Rock in Food

You probably ate a bunch of rock yesterday! And will today!

Foods contain many naturally-occurring minerals such as calcium, iron, magnesium, zinc, copper and salt that are essential to our health. Plants absorb minerals from soil (which is eroded rock) and water absorbs minerals as it interacts with rock underground. We get minerals by eating plants and drinking water that contain them. We also get them by eating animals that, like us, get minerals from eating and drinking.

Many foods also have minerals added to them, usually in the form of powdered rock provided by mining, as ingredients that serve specific purposes or for their health benefits.

Gypsum (aka calcium sulphate) is used as an ingredient in many foods. For example, it is used in bread as a pH control agent, processing aid, stabilizer, thickening agent and to make bread less sticky in manufacturing.

It is also often added for health reasons to flour that is low in calcium (calcium makes our bones and teeth strong). Gypsum is about 23-29% calcium. Gypsum is also used to make calcium supplements.

Gypsum has been used by brewers for centuries. It fixes mineral deficiencies in water and makes it harder. This eliminates variations in water sources and lets brewers produce a consistent product. It also establishes proper pH of the mash (the grains and water) and the wort (liquid extracted from the mashing process) and provides sufficient calcium ions essential for enzyme function, kettle protein coagulation and yeast metabolism.

Ground gypsum is used as a coagulant/thickener in most tofu to give it its texture and firmness. Gypsum is the traditional Chinese ingredient used in tofu because it is an excellent coagulant and it does not mask the taste of the soybeans.

Gypsum is approved by regulators around the world for use as a food additive. It is used in many other foods including baked goods, frosting, candies, ice cream and other frozen dairy products, puddings, gelatins and pasta.

Gypsum also controls the tartness and clarity of wine, and is as an ingredient in canned vegetables, processed fruit, cereal, condiments and a number of cheeses.

Nova Scotia has traditionally been one of the world’s biggest producers of gypsum, supplying many plaster, and later wallboard, factories on the US east coast. Today, the walls of most Nova Scotian homes contain gypsum quarried in the province. An average home contains about seven tons of gypsum in its wallboard. Gypsum is 21% water at the molecular level so it slows the spread of fire and saves lives.

Nova Scotia’s huge gypsum deposits started forming 327-342 million years ago when global sea levels rose and fell many times. This repeatedly flooded Nova Scotia with what we call the Windsor Sea. Nova Scotia was near the equator at that time so the sea also evaporated repeatedly in the tropical sun.

This process gave us huge gypsum deposits because gypsum forms when water high in calcium and sulfate evaporates, leaving the calcium and sulfate behind as sediment. The sediment builds up and is eventually turned into gypsum rock by heat and pressure.

The lake below is a reclaimed area at the Milford gypsum quarry in East Hants.