MTF Thread Highlights

This page is a dedicated archive to threads on the MTF Facebook group that we feel stand out and are worth remembering and reviewing. Keep in mind that only group members can view these threads.

General Discussions

A general bucket of funky threads.

Overview	Thread Starter	Date
Brendan Palfreyman helps "Milk The Funk" become a registered trademark.	Devin Bell	01/13/2017
Subthread that contains other links to discussions regarding the attenuation ability of WLP645, and contamination issues in the vials themselves.	Phil Culture	12/29/2016
Andrew Zinn from Wicked Weed gives in depth advice on using WW dregs.	Tracy Mellody	09/07/2016
Fermenting a Brettanomyces beer under 15 PSI versus the same beer in a carboy with no head pressure. Which do you think got funkier?	Devin Henry	07/27/2016
Speculations on what factors effect funky flavors versus fruity flavors in Brettanomyces beers.	DeWayne Schaaf	06/29/2016
Bootleg Biology collects dregs from homebrewers at the Milk The Funk Meetup and Bottle Share at HomebrewCon 2016, and offers the mixed culture as a one time only deal to MTF'ers!	Jeff Mello	06/22/2016
Cassie from GoodBelly drops by to say hello to MTF membes, and asks for recipes for their blog.	Cassie At GoodBelly	04/08/2016
Vinnie Cilurzo's barrel racking technique and discussion.	Jay Bakula	03/18/2015
Testing different cooling rates for spontaneous fermentation by cooling in an insulated plastic cooler next to a steel kettle with no insulation.	Caleb Buck	11/24/2015
Do you oxygenate wort for mixed cultures with LAB?	Brandon Jones	11/22/2015

Funky Science Fridays

James Sites might have started Funky Science Friday, but MTF milked it (thanks, James)!

