Fighting food waste with nanotechnology
According to the United Nations Food and Agriculture Organization, half of the world’s fruit and vegetable harvests go to waste every year, for reasons varying from pests and drought to issues with transportation, storage, and retail. Accounting for 8-10 percent of global greenhouse gas emissions (GHGs), food waste is also a contributing factor to climate change and undesirable weather events such as droughts and flooding.
A vicious circle
Changes in the global climate and the overuse of agricultural land has a negative impact on crop yields and their nutritional quality, which could potentially lead to an increase in demand that the farms will simply not be able to meet at a certain point. Reducing food waste worldwide could be a critical factor in securing sustainable agrifood systems that make efficient use of the planet’s resources and provide food security and quality nutrition.
The 2030 Agenda for Sustainable Development aims to halve per-capita global food waste at the retail and consumer levels while also reducing food losses along production and supply chains, including post-harvest losses (SDG target 12.3). Reaching this target would have significant implications for breaking the vicious circle in the relationship between food waste, climate change, and the food crisis.
Technology against food waste
There are many measures that could stop or at least reduce food waste, at every step of the production chain, starting with minimizing waste on farms and ending with educating consumers about it. Technological innovation plays an important role here, as most of the initiatives rely on technologies like AI, robotics, additive manufacturing, and even nanotechnology.
Aside from wrapping in plastic (which comes with its own set of sustainability problems), one of the preferred methods in the industry for reducing post-harvest waste is coating fruits and vegetables. These thin layers are made from various substances, depending on the producer, and act like a barrier between the food and the external environment. This slows down the degradation process of fresh produce by preventing direct interaction with atmospheric gases and microbes. The resulting longer shelf-life offers more chances for the product to be bought or consumed, thus decreasing the probability of waste.
Edible wax coating is the most preferred method in doing so, but oftentimes, the wax is mixed with chemical components that are potentially harmful to human health. Many research facilities world-wide are dedicating their efforts to developing such edible coatings that are also harmless to consumers, and many have succeeded. More often than not, however, these biofilms are costly, restricted to the industry, and therefore inaccessible to a wider range of farmers.
A safe and inexpensive edible coating made with nanotechnology
A team from the Nanobiotechnology Laboratory and the Department of Biosciences and Bioengineering at the Indian Institute of Technology Roorkee has developed a nanofiber coating using a blend of silk fibroin, PVA, honey, and curcumin. Their edible biofilm, made with techniques like electrospinning and dip-coating, is cost-effective, and the ingredients used are all FDA-approved.
As a base for their coating, the team used the biomaterial silk fibroin protein extracted from local silk cocoons because of its biocompatibility, non-toxic, higher stability, and good mechanical strength. They added PVA as a supporting polymer for electrospun coating, curcumin for its antioxidant and antibacterial properties, and honey as a natural moisturizer.
The researchers tested their coating on several types of horticulture products, but they selected bananas as a model fruit because of their short shelf life of four to five days. Yellow bananas coated with edible silk fibroin nanofibers (SFNSs) remained fresh for more than four days, maintaining their texture and quality.
In the unripe green banana coated with SNFSs, the ripening process was delayed by two weeks, after which it was ready for consumption as a fruit (yellow banana), while the uncoated green bananas from the control group ripened after two weeks, but could not be consumed and were affected by fungal growth. The coated ones remained unaffected by fungi, thanks to the presence of nano curcumin, an effective antimicrobial agent.
The team tested SNSFs on apples as well, only to discover a spectacular one-month increase in their shelf-life, while preserving their texture, quality, and stiffness.
Another promising result in the experiment was obtained when performing the test of stability on fish. The coated zebrafish retained its morphology and internal fluids, while the uncoated fish dried up entirely.
The conclusion of the study was that silk fibroin as a method of coating is a very promising solution in the food nanotechnology field. It can be tested and extended to the preservation of meat or other non-veg foods that decay very quickly during long-distance transport.
This method is cost-effective, does not require any special expertise, and the edible coating is biodegradable and non-toxic. Furthermore, the team utilized silk cocoons discarded by the industry, so the production method favors the circular economy concept, and the curcumin and honey add extra nutrition to the food.
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