No one likes to think that the food they have produced has caused death or serious illness – but when working with fresh produce, that possibility is always present. Produce Business UK looks at some of the risks and the innovations that are coming onto the marketplace to mitigate them
The recent UK outbreak of E.coli linked to salad leaves, which had possibly been imported from the Mediterranean, bore this out all too vividly. Not just a food supplier’s worst nightmare, tragically it resulted in two deaths and a further 161 people falling ill. Such outbreaks have occurred before – there was an outbreak involving watercress sold by Sainsbury’s in 2013 while in 2011 a major E.coli outbreak on the continent resulted in 50 people dying.
And it is not just E.coli that causes problems. There are many other potential illnesses caused by food contamination such as salmonella and norovirus. In April 2016, there were 23 outbreaks of norovirus across Denmark and Sweden affecting 1,497 people. The cause was traced to lollo bionda lettuce of French origin that had made its way into the foodservice supply chain.
Then there is risk of contamination by foreign objects. This is a problem that unfortunately appears to be increasing. Research carried out by insurance firm Lockton indicates that the number of food recalls by the Food Standards Agency in 2015 grew by 78% compared with the previous year. Recent examples include a recall of Asda 4 Vegetarian Vegetable Burgers in June following reports of pieces of plastic being found inside. Yeo Valley had to recall large quantities of yoghurt due to rubber being found in fruit conserve. And from time to time there are reports of consumers buying salads or vegetables and finding insects and even slugs present. Such events invariably hit the news headlines.
Reducing the risk of such contamination is therefore a priority for every food company. Quite apart from the health risks, contamination of this kind can result in major financial implications. Product recalls are expensive. Large quantities of produce may have to be destroyed. Then there is the bad publicity engendered as well as the costs of undergoing thorough cleaning and checks within production and supply facilities. Production may well have to cease for a while, resulting in a loss of sales. And consumers often change suppliers or brands as a result of perceived food-safety risks, thus further damaging a company’s position in the market.
Source identity
Identifying the source of the contaminant is essential which is why public-private joint venture Fera Science has launched OriGen, a new service for food manufacturers which helps to deal with this situation. OriGen is an innovative process that uses Whole Genome Sequencing (WGS) to identify the source and trace the route of bacterial contamination. It is a method that can be sufficiently accurate to establish not just the exact source, but pinpoint a single machine as the root cause if necessary. Andrew Hudson, head of microbiology for Fera Science says: “WGS allows for a new level of precision in dealing with bacteria entering the food supply chain, dramatically increasing the chances of minimising future contamination from the same source.”
The new test can identify the source of the three major food borne bacteria: Salmonella, Listeria and Campylobacter. A similar test for the pathogenic E.coli is being made available. And happily, the test is very simple as Edward Haynes, Food Standards Agency-Fera joint fellow in molecular epidemiology explains: “The first step is a customer contacting us – normally after they’ve had a product recall or contamination alert – and requesting that we help them track down the source of the problem. We need extensive samples from across the supply chain or facility. We will either send out an environmental testing pack from Fera or the customer will provide us with pre-existing samples. By running these through the DNA sequencing machine we have at Fera, we’re able to sequence the entire genome of every bacterium – meaning we can match up two or more bacteria with pinpoint precision and identify where any contaminant is likely to have entered the supply chain.
“This test provides a higher level of accuracy. It means that manufacturers and processors can develop a very strong idea of the exact source of the contamination. For the fresh produce business, it will be a very effective way of ensuring that when bacterial contaminants are identified the supplier is able to track down the problem and deal with it. However, it won’t work without a sample of identified bacteria; it isn’t a preventative tool. In the case of the recent E.coli outbreak, the precise cause of the contamination has not yet been identified – and so without a sample to test against, our new test would not be able to help.”
Prevent strategy
Prevention is all about reducing risk and here hygiene and cleanliness are a key priority. Continuous staff training, a permanent emphasis on correct hand washing systems and intensive cleanliness procedures are essential. Mark Burnett, vice-president of the Lubricants and Fuel Additives Innovation Platform of NCH Europe points out that companies need to be mindful of the products that they use to clean and degrease their equipment. “Degreasers are used to remove the grease, dirt and soil that build up on machinery and can leave residue behind that can contaminate produce,” he says.
“In the produce industry, factories must strike a fine balance between using chemicals that are tough enough to remove grease deposits and stubborn dirt, while also being suitable for food production environments. Foaming degreasers are ideal for this due to their increased contact time, as they don’t run off surfaces. They have more time to emulsify the fats and oils, breaking the bonds so the stubborn dirt and grease can be wiped away.”
But there are other concerns too. “A big change under EU disinfectant legislation relates to the maximum residue levels for chemicals used for hygiene,” Rowan Gardner, ceo at Ozo Innovations, which has developed electrolysis system, Elocube, says. “These have been standardised at a lower level than is used for drinking water. The industry has relied on various chlorine disinfectants as safe washing products. These have become more limited due to the need to comply with EU legislation.”
