Guwahati, Aug 29: A research team from the Indian Institute of Technology-Guwahati (IIT-G) has developed an edible coating that it claims to extend the shelf life of fruits and vegetables, and more importantly, reduce wastage of food.
According to the researchers, the coating was tested on vegetables such as potato, tomato, green chili and fruits such as strawberries, Khasi Mandarin (orange), apples, pineapples and Kiwi fruit and was found to keep them fresh for nearly two months.
The research team from the institute was led by Vimal Katiyar from the department of chemical engineering and Centre for Excellence in Sustainable Polymers (CoE-SusPol), IIT-G.
The team also comprised Vaibhav V. Goud, from the department of chemical engineering, IIT-G and CoE-SusPol, along with research scholars, Kona Mondal, Tabli Ghosh, Mandavi Goswami, Shikha Sharma and Sonu Kumar.
The research was carried out with an aim to help farmers keep their produce safe from sprouting and rotting for longer durations and help the country meet the UN Sustainable Development Goal (SDG) targets on reducing food losses in production and supply chains, including post-harvest losses.
The results of the research have been published in the prestigious journals including Royal Society of Chemistry Advances, Food Packaging and Shelf Life, Food Chemistry, IJBM, ACS-JAFC and American Chemical Society’s Food Science and Technology.
“According to the Indian Council of Agricultural Research, between 4.6 and 15.9 percent of fruits and vegetables go waste post-harvest, partly due to poor storage conditions. In fact, post-harvest loss in vegetables such as potato, onion and tomato can be as high as 19 percent, which results in high prices for such highly consumed commodities,” Katiyar said, highlighting the need for such research.
The team used a mix of a micro-algae extract and polysaccharides to produce protective, edible films for coating on vegetables and fruits.
The marine microalgae called Dunaliella tertiolecta is known for its antioxidant properties and has various bioactive compounds such as carotenoids, proteins, and polysaccharides.
It is also used as a source of algal oil, which is used as a non-animal source of omega-3 fatty acid, and is being considered as a source of biofuel. After the oil is extracted, the residue is usually discarded.
The researchers used extracts from this residue in formulating their film, in combination with chitosan, which is a carbohydrate having antimicrobial and antifungal properties and can be made into edible films.
The properties of films with varying algal extract contents were analysed and compared with controls. The fabricated edible films displayed a superior antioxidant activity, total phenolic content, water vapour barrier property, thermal stability, and mechanical strength.
Further, multiple other customised edible coating formulations were developed to enhance the shelf-life of products based on the requirement.
The researchers also tested the bio-safety of these coatings by treating BHK-21 cells with these coating materials.
BHK-21 cells are derived from the kidneys of baby hamsters and are used for studying the toxicity effects of various materials.
“The newly-developed coatings can be mass-produced and are unique. They are very stable to light, heat and temperature up to 40 degrees Celsius, edible and can be safely eaten as part of the product formulation and do not add unfavourable properties to it,” Katiyar said.
“They retain the texture, color, appearance, flavor, nutritional value and microbial safety of the fruit or vegetable that has been coated, thereby enhancing their shelf life to several weeks to months,” he said.
The researchers tested the coatings on a range of vegetables, including potato, tomato, green chilies, besides fruits such as Khasi Mandarin, apples and strawberries (both sliced and whole).
The coatings can also be directly coated on the vegetable, or made into a vegetable storage pouch, and in both cases, the shelf-life of the vegetables can be extended. It is a simple and elegant dip coating technique with no significant cost added to the post-harvest processing.