Cucumber Peels for Ecofriendly Food Packaging

Are you throwing away the cucumber peels after preparing your salad? You may soon have them back in your kitchen as the eco-friendly packaging material for food items.

IIT Kharagpur researchers have developed cellulose nanocrystals from cucumber peels with high cellulose content, compared to other peel wastes, which can be used to create food packaging materials.

While single-use plastic is consciously being avoided by consumers, they still remain largely in circulation as food packaging items. Natural biopolymers are unable to make way in this industry as they lack strength, elongation, barrier property, optical property, and in some cases even biological safety. The cellulose nanomaterial developed by researchers, Prof. Jayeeta Mitra and N. Sai Prasanna at IIT Kharagpur’s Dept. of Agricultural and Food Engineering from raw cucumber waste, has addressed this challenge.

What are cellulose nanocrystals?

Food packaging materials require nano-filler reinforced bio-composites which can be derived from the cellulose widely available from the outer skin of fruits and vegetables. These cellulose fibres can be used to produce cellulose nanocrystals (CNCs), bio-based nanomaterials with defined nano-scale structural dimensions. They are produced through controlled acid hydrolysis which removes amorphous regions, and produces more crystalline regions.

The product from raw to final form: Top – Cucumber Peels, Bottom Left – Raw Fibre, Right – Dried cellulose nanocrystals

Cucumber-based CNCs Developed by IIT Kharagpur Researchers

In India, cucumber finds wide use in salads, pickles, cooked vegetables or consumed raw and also in the beverage industry leading to a large volume of peel biowaste which is rich in cellulose content.

“Cucumbers generate about 12% residual wastes obtained after processing either the peels or whole slices as waste. We have used the celluloses, hemicellulose, pectin extracted from this processed material for deriving new bio-materials which are useful as nano-fillers in bio-composites,” said Dr.  Jayeeta Mitra, Assistant Professor at the Dept. of Agricultural and Food Engineering.

Talking about the findings, she further added, “Our study shows that cellulose nanocrystals derived from cucumber peels possess modifiable properties due to the presence of abundant hydroxyl groups, which resulted in better biodegradability and biocompatibility. These nanocellulose materials emerged as strong, renewable and economic material of the near future, due to unique properties like a high surface area to volume ratio, light in weight, and excellent mechanical properties. Thereby, such nanocrystals, when reinforced as nano-fillers in bio-composites films, can produce effective food packaging materials with low oxygen permeabilities.”

Schematic sketch on cellulose nanocrystals through acid hydrolysis

The present study revealed that cucumber peels possessed greater cellulose content (18.22%) than other peel waste. It also provided better insights into their crystalline, thermal and colloidal properties of cucumber cellulose.

Research scholar N. Sai Prasanna said, “The crystallinity percentage as high as 74.1 % along with thermal stability of more than 200 °C negative zeta potential values (< -30 mV), and acid hydrolysis yield of 65.55%, make the material a strong nano-filler reinforcement as bio-nano composite. This offers the much needed mechanical, barrier, optical, rheological properties, nontoxicity, etc. required for food packaging materials which has the strong market potential to replace plastic.”

Market Potential – Application of CNCs and Environmental Sustainability

This non-toxic, biodegradable and biocompatible product has no adverse effects on health and the environment hence could have a huge market potential by rendering management of organic waste with high cellulose content profitable.

“Apart from the food packaging and beverage industries the researchers are optimistic about its scope in various fields like thermo-reversible and tenable hydrogels making, paper making, coating additives, food packaging materials, bio-composites, optically transparent films, as stabilizers in oil-water emulsion. Also, CNCs find good potential applications in biopharmaceutical applications such as drug delivery and fabricating temporary implants like sutures, stents etc.,” added Sai Prasanna.

The researchers further made a note for packaging industry players in our country for substantial investments to improve packaging material properties for better sustainability, disposal and decomposition issues. All these demands for biodegradable packaging will propel the nanocellulose market in the coming timeframe contributing towards a sustainable and plastic-free world, opined Prof. Mitra.

“The incremental usage of petroleum-based plastics in food packaging, spanning a few decades, has raised many challenges as these plastics are the indomitable sources of environmental pollution since nearly 60% of it is converted to landfill, and rest is recycled only once. More research and product development focused on various biopolymers from either macromolecules or from the microbial polymers would be able to make the sector acceptable to packing material producers with wider awareness, alternative products at economic prices,” she remarked.