The very nature of fresh produce means that it is affected by lots of bacteria due to the way it is grown. Soil contains its own bacteria and rain showers can result in soil and bacteria being splashed on the produce and its leaves. Bacteria can move into the leaf because it passes through the leaf cells. Even in produce grown in polytunnels, the risks are still present since splashes can occur during irrigation.
Gardner says: “There are alternative technologies being pioneered for disinfection. We create a next generation electrolysis system that uses salt and water solution to make a strong solution of hypochlorous acid. You get more of the active ingredient by this method, which is still compliant with EU legislation but the process is super effective. Hypochlorous acid is the same chemical that your body makes to fight off bacteria. What we do is manufacture it at higher concentrations than has traditionally been used and apply to fresh produce in new ways to achieve very effective results.
“If you can kill 99.9% of bacteria in salad leaves that helps protect consumers. However, the bacteria left will start multiplying as soon as salad is bagged, although the fewer there are then the better the shelf life and the overall condition of the produce. We recognise that the remaining bacteria are a challenge, especially those that get into the cells of the leaves. Those bacteria can be killed in laboratory tests, but it is not practical in real life because lettuces and leaves are not uniform. They have lumps and bumps; uneven edges which make it hard to capture all the bacteria. Produce companies are always trying to push the barrier to keep people safe microbiologically, but it has to be practical. You can destroy all bacteria, but this is not useful if you produce a bag of black lettuce that no one will buy.”
Phage trials
Another method being trialled is one using phage systems. These are naturally occurring viruses that target bacteria within the environment and have been used therapeutically in some eastern European countries to fight infection. There have been calls to use phage on lettuce leaves as a way of killing the bacteria within the leaves.
Gardner believes that this system possesses an inherent weakness. “The problem is that while phage kill bacteria, they pick up other bacterial genes during their reproduction process. This could transfer antimicrobial resistance between common microorganisms, which would be irresponsible. To avoid this risk, the industry would have to use phage that does not reproduce which is very challenging. It can raise questions of legislative issues, and how to manufacture in large enough numbers.”
Consumer education must be part of the solution. Too many consumers assume that washed leaves in salad bags are clean and useable straight from the bag and even eat raw carrot batons intended for cooking. “Consumer behaviour is part of the problem and concerns the food industry,” says Gardner. “It is important to investigate ways in which it is possible to remind customers to wash salad before eating. There have been suggestions that a sachet of vinegar should be included in each salad bag along with instructions to put the vinegar in a bowl with water and place the leaves in the solution for two minutes prior to adding to the salad bowl. All of us – the industry, retailers and consumers – innovating together is how we will be successful in keeping people safe.’
Early detection
For growers another issue in terms of contamination is the presence of soil-borne diseases, which can expand at an alarming rate. The most common pathogen is Phytophthora, which until now, could only be detected when it infected plants, at which point it was too late for treatment.
A new device is being created to deal with this, and ultimately other soil borne pathogens. FungiAlert uniquely will be able to monitor the health of soil and irrigation water, thus alerting growers to the risk of infection. The device can be used in fields as well as greenhouses and polytunnels. It is the brainchild of Kerry O’Donnelly and Angela de Manzanos, who came up with the idea during their PhD studies at Imperial College, London. O’Donnelly says: “We are currently targeting Phytophthora, but our device can be tailored for other pathogenic spore producing fungal or fungal-like diseases. Phytophthora is particularly problematic for soft fruit and orchard fruits, and can affect horticultural products such as peppers, tomatoes, aubergines and cucumbers. Once a plant has been infected, it cannot be saved, and the disease can spread very quickly. One strawberry farmer lost 28% of his yield due to fungal diseases.
FungiAlert in action
“There is a need for early detection systems. FungiAlert is the first in-situ, early detection device for plant disease in the soil. Our device is a pod that can be inserted into the soil, and the user is alerted to the presence of disease, so that they can take remedial action. At the moment, the read-out is a simple colour change but we are looking to incorporate remote sensing into the device, such as wireless and bluetooth.”
Angela de Manzanos added “Our product gives an immediate reading from the spores of the plant and does not require specialist labour, which can save farmers a significant amount of money in terms of testing. Furthermore, by knowing the safety of the soil they are using, farmers can be more selective in their use of fungicides, which presents another opportunity to lower costs.”
The FungiAlert concept has developed rapidly, since it was first launched as the winning viable at the Imperial College’s Centre for Doctoral Training accelerator scheme in 2015. This provided the seed corn funding that has led to further investors becoming involved. It has also attracted considerable attention particularly from strawberry growers in the UK and US.
FungiAlert is now under final testing at Rothamstead Research in Harpenden. Field trials will be taking place next year, when O’Donnelly and Manzanos plan to work with a range of growers within the UK.
