The pear necessities

The nopal cactus, commonly known as the prickly pear reveals itself as an important source of minerals in the diets of people in Mexico and the rest of Latin America, thanks to analyses with atomic spectroscopy and other techniques. Researchers in Mexico have tested the plant at different stages of its maturation to demonstrate its nutritional profile.

Prickly pear species grow in most environments around the globe and have for many years been investigated as putative health supplements and as a source of nutrition, beyond their native habitats. Previous research has also looked at the effects of a diet containing nopal and found it to have has no effect on blood glucose, total cholesterol or high-density lipoprotein (HDL) cholesterol levels. However, it has been shown in laboratory tests to reduce low-density lipoprotein (LDL) cholesterol but only if eaten raw in relatively large amounts.

Other medicinal effects have also been reported. For instance, there is some evidence from other limited studies that the plant can affect blood glucose levels. There are hopes that should some extract of the plant may provide a novel lead for blood glucose control and potentially in diabetes treatment.

Now, Mario Rodríguez-Garcia of the Centro de Física Aplicada y Tecnología Avanzada, in the Departament of Nanotechnology at the Univeridad nacional Autonoma de Mexico, in Queretaro and colleagues studies samples of fresh nopal pads (Opuntia ficus indica, Redonda variety) , known as cladodes and nopal powder. They carried out various analytical tests at different stages of the plant's development, with nopal powder being produced by dry vacuuming at low temperature (40 Celsius).

The researchers determined levels of the toxic natural product, calcium oxalate, using X-ray diffraction and scanning electron microscopy (SEM) and quantified using atomic absorption spectroscopy. They found that calcium content increases during maturation while phosphorus and oxalate content falls. Soluble fibre levels also decrease from about a quarter to about 15% while insoluble fibre increases from less than a third to just over 40%.

There is a significant body of research into the constituents of Opuntia species, but much of this is at least two decades old. Current studies using modern techniques will help bring the nutritional and constitutional status of the prickly pear up to date.