For many growers, their management of the crop doesn’t end at harvest. Storing vegetables for short or longer periods is an essential part of the fresh produce supply chain. Improved technologies including humidity and atmospheric controls can improve quality and extend shelf life for significant periods, but there is always a balance between the value of the crop and potential returns versus the cost of new infrastructure and technology.
“We are seeing high interest in large stores for the long-term storage of green vegetables, especially cabbage but generally across the whole leafy veg. spectrum,” comments John Dye, Chairman, JD Cooling Group. There is no doubt that concerns about Brexit have caused many suppliers to consider how they can extend the UK season to reduce the industry’s reliance on imported product, and this may be reflected in investment in storage technology.
“We have been working with a number of major suppliers to the retail sector who have to provide a year-round supply of fresh vegetables,” says John. He points out that in order to do this most companies currently rely on supplies from other parts of the world, especially southern Europe, but that this scenario introduces additional costs to the supply chain. “There has therefore been attention on extending the UK season for a number of crops,” he continues. “With Brexit, and what now seems a genuine shift in attitude towards the environmental impact of importing produce which can be grown here at home, we have been carrying out a number of trials on various vegetables to determine their suitability for extended storage through controlled atmosphere.”
Pictured above: PG Rix – Onion Stores
John points out that many types of fresh produce are already stored in controlled atmosphere conditions, including top fruit such as apples and pears, but also cabbages and onions, but, as with many areas of crop production, the cost pressures of the market sometimes mean that using the available technology for a particular crop is not cost-effective. “There seems to be a distinct difference in the cost pressures from retailers across these various crops. Some supply chains achieve the necessary value to warrant CA storage but other crops, in particular onions, just don’t have sufficient returns to compensate the growers for the additional costs of CA storage.”
As a result, the UK is still reliant on out-of-season imports of onions from as far afield as New Zealand, even though we can grow quality onions in the UK and have the technology to store them in a manner which could almost satisfy the entire year-round supply requirements. As John points out, “The introduction of dynamic controlled atmosphere for top fruit has seen the potential for 12-month supply realised and subsequently UK growers are increasing their orchard acreage year on year. We have seen excellent results from early trials on vegetables such as leeks and see no reason why many other vegetable crops that are currently imported from Europe, cannot enjoy an extended UK season by being stored in controlled atmosphere stores without loss of quality.
“There is a real opportunity here to create jobs and wealth through expansion of UK farming in conjunction with advanced storage solutions, such as controlled atmosphere, however the Government need to recognise this and support UK growers in making such investments.”
Pictured above: G’s Growers – Cold Store and Fogging for Radishes
There are inevitably some differences between how crops are stored, but most long-term storage of vegetables is carried out in wooden boxes with the crop harvested straight from the field. Any increased risk of diseases development and contamination is usually managed by good airflow and temperature control. “Many vegetable crops can suffer minor damage during any sort of washing process and the additional handling that these washing processes introduce invariably leads to problems in storage over the longer term,” says John. “Of course, the whole growing, chilled storage and onward cold chain is key to the overall success of producing fresh produce which will be suitable for longer term supply from temperature-controlled storage.”
He also stresses that one of the key points within this chain is harvesting. “It is at this point that the finished crop is disturbed from the comfort of the field and transferred to the box, in which it will ideally spend as long as it has in the ground or on the plant,” he stressed. “Being able to harvest when the crop is in peak condition and the field and weather are at their best, will result in the best results from long term stores of vegetables.”
Following harvesting, the next most important part of the post-harvest life of fresh produce is getting it from the field to the store as quickly as possible and removing field heat rapidly and with as little as possible dehydration. Whether this involves dedicated systems such as vacuum coolers or not, having stores constructed in a location which allows the efficient transfer of crop from the field can present various challenges.
Pictured above: Beeswax Dyson – Conditioned Potato Storage Facility
“The availability of an adequate electricity supply for the stores is almost always a major challenge for the farmer or grower and invariably can introduce frustrating delays when there may be a need to operate the cooling plant on a temporary generator for extended periods until the permanent supply can be connected,” warns John. “We always try to highlight this issue at the outset of a project and assist with projected supply requirements to allow the application for power supplies to be made as early as possible. We are also heavily involved with designing combined power solutions for our clients. Working with our sister Company JD Power we are able to look into combining a limited mains supply with solar power, battery storage and generator all coming together to resolve a limited site power availability problem. These solutions can often obtain funding support as well as delivering overall operational cost reductions.”
There is no doubt that the storage technology exists to help many vegetable crops benefit from the renewed interest in homegrown produce, but the market and policy makers need to ensure that the industry provides growers with sufficient returns so that the appropriate investments can be made.
Permission to use granted by The Vegetable Yearbook 2021
All photos are owned by: JD Cooling Group