Soured Fruit Beer

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The acidity and fruity characteristics in many mixed-fermentation beers make them good candidates for fruit additions. It is not recommended to put fruit into a beer to cover up some major flaw or off character. Fruit can complement a good beer but it will likely not fix problems. Quality fruit is expensive and you'll want to start from a good base if you are going to invest the time and money in good fruit for a beer.

Some producers use the term maceration to describe the addition of fruit or herbs to a beer. Maceration in beer is the extraction of flavor-active and colored compounds as well as other constituents of fruits and herbs by soaking them in the beer. The rate at which compounds are extracted during maceration depends on factors such as temperature and pH.


When To Add Fruit

When to add the fruit depends on the style of beer and what the brewer is going for. Generally, fruit is added after a sour or mixed fermentation beer has finished aging and maturing. This preserves the fruit character more than other methods. For example, a mixed fermentation sour beer might take 6-12 months for the Brettanomyces character to develop fully. After this maturation, the fruit should be added, and then aged for another 1-2 months. For a kettle sour, the same rule applies, but the time frame is generally much shorter. Since kettle sours generally mature much faster than mixed fermentation beers, fruit can be added much sooner. For example if the kettle sour is done fermenting after two weeks, fruit can be added at that time.

Another method would be to add the fruit earlier on during the aging process. This can help extract more from fruit skins or seeds, but some of the more delicate aromas and flavors of the fruit could age out of the beer in that time. For example, Belgian kriek style beers are sometimes aged on cherries for ~6 months, which is believed the time required to extract character from the pits.

A combination of adding fruit earlier on in the fermentation, and then again after the beer has matured is another technique that brewers have used.

For how long to age the beer on fruit, see Aging Vessels and Refermentation and Usage Suggestions contact time below.

Aging Vessels and Refermentation

In wood or steel (or glass or plastic).

When adding fruit to a non-pasteurized beer that does not contain living Brettanomyces but does contain living S. cerevisiae (for example, kettle sours), a re-fermentation will often occur a day or two after adding the fruit. This re-fermentation can last 1-2 weeks until the sugars from the fruit are fermented. Sours such as kettle sours that do not contain living Brettanomyces can be treated like adding fruit to any other type of "clean" beer (see this article, for example). Beers that are fully pasteurized, for example from a flash pasteurizer, or aged for longer than 6 months or so, will not re-ferment the fruit because all of the yeast is dead.

Things change a little when adding fruit to aged sours that contain living Brettanomyces. When adding fruit to an aged, non-pasteurized sour beer that contains Brettanomyces, a secondary fermentation will generally occur after a few days of adding the fruit, and will generally last 1-2 months (see contact times below). A seven-day lag time is not unheard of, as this follows the growth cycle of many Brettanomyces strains. The visual indicators of this fermentation will depend on the strain(s) of Brettanomyces and other microbes that have survived the previous aging process, and can range from active fermentation to developing a pellicle to having no visual fermentation at all. Active fruit fermentation may cause fruit particles to clog the airlock or bung and prevent the vessel from venting pressure. This may cause the airlock to shoot off or worse. The Rare Barrel prevents this problem in vigorously re-fermenting beers by stabling foil over the bung holes of barrels of actively fermenting fruit beer rather than using a bung[1] (~52 minutes in). Raf Soef uses stainless mesh from a tea ball on the bottom of bungs to prevent fruit pieces from clogging the bung or airlock [2]. Raf also suggests filling only 80% of the capacity of the vessel with fruit and beer, and then topping up after the re-fermentation of the fruit [3].

When using whole fruit, it is typical for the fruit to be carried to and held at the top of the fermenter due to carbonation. Some producers have voiced concern over the fruit sitting for prolonged periods of time in contact with air and prefer to push the fruit cap down periodically (and to ferment in such a vessel as to allow this)[1] (~40 minutes in). If you are fermenting in carboys and feel that you are getting acetic character from the fruit cap being in contact with air you can swirl the carboy periodically. Note that many who have used whole fruit have not noticed any problem with a fruit cap being in contact with air, so you may or may not find that this is a concern for you[4].

