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Old September 15, 2017   #1
bower
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Default rainbow of colors in garlic wrappers

This year I harvested and cleaned and trimmed a fair bit of garlic at the farm as well as my own, so my thoughts are always turning to being a good hand for garlic in the field - recognizing if anything is wrong with a bulb so you don't end up spreading a bad thing to the good garlic.

Anyway I noticed this year that a lot of the Spanish Roja we pulled at the farm had many colors in the outer wrappers when pulled, as I've always seen before with the New York White (strangely named I thought because it is so colorful - at least, when freshly from the ground). Some of the SR that I trimmed a few weeks later - in a very humid shed - were also still showing a full rainbow of colors from yellow-green-blue-purple-to reddish.

I also had a bulb at home that I had partly stripped all the outer wrappers, due to wireworm damage, and the clove wrapper turned bright yellow as it cured. Shockingly yellow.

All of this left me wondering what are the colors telling me, that I might need to know.
As google is my friend, I did some digging and found out about these colors of garlic, which they come by naturally - pyrrhole pigments involving sulfur and amino acids.
So I thought I would start this thread to share our observations about colors in garlic - both natural and enemy colors - and what they tell us about its condition or about the environment.

I regret I wasn't taking pix while I cleaned the garlic at the farm, but here are a few colors from my New York White last year...
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File Type: jpg 2016-NYW-colors.JPG (165.6 KB, 83 views)
File Type: jpg colors-NYW-wrapper.JPG (203.7 KB, 82 views)
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Old September 15, 2017   #2
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Here is what I learned from the garlic wiki:

"Abundant sulfur compounds in garlic are also responsible for turning garlic green or blue during pickling and cooking. Under these conditions (i.e. acidity, heat) the sulfur-containing compound alliinase react with common amino acids to make pyrroles, clusters of carbon-nitrogen rings.[74][75] These rings can be linked together into polypyrrole molecules. Ring structures absorb particular wavelengths of light and thus appear colored. The two-pyrrole molecule looks red, the three-pyrrole molecule looks blue and the four-pyrrole molecule looks green (like chlorophyll, a tetrapyrrole). Like chlorophyll, the pyrrole pigments are safe to eat.[76]"
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Old September 15, 2017   #3
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A scientific paper experimenting with garlic pigments, to be found here:

http://onlinelibrary.wiley.com/doi/1...8.00986.x/full
From the abstract:
"The color-forming ability of amino acids with thiosulfinate in crushed garlic was investigated. We developed reaction systems for generating pure blue pigments using extracted thiosulfinate from crushed garlic and onion and all 22 amino acids. Each amino acid was reacted with thiosulfinate solution and was then incubated at 60 °C for 3 h to generate pigments."
"..Our findings indicated that green discoloration is created by the combination of yellow and blue pigments. Eight naturally occurring blue pigments were separated from discolored garlic extracts.."

Here is the table of colors produced by these experiments, which you can read in full at the link above, and the corresponding amino acids... amazing!!!
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File Type: png garlic-rainbow-aminotable.png (30.7 KB, 82 views)
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Old September 15, 2017   #4
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Several of the yellow pigments involved in garlic greening were identified by others:
http://www.sciencedirect.com/science...08814609004427
and these also were produced by the interaction of sulfur compounds with amino acids.

But while dampness, acidity, maybe the presence of some free aminos in the environment will explain the outer rainbow, I don't have a full explanation of my yellow clove wrapper.
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File Type: jpg garlic-yc-red-inside.JPG (180.5 KB, 79 views)
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Old September 15, 2017   #5
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It is interesting that the clove wrapper is only yellow on the part that was exposed by stripping the outer wrappers before it had cured. I am hazarding a guess that exposure to air may have changed the color reaction which is going on as the clove wrappers are curing.
I also noticed that other cloves with wireworm damage showed a yellowing of the wrapper around their nasty bites.
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Old September 15, 2017   #6
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I bet it is hotter than hell.
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Old September 15, 2017   #7
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I would like to know more about the difference between clove wrappers and the outer wrappers. You may have noticed that each time you strip off a wrapper, you can see lovely colors, however they fade as the garlic cures, until only the clove wrapper really retains a lot of color. And these wrappers - on hardnecks - are not at all like the papery outer wrappers. They are really quite hard, glossy and a bit brittle. Since the color is permanent I'm guessing there are amino acids involved in that clove cover structure - and the specific amino acid composition is typical of a variety, which gives them a distinctive clove color.
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Old September 16, 2017   #8
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The yellow happens when the outer wrappers split early in the bulb development if you harvest a bulb early and peel of the outer wrappers the cloves are white but will turn yellow.
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Old September 16, 2017   #9
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Quote:
Originally Posted by Worth1 View Post
I bet it is hotter than hell.
Worth
Reckon that's a sulfur yellow, eh?

Indeed there's plenty of sulfur in the environment here. I like my garlic hot!!
I had a couple of others that turned yellow, exactly as Henry said, on the parts exposed when the wrappers were peeled back, but they weren't as yellow as this one in the picture. The natural clove color as shown on the inside wrappers of the same clove, is also really dark, kind of purplish red.
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Old September 16, 2017   #10
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I thought it was very cool, when I grew out my Porcelain bulbils the rounds turned out to have several different colors. Music had mostly white with faint purple stripes and then a few dark purple ones. This past lot of the Argentina had mostly white dominant too but there are more of the purple and a nearly equal number with nut brown wrappers.
I think I'm going to plant these by color and see if the wrapper color continues in the next generation.
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Old September 20, 2017   #11
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Interesting information about the bulb wrapper color. I had quite many bulb this year with blue color on the outer wrappers and was first worried that it is some kind of disease. The blue was only on the wrapper layer, which was in contact with the soil and the other wrappers had the normal white and purple coloring.
I was wondering, if the blue color was caused by the granular lime or fertilizer, which was still partially undissolved in the soil when I pulled my garlic. Some of the granules had been touching the bulbs. Last fall I did not do really good work mixing the lime and fertilizer to the soil prior planting. I just spread it on the surface and mixed with a rake. Some of the granules fell in the planting holes, when I planted the cloves.

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Old September 20, 2017   #12
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Yes, I thought about the fertilizer too. Amino acids would also be present in natural ferts, I think. The outer wrappers might be in contact with amino acids that way... Interesting that the experimental conditions were heat, moisture and acidity - which N ferts could cause as well. But this is surprising to me in regards the blue colors, because in dyes made from other natural material, blue color is the most difficult to get and requires really alkaline conditions in all cases I know of (including indigo, dye mushrooms etc.).

Sulfur dyes though were one of the great successes of chemical industry. They are quite light fast and wash fast, easily made from chemicals and iirc this is why they took the place of natural dyes as much cheaper.

I know onion skins are commonly used for natural dye, and produce brown or black colors. But I never heard of anyone using garlic juice to dye cloth blue or purple. I guess in former days, no one had access to anything like pure amino acids. Very tempted to do a few experiments.
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