Overview	Thread Starter	Date
Overview of a study that showed that 100% Brettanomyces fermentation had more phenol production than when it was c-fermented with the EC1118 wine strain (maybe due to EC1118 being HCDC+), as well as the gene expression difference in EC1118 when co-fermented with B. bruxellensis which made it compete harder for oxygen, and slightly increased the Brettanomyces growth rate in the presence of EC1118. The change in genetic phenotypes of the EC1118 shows that they are involved in interspecies competition between S. cerevisiae and B. bruxellensis.	Richard Preiss	07/26/2017
Bryan of Sui Generis blog and Devin Henry, shares their discovery that White Labs WLP648 Brettanomyces bruxellensis Trois Vrai contains two closely related Brettanomyces bruxellensis strains, but have two very different flavor profiles and morphologies.	Bryan	05/12/2017
Results of an experiment at Blue Owl Brewing that analyzed populations of microbes and acid formation in wort soured from different grain sources.	Jeff Young	04/21/2017
A poster presentation of one lab's work to transfer the gene that produces phenols in Brettanomyces to E. coli for the purpose of researching the enzyme (phenolic acid decarboxylase) that produces phenols.	Mike Lentz	03/31/2017
A review of the role of glycerol in sour beer, with a few answers and many questions.	Josh Kauffman	02/17/2017
A look at recent studies that show that lactic acid promotes stuck wine fermentations by altering the genetic phenotype of yeast to ferment multiple classes of sugars at the same time (as opposed to preferring glucose first).	Richard Preiss	12/07/2017
MTF looks at the science behind the claim that StarSan™ (Star San) is not efficient at killing yeast and mold with an expert on microbial cell wall ionic charges.	Dan Pixley	10/14/2016
Sharing Dr. Roy Ventullo's experiment results comparing Samuel Aeschlimann's "Eureka" Lactobacillus starter versus traditional MRS media. Results: similar growth, however the "Eureka" media appears to be healthier for Lactobacillus for a longer period of time.	Dan Pixley	09/23/2016
Scientific research on how thiols from hops create aromatic compounds, and how different strains/species of yeast produce them.	James Sites	08/12/2016
Part 1 and Part 2 of a scientist discussing his findings with Brettanomyces and lactic/acetic acid production: more accurately counting pseudohyphal cells using fluorescence capability of a Cellometer, developing a better way that Titratable Acidity to measure acids using HPLC/UPLC-ELSD (TA measurements can be skewed by the presence of other acids), and an interesting observation that Brettanomyces cultures contaminated with a small cell count of S. cerevisiae responded differently to aeration. By not aerating, the Saccharomyces grew more rapidly and sugar was consumed at a faster rate, and by aerating the Saccharomyces growth was limited which allowed the Brettanomyces to out-compete it (and sugar was consumed at a slower rate).	Brian Martyniak	07/29/2016
Culturing Brettanomyces from 8 vintage Berliner Weisse courtesy of Mike Marcus at Chorlton Brewing Company. Watch for updates.	Richard Preiss	07/15/2016
Mark Trent details his method for isolating Brettanomyces from Saccharomyces from dregs or other mixed cultures.	Mark Trent	07/01/2016
Discussion on a new published study about Brettanomyces evolution based on genome sequencing, vacuole selection that might help Brett survive acidity, and a genetically understood reason for the lack of glycerol production in Brettanomyces.	Richard Preiss	06/17/2016
Discussion with Lorenzo Peyer, a scientist that studies Lactobacillus flavor production in malt-based drinks; primarily discussed the possibility (or lack of) of butyric acid production by Lactobacillus.	Dan Pixley	05/29/2016
Hydroxilation of fatty acids by Lacto and then lactonization of the HSA's by Saccharomyces to produce novel lactone esters.	Dan Pixley	04/29/2016
New scientific data on 100% B. bruxellensis fermentations, including measurements of esters vs phenols, and differences between strains isolated from wines versus those isolated from beer.	Richard Preiss	04/15/2016
Funky Science... Thursday? Link to a new article on Torulaspora delbruekii in beer fermentation, and discussion of the article, including questions about high acetaldehyde amounts and how dangerous that can be to health.	Mike Lentz	03/24/2016
Sensory testing of 6 wild caught B. anomalus strains (verified via RFLP analysis of the 5.8S rDNA/ITS region).	Mike Lentz	01/15/2016
Testing Brettanomyces ester/phenol production based on pitching rate in secondary. See Brettanomyces secondary fermentation experiment for the wiki write up.	Lance Shaner	12/04/2015
Brettanomyces growth experiment measuring aeration and agitation. See Brettanomyces Propagation Experiment for the wiki write up.	Mark Trent	10/23/2015
Richard isolates Brettanomyces and Pichia from an 18 year old gueuze.	Richard Preiss	10/23/2015
Say it with me, Tetrahydropyridine.	Dan Pixley	10/02/2015
Mark Trent's Back To The Future Machine (a custom vessel that is a boil kettle, fermenter, bottling vessel, bright tank, and sterilizer).	Mark Trent	09/04/2015
Advice for growing Lacto on plates.	Mark Trent	09/04/2015
Brett forms a biofilm, which makes it harder to clean.	Mark Trent	08/07/2015
Richard shows us that refrigerated storage of Brett is better than room temperature storage. See Storing Brett for more information.	Richard Preiss	0724/2015
Lance Shaner demonstrates why full attenuation and krausen after pitching only a Lacto culture are signs of yeast contamination.	Lance Shaner	07/21/2015

Microbiology and Science

It's not Funky Science Friday, but it's still pretty geeky.