Forms of Fruit

(in progress)

Fruit is available to the brewer in multiple different forms.

  • Whole or sliced fresh - Use a CO2-purged keg or minimize headspace in a carboy. Mold and acetic acid bacteria can grow on the skins of floating fruit [5]. Brettanomyces can also produce acetic acid in the presence of O2, and it is possible that this is the source of acetic acid sometimes found in beers with floating fruit rather than acetic acid bacteria. Some brewers like to swirl the fermenter every few days or to keep the alcohol in contact with the fruit, though some others report no ill effects from not swirling the fermenter (and this is impractical in commercial settings). If using a barrel or larger fermenter, you may try using a punch-down technique. If punching down the fruit, purge the headspace of the vessel with CO2 to avoid oxygen exposure to the beer. Allow the fruit to get fully or possibly even over-ripe (not rotten) for best flavor. Whole fruit may take longer to ferment but it also can give the most complexity [6]
  • Whole or sliced frozen - Bulk freezing fruit has a few main potential benefits. First, freezing fruit helps to break down cell walls, which may make the fruit easier to access for yeast and bacteria in the beer [7]. Freezing fruit can also knock back the microbes present on the fruit. Note however that freezing does not kill all the microbes on the fruit. Finally, freezing fruit allows the brewer (especially the homebrewer) to take advantage of local and seasonal fruits when they may not have a use ready for those fruits in season. Frozen fruits are also available as IQF, or individually quick frozen fruit. IQF fruit is frozen but each berry is distinct rather than a single frozen mass. This allows for easier handling, helps prevent clumping, makes for easier fitting of fruit into small openings in carboys or barrels, and allows screening and removal of bad looking fruit. The cell walls of IQF fruit are less broken down than bulk frozen fruit, so there might be a slower extraction rate when using IQF [8]. Defrost frozen fruit in the microwave or in the fridge over night. The fruit doesn't necessarily have to come all the way up to cellaring or room temperature. Adding frozen fruit without thawing it first is probably fine as well. The beer and frozen fruit will come back up to ambient temperatures over night [9].
  • Pureed fresh - pureeing fresh fruit has the benefit of extracting the fruit flavor faster. It also sinks to the bottom of the fermenter [10], so the problem of floating whole fruit is avoided. Puree can be difficult to rack the beer off of, and more beer may be lost compared to using whole fruit. Some brewers choose to heat pasteurize freshly made puree.
  • Aseptic puree - Same as "Pureed Fresh", but has already been pasteurized. This is usually the case for commercially available puree. We recommend Oregon Specialty Fruit or The Perfect Puree for quality commercial puree. These purees often have antioxidants such as citric and absorbic acids, cane sugar, and other juices added to them [11]. Check the ingredients list of any product before ordering it. Much like fresh purees, aseptic purees or pulps may result in a fair amount of volume loss at packaging, and some puree making it into the final package can be problematic for gushing [12]. See the Oregon Fruit webpage for tips on usage amounts and how to use puree for brewing (they recommend 1/2 to 2 pounds of puree per gallon of finished beer).
  • Concentrates and extracts - Concentrates can lose aromatics due to the process, and are generally not as recommended. Some manufacturers such as Kings Orchards uses a process that reintroduces the aroma back into the concentrate [5].
  • Juice - Make sure there is no sugar or preservatives added [5]. R.W. Knudsen and Lakewood Organic brand juices have been recommended if available [13][14]. Juice ferments out faster than whole fruit. This gives the advantage of being able to add a little bit at a time to the secondary fermenter, and being able to add to taste.
  • Dried/Dehydrated - Make sure they are oil and sulfur free. Oils can be considered a processing aid, and don't have to be listed on the ingredients list.

