Sound Bites: Swetha Sivakumar on chewing gum

Humans have been chewing on gums, resins and nuts for thousands of years. The Arabs preferred gum arabic, Indians loved betel nut, Greeks used mastic gum, Europeans had spruce gum. These substances helped them stay alert, pass the time or stave off hunger.

But none of them had the kind of elasticity that came from chicle, the latex from the sapodilla tree. The Mayans were the first to boil chicle down to a hardened gum. The Aztecs followed. But they frowned upon the habit of chewing – for them it was linked to amoral women and effeminate men.

But by World War II, the ration kits of American soldiers were always stocked with gum as a small indulgence in tough times. It became associated with American patriotism and bravery. Sports players, often idolised, are depicted chewing gum during long stretches of the game, to prevent their mouth getting dry.

Chewing gum is still considered disrespectful in some situations, like in places of worship or at an interview. In Singapore, chewing gum has been banned since 1992, simply because it costs a lot of money to clean up the chewed bits of gum that get stuck on streets and at park benches. Power washing typically dislodges the gum, but too much pressure risks damage to the concrete underneath.

So, what makes this chewing gum so sticky? Regular chewing gum consists of 70% water-soluble ingredients like sweeteners and stabilisers, and 30% of an indigestible water-insoluble “gum base”. This is made from different proportions of resin, elastomers and softeners depending on the desired texture of the end product.

Chicle, the natural gum base, is made up of roughly 60% resin, 15% rubber, water and small amounts of micronutrients. But now, almost all every major manufacturer uses a synthetic gum base. The reason for this is simple – there just isn’t enough chicle for the world to chew on. A sapodilla tree, once tapped fully, needs a healing period of 4 to 5 years before it can be tapped again. Latex, the tree sap, is produced as a defence mechanism for the plant to prevent attacks from bacteria, fungi and insects. It is estimated that about 5% of the trees are unable to survive post tapping.

Even as early as the 1930s, global demand was so high that it threatened to wipe out the sapodilla tree in 40 years. So, now the world mostly chews synthetic gum bases made from ingredients like styrene-butadiene, polyvinyl acetate and partially hydrogenated gum. You won’t find them on the ingredient label. They all come under the category of “gum base.”

Sugar-free gums, flavoured with xylitol and other sugar alcohols are all the rage now. Demand is rising at a healthy 7% annually, mostly from consumers trying to limit their sugar intake and prevent tooth decay.

Another exciting innovation in the gum space is called microencapsulation. You know how you get bored of chewing the gum once all the flavours and sweeteners get dissolved? In this technology, the flavours are released in stages of 15-45 seconds after you first bite down on the gum. One way to achieve that is by using both oil-soluble and water-soluble flavours to portion out the release. Additionally, flavours are locked in shells surrounded by hydrophobic proteins that only release after prolonged chewing. Finally, the tensile strength needed to break the shells is set at different levels for different flavours which again spaces out their release.

We have come a long way from the chicle sap collected by the Mayans, but the science seems on par for a small, wrapped product commanding a global market of $ 32 billion.