Overview	Thread Starter	Date
Culturing Brettanomyces from ~40 year old commercial German Berliner Weisse bottles.	Richard Preiss	07/11/2017
Discussion and debate on whether Pediococcus based beers are more "complex" than kettle soured beers, and an informed debate on the science of boiling secondary metabolites and their volatility (see subreplies).	Nèque Bier'd	05/31/2017
Small DIY yeast propagation setup for 60bbl batches of beer, examples of other cheap/DIY yeast propagation systems for small breweries, and challenges of fed-batch culturing explained by Richard Preiss.	Derrick Morse	04/18/2017
Data points on dissolved oxygen in wort that has been cooled over night in a homebrew kettle, with questioning of the reported results by Bryan of Sui Generis based on how much O2 can dissolve in water.	Andres Edward Cruz	03/02/2017
Justin Amaral reports his experience with yeasts sent to him by Dr. Matt Bochman at Wild Pitch Yeast: Hanseniaspora vineae, Wickerhamomyces anomalus, and Lachancea fermentati which are believed to produce significant levels of lactic acid. Also Schizosaccharomyces Japonicus. Scroll down for comments by Dr. Bochman himself, as well as skeptical debate of the idea that these species produce significant lactic acid by Bryan of Sui Generis blog.	Justin Amaral	11/02/2016
In depth biology regarding the "myth" that Brettanomyces produces more CO2 per volume of sugar metabolized versus Saccharomyces.	Sean White	10/27/2016
Discussions of the mechanisms of botulism poisoning, and how it applies to different brewing processes.	Moby Toazwith Sandaltann	10/24/2016
Thomas Hübbe uploads his masters thesis on microbes and fermentation in traditional German Berliner Weisse to MTF, along with Q&A.	Thomas Hübbe	09/15/2016
Commentary on the new Verstrepen/White Labs published study on the family tree of yeasts.	Lars Marius Garshol	09/08/2016
Post 1 and Post 2 on a yeast called Lachancea thermotolerans that can produce significant lactic acid without modification. See also this thread on a lab's application to patent pitching this yeast into wort.	Richard Preiss and Devin Henry	08/04/2016 and 08/18/2016
The L. acetotolerans that contaminated Goose Island's Bourbon County brand beers, including notes from Brett Porter's MBAA presentation on the issue and microbiological information.	Richard Sigesmund	08/04/2016
Lars Marius Garshol sends a collection of samples of Norwegian Kveik from various families to Escarpment Labs for identification, banking, and profiling.	Richard Preiss	06/18/2016
Opinions and discussions on whether fermenting Brettanomyces under pressure, in secondary after a Saccharomyces primary, and other variables play a role in what esters are produced.	Devin Henry	06/01/2016
Technical discussion on the effects of freezing fruit and microorganisms.	David Mast	05/09/2016
Discussion on the difficulty and possibilities of identifying Brettanomyces versus Saccharomyces based on morphology and selective media.	Brian Martyniak	04/30/2016
Data that shows a correction factor of 0.1-0.2° Plato for 0.4-1% lactic acid solutions.	Jeff Young	04/28/2016
Brettanomyces does not "eat everything," and Nathan Gibbon from Omega Labs shows why by comparing growth on lactose growth media for different species of Brett.	Lance Shaner	04/07/2016
Ehren Schmidt from Toolbox Brewing Co. finds Rhodotorula, a potential pathogen, in fermented beer.	Ehren Schmidt	03/05/2016
Comparing fermentation profile and microbial populations of spontaneously inoculated wort at Black Project Spontaneous & Wild Ales: one starting at 5.9 pH, and one starting at 4.0 pH. Also compared sterile flask fermentation versus barrel fermentation to see how much influence the barrels have. See also Update 1 on 03/15/2016.	James Howat	02/26/2016
Suggestions on getting started with a equipment and procedures for a Quality Assurance/Quality Control program at a brewery.	Stefan Wiswedel	02/18/2016
In depth biology discussion on genetic drift during repitching and when/if it always occurs with comments by Matt Humbard, Richard Preiss, and other scientists.	Lars Marius Garshol	02/03/2016
Rarely do infections get identified; this one was identified in a lab as Penicillium.	Julian Buck	01/24/2016
Sub-thread discussion about yeast and LAB in the guts of bees and wasps, and how to collect it from them.	Matt Spaanem	01/20/2016.
Biology discussion on whether or not Brettanomyces attenuates further when combined with Saccharomyces, and what those mechanics might be (or not be).	Per Buer	01/19/2016
A controlled experiment shows that WLP644 Saccharomyces "Trois" does not form a full pellicle in airlock-fitted flasks stored for 3+ months.	Lance Shaner	01/06/2016
Suregork's cross between Conan yeast and WLP644 Saccharomyces "Trois". Fermentation trials have been promising, showing increased esters and better fermentation performance and attenuation. Kristoffer sent samples out for MTF members to try. See also the results of fermenting an IPA with this yeast by Alex Loijos.	Kristoffer Krogerus	11/06/2016
Mark Trent and Lance Shaner explain why output from traditional yeast pitching rate calculators actually produce up to 4x the amount of cells then what they say they will produce for Brett.	Mark Trent	07/21/2015
Archive of discussions, evaluations, and confirmations of Lance Shaner's discovery that WLP644 Brettanomyces Trois was found genetically to be Saccharomyces cerevisiae.	Dan Pixley	06/27/2015
Best plates for isolating Brett vs Sacch, and growing LAB.	James Howat	08/19/2015
Fermentation and pellicle formation with Hanseniaspora uvarum.	Matt Humbard	08/14/2015
Bryan of Sui Generis Blog educates about Rhodoturula.	Nathan Gibbon	06/26/2015
There's a little more to it than just homoefermentative and heterfermentative LAB.	Dan Pixley	06/09/2015
Bryan of Sui Generis Blog educates on the complexities and unknowns of Lactobacillus fermentation byproducts.	Josh Newby	05/24/2015
Bryan of Sui Generis Blog and Matt Humbard agree on why we taste "differences" between Pedio and Lacto driven beers.	Amos Browne	05/14/2015
Discussion on the presence of Brett in the air versus barrels.	Adam Boura	04/14/2015
Bitterness from Brettanomyces.	Dan Pixley	12/07/2015
Can Brettanomyces become airborne?	Asa Dunkerton	07/14/2015