Fruit varieties and usage suggestions

Specific notes on select fruit varieties

  • Apples - Orchard apples often contain interesting wild yeasts and bacteria, and can be chopped and added directly into secondary; do not pasteurize or freeze for maximum microbial potential [15].
  • Apricots - Apricot pits contain a cyanide precursor, though unpitted apricots, and sometimes exclusively the pits (e.g Cascade Noyaux) are used with success in beer. This would suggest that the amount of cyanide in pits is likely low enough to be ok [16], and that the pits may add a certain character that some brewers desire. If you are concerned about it, then do not use apricot pits. Cantillon reports limiting the contact time of their lambic with apricots for 8 weeks, otherwise the beer becomes too acidic. This may be due to microbes living on the apricot skins and is likely not due to acids in the apricots themselves. Cantillon uses 2/3 pitted and 1/3 unpitted apricots [17].
  • Autumn Olive - This is a shrub producing small tart fruits native to Asia and found naturalized in eastern US (though it is considered invasive).
  • Black Currants - Finding black currant juice without added sugar can be difficult because of the juice’s high acidity. Keep this in mind when tasting the juice, as the amount of added acidity after refermentation can make the beer unpalatable [18].
  • Blackberries - Adds citric acidity; milder flavor compared to raspberries. Works well mixed with cherries. Can also add a lot of tannin character to a beer [19].
  • Cherries - Both sweet and sour varieties of cherries are available. Generally sour cherries are used in beer. They are more difficult to find and to source some you may need to look into smaller local farmers or frozen or juice options. Varieties of sour cherries include Schaerbeekse (traditional in lambic), Montmorency, Balaton, Morello and Amarelle. The stones also produce some character and can add to the beer, so you may want to consider leaving the pits in with some or all of the fruit. Cherry pits also have a cyanide precursor (see Apricot, above); however given the success of many brewers using whole cherries in beer for decades or more, the levels of cyanide precursor in cherry stones may not be an issue. If you are concerned about it, then remove the stones from cherries when using whole fruit. See [[Glycosides#Cyanogenic_Glycosides] for more information.
  • Cranberries - Consider adding a some raspberries to go with the cranberries for added complexity [20].
  • Elderberries - Avoid using underripe elderberries (and elderberry leaves); they may contain cyanide precursors [21].
  • Fuyu Persimmon - Works well with fruity Brett character.
  • Grapefruit - Can be combined with zest (as can other citrus fruits). Use 5-10 grams of zest for ~5 gallons. Some prefer pink grapefruit [22].
  • Grapes - Wine grapes are preferable for their depth of flavor compared to table grapes. Consider both the influence of the juice of the fruit as well as the potential to pull tannins and flavor/aroma from skins. Some homebrewers have experimented successfully with blending finished wine with beers, and for many brewers you will have much easier access to good wine than good wine grapes [23] [24]. If you are interested in sourcing quality grapes and you live in a wine region, make friends with your local wineries. It will probably be good for you even if grape requests do not bear fruit (see what I did there, that was pretty funny).
  • Kiwi - Peel and dice or slice; optionally freeze. Leave out skins [18].
  • Kumquat - Can get too bitter if too many are used. It doesn't take much to get a nice citrus and rind character [22].
  • Loquot - Leave out pits.
  • Lychee - Not much yield when using whole fruit. Difficult to work with because it has a tough rind and large seed. Flavor can be subtle. Recommended to use juice or puree instead of whole fruit [25].
  • Passion fruit - When using whole fruit, use the pulp only. Whole passion fruit can be expensive, so puree or pulp is a good option. Goya Fruta brand has been recommended at 1 package per gallon, and can be found at world markets (Asian and Latino groceries) [26].
  • Paw Paw - It can be burdensome to remove the flesh from the skins and seeds by hand. MTFer Mark W. recommends using a potato ricer for this [27].
  • Pineapple - Leave the skins out.
  • Prickly Pear - Difficult to process. Some advise burning the hairs off and leaving on the skins, however the skins may contribute a slight "pithy" character (some brewers report getting no pithy character by leaving on the skins). Some brewers blend into a puree, and use a food processor to remove the seeds. Others use a press to press out the juice and leave the skins/seeds behind. Others advise to cut them up, add a cup of water, and bring them up to 180°F, and then use a potato masher to mash them up. Hang in a hop sack to drain over night. They are high in pectin and mucilage, so using pectinase to help with clarity is an option (see using pectinase instructions below) [28][29].
  • Quince - Very aromatic, but also has pectin haze. Also able to be used are Japanese flowering quince (Chaenomeles) [18].
  • Raspberries - Advice: use a fine-mesh bag for whole fruit or a fine-mesh strainer for puree since seeds/skins may not settle even with extended aging. Frozen products tend to be more consistent than fresh [18]. Raspberries can pair well with both pale and darker sour beers.
  • Sumac - Provides a lot of "lemony" acidity. Can boil it, but don't boil for too long or the nice red color will turn brown.
  • Strawberry - It is thought that the seeds might carry a lot of p-coumaric acid, which can transform into 4-vinylphenol and 4-ethylphenol in the presence of Brettanomyces, which tastes like plastic. Some people have had luck juicing strawberries and removing any seed or vegetal material (or using strawberry juice) to avoid plastic flavors [30][31]. To remove pulp and seeds, MTF members have advised using a flotte lotte, basket press, or Breville Juice Fountain Elite juicer [32].
  • Tamarind - Provides an umami flavor that some people might not like [18].
  • Vanilla Fruit (Beans/Extract) - Organic/natural recommended for extract. Start at 1 teaspoon per 5 gallons of beer, and add more to taste. For whole beans, cut long ways and scrape out the insides, add entire bean. Balances well with acidity, and some have reported that it adds some mouthfeel to Brettanomyces based beers [33][34].
  • Watermelon - Watermelon flavor can be difficult to achieve. Jeffrey Airman of Paradox Brewing Co. uses fresh watermelon with the rind, and supplements with a lot of juice [35]. Steph Cope of CraftHaus Brewing Co used 10 large watermelons/3bbls of kettle soured gose. An immersion blender was used to pulverize; it took a long time for that much watermelon to drop clear, and low yield (but strong watermelon flavor) [36]. Thomas Morley recommends that the watermelon pulp be filtered out to avoid the cloudiness issues (Jester King uses a press [37]) [38]. James Sites advises juicing the watermelon, then reducing it to remove the water content [39]. Bob Sylvester advises using an "overwhelming amount" of watermelon, and using some of the rind to bolster the flavor [40].
  • Yuzu - Juice form can be very strong. Taste first. Start with 1 ounce per gallon, and add more to taste [41].

