Reducing waste and enhancing safety of fresh produce by hydraulic shock washing

Lead Research Organisation: University of Southampton
Department Name: School of Biological Sciences

Abstract

This project aims to improve the efficiency, sustainability and safety of bagged salad production, worth over £450M retail
sale value in the UK, through more effective processing of fresh produce. A novel hydraulic shock washing process
designed to be installed in commercial washing systems will be investigated. The process has the potential to extend the
shelf life of prepared salads and other foodstuffs prone to microbially driven spoilage. The process can also reduce the total
amount of water used, and the environmental impact of toxic biocides used in many wash systems. The consortium will be
led by a leading salad producer, and involve members of the salad packaging, retailing, and equipment manufacturing
industries, supported by one of the UK's leading surface biofilm research teams, thus demonstrating integration across the
food manufacturing industry, and the research base.
The existing laboratory Pulsifier works on the principle of a plastic bag containing food and diluent inside a metal ring which
is cycled to generate the required shock waves. This project will build on the success of the laboratory equipment to
remove biofilms with minimal tissue damage, to develop a robust continuous flume system. The innovation therefore is in
developing a system which will work in a continuous mode, and can be assimilated into a typical contra-flow washing
process (rather than the batch process in which the lab Pulsifier works). There is no such system in place today, and hence
the new equipment and process will be completely novel.
UoS will lead the laboratory validation and be involved with on-site factory testing when hydraulic shock prototypes are
being evaluated. Overall the project will involve 9 WPs with UoS involved in WPs 1, 3, 5, 7 and 9:
WP1. Assess the Pulsifier in the laboratory (determine effects of varying Hz, amplitude and duration parameters on
physical performance and microbial removal)
WP2. Develop prototype 1
WP3. Assess prototype 1 in the laboraory (benchmarked against the Pulsifier performance)
WP4. Develop prototype 2
WP5. Assess prototype 2 and consider scale up challenges
WP6. Installation of equipment in factory line
WP7. Factory testing
WP8. Final assessment of performance
WP9. Project management (Quarterly review meetings, assess business plan and risk register)

Technical Summary

UoS will lead the laboratory validation and be involved with on-site factory testing when hydraulic shock prototypes are
being evaluated: (i) Lab development: the energies required to release the natural biofilm, Enterobacteriaceae and E. coli
on fresh produce such as lettuce and spinach, and samples spiked with important pathogens such as E. coli O157,
Salmonella Typhimurium and Listeria monocytogenes will be evaluated in a HG2 containment laboratory. Detachment will
be assessed by standard culture recovery techniques of the water used post treatment and advanced light microscopy
techniques such as Episcopic Differential Interference Contrast (EDIC) microscopy of the treated leaf surface for biofilm
presence together with epifluorescence (EF) microscopy of green fluorescent protein-labelled pathogens so that they can
be tracked during processing; (ii) Commercial development: On-site factory validation: factory scale prototypes of the
hydraulic shock equipment made by Ambit will be evaluated by visiting Vitacress on-site and collecting leaf and water samples; (iii) Samples from the commercial facilities will be returned to the laboratory for examination, specifically
quantification of pseudomonads and Enterobacteriaceae using culture recovery techniques and EDIC microscopy for
remaining biofilm presence on leaves; (iv) Validation: These techniques will be used to confirm that the scaled up
equipment works successfully in the factory setting and maintains quality on the supermarket shelf in Vitacress and SSL
trials; as such samples will be returned to UoS for the detailed microscopy and microbiological analyses described above.