Cite this paper: Prasanna, N. S., & Mitra, J. (2020). Isolation and characterization of cellulose nanocrystals from Cucumis sativus peels. Carbohydrate Polymers247, 116706. https://doi.org/10.1016/j.carbpol.2020.116706

Contacts:

For Research:

Dr. Jayeeta Mitra, Assistant Professor  

Agricultural & Food Engineering Department

Email: jayeeta.mitra@agfe.iitkgp.ac.in

For Media:

Shreyoshi Ghosh, EO (M&C)

Office of Director, IIT Kharagpur

E: shreyoshi@adm.iitkgp.ac.in

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About Dept. of Agricultural and Food Engineering

IIT Kharagpur has the sole distinction of having a department in the area of Agricultural & Food Engineering, which comprises six disciplines such as Farm Machinery and Power, Land and Water Resources Engineering, Agricultural Biotechnology, Food Process Engineering, Agricultural Systems Management and Aquacultural Engineering, respectively. The major domain of research and development includes Precision agriculture, biofuel and bioenergy, modern food processing, plasticulture and micro-irrigation, Climate Change, hydrological modeling, groundwater management, water management, agricultural biotechnology, pollution abatement, extrusion technology, intelligent and high-pressure packaging, soil mapping and image analysis for plant phenotyping. Sponsored research projects and development activities deal with Integrated Rainwater Management, Soil Tillage, Utilisation of Fly ash, Ergonomic Database for Agricultural Equipment, Integrating Remote Sensing Data with Distributed Hydrological Models, Model Pilot Plant and koji room facilities for the production of industrial enzymes etc. More info . . .

Way to Zero Waste

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While passing through the newly developed, urban elite settlements, the dumpsites waiting treatment are becoming increasingly common. Municipal Solid Waste (MSW) in India continues to remain a neglected area with inefficient source segregation. Further, the moisture content in waste adds to India’s challenge in solid organic waste management because of our food habits and socio-cultural habits. This is leading to environmental hazards of pollution of air and nearby water bodies, surface and subsurface soil. Added to this, decomposing organic waste generates methane which is the single largest contributor to global greenhouse gas emissions. With the Prime Minister’s Swachh Bharat Abhiyan set for a new lease of life, a crucial avenue which is now being explored is efficient urban waste management.

A team of researchers led by Prof. Brajesh Kumar Dubey from the Department of Civil Engineering at IIT Kharagpur has adapted a process called Hydro Thermal Carbonization (HTC) for Indian conditions which can effectively manage mixed MSW with high moisture content.

Through the process, most of the mixed MSW can be converted into biofuel, soil amendment and absorbents.

The current waste incineration processes adopted from the developed nations are primarily focused on treating drier waste content. This requires high energy input to combust mixed MSW with high moisture content.

“India’s tropical weather, open collection systems and mixed waste make the output yield much less fuel-efficient. Only 20-30% of the organic fraction of municipal solid waste is being recycled to biofuel. Hence there is a need to develop treatment system which can address the challenge indigenously,” opines Prof. Dubey.

Here is the goal which has been scored by the research team. They have developed a technology to convert the organic fraction of MSW into ‘Hydrochar’ by using a batch reactor. The moisture in the waste is used to the advantage of the process which uses water for the reaction. The process has increased the resource recovery yield to 50-65% of urban organic waste.

“The process novelty lies in the use of water for the reaction thus the moisture in the MSW gets used during the recycling process without requiring any removal of moisture from the segregated waste or high energy intake. This is effective for mixed municipal solid waste management in India,” explained Hari Bhakta Sharma.

For example, 1gm yard waste and 4gm water are being used in the laboratory reactor. The waste output is 1gm of biofuel with a calorific value of upto 24.59 MJ/kg, while the water remains available for reuse.

The key to the success of the technology lies in designing a proper industrial-scale HTC reactor with improved heat integration system. The technology can be deployed by municipalities at various locations within a city thus ensuring easy management of logistics of waste.

Another novelty of this technology is the zero waste scale reached through this process.

“Once the yard waste is entered into the process, the outputs generated are all usable including the water which can either be reused in the processor can be converted to biogas or methane through anaerobic digestion,” explained another researcher Sagarika Panigrahi.

The biofuel generated as the recovered output is comparable to lignite coal which could significantly address the fossil fuel depletion issue and helping to curb air pollution issues, pointed out Prof. Dubey.

The product can further be used as an absorbent to manage soil contamination.

The calorific value or energy yield and quantity yield however are inversely correlated and depends on the end-use of the product.

“So if you are looking for biofuel, the temperature at which the reaction is conducted needs to be kept very high which will increase the calorific value of the fuel however decreasing quantity yield, while in the case of the soil contamination absorbent, the low temperature will increase the product quantity yield with low energy yield,” confirms Hari Bhakta Sharma.

“This could significantly help brownfield sites or contaminated industrial sites or landfills,” added Prof. Dubey.

According to the Ministry of New and Renewable Energy (MNRE) estimates, there exists a potential of about 1700 MW of energy from MSW and sewage. Of this, only about 24 MW have been exploited, according to MNRE. Thus, less than 1.5% of the total potential has been achieved. The waste to energy mandate of Govt. of India could also be met through this innovative process.

“As of July 2017, thermal-based Waste-to-Energy plants in India have a capacity to process 5,300 tons of garbage and produce 53.5 MW/day. There is a big market on waste treatment and this technology can serve well for the organic fraction of municipal solid waste,” hoped Prof. Dubey.