Usage Suggestions

"Contact time" in the table below is for mixed fermentations with Brettanomyces. Kettle sours or beers that do not contain live Brettanomyces can have a much shorter fruit contact time (generally 1-2 weeks). All contact times are assumed to be applied in secondary, and at the end of aging. Keep in mind that this is just a general guideline for usage amounts. Brewers should consider their base beer's characteristics such as abv, flavor profile, acidity levels, etc. when considering how much fruit to add. It is common for lambic brewers to age much higher fruit to beer ratios and then blend back with unfruited lambic to the desired g/L amount. If you are really trying to nail the perfect fruit amount, applying this sort of technique could be useful (assuming you have suitable beers around to blend back). This will allow you to try different blend ratios to determine the appropriate amount of fruit for your beer and desired outcome. In regard to fruit ratios, Belgians calculate fruit ratios by : Fruit ratio (g/l) = (KG of Fruit / (KG of fruit + liters of beer))*1000 [42]. Maintain a temperature range from 65-75°F (18-24°C) during the fermentation of the fruit if possible, however temperature swings during fruit fermentation are generally more forgivable than when temperatures swing during primary fermentation.

Fruit displacement isn't a huge concern; 10 pounds of fruit generally requires an extra gallon of head space (the exact volume depends on the volume of the fruit [43]). However, the fruit will usually re-ferment, causing a blow off, so allowing for extra headspace is a good idea. This site might assist with calculating the displacement volume of fruit.