Planned Impact

The project will investigate decontamination of biofilm and zoonotic pathogens on the salad leaf phylloplane for enhanced
food security and safety. Thus, the project provides a major opportunity for UK PLC, firstly through its delivery of safe,
nutritious food products which helps the government meet its healthy eating challenges. While there is scope for new
product development in bagged salads, improvement in nutritional value per se is essentially a public good benefit for
which industry would be unlikely to invest alone. Secondly, benefits to the wider industry from this research in terms of
reduced chemical use. Thirdly there is a potential new export opportunity for the UK manufacturing base since the work
requires development of a new Pulsifier design whcih can be translated into the factory. Consequently, all of the skills of
the partners are required to make the project a success and all will share in the IP and licensing agreements.
Immediate beneficiaries will include all fresh produce suppliers and retail outlets in the UK and internationally. The
producers will better comply with international sanitary standards for the sale of fresh produce and will benefit from reduced
water use during washing due to improved bacterial removal and reduced use of sanitisers when water has to be recycled;
the retailers will benefit from improved customer confidence and sales, and extended shelf life due to reducing the biofilm
spoilage (costing one UK supermarket chain £9 million per year). The consumer will benefit since it is critical to establish
the safest means of salad production from the farm to the fork to protect the public health, improve their diet, and maintain
consumer confidence following the regular reports of salad-borne disease outbreaks. Thus, directly impacting on the
nation's health, wealth and culture.

Publications

10 25 50
 
Description The laboratory prototype and factory prototype hydraulic shock washers showed the feasibility of reducing the microbial contamination on salad leaves by at least 90% (1-log) without the need for disinfectants, as stipulated by the industrial partners. However, the washing action was too aggressive and significantly reduced the shelf life of the salad leaves, making the process uneconomic to pursue. It may be more suitable for robust vegetables such as carrots and potatoes. Nevertheless important information was gained on how biofilms and pathogens attach to salad leaves and the forces required to remove them. This is leading to new research with a variant of the washing concept which is anticipated to remove bacteria from salad leaves without reducing shelf life.
Exploitation Route Important information was gained on how biofilm microbiomes and pathogens attach to salad leaves and the forces required to remove them by varying the laboratory and factory prototypes' amplitude, speed, contact time, temperature and air/water ratio. This is leading to new research with a variant of the washing concept which is anticipated to significantly remove microorganisms, including pathogens, without reducing shelf life.
Sectors Agriculture, Food and Drink,Healthcare

 
Description The work was successful in identifying key physical parameters for releasing microbiome biofilm bacteria and pathogens from different salad leaf surfaces, which gave novel insights into their attachment and survival on the phylloplane. This is now being used for a variant washing technology which has the potential to significantly remove adherent microorganisms, including pathogens, from salad leaves without causing damage and reducing shelf life.
First Year Of Impact 2015
Sector Agriculture, Food and Drink
Impact Types Economic

 
Description 2017 Biofilms IKC Full Stage
Amount £12,500,000 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 10/2017 
End 09/2022
 
Description BBSRC CASE
Amount £100,000 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 10/2014 
End 09/2018
 
Description EPSRC DTP/Vitacress Salads ltd Industrial Award
Amount £155,440 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 10/2017 
End 09/2021
 
Title Laboratory and factory scale hydraulic shock washing equipment 
Description UoS undertook the basic laboratory research to understand for the first time the dynamics of the commerical Pulsifier device to release bacteria from salad leaves in terms of optimising the device amplitude, speed, contact time, temperature and air/water ratio. This information was supplied to the engineers for them to develop the small scale prototype device 1 which was assessed in the laboratory and then the large scale prototype 2 device for factory evaluation. 
Type Of Material Technology assay or reagent 
Provided To Others? No  
Impact The knowledge gained from understanding the release parameters for biofilm and pathogens from leaves using the hydraulic shock washing prototypes is applicable to other food industries and food types, such as efficiently washing more robust produce such as potatotes, carrots, apples etc. One of the industrial partners, Ambit, is investigating this potential use. 
 