Unique Processes

These processes may or may not make good beer, but they get an A+ for creativity!

Overview	Thread Starter	Date
A homebrewer with 110 gallons of sour/Brett beer split across 22 carboys details his experience with THP, acetic acid, and blending.	Robert Neuhaus	07/22/2017
Discussions on how colder temperatures affect Brettanomyces fermentation, including historical perspectives on one ~100 year old Czech beer that had Brettanomyces and acetic acid in it.	Dave Janssen	06/12/2017
Primitive Beer Project up in woodlands near Nymans Sussex. Day 1: tapping birch trees for sap, smoking 2kg malt with sweet chestnut. Day 2: collecting juniper, Brewing the beer with stream water collected and filtered on site as well as birch sap, fire fueled by wood from site, wort cooled down by stream water.	James Thor	03/25/2017
Experimenting with funky cider in a traditional multi-vessel solera system, along with tips on blending funky/sour cider and dealing with malolactic fermentation.	Tariq Ahmed	03/13/2017
A possible answer to the mysterious NHC 2016 (first round at Nashville) "Green Sour Beer".	Dean Volungis	01/24/2017
Testing lactic acid producing yeasts sourced by Dr. Matt Bochman Hanseniaspora vineae, Wickerhamomyces anomalus, and Lachancea fermentati, along with Schizosaccharomyces Japonicus.	Justin Amaral	11/02/2016
Council Brewing Co's Jeff Crane reports on spontaneously fermenting wort using apple pomace as the only inoculate.	Jeff Crane	09/14/2016
Barrel fermented porter with 100 lbs of Cabernet Sauvignon grapes with stems, fermented with red wine yeast (BM45) and B. bruxellensis. More tips for using Brett in wine from Dara here.	Dara Piraino	08/31/2016
Beer fermented with a Vietnamese culture called "Con me" which translates loosely to "mother" that usually contains LAB and Nematodes.	Mark Trent	07/27/2016
Aging Brettanomyces beer (bottled with corks) in a cheese cave to absorb the aroma of the cheese.	Mark Trent	07/12/2016
Positive results of MLF using O. oeni in mixed fermentation cider, as well as questions and answers with an award winning mixed fermentation cider maker.	Tariq Ahmed	07/11/2016
Homebrewing a beer inspired by traditional brewing methods of Norwegian farmhouse ales using Voss Kveik, along with tips on how to forage for juniper (Juniperus communis).	James Thor	06/18/2016
The effects of using sugar in Brett saisons, and how that effects mouthfeel and dryness, as well as discussions on how water chemistry and hops come into play.	Josh Kauffman	06/13/2016
Using a spontaneous culture from Rubio tequila factory in Tequila, Mexico to ferment a blond ale with agave syrup.	Alex Loijos	06/11/2016
DeWayne Schaaf's journey into bioprospecting and fermenting wine juice with wild caught yeast and bacteria.	DeWayne Shaaf	06/06/2016
Hilton Meyer tracks down potter Daniel Toberer who makes amphora and provides tips to make them with photos.	Hilton Meyer	04/24/2016
Experiences drying and storing yeast on paper or wood with references to historical preservation of Kveik yeast. Also see Kveik.	Per Buer	04/07/2016
Q&A about species of juniper to use for Norwegian farmhouse ales, as well as other types of trees/branches.	Mike Karnowski	03/14/2016
"Reverse MTF Souring." Devin Bell's experience with co-pitching probiotic L. plantarum with yeast, or pitching it after primary fermentation, and still getting sourness. Also demonstrates a very easy extract sour recipe/method for beginners.	Devin Bell	01/20/2016
Sun dried wild yeast (might be Kluyveromyces?) from the Republic of Benin in West Africa used to ferment sorghum beers.	Ingo Janssen	01/14/2016
Discussion of historic approaches to Belgian Wits - Short/no boils, very fast turnaround, etc.	Amos Browne	12/28/2015
Continuous inoculation of wort with a developing sauerkraut culture.	Alex Loijos	11/29/2015
100% malted sorghum Berliner Weisse.	Joel Piazza	12/02/2015
Runoff through a channel in a pine tree into a barrel used as a coolship.	Michael Detar	11/20/2015
Open barrel fermentation with a house culture of English yeast and B. claussenii using top cropping techniques.	Joel Stickrod	10/06/2015
100% fermented B. claussenii wine from Malvasia, Petite Manseng and Viognier grapes.	Dara Piraino	09/12/2015
Amphora discussion and personal Amphora building. See also this MTF thread and this MTF thread.	Eccentric Beekeeper	09/26/2015
4 day open fermentation with Trois and Claussenii.	John Yorger	02/10/2015
The birth of using probiotics to make sour beer on MTF by Josh Osborne and Devil Bell.	Josh Osborne	01/03/2015