Fruit can be used for a 2nd steeping and second use of fruit can still provide flavor and color, but in a more subdued way than first use. Both Jester King and the Rare Barrel use fruit more than once, and Jester King reports preferring their second use fruit beers to their first due to more subtlety and balance[44] (~15 minutes in). Other breweries, including Cantillon[45], The Bruery, and Upright[46], also report multiple conducting steepings of fruit, at least at one point if not currently.

Jay Goodwin from The Rare Barrel suggests using 42 lbs/oak barrel (0.7 lbs/gallon) as a good starting point for fruit puree [47] (~22 minutes in).

Don't be afraid to experiment outside of these guidelines.

Fruit Juice Concentrate Purée Dried Whole Contact Time Commercial Examples
Apple 0.5 lb/gal [18] 1-2 lb/gal [15] 6-8 weeks
Apricot 0.75 lbs/gal[44] (~56 minutes in) 1-2.5 lbs/gal 6-8 weeks 300 g/l (2.5 lbs/gal) Cantillon Fou Foune - 2/3 pits, 1/3 unpitted - max 8 weeks contact time [17]
Autumn Olive (Autumn Fruit) 1-1.5 lbs/gal [18] 2 lbs/gal [18] 6-8 weeks
Black Currant 24-36 fl oz/gal [18] 3 weeks juice/6-8 weeks whole
Blackberry 0.7-3 lbs/gal [18] 6-8 weeks 350 g/l (2.9 lb/gal) Tilquin Mure
Blueberry 2[48]-3 lbs/gal 6-8 weeks
Cantaloupe 0.5 lb/gal [18] 6-8 weeks
Cherry (Tart) 12-24 fl oz/gal 4-8 fl oz/gal [18] 2+ lb/gal [49] 0.5-1.5 lbs/gal [50] 1-3.3 lbs/gal 3 weeks juice/6-8 weeks whole [18]. Lambic brewers/blenders sometimes age longer (6-12 months)[51] 200 g/l (1.67 lbs/gal) Cantillon Kriek, 300 g/l (2.5 lbs/gal) Cantillon Lou Pepe Kriek, Oud Beersel Oude Kriek, 400 g/l (3.33 lb/gal)
Clementine 1 lb/gal [22] 5 weeks [22]
Coconut
Cranberry 32 fl oz/5 gal [52] 1 lb/gal [20] 6-8 weeks
Elderberry 0.5 lbs/gal [18] 6-8 weeks
Fuyu Persimmons 2.5 lbs/gal [18] 12 weeks [18]
Grape (Table)
Grape (Wine) 2-3 lbs/gallon 300 g/l (2.5 lbs/gal) Cantillon St. Lamvinus and Vigneronne
Grapefruit 3.5-5.5 fl oz/gal [22]
Guava 1-2 lbs/gal [18] 6-8 weeks
Key Lime 100mL/gal [53] Added as priming sugar at bottling
Kiwi 2 lbs/gal [18] 6-8 weeks
Kumquat 0.25-0.60 lbs/gal [22] 6-8 weeks
Loquat 2 lbs/gal 6-8 weeks
Mango 18 fl oz / gal [12] (note that this resulted in significant loss of beer volume); 2 lbs/gal 6-8 weeks
Nectarine 1-2 lbs/gal 6-8 weeks
Olallieberries 3 pounds per gallon (maybe on the higher side but good)[54] [55] 2 months [54]
Passion Fruit 250-500mL per 5 gal [56] 0.5-1 lbs/gal [57][58] 6-8 weeks
Paw Paw >1 lb/gal (flesh only) [59] > 2 weeks (at ~1lb/gal)[59]
Peach 0.5-2 lb/gal [18] 1-2 lbs/gal 6-8 weeks
Pear 6-8 weeks
Persian Lime (loomi/dried lime/black lime) ~1 lime per gallon, or less [60][61] One quarter added during boil, rest added to secondary for 6-8 weeks (or all added to late boil, or all added to secondary) Upright Brewing Saison Vert.
Pineapple 1 pineapple/gal [18] 6-8 weeks
Plum 2-3 lbs/gal[62] Some prefer shorter contact (1-2 weeks) and higher rate, others suggest longer contact (3+ months) and lower fruiting rates[62] 250g/l (2 lbs/gallon) Tilquin Quetsche (contact time of 4 months)[63]
Pomegranate 8-13 fl oz/gal [18][64] 6-8 weeks
Prickly Pear 0.5 lb/gal [18] 6-8 weeks
Quince 2 lb/gal [18] 6-8 weeks
Raspberry 1-2.5 lbs/gal 6-8 weeks 200 g/l (1.67 lbs/gal) Cantillon Rose de Gambrinus, 300 g/l (2.5 lbs/gal) Cantillon Lou Pepe Framboise
Rhubarb 0.5-1.0 lb/gal [18][65] 6-8 weeks
Salmonberries 1 lbs/gal [66] 6-8 weeks
Strawberry 0.5-1 lbs/gal [18] 2-3 lbs/gal 6-8 weeks
Vanilla Fruit (Beans) [33] (Extract) 2 teaspoons/5 gal (Whole pods) 1/2-2 beans per 5 gal Rare Barrel Home Sour Home
Watermelon 40-64 fl oz/gal [18][38] 6-8 weeks Jester King Hibernal Dichotomous (12% watermelon juice [37]), and another beer rumored to use 30% fresh watermelon juice [38].
Yuzu (citrus) 1-5 oz/5gal [41][67] ~2 lbs/5 gal [41] Added at packaging
Zante Currant 5-10 fl oz/gal 0.2-0.4 lbs/gal 4-8 months [68]

