Homestead mailing list

[Gene GeRue <genegerue AT ruralize.com>]

On Mar 17, 2007, at 9:11 PM, Marie McHarry wrote:

> Solanine, the alkaloid in potatoes, is poisonous, but you would have
> to eat several pounds of potatoes to be affected.

Thanks for reminding me of that word. I looked it up. The following  
is enlightening, sobering, and instructional. We are well advised to  
grow our homestead potatoes in a manner certain to keep solanine  
levels low, either by hilling or by heavy mulch. And note the higher  
solanine level if late-blight occurs.


Solanine
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Solanine
Identifiers
CAS number      [20562-02-1]
PubChem         30185
MeSH    Solanine
Properties
Molecular formula       C45H73NO15
Molar mass      868.059
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Solanine is a glycoalkaloid poison found in species of the nightshade  
family. It can occur naturally in any part of the plant, including  
the leaves, fruit, and tubers. It is very toxic even in small  
quantities. Solanine has both fungicidal and pesticidal properties,  
and it is one of the plant's natural defenses.
Contents
[hide]

    * 1 Solanine poisoning
          o 1.1 Symptoms
          o 1.2 Correlation with birth defects
    * 2 Solanine in potatoes
          o 2.1 Avoidance
    * 3 Other uses of solanine
    * 4 References
    * 5 External links

[edit] Solanine poisoning

[edit] Symptoms

Solanine poisoning is primarily displayed by gastrointestinal and  
neurological disorders. Symptoms include nausea, diarrhea, vomiting,  
stomach cramps, burning of the throat, heart arrhythmia, headache and  
dizziness. Hallucinations, loss of sensation, and paralysis, fever,  
jaundice, dilated pupils and hypothermia have been reported in more  
severe cases.

In large quantities, solanine poisoning can cause death. One study  
suggests that doses of 2 to 5 mg per kilogram of body weight can  
cause toxic symptoms, and doses of 3 to 6 mg per kilogram of body  
weight can be fatal.

Symptoms usually occur 8 to 12 hours after ingestion, but may occur  
as rapidly as 30 minutes after eating high-solanine foods.

[edit] Correlation with birth defects

Some studies show a correlation between the consumption of potatoes  
suffering from late-blight (which increases solanine and other  
glycoalkaloid levels) and the incidence of congenital spina bifida in  
humans. However other studies have shown no correlation between  
potato consumption and the incidence of birth defects. [1]

[edit] Solanine in potatoes

Solanine occurs naturally in all nightshades, including tomatoes,  
capsicum, tobacco and eggplant, as well as plants from other species.  
However the most ingested solanine is from the consumption of potatoes.

Potatoes naturally produce solanine and chaconine, a related  
glycoalkaloid, as a defense mechanism against insects, disease, and  
predators. Potato leaves and stems are naturally high in glycoalkaloids.

When potato tubers are exposed to light, they turn green and increase  
glycoalkaloid production. This is a natural defense to help prevent  
the uncovered tuber from being eaten. The green colour is from  
chlorophyll, and is itself harmless. However, it is an indication  
that increased level of solanine and chaconine may be present.

Some diseases, such as potato blight, can dramatically increase the  
levels of glycoalkaloids present in potatoes. This is believed to be  
a natural reaction of the plant in response to disease and damage.

Commercial varieties of potatoes are screened for solanine levels,  
and most have a solanine content of less than 0.2mg/g. However  
potatoes that have been exposed to light and started to green can  
show concentrations of 1mg/g or more. In these situations a single  
unpeeled potato can result in a dangerous dose.

[edit] Avoidance

Solanine and chaconine are present in potato shoots. In potato tubers  
30–80% of the solanine develops in and under the skin and thus may be  
removed by peeling and removing the eyes. This is advisable if the  
tubers show green, but is not a guarantee of safety. Potatoes that  
show green under the skin should never be eaten. Potato greening  
strongly suggests solanine build-up although each process can occur  
without the other. A bitter taste in a potato may be a more reliable  
indicator of toxicity.

Deep-frying potatoes at 170° C (306° F) will effectively lower  
glycoalkaloid levels, but microwaving is only somewhat effective and  
boiling is not.

http://en.wikipedia.org/wiki/Solanine