Pistachio

Pistachio — The pistachio (Pistacia vera L., Anacardiaceae; sometimes placed in Pistaciaceae) is a small tree up to 10 m tall, native to mountainous regions of Iran, Turkmenistan and western Afghanistan. It has deciduous pinnate leaves 10–20 cm long.

The plants are dioecious, with separate male and female trees. The flowers are apetalous and unisexual, and borne in panicles. The fruit is a drupe, containing an elongated seed (a nut in the culinary sense, but not a true botanical nut) with a hard, whitish shell and a striking kernel which has a mauvish skin and light green flesh, with a definitive flavour.

When the fruit ripens, the husk changes from green to an autumnal yellow/red and the shells split partially open (see photo). This is known as dehiscence, and happens with an audible pop.

The kernels are often eaten whole, either fresh or roasted and salted, and are also used in ice cream and confections such as baklava. In July 2003, the Food and Drug Administration (FDA) approved the first qualified health claim specific to nuts lowering the risk of heart disease: “Scientific evidence suggests but does not prove that eating 1.5 ounces (42.5g) per day of most nuts, such as pistachios, as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease”. In research at Pennsylvania State University, pistachios in particular significantly reduced levels of LDL, the ‘bad’ cholesterol, in the blood of volunteers. Pennsylvania State University’s Department of Nutrition and Sciences has also conducted related research on other health benefits of pistachios, including an April 2007 study concluding that pistachios may calm acute stress reaction, and a June 2007 study on the cardiovascular health benefits of eating pistachios.

On the Greek island of Chios, the husk or flesh of the pistachio fruit surrounding the shell is cooked and preserved in syrup, a spoonful of which would traditionally be offered as a sweet delicacy to guests.