What Is Gum?

My son loves candy. This really isn’t a surprise – we all do.  After all, the brain accounts for nearly 20% of our resting metabolic rate, and sugar is pretty much raw calories.  Not that he cares about any of that, mind. He just enjoys it because it’s sweet and tastes good.

He’s not so sure about gum, though. Mostly, I think, because you can’t actually eat it.  I think that’s what led him to ask, when he was given a whole pack of chewing gum, “dad, what’s gum?”

Uhm… rubber?  Or maybe it’s tree sap?  I remember something about something called “chicle” as well, I think. But to tell the truth, I’ve got no idea.

What is gum?

According to Wrigley, chewing gum is made of “gum base” – a statement that, although accurate, is not terribly informative.  Fortunately, the International Chewing Gum Association (ICGA) provides additional information:

1. What is gum base?

Gum base is what gives chewing gum its “chew.” It is made of a combination of food-grade polymers, waxes and softeners that give gum the texture desired by consumers and enable it to effectively deliver sweetness, flavor and various other benefits, including dental benefits.

2. What are polymers?

A polymer is a string of molecules (monomers) that usually contain carbon and hydrogen. Polymers are found naturally in the human body, animals, plants, and minerals. For example, DNA is a polymer, as are the proteins and starches in the foods we eat. 

Man-made polymers can be identical in structure to those found in the natural environment, but in many cases, these polymers provide guaranteed consistency, quality and purity that are not always found in some natural materials. This quality is particularly important for food-grade polymers used as ingredients.

3. What are food-grade polymers?

Food-grade polymers have been rigorously tested and have been determined to be safe for use in food. In chewing gum, polymers are what provide gum with its basic elastic properties. All polymers used in gum are food-grade and are legally permitted for use by international/national regulatory agencies, including those in the U.S., Europe, and Asia.

The most common food-grade polymer is Polyvinyl Acetate (PVAC Food Grade), a clear, solid resin that is also used in cosmetics and as a hair fixer.  It is water insoluable, but dissolves in acetone.

I suppose I could join the ranks of the tinfoil-hat-wearing alarmists who make a virtue of ignorance by proclaiming that you should only eat things you can pronounce, but I won’t. I will observe that, yes, polyvinyl acetates are also found in some glues and are used in bookbinding. But there’s a key phrase here:  “food safe”.  Food-grade PVAC meets FDA reequirements and is safe for human consumption. I don’t eat it, but that’s just because I don’t like gum.

Was gum always polymers?

It wasn’t always PVAC, anyway. Wrigley’s gives an overview of the history of gum (not surprisingly, given their professional interest…), pointing out that a number of cultures chewed tree resins to freshen their breath and help combat thirst. Modern gum starts with chicle.

Chicle is the juice of the Manilkara zapota, a tropical to subtropical evergreen in the Americas.  The juice is harvested and boiled to remove the excess water, forming a rubbery mass.

And the fact that it becomes a rubbery mass makes sense.  After all, chicle is a food-grade polymer – a polyterpene hydrocarbon nearly identical to rubber.

Can you eat it?

Not really, no.  It won’t stay in your gut for years -urban legends notwithstanding – but the human digestive tract can’t digest gum (whether made of polymers created in a tree or in a vat). It takes about a week to pass through you, and leaves the body in the usual manners along with all of the other indigestible things you consume.


How Do You Make Chocolate?

Valentines Day is coming up, and my son’s preschool is – like most preschools and elementary schools – going to have a party. My wife is making homemade candy for his class, and he (and three of his friends, and the mother and grandmother of those friends) helped. I missed out on the candy making, though, because I was at home getting our laundry caught up.

When we first told him about the project, he was excited. Because, you know, candy. The very first question he asked was “How do you make chocolate?”

“Well,” I explained, “you melt the chocolate in a double boiler and…”

“No, no. How do you make chocolate?”

Beans, I guess? I think I know that chocolate comes from something called a carob bean, but I’m not even certain about that. I know it’s some sort of bean, though, partly from watching an episode of Good Eats on the subject. So, let’s see if we can’t get an answer!

