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In China, where I live, most pistachio nuts sold on the market have very white shell, and yellowish skin and flesh, like this:

enter image description here

Today I read some articles claiming that these pistachio nuts were so white because they had been bleached using hydrogen peroxide, and good pistachio nuts should have yellowish shell, purplish skin and greenish flesh, like this:

enter image description here

So, my question is: have white pistachios been bleached? What colour do pistachio nuts in your country have?

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Looks like the usual name for the process is bleaching (using hydrogen peroxide). I found some things online searching for that; hopefully someone will be able to provide a full answer. –  Jefromi Jul 23 '12 at 16:11
    
@Jefromi, Thanks for the tip on the name of the process, but I'll keep the "bad for health" part because that is part of the claim. :) –  Betty Jul 23 '12 at 16:31
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@betty we do not tackle nutrition/healthy eating here, mostly because for each question, there are 3 reputable studies claiming one answer, 3 claiming the opposite, and 30 quacks who put up websites with pretty pictures. We allow food safety questions, but we only tell you if a government authority has approved a certain process, not if something is "unhealthy". See the faq for topics we don't allow on the site. –  rumtscho Jul 23 '12 at 16:45
    
Okay, I edited it again to more explicitly ask about food safety, rather than possibly making an implication about health. Hydrogen peroxide is commonly recognized as safe (e.g. by the FDA) when used in certain ways in food preparation, and I want to try to avoid any unfounded health claims. –  Jefromi Jul 23 '12 at 16:45
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Those are definitely bleached. Not only are they impossibly white (whiter than Macadamia nuts!) but there is no colour variation of any kind. Natural foods are never that uniform unless/until they've been processed somehow. –  Aaronut Jul 28 '12 at 12:26
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2 Answers 2

up vote 8 down vote accepted

The natural colors for pistacio meats are green, yellow-green, purple and/or red. Shells are beige. The Kerman variety, which account for 90% of the pistachios grown in California, are yellow-green to deep green. Pistacios from Iran tend to be more in the red-purple spectrum, and are alleged by their partisans to be superior to California pistacios. Personally, I like both the Kerman and the Iranian ones I've been able to sample.

Looking at the picture, I'd say that those nuts were clearly bleached, due to the excessive whiteness of the shells. This seems to be a common practice in China, enough to cause the government to debate a ban on bleaching. Per that article and others, there is no health risk associated with peroxide bleaching, but there is thought to be a significant loss of vitamins due to bleaching.

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Thanks. When you say "meats", do you include the skin (the thin and fragile layer wrapping the flesh)? Because for some pistachios skin and flesh have different colours. –  Betty Jul 27 '12 at 1:58
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I can't tell you for sure if white pistachios are bleached or if they are another type of pistachio.

The pistachios in Belgium are like the one in your second picture, thus a bit of purple skin, with a green outside and light green/yellow on the inside. I'm not sure how to name the colour of the shell. The ingredient list is just pistachio nuts and salt.

The nuts I have now are actually from the brand Trader Joe's (which is American, I think), but the address is from Germany while the package states 'California nuts'. I will put a picture here if I open this package.

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Thanks. Waiting for your picture. :) –  Betty Jul 27 '12 at 1:50
    
The package is done :-( I forgot, sorry. But they really were purple & green. –  Mien Jul 28 '12 at 21:10
    
LOL. It's alright. :) –  Betty Jul 30 '12 at 4:32
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