and 2017, Dr. Matt Bochman and Jeff Young of Blue Owl Brewing conducted an experiment to map the microbiome of wort that was inoculated with several years and harvests of malted barley. Using DNA sequencing, they analyzed the microbes present in 110°F wort that was inoculated with crushed malted barley at 0 hours, 24 hours, and 48 hours. The 7 malted grains that used to inoculate the wort were 2015 Breiss Merit 57, 2016 Breiss Merit 57, 2015 Patagonia Sebastien, 2015 Briess Copeland, 2016 Blacklands Endeavor, 2016 Breiss Synergy, and 2016 Weyermann Barke.
The grain samples before inoculation hosted a large variety of microbes, but immediately after inoculating the malted grains into 110°F wort, all of the grain samples were dominated by ''Weissela cibaria'' (ranging from 92-99% across all samples), a Gram-positive bacteria that is in the same order but a different family as ''Lactobacillus''. All but one of the grain samples also had a much smaller but not insignificant population of ''Salmonella bongori'' (1-4% across all samples), which has been associated with non-lethal food poisoning <ref>[https://en.wikipedia.org/wiki/Salmonella_bongori#Pathogenicity_and_epidemiology "Salmonella_bongori". Wikipedia. Retrieved 06/15/2017.]</ref>. There were also trace populations of other bacteria such as ''Enterobacter'' spp., ''Pantoea'' spp., ''Erwinia'' spp., and ''Lactococcus lactis'' in most of the samples. There was a significant ''L. lactics'' population in the 2016 Weyermann Barke, as well as ''Enterobacter aerogenes'' <ref name="blueowl_2017">[https://experiment.com/projects/mapping-the-sour-beer-microbiome/results "Mapping the sour beer microbiome".
Matthew Bochman and Jeff Young. Experiment.com. 2017. Retrieved 06/15/2017.]</ref>.
After 24 hours of continued 110°F inoculation in the wort, all but 2 samples were almost completely dominated by ''Weisella cibaria'' (98-99% across all samples). The 2016 Weyermann Barke also had a small population of ''Lactococcus lactis'' (5%). The 2016 Breiss Merit 57 was significantly different than the other grain samples, and was the only sample with a very large population of several species of ''Lactobacillus'' (38% ''Lactobacillus reuteri'', 23% ''Weissla cibaria'', 15% ''Lactobacillus delbruekii'', 12% ''Pedioccocus pentosaceus'', 8% ''Lactobacillus fermentum'', and 3% ''Lactobacillus helveticus''). This data indicates that ''Lactobacillus'' is not present on all malted grain samples, despite popular belief. In addition, only a very small population is required to begin with on samples that do, and once inoculated into wort at 110°F, their population will increase significantly <ref name="blueowl_2017" />.
After 48 hours, ''Weissella cibaria'' continued to dominate all of the grain samples except the 2016 Breiss Merit 57 (note that the 2015 Breiss Merit 57 was dominated by ''Weisella cibaria''). Two samples, the 2015 Breiss Merit 57 and the 2016 Blacklands Endeavor, also saw an increase in the population of ''Shiggela sonnei'' (2.5%). The ''Salmonella bongori'' was still present in samples after 48 hours, but decreased to less than 1% <ref name="blueowl_2017" />.
==Miscellaneous==