Where Does Chocolate Come From?
chocolate tree

This is a cocoa tree, also known as a cacao tree. Formally, it’s Theobroma cacao, part of the Malvaceae family (the “mallows”, which also include okra and cotton), which is part of the Malvales order, which is part of the Plantae kingdom. No surprise there, really. Kew Gardens says that

The scientific name Theobroma cacao was given to the species by the Swedish botanist Carl Linnaeus in 1753, when he published it in his famous book Species Plantarum. Theobroma means ‘food of the gods’ in Latin, and cacao is derived from the Nahuatl (Aztec language) word xocolatl, from xococ (bitter) and atl (water).

They go on to note that cocoa trees are native to Mexico, Central America, and northern South America, and have been introduced to a number of African and Asian countries. It’s an evergreen with small yellowish-white to pale pink flowers, and generally grows along river banks in the shade of larger trees in a rain forest. When pollinated, the flowers develop into reddish-brown berries.

cacao berry

How Is Chocolate Made?

It turns out that pretty much every chocolate company on the internet has a “how is chocolate made” page. This information is a synthesis of several of them, but all of them agree on the basics. First, the berries (also known as “pods” are harvested. This is something that can generally be done twice a year. The pods are cut open, and the seeds and the white pith (called baba inside are removed.

cocoa pod

The seeds (which are what we generally think of as the “cocoa bean”) are cleaned, but the white pulp is left in place to help develop flavor. They are then fermented, either by being piled in a heap or stored in boxes. Either way, they are left to ferment for between two and nine days. Once fermented they are dried (requiring one to two weeks), graded, and packed for shipment. The processor cleans the beans (again), then roasts and shells the beans to remove the “nibs” – the meat of the bean. These nibs are finely ground into “cocoa mass” (aka “cocoa liquor), a fine powder. At this point, there are two things you can do:

1. Press the cocoa liquor. This creates cocoa powder, and cocoa butter.
2. Make chocolate.

To make dark chocolate, you combining the cocoa mass (or the appropriate volumes of cocoa powder and cocoa butter) with more cocoa butter and sweetner (usually sugar). Milk powder is added to the mix to make – wait for it – milk chocolate. Either way, the mix goes through a process of “conching”, which is when you heat and mix and heat and mix the mixture until the chocolate takes on the desired texture and flavor. Why’s it called “conching”? Because you use a machine called a “conche” to do it.


Finally, the chocolate is poured into appropriate moulds and tempred – that is, brought to a specific temperature to help it solidify evenly.
What’s White Chocolate?

Related to chocolate is white chocolate. This is made by mixing cocoa butter with milk and sugar and other flavoring ingredients as desired. The FDA specifies that it must

contain “not less than 20 percent by weight of cacao fat as calculated by subtracting from the weight of the total fat the weight of the milkfat, dividing the result by the weight of the finished white chocolate, and multiplying the quotient by 100. The finished white chocolate contains not less than 3.5 percent by weight of milkfat and not less than 14 percent by weight of total milk solids, calculated by using only those dairy ingredients specified in paragraph (b)(2) of this section, and not more than 55 percent by weight nutritive carbohydrate sweetener.

There is apparently some controversy about whether or not white chocolate is actually chocolate, since it contains no chocolate liquor – just a byproduct of processing chocolate liquor. The FDA sometimes gets roped into this, since it regulates food in the United States, but they don’t take a stand other than to place it as a category of Cacao Products. For my part, I don’t really care. Chocolate or not, I’ll eat it.

So, What Was That Carob Thing?

Now, remember how I thought chocolate came from something called a carob bean? Well, this is a carob tree (aka locust bean and St. John’s bread).

carob tree

Formally, it’s Ceratonia siliqua, part of the Fabaceae family, which is part of the Fabales order, which is part of the Plantae kingdom. Which is a fancy way of saying that you have to go back a ways on the phylogenetic tree to find a common ancestor between cocoa and carob. It is native to the eastern Mediterranean, Arabian peninsula, and north Africa. And it grows pods too.

carob pod

These pods (not the seeds!) can be processed into a brown powder that can be used as a chocolate substitute. How well it substitues is really a matter of taste – I ate it as a child and found it acceptable in candy bar format, although it was a bit gritty.