Beer History and Culture

Research and thoughts on how beer was made back in the day, as well as cultural alcoholic mixed fermentation.

Overview	Thread Starter	Date
Blog post discussion on Blanche de Cambrai (historical Northern France white beer), and comparisons to historical Berliner Weisse brewing. See also Dave Jassen's direct blog post on Hors Categorie blog.	Dave Janssen	07/24/2017
Traditional Thai Sahto (fermented rice wine) and the distilled version Lao Khao, fermented with balls of dried yeast.	Stefan Wiswedel	05/13/2017
Write up and links to information about "Chhang", a barley-based fermented beverage made all around Tibet and the Himalayas. This version is made in Ladakhi.	Alex Loijos	04/09/2017
Tips on brewing Lichtenhainer from Kristen England and others.	Stephen Knapp	04/06/2017
Exploring spontaneously fermented banana and coconut water wine on the island of Rarotonga in the Cook Islands.	Ehren Schmidt	03/07/2017
Discussion on Belgian Wits historically being very young spontaneously fermented beer, with links from Yvan de Baets, references to "Brewing With Wheat", Ron Pattinson references, and a link to Mike Karnowski's recreation of such a beer.	Levi Fried	01/25/2017
English translation of several 1800's texts about how Gose was made by forming a "thick layer of mold" on top, and bottled in longneck bottles so that the yeast pellicle would dry out to trap the CO2 instead of using corks. Also information about gravities during fermentation, lactic acid content, salt content, and alcohol content.	Benedikt Rausch	01/17/2017
Tony Yates in Norway videos brewing a traditional Norwegian farmhouse ale, and splits the batch with several kveik yeasts: Stig Staljen (Hornindal), Arve Espe Espa (Hornindal), John Nornes (Voss), Sigmund Gjernes (Voss) and Bjarne Mur (Olden).	Dan Pixley	12/26/2016
Translation of a text from A. Dörfel written in 1947 about the creation of Berliner Weisse (process portion only).	Benedikt Rausch	12/31/2016
A kveik ring from Vågå, Norway that hasn't been used since WWII, and attempts to culture yeast from it.	William Holden	12/10/2016
Discussing a YouTube video of Finnish brewers brewing a traditional Sahti, including translation of the process portions by Teemu Halonen.	Devin Bell	12/8/2016
Ryan Deaver's detailed report on the local/indigenous fermentationists in Benin, West /Africa, complete with images and descriptions of their fermentation processes. The first installment is about spontaneously fermented Palm Wine and the distilled version, Sodabe. See also Ryan interviewed by James Spencer on BasicBrewing Radio (02/02/2017).	Ryan Deaver	11/08/2016
MTF tracks down Mike Matucheski, currently a master cheesemaker at Satori, who was a homebrewer who barrel fermented wild ale in the late 80's and early 90's in the USA before most people could taste commercial examples from Belgium.	Dan Pixley	09/11/2016
Dave Janssen's research on historical "Northern French white beers" from circa 1900.	Dave Janssen	07/25/2016
The invasion of ancient Norwegian yeast. See Kveik for more information.	Lars Marius Garshol	03/21/2015

Brewing Philosophy Discussions

Informed, controversial, opinionated, discussions on sour and funky brewing processes and industry.

