The polythene ban will come into effective 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 relieve you of a lot of lunch related troubles.
Dr. Sujatha 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 in. Food wrapped in banana leaf is imbued with an appetizing aroma and an earthy, leafy taste that is the signature of the banana leaf. Unfortunately they are rigid around the stem and tend to tear. Besides, not many have a steady supply of banana leaves.
But this new method makes it possible to keep banana leaf wrappers for many weeks, if properly prepared and stored in cold 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. Plus it’s no rocket science and anyone who has a refrigerator to store the product can make these bio wrappers right at home. Dr. Weerasinghe and her team have also developed a method to manufacture plates, cups and other containers using the refused torn leaves and yellow ripened leaves.
Dr. Weerasinghe commenced her research in 2007. The banana tree was her pet crop and her research involved investigating into possible money making methods using any part of the banana tree as raw material. Her research has shown such promise that it had 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 substitute for lunch sheets was rekindled, but waned when the plans for banning polythene was lifted.
She revealed that it proved difficult when introducing the product commercially into 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 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 banana leaf bio wrapper production, the banana leaf is cut into lunch-sheet size squares.” The stem has to be trimmed to reduce the width. The sheets are then washed and the ash-like 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 wind dried for five to six hours on a cloth line.
“If the wrapper can be crumpled without tearing, then it’s the right consistency,” explained Weerasinghe. These bio wrappers can be folded in 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 under a temperature between 1,500 oC to 1,800 oC.” Weerasinghe suggests that it’s best to do a test run first. When it’s the right consistency the leaves take a light green color, emitting a pleasant aroma. According to Weerasinghe plates, cups and other containers can be made using the refuse; torn leaves or the yellow ripened leaves. “You can cut a fresh banana leaf into the shape you need the plate to be; round, square.” These are washed, dipped in boiling water for two to three seconds. She explained that three to four such layers can be pasted together using sago and refused leaves, ripe yellow leaves and stem can be added in the middle layers.
This is then put 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 skillet.” Any blacksmith can make this basic machine that costs somewhere between Rs 1,000 to 1,500. Weerasinghe said that this machine has room for improvement by any interested party. “It can easily be adapted to be electrified.”
She pointed out that it is an industry with high demand. “Raw material is a problem. Only 1,000 banana trees per hectare can be planted if the intension is obtaining 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 conceded that it is impossible for her to visit all those who request for information, but said that her department is more than willing to give out information or necessary training over the phone. Those interested can call Dr. Sujatha Weerasinghe on 0712092001.