Going bananas

Banana leaf bio wrappers best substitute for polythene lunch sheets

File photo

The polythene ban will come into effect from September 1. While little can be done about the woes of polythene manufacturers and recyclers, a new banana leaf bio wrapper, introduced by Senior Lecturer of Weligaththa Rural Technical Institute, Hambantota, Dr. Sujatha Weerasinghe, may just save you a lot of lunch related trouble.

Weerasinghe spoke to The Nation on how to use banana leaves as a potential substitute for lunch sheets. Banana leaves have been used by Sri Lankans for many years to wrap food. Food wrapped in banana leaf is infused with an appetizing aroma and an earthy, leafy taste that is the signature of the banana leaf. Unfortunately, the raw banana leaf is rigid around the stem and tends to tear. Besides, not many have a steady supply of banana leaves.

But this new method extends the shelf life of banana leaf wrappers by many weeks if properly prepared and stored at low temperature. The treated leaves are flexible and do not tear. But, perhaps the greatest advantage is that these bio wrappers are not treated with any preservative or chemical. Besides, it's not rocket science and anyone with a refrigerator to store the product can make these bio wrappers right at home. Weerasinghe and her team have also developed a method to manufacture plates, cups and other containers using the refuse torn leaves and ripe yellow leaves.

Dr. Sujatha Weerasinghe

Weerasinghe commenced her research in 2007. The banana plant was her pet crop and her research involved investigating possible money-making ventures, using any part of the banana plant as raw material. Her research has shown such promise that it has inspired Indian researchers to adopt the technique, the success stories of which were subsequently reported in The Hindu.

During repeated proposals to ban polythene, Weerasinghe's interest in devising a way to use banana leaves as a substitute for lunch sheets was rekindled but waned as plans for banning polythene were abandoned.

She admitted that it proved difficult to introduce the product commercially, into the market. The underside of the banana leaf contains an ash-like substance. Moreover, the banana leaf tends to tear and the product had to be small enough for commercial marketing and storage purposes. “Therefore the process required quality addition. The technology for home-based production of bio wrappers is different from that of the industrial production method.”

Weerasinghe explained that the process of home-based bio wrapper manufacture involves treating the leaves with hot water. “In the home-based bio wrapper production, the banana leaf is cut into lunch-sheet size squares.” The stem has to be trimmed to reduce width. The sheets are then washed and the ashy substance on the underside of the leaf is wiped off using a wet cloth or sponge. These are then dipped for two seconds in boiling water and sun-dried for approximately two and half hours or air-dried for five to six hours on a line.

“If the wrapper can be crumpled without tearing, then it’s the right texture,” explained Weerasinghe. These bio wrappers can be folded into four. Up to five wrappers can be wrapped together in oil paper and refrigerated. They have to be refrigerated at all times and can be kept up to three months.

In commercial production, the sheets do not require prewashing or removal of ash. “Depending on the oven, the leaves can be baked at a temperature between 1,500 0C to 1,800 0C.” Weerasinghe suggested a test run first. When it’s the right texture, leaves turn light green, releasing a pleasant aroma. Plates, cups and other containers can be made using refuse - torn leaves or ripe yellow leaves. “You can cut a fresh banana leaf into the shape you need the plate to be - round, square.” These are washed and dipped in boiling water for two to three seconds. She explained that three to four such layers can be pasted together using sago and refuse leaves, ripe yellow leaves and stems can be added to the middle layers.

This is then placed between two model plates and pressed using a machine. The press with the plate is then boiled for seven minutes. “You can remove the finished plate as if you are removing a hopper from a pan.” Any blacksmith can make this press, a basic machine, at a cost of Rs 1,000 to 1,500. Weerasinghe said that the machine has room for improvement. “It can easily be adapted to run on electricity.” She pointed out that it is an industry with high demand. “Raw material is a problem. Only 1,000 banana plants per hectare can be planted if the intention is to obtain fruits. But if you’re planting just to harvest the leaves you can move it up to 6,000 plants a hectare,” explained Weerasinghe. Of course, the lone banana bunch at the end of the harvest is an added advantage.

Weerasinghe admitted that it is impossible for her to visit all those who request information, but said that her department is more than willing to offer information or necessary training over the phone. Those interested can call Dr. Sujatha Weerasinghe on 0712092001.

The article was originally published in The Nation