Oxalate Lab Report

1.0 Introduction

Oxalates which refer to any salt or ester of oxalic acid are common constituents of plants and are found in the majority of plant families. They occur either as free acids, soluble salts of potassium, sodium and magnesium and the insoluble salt of calcium. The amount of oxalates in plants ranges from a few percent of dry weight to up to 80% of the total weight of plants. (Garcia-Fernandez et al., 2014)

The amount of oxalates in plants ranges from a few percent of dry weight to up to 80% of the total weight of the plant. These compounds are usually accumulated within the vacuoles of plant cells, although crystalline calcium oxalate may form within cell walls of some higher plants. Since plant cells in general have a large vacuolar

Occurring in plants, especially spinach, rhubarb, and certain other vegetables and nuts, and capable of forming an insoluble salt with calcium and interfering with its absorption by the body. (Garcia-Fernandez et al., 2014)

Structure of oxalate ion Structure of calcium oxalate

(Source: Garcia-Fernandez et al., 2014)

1.1 Oxalates in Food

Food Category Example of foods

Fruits Blackberries, blueberries, raspberries, strawberries, currants, kiwifruit, concord grapes, figs, tangerines, rhubarb and plums

Vegetable Spinach, Swiss chard, beets (root part), beet greens (leaf part), collards, okra, parsley, leeks and quinoa are among the most oxalate-dense vegetables. Celery, green beans, rutabagas, and summer squash would be considered moderately dense in oxalates.

Nuts and seeds almonds, cashews, and peanuts

Legumes soybeans, tofu and other soy products

Grains Wheat bran, wheat germ, quinoa

Others Cocoa, chocolate, and black tea

(Source: DeBruyne et al., 2011; Attalla et al., 2014)

2.0 Synthesis in

In plants, crystals of calcium oxalates can be formed in various types and sizes which are mainly classified based on their morphology into five categories. These categories are, crystal sand, raphide, druse, styloid, and prismatic (Faheed et al., 2013). The deposition of calcium oxalate in plants is common where more than 215 plant families accumulate crystals within their tissues (Nakata, 2003). The formation of these crystals is specific where they have a defined shape and specific site. It usually takes place inside the vacuole of specialized cells called crystal idioblasts. The specialized cell has enlarged nucleus, specialized plastids, increased endoplasmic reticulum, elevated levels of rRNA, and unique vacuolar components. The abundant Golgi complexes in these idioblasts have also been found to be involved in transporting a calcium binding crystal idioblast specific protein, a matrix protein, to the vacuole (Faheed et al.,