Removing fruit

(In Progress) Once your fruit beer has reached the character you desire, you will want to remove the beer to a packaging/further aging vessel or to a final package while leaving the fruit behind. Depending on the type and form of fruit you used, this can be a challenging task. Juices should not present a problem and purees will generally settle out. Larger chunks or whole fruits (fresh, frozen, or dried) may be more easily avoidable however some fruits, such as raspberries, tend to disintegrate and can be especially troublesome. Link to this MTF post

Filtering and Removing Haze

Over time, most beer will clear eventually. However, there are methods for clearing fruited beer quicker and perhaps to a greater degree than natural conditioning.

Filtering

Some types of fruit and/or brewing systems may require filtering. One option is to use a filter, such as a GW Kent Lenticular Filter Housing. On a homebrew level, using any system that is designed to filter dry hops from the fermenter should also work for filtering fruit. Examples include using a fine mesh bag on either the receiving or exiting end of a siphon, or using a 300 micron stainless steel "Dry Hopper for Glass Carboys" which fits over the receiving end of most homebrew auto-siphons. Filtering may not remove haze from pectin. Some brewers believe that pectinase can help with getting the fruit to separate from the beer [69]. For filtering fruit that has been added directly to a barrel, Brandon Jones advises securing a stainless steel scrubby to the end of a barrel racking cane using a stainless worm clamp [70].

Removing Haze

Different types of fruit contain differing levels of pectin, which cause haze. One option, and perhaps the preferred option for both commercial and homebrewers, is to use pectic enzyme (more formally called pectinase). Pectic enzyme is available from brewing supply retailers, and is available in both powdered and liquid format. The liquid format tends to be easier to use, and requires less of it to work. Add the pectic enzyme when adding the fruit (before re-fermentation of the fruit) if possible, but the pectic enzyme can be added after the fruit ferments as well. Pectic enzyme is sensitive to ethyl alcohol, so a 50-100% increase in the dosage that the manufacturer recommends may be needed when adding it to an alcoholic beverage. Using this much pectic enzyme should not contribute a flavor difference or impact the health safety of the beer. The beer should clear in a matter of weeks at the most [71]. Some brewers believe that the use of pectinase also helps improve the quality of the fruit flavor [69].

