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Author Topic: "Homebrewing" Hop extracts  (Read 4648 times)
JWChesnut
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« on: December 07, 2011, 02:25:31 PM »

I was stymied by the "applicator license" requirement to purchase HopGuard in California.

I decided to investigate "homebrewing" of a analog. Has anyone else attempted this?

The patent describing HopGuard is available. COMPOSITIONS AND METHODS FOR CONTROLLING A HONEY BEE PARASITIC MITE
 Gene Probasco
http://www.google.com/patents?id=NV3OAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false

The patent is worth reading, even if you have access to the commercial formulation.  (Unfortunately, the patent was prepared by a clever lawyer who sought to broaden the claims, so the practical knowledge is buried under an expansion of duplicative but abandoned methods).

It is my understanding that HopGuard consists of 16% (by weight) beta-acid hop extract stabilized by converting to "soap" or Potassium salt and coating a cardboard strip.  It appears the agent kills mites either by contact or by consumption into the bee's body fluid.  I am not certain, but (from the patent) it appears the extract is made attractive to the bees by adding sugar.

Mr. Probasco tested a broad array of hop extract mixture against mites and honeybees (see Table 1).  Three of his replicate tests had honeybee mortality: 5% Beta Acid on filter paper  had 20% mortality after 22 hours, and  30% alpha-acid in water had 33% mortality. An isomorhized version of alpha-acid had 7% mortaility.  Since higher and lower dosages of alpha and beta acid had no detectable mortality, the reason for the bee death is not clear, but Probasco did do replicate experiments.    His method were to introduce bees to a filter paper lined petri dish, an easily replicated test for a home-brewed substitute.

Hops have three classes of active compounds: alpha-acids, beta-acids and hop oils.  Alpha acids are used to provide "bitter" flavor and anti-microbial impact. Beta-acids are not bitter and have the same anti-microbial  usage, but accompany the complex hop oils used to impart flavor.  In modern industrial brewing, Alpha oil is extracted using liquid CO2, leaving behind the  "base extract" (or the beta-acid and hop mixture).  The base extract can be further refined to separate the hop oils from the beta-acid.   Hop Oil can be injected  into the finished beer at bottling to highten the flavor (called dry hopping in traditional brewing).

All three classes of compounds (and complex magnesium salt isomerizations) are available at the industrial scale. (footnote: beer is light sensitive, and the isomerizations were created to allow beer to be sold in clear rather than brown bottles without going "skunky" from sunlight exposure). Beta-acid is mostly a by-product. Beta acid is described as an addition to Sugar Beet processing to prevent Listeria micro-organism from growing.  An interesting Japanese patent mixes Hops and Wasabi mustard extract to protect pickled vegetables from decay.  Hops and Rosemary extract are sprayed on  raw meat to prevent  micro-organisims,  oxidation and discoloring.

  At the hobby level, online availabiltiy of unseparated extract of "Amarillo" hops is offered at 5ml (in syringes) for $1.99.  Since dosage of HopGuard is 3.84 g per hive, the 5ml syringes would offer (very roughly) equivalent dosage but in an alpha-acid dominated combination. Hop extract are about 50% alpha, 30% beta, and 10% hop oil (depending on the cultivar).   "Aroma oil" is also available (2 oz bottles) but this appears to be only the hop oil with the virtually all the active alpha and beta acids removed.   Naturapathic herb outlets have water or alcohol extracts of "hops" in 1 to 4 oz bottles, but these have no accompanying analysis, so the concentration is guestimate.    Raw or pelleted hops (in a dizzying variety of cultivars) are widely available.  Pelleted hops are just cold ground and pressed hop cones.  They could be extracted by boiling or placed in an expresso or french press coffeemaker.  Pelleted hops are about 15% (by weight) active compounds, extraction values are low.  Price is about $5/oz or $20/lb.  Extraction of a pound of 15% product with a yield of 25% would generate 17 g of mixed acids, or about $1/gram.  I suppose a NaOH solution might raise extractions, followed by a vinegar/ascorbic acid neutralization.  This would allow a whole or pellet product to be roughly cost competitive.

The commercial product uses the beta-acid salt.  At the hobbyist level, some cultivars of hops have higher "beta-acid" ratio than others, and some cultivars have a higher total compound.  Modern selections are much higher in total compounds than historic varieties.  Names showing high or relatively high beta level are: Mt Hood, Cascade, Crystal, Liberty.  Names with exceptionally high total oil/acid are: Columbus, Galena, and a number of the new introductions.

The raw extract of hop acids and oils are unmixable in water or immiscable and are unstable. Industrially, a metal salt is added to produce a "soap" product that is dissolvable in solution and is stable on drying over the longterm.   Patents describe the  use of strong Potassium Hydroxide (KOH) or Lye (NaOH) to make the mixture alkaline (ph 9-11) followed by addition of acid (typically sulfuric) to neutralize and spray drying to create a powder.

Other patents (for use of hops  in human foods) describe the addition of ascorbic acid or rosemary extract to provide anti-oxidant donors to protect the hop-oil from denaturing.  Propolyene Glycol is often the base solution for hop oil mixtures. 

Lecithin is mentioned only in passing in the patents.  However, this is used frequently in "Bee" recipes to emulsify fats and oils with sugar solutions.  For a home-brew approach using lecithin as an easily available emulsifying agent to make hop-extract mixable seems a good approach.