Overview	Thread Starter	Date
Exploring the role that water chemistry plays in saisons, wild beers, and sours.	Garrett Hoepker	07/28/2017
Bryan of Sui Generis Blog schools us on how Lactobacillus protease works to reduce head retention proteins, techniques to prevent this, and counters certain claims about long cold lactic fermentation to maintain head forming proteins (the original poster removed his comments, so some context is missing, but Bryan's information is worth saving).	Bryan	06/12/2017
Who here does dirty and clean beers on the same gear in a commercial brewery (and lots of advice on cleaning/sanitizing on a commercial brewery level when brewing sours along side clean beers)?	Wilf Horsfall	06/05/2017
MTF helps Josh identify the owner of and take action against a fake website pretending to sell oak barrels to rip people off.	Josh Kauffman	01/16/2017
Discussing the idea of birthing a style, "Cervino", a spontaneous blend of wort of wine must.	Levi Funk	11/15/2016
MTF'ers share their methods of building a mixed culture.	Sean McVeigh	08/25/2016
Experiences on how different bottles of 88% lactic acid from the same manufacturer taste differently in tasting panels, and some potential explanations from chemist Mike Castagno.	Ron Smith	08/17/2016
Example of GM yeast that glows in the dark, and discussions of GM and intellectual property of resulting microorganisms. See also this subthread with yeast experts on the use of IP on yeast strains.	Nick Moench	07/11/2016
Discussing the mechanics of gushing and what causes gushing in sour beers.	Kyle McHerron	06/30/2016
Questions answered regarding what category to enter fruited Gose or fruited Berliner Weisse into for BJCP competitions, with advise from Gordon Strong.	Andrew Grumke	04/05/2016
General advise and approaches to making "quick turn around" mixed fermentation sours (1-3 months).	James Thor	03/24/2016
Questions and answers on contracting wort production from another brewery for a sour brewery. Answers from brewers, including Jeff Porn and Levi Funk.	Rion Spurlock	02/29/2016
Discussion on how much coolships might influence Belgian Lambic versus barrels with scientific studies discussed, and insights from Pierre Tilquin and James Howat.	Ron Smith	01/29/2016
Discussion on Jester King's new coolship, discussing supplementing spontaneously inoculated wort with pure cultures versus 100% spontaneously fermented beer with comments by James Howat, James Sites, and Garrett Crowell.	Mark B. Fry	01/12/2016
Discussion on the new trend towards green bottles, which devolved into a discussion of saison/farmhouse beer history with Lars Garshol. See also this thread started by Jeff Porn on the recent trend of using green bottles.	James Howat	12/04/2015
Discussion on whether or not Lambic has to be brewed in Belgium in order to be called "Lambic".	Devin Bell	02/06/2015
Discussion of why some brewers warn against kettle souring.	Wayne Wambles	05/11/2015
Discussion of what inspires us to brew funky/mixed fermentation beers.	James Sites	11/19/2015
A microbiologist view on why using dregs is non-ideal.	Tamir Danon	10/08/2015
Discussion of lactic acid production with Bryan of Sui Generis Blog and Matt Humbard, as well as why you shouldn't use WLP677 and the beginning discussions of why Lacto can't fully attenuate wort on its own. Also the source of the great Lance Shaner quote, "Agree that maths are hard."	Lyall Anderson	05/06/2015
Warning against using plastic containers as coolships from a polymer chemist, and coolship dimension philosophies from James Howat and Kristen England (read all of the sub-replies).	Dave Stokley	11/12/2015
Discussion on whether or not some 100% Brett fermentations that perform like Sacch fermentations actually contain cross contamination of Sacch yeast.	Lance Shaner	08/12/2015
Discussion of the use of the term saison (read all of the sub-replies). See also this similar discussion from the Saison, Biere de Garde & Farmhouse Ale group.	Bob Sylvester	12/28/2015

See Also

Additional Articles on MTF Wiki

• Sour Brewing FAQ

External Resources

• Milk The Funk Facebook Group