Another option is to try to use BSG Biofine® Clear after the beer has fully extracted the fruit. Be sure to cold crash the beer down as close to 0°C as possible when using this product. Use a higher dosage if the beer is not clarifying. This product should produce clear beer in most circumstances, however there have been reports of it not clearing up pectic haze [72].

See Also

Additional Articles on MTF Wiki

External Resources

References

  1. ↑ 1.0 1.1 The Sour Hour #14: with Jester King, pt. 1
  2. ↑ Raf Soef's tea strainer modification
  3. ↑ Conversation with Raf Soef on MTF regarding re-fermentation of fruit and dealing with blow off. 11/30/2015.
  4. ↑ MTF facebook thread about fruit caps
  5. ↑ 5.0 5.1 5.2 Conversation with Kyle Kohlmorgen on MTF regarding fruit. 10/23/2015.
  6. ↑ Thoughts from Raf Soef on using whole fruit in a MTF thread
  7. ↑ "Effects of freezing and thawing on texture, microstructure and cell wall composition changes in papaya tissues." Phothiset S, Charoenrein S. 2014.
  8. ↑ Conversation about freezing fruit on MTF. 05/10/2016.
  9. ↑ Conversation with Devin Bell on MTF. 01/17/2016.
  10. ↑ Conversation with Dara Piraino on MTF regarding puree. 11/1/2015.
  11. ↑ Conversation with Ehren Schmidt about Perfect Purees having cane sugar and acids added to them on MTF. 05/18/2016.
  12. ↑ 12.0 12.1 Adi mango pulp discussion
  13. ↑ Pomegranate Margarita Gose. Ale of the Riverwards Blog. Ed Coffey. 11/13/2015. Retrieved 11/19/2015.
  14. ↑ MTF Thread on Lakewood Juice. 03/07/2016.
  15. ↑ 15.0 15.1 Conversation with Aiden Robert Jönsson regarding using apples on MTF. 06/01/2016.
  16. ↑ MTF conversation about cyanide in stones
  17. ↑ 17.0 17.1 Private conversation between Jean Van Roy and Richard Sigesmund.
  18. ↑ 18.00 18.01 18.02 18.03 18.04 18.05 18.06 18.07 18.08 18.09 18.10 18.11 18.12 18.13 18.14 18.15 18.16 18.17 18.18 18.19 18.20 18.21 18.22 18.23 18.24 18.25 Conversation on MTF about adding fruit to sour beer. 10/23/2015.
  19. ↑ Thread on MTF regarding blackberries and tannins. 08/16/2016.
  20. ↑ 20.0 20.1 Conversation with Dustin Carver on MTF for cranberry usage. 11/16/2015.
  21. ↑ "Searching for cyanide". Nordic Food Lab. 09/05/2013. Retrieved 07/27/2016.
  22. ↑ 22.0 22.1 22.2 22.3 22.4 22.5 Conversation with Derek Springer, Murray Sharp, Steve Holat, Brandon Jones, and Dara Piraino on MTF. 01/21/2016.
  23. ↑ Mad Fermentationist blending wine and lambic
  24. ↑ Mad Fermentationist New Zealand saison
  25. ↑ Conversation about lychee fruit on MTF. 04/14/2016.
  26. ↑ Passion fruit recommendation from Alex Aguillon. 11/13/2016.
  27. ↑ Paw Paw discussion on MTF FB page
  28. ↑ Conversation on MTF on prickly pear fruit. 02/20/2017.
  29. ↑ Conversation about prickly pear fruit on MTF. 09/17/2016.
  30. ↑ Discussion with James Sites on MTF regarding strawberries and 4EP precursor. 05/09/2016.
  31. ↑ Conversation with Kyle Pittser on MTF regarding the use of strawberries. 03/01/2017.