It is not clear to me from the patents whether the toxicity of hop oils during in ingestion by bees was addressed. The miticide property may come from both external grooming of the oil/acid/soap compound or ingestion.  It may be a treatment that is more oriented to external spreading than ingestion will be safer.

One inexpensive approach may be to make a water/lectithin/sugar solution and boil pellets or whole cones in the solution and feed the mess of pellets/sugar to the bees in a feeding tray.  I would want to perform the 100 bees in a petri dish toxicity assay on this.

Further information can be found in the patents.
COMPOSITIONS AND METHODS FOR CONTROLLING A HONEY BEE PARASITIC MITE
 Gene Probasco
http://www.google.com/patents?id=NV3OAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false


METHOD FOR PREPARING STABLE HOP POWDER
 Naoto Yamaguchi et al
http://www.google.com/patents?id=o0O_AAAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q&f=false

Process for producing inorganic salts of hop acids
 Kevin K. Madsen et al
http://www.google.com/patents?id=8k-cAAAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q&f=false

Hop beta acid compositions for use in food products
 Dennis L. Seman et al
http://www.google.com/patents?id=GjKVAAAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q&f=false


Solid salts of hop acids
 John P. Maye et al
http://www.google.com/patents?id=PM4bAAAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q&f=false

Feeds containing hop acids and uses thereof as supplements in animal feeds
 Francis L. Rigby et al
 http://www.google.com/patents?id=rkXtAQAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q&f=false
 
 Antimicrobial compositions comprising hop acid alkali salts and uses thereof
 Mitsunori Ono et al
 http://www.google.com/patents?id=VrilAAAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q&f=false
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doggonegardener
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« Reply #1 on: December 07, 2011, 09:41:02 PM »

Hops prices vary greatly with availability.  Last year they were virtually unavailable in any form and the price went through the roof.  However, growing hops is EASY.  We live in Wyoming.  Not a totally suitable climate for the growing of hops.  We currently grow 6 varieties in our garden.  They all grow like weeds.  We grow Cascade, Centennial, Fuggles, Goldings, Sterling and Willamet.  The best producers are Fuggles and Goldings with Centennial and Willamet in close second.  Success for our varieties may have more to do with sun exposure than variety. 

They grow readily and multiply yearly.  Aphids are a problem but easily managed.  I would think if you have a little space in the bee yard and you don't mind experimenting, you might grow some yourself for cost effectiveness.  Just a thought.  Then you have a ready supply of virtually free hops for the next time there's a bad year and shortage leads to hellish prices.

Happy hop growing!   Smiley

Rene
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JWChesnut
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« Reply #2 on: December 07, 2011, 10:06:30 PM »

Definitely, I am scraping the endless variety lists for a rootstock that will accept coastal Calif Fog and have the correct acid balance.  Most online supply say rootstocks begin shipping in February, when I checked in June of this past summer they were sold out.

Since the patent indicates that the beta-acid formulation may not be definitive, just convenient, I am going to try hops from some of the more tolerant high alpha-acid types and look for response and activity. 

A pound of hop cones should supply ingredients for 6-8 hive treatments, grow your own might easily supply a beeyard's need.
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PeeVee
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« Reply #3 on: March 23, 2012, 08:36:41 PM »

I have hops growing wild here - cascade I think. Last year I places a big handful on each of two colonies. Right on the top bars. They dragged the debris down and out. Unfortunately I was unable to do any kind of study to determine Varroa mite kill.

Ordered rhizomes for delivery In april that I plan on planting along the snow fence/ wind barrier along with Trumpet vine.

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-Paul VanSlyke - Cheers from Deposit,NY
Bush_84
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« Reply #4 on: February 05, 2013, 05:49:06 PM »

Hate to gravedig, but have you done any further study on this?  It would be fun to see the possibilities of making your own hopguard. 
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Keeping bees since 2011.

Also please excuse the typos.  My iPad autocorrect can be brutal.
JWChesnut
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Location: Coastal Central California


« Reply #5 on: March 28, 2013, 01:02:43 AM »

I steam extracted hop pellets (packed an expresso machine). Added KOH (potassium hydroxide) and neutralized with muriatic acid.  Added sugar and saturated stiff chipboard (cereal box) strips.   

Bees chewed up the cardboard strips, light mite fall, no real control observed.   I post-treated with Formic, and saw substantial mite drop.

I don't believe the steam extraction yielded sufficient hop-oil.  The "expresso cup" showed a light green oil film and globules, but not substantial volume of oil.  Hop oils can be purchased refined via the interwebs and might be a better starting point.
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PeeVee
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« Reply #6 on: April 11, 2013, 07:41:59 AM »

Just revisited this post.

I have not done further study on the application as I did it. I have thought of going to a small brewery to check on the availability of hops that they would be tossing out. They buy in bulk and if the hops are not used in a timely fashion they go "stale" losing what the brewer needs but might still be useful for my needs.

The hops rhizomes I planted last year didn't grow as rapidly as I had hoped - maybe they will take off this season. 
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-Paul VanSlyke - Cheers from Deposit,NY
Bradeeen
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« Reply #7 on: August 13, 2013, 05:04:02 AM »

Well interesting topic here and good information for others who are interested in it.
I am really impressed by it. Good work keep it up..
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