Description TSB partners 
Organisation Ambit Projects
Country United Kingdom 
Sector Private 
PI Contribution This BBSRC funded project was part of a joint co-funded project with TSB. This provided funding to the industrial partners: Vitacress Salads ltd, Sainsburys plc and Ambit ltd.
Collaborator Contribution Vitacress provided factory access and salad leaf processing. Sainsburys provided commercial requirements and assessment of salad leaf shelf life and quality. Ambit provided engineering to design new salad leaf vibratory processing equipment to factory scale.
Impact Commercial in confidence agreements in place subject to partner approval. The project has finished and successfully translated our expertise in a laboratory pulsification decontamination system into a factory hydraulic shock unit for cleaning salad leaves. Valuable information was obtained that aggressive hydraulic shock washing is required to reduce the microbiome and zoonotic pathogens present on salad leaves while unfortunately reducing product shelf life. This knowledge is now being taken forward with a PhD studentship with Vitacress Salads to develop a new, more gentle leaf cleaning procedure with initial promising results. In addition, a follow-on BBSRC CASE studentship with Vitacress Salads has also started to understand the links between lettuce leaf phenotypes and the abundance and diversity of microbes with a view to breeding for improved shelf life and safety.
Start Year 2013
 
Description TSB partners 
Organisation Sainsbury's
Country United Kingdom 
Sector Private 
PI Contribution This BBSRC funded project was part of a joint co-funded project with TSB. This provided funding to the industrial partners: Vitacress Salads ltd, Sainsburys plc and Ambit ltd.
Collaborator Contribution Vitacress provided factory access and salad leaf processing. Sainsburys provided commercial requirements and assessment of salad leaf shelf life and quality. Ambit provided engineering to design new salad leaf vibratory processing equipment to factory scale.
Impact Commercial in confidence agreements in place subject to partner approval. The project has finished and successfully translated our expertise in a laboratory pulsification decontamination system into a factory hydraulic shock unit for cleaning salad leaves. Valuable information was obtained that aggressive hydraulic shock washing is required to reduce the microbiome and zoonotic pathogens present on salad leaves while unfortunately reducing product shelf life. This knowledge is now being taken forward with a PhD studentship with Vitacress Salads to develop a new, more gentle leaf cleaning procedure with initial promising results. In addition, a follow-on BBSRC CASE studentship with Vitacress Salads has also started to understand the links between lettuce leaf phenotypes and the abundance and diversity of microbes with a view to breeding for improved shelf life and safety.
Start Year 2013
 
Description TSB partners 
Organisation Vitacress Salads ltd
Country United Kingdom 
Sector Private 
PI Contribution This BBSRC funded project was part of a joint co-funded project with TSB. This provided funding to the industrial partners: Vitacress Salads ltd, Sainsburys plc and Ambit ltd.
Collaborator Contribution Vitacress provided factory access and salad leaf processing. Sainsburys provided commercial requirements and assessment of salad leaf shelf life and quality. Ambit provided engineering to design new salad leaf vibratory processing equipment to factory scale.
Impact Commercial in confidence agreements in place subject to partner approval. The project has finished and successfully translated our expertise in a laboratory pulsification decontamination system into a factory hydraulic shock unit for cleaning salad leaves. Valuable information was obtained that aggressive hydraulic shock washing is required to reduce the microbiome and zoonotic pathogens present on salad leaves while unfortunately reducing product shelf life. This knowledge is now being taken forward with a PhD studentship with Vitacress Salads to develop a new, more gentle leaf cleaning procedure with initial promising results. In addition, a follow-on BBSRC CASE studentship with Vitacress Salads has also started to understand the links between lettuce leaf phenotypes and the abundance and diversity of microbes with a view to breeding for improved shelf life and safety.
Start Year 2013
 
Description 2015 Horticulture and Potatoes: Unlocking Innovation through Science and Collaboration 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact 26 February 2015. Prince Phillip House, 3 Carlton House Terrace, London, SW1Y 5DG
BBSRC, NERC and HIP networking event to present industrial collaborative research projects - 2015 Horticulture and Potatoes: Unlocking Innovation through Science and Collaboration. The event provided the horticulture community with insights into current successful collaborations from leading companies and researchers, plus hints and tips in building collaborations, securing public-private funding and delivering exploitable outputs. With an overview of future funding opportunities and a reference catalogue of current underpinning and
industry-collaboration research projects, delegates left with a toolkit and network of contacts to unlock their own Horticulture and
Potato Innovation through science and collaboration.
Year(s) Of Engagement Activity 2015