  32. ↑ Ingo Janssen, Thomas Creighton, and Ryan Adam Bickley. Milk The Funk Facebook group. 03/24/2017.
  33. ↑ 33.0 33.1 MTF thread recommendations by Nathan Peck, James Sites, Justin Amaral, Dustin Carver, and Rodney Beagle. 12/8/2016.
  34. ↑ Milk The Funk Facebook thread on vanilla beans. 03/05/2017.
  35. ↑ Conversation with Jeffrey Airman on watermelon use. 06/03/2016.
  36. ↑ Conversation with Steph Cope on watermelon usage. 06/03/2016.
  37. ↑ 37.0 37.1 "Introducing Jester King Hibernal Dichotomous". Jester King's Blog. Retrieved 11/13/2016.
  38. ↑ 38.0 38.1 38.2 Conversation with Thomas Morley about watermelon usage. 11/12/2016.
  39. ↑ Conversation with James Sites on watermelon usage. 05/06/2016.
  40. ↑ Sylvester, Bob. Milk The Funk Facebook group. 03/31/2017.
  41. ↑ 41.0 41.1 41.2 Conversation with Matt Bing and Dennis Lovelock on MTF. 01/28/2016.
  42. ↑ MTF Facebook comment from Raf about fruiting ratios
  43. ↑ Displacement (fluid). Wikipedia. Retrieved 05/05/2016.
  44. ↑ 44.0 44.1 Sour Hour episode 15 - Jester King pt. 2
  45. ↑ Cantillon Kriek
  46. ↑ Upright Special Herbs
  47. ↑ The Sour Hour episode 10
  48. ↑ Steve R on MTF facebook page
  49. ↑ Zinn, Andrew. Milk The Funk Facebook group. 03/26/2017.
  50. ↑ MTF Thread by Eccentric Beekeeper on using dried cherries. 01/16/2016.
  51. ↑ Raf Soef. Milk The Funk Facebook group. 04/08/2017.
  52. ↑ Conversation with James Sites on cranberry juice on MTF. 11/17/2015.
  53. ↑ Conversation with Richard Preiss on MTF regarding key lime juice. 01/21/2016.
  54. ↑ 54.0 54.1 MTF_Thread by Trey Rabinek
  55. ↑ MTF follow up by Trey Rabinek
  56. ↑ Conversation about passion fruit concentrate on MTF. 11/11/2016.
  57. ↑ Conversation with Allen Stone on passion fruit usage. 11/12/2016.
  58. ↑ Conversation with Manny Jannes and Kristopher Johnson (Green Bench brewer) on passion fruit additions on MTF. 10/22/2015.
  59. ↑ 59.0 59.1 MTF Paw Paw thread from 8-Sept-2016
  60. ↑ Conversation with Caroline Whalen Taggart on MTF regarding Persian limes. 12/06/2016.
  61. ↑ Tips from various brewers on using black lime on MTF. 05/07/2017.
  62. ↑ 62.0 62.1 MTF thread about plums, 14-Sept-2016
  63. ↑ Tilquin Facebook Post 22-Sept-15
  64. ↑ Ale of the Riverwards Blog by Ed Coffey, Pomegranate Margarita Gose. 11/13/2015.
  65. ↑ [https://www.facebook.com/groups/MilkTheFunk/permalink/1712572182104322/?match=d2lraQ%3D%3D Mitch Ermatinger, Brian King, Matt Kent. Milk The Funk Facebook group post. 06/08/2017.]
  66. ↑ MTF thread by Kyle Hammock. 01/15/2016.
  67. ↑ Conversation with Doug Stallard on MTF. 05/17/2016.]
  68. ↑ Russian River Consecration Description. Retrieved 10/21/2015.
  69. ↑ 69.0 69.1 Conversation with Alex Loijos and James Sites on pectinase usage. 08/17/2016.
  70. ↑ Brandon Jones. Milk THe Funk Facebook group. 07/11/2017.
  71. ↑ Conversation with James Sites and Nick Moench on MTF. 04/15/2016.
  72. ↑ Conversation with Ehren Schmidt and Daniel Addey Jibb on MTF. 04/16/2016.
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