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a field of baby spinach growing in it

How many times have you bought a bag of spinach with great plans for it, only to find the leaves wilting and weeping in the packaging a few days later so you throw the whole lot in the rubbish? In Ireland alone we generate an estimated 61kg of plastic waste each year per person, and as nation we throw away about a million tonnes of food annually. 

But what if we could grow spinach and other quickly perishing food crops so that they remain attractively edible for longer and make it into a meal rather than the bin?

​The SFI-funded Leaf No Waste project led by Lorraine Foley and Professor Jesus Maria Frias Celayeta at Technological University of Dublin is on a mission to grow foods smartly, with quality preservation in mind. “The horticulture sector in Ireland deserves a lot of credit, they work very hard to grow fresh foods, and sometimes plastic packaging helps to keep those foods fresher for longer,” explains Foley.

Alternative plastic packaging such as compostable plastics, can help to take the sting out of over-reliance on single-use plastics, but even with those some foods struggle to maintain freshness, notes Foley. 

“Some plants just don’t do well in certain alternative packaging types,” she says.

“So a bunch of parsnips might be fine and keep fresh for quite a while when wrapped in a compostable plastic, but leafy greens such as spinach are very sensitive to their environment after they are harvested and can wilt quickly. The properties of the alternative plastic are not aligned to the leafy greens respiration rates. As a result, they lose freshness quicker which increases the risk of food spoilage. In response to moving away from plastic, it is crucial to address the risk of indirect food loss and build resilience into the food supply chain.”

Foley, a lecturer in Horticulture at TU Dublin, has long had an interest in how growing conditions can affect the levels of nutrients in plants, and she has recently turned her attention to how growing conditions might also affect longer-term freshness. “I’m exploring the use of biostimulants, which are different from fertilisers, as they can help to strengthen the plant’s immune system and possibly improve the quality of the plant in the longer term,” she explains. 

“In this project we are looking at applying silicic acid or silicon, which has a positive physiological impact on plants during growth. Silicon is often applied to help products such as rice and sugar cane improve their physical strength and ability to defend themselves - but how can applying silicon to the leaves of plants such as spinach help keep its quality after it has been harvested and packaged? It’s not so much about extending the shelf life but to consistently maintain the quality of the food during that shelf life.”

This quality is measured using a mathematical modelling tool to predict food waste, allowing the researchers to optimise the packaging design and reduce possible drawbacks related to changes of material. “This agricultural intervention provides an opportunity to reduce plastic and avert indirect food loss arising from using alternative packaging,” says Foley.

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The project spans the entire life cycle of the plant, from growing it through packing and storing, so it is crucial that the TU Dublin team works closely with other researchers and growers who have expertise in those fields. 

“We have great partners,” says Foley. “We work with Dr Lael Walsh and Dr Shivani Pathania at Teagasc, so we can grow the plants in controlled environments such as polytunnels and glasshouses, and we benefit from expertise in food packaging. We are also collaborating with commercial growers, including Stephen McCormack, who grows fresh herbs and other produce in Meath.”

Leaf No Waste won funding of €2 million through the SFI Future Innovator Prize Programme, and this will see the project both expand and deepen its work. 

“We are bowled over and delighted to have won the Prize,” says Foley. “It means that we now have the resources to explore how the growth environment could help plants to become more resilient against climate change and pests, and we can build in more expertise about consumer perspectives, what do people who buy the produce want. We are also expanding out to look at other products such as soft fruit and mushrooms, and exploring how we could apply the research to hydroponically grown plants. We have a range of ideas and ultimately we want to build a green business model to improve the quality of plants and reduce food waste in the transition to sustainable food production.”