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Reducing post harvest losses and wastage in UK potato storage due to sprouting. - FO0217

Potatoes are a staple crop and a good source of nutritional compounds. They represent a significant proportion of the UK diet with three out of five meal occasions in the UK including potatoes in some form (Terry et al., 2010). Some six million tonnes of potatoes are grown in UK annually and around 60% of the crop is placed in storage for supply during November to July (Potato Council, 2010), before suitable crop becomes available again. Due to advances in storage technologies, the UK is nearer to self sufficiency for potatoes as compared to other similar fresh produce types; however sprouting still represents the principal cause of postharvest loss during storage, retail and in the home (WRAP, 2009; Terry et al., 2010). Ensuring adequate supply of affordable tubers whilst minimising inputs is central to Defra`s food security policy.

The quality of stored potatoes is maintained by controlling the temperature of stores and the application of sprout growth suppressing treatments. Despite research into alternative treatments (e.g. ethylene, Defra LK09127; PCL projects R298 and R412; Foukaraki and Terry, 2009), the main treatment used is chlorpropham (CIPC), on which the potato industry is still heavily reliant. Although research has resulted in dramatic reductions in CIPC requirements, this has been limited to certain store types, and changes in legislation controlling how much pesticide can be used, as well as general retailer and consumer pressure to reduce pesticide use (and residues of pesticides on foods), are limiting the effective storage duration that can be obtained. Alongside reductions in CIPC use, research continues to explore alternatives to CIPC, but this has tended not to consider abiotic methods of sprout control. Low temperature storage is employed but gives rise to a high sugar concentration that impairs the eating and processing quality of potatoes, as well as requiring large amounts of electricity/carbon throughout long-term storage. Gamma irradiation can be effective but has detrimental effects on potato quality (Ezekiel et al., 2008; Anon., 1988) and is currently prohibited from use.

Improved use of existing solutions and alternative, yet innovative, postharvest solutions to CIPC are thus required. The project aims to provide solutions for more efficacious use of CIPC and explore commercially viable alternatives to controlling sprouting in potatoes.

More specifically, the objectives of the project are as follows:
1. Improve effectiveness of current CIPC usage
Research will be carried out with the aim of improving the effectiveness of conventionally applied CIPC by creation of a reduced scale physical model of a potato store. This will facilitate investigations of key parameters linked to CIPC application such as: concentrations, mass flow rates, pallet arrangement, locations of air inlets and exhausts. This will allow modelling of current and novel alternative storage configurations, greater understanding of airflow through storage boxes and therefore predicted CIPC doses. The model will be verified by measuring actual CIPC residues in tubers distributed in the storage environment.
2. Further develop CIPC vapour as a potential sprout control method
Conventional applications deposit particles of CIPC on potatoes and store fabrics. These particles evaporate and the vapour evolved controls sprout growth. A novel method has been developed (Cunnington et al. 2006) whereby the pool of CIPC is retained in a formulation, and only the vapour required for sprout control is delivered to the crop. The effectiveness of vapour CIPC has been shown in small scale trials and further work is being carried out to assess the scope of such treatments on a semi-commercial scale (Potato Council project R288). CIPC applied in vapour form has the potential to dramatically reduce the amount required for effective sprout control.
3. To develop an alternative or complementary sprout suppression technology based on a physical control
An alternative, non-chemical method of sprout suppression will be examined.
4. Develop alternative chemical treatments to replace or complement CIPC
A small range of alternative chemicals can be used to control sprouting. These compounds are at different stages in the pesticide registration approval process. Candidates have been identified and their potential for reducing CIPC inputs will be assessed, either as treatments in their own right or in conjunction with CIPC. It has been agreed that this work will be funded by the potato industry and prospective approval holders.

(Figures and references included in Q7b attachment)
Objective 1. Improve effectiveness of current CIPC usage

Technical & scientific aims:

• Modelling: Development of an experimental (scale) model that faithfully predicts airflows and particulate CIPC flows & distribution in commercial stores and will allow the effects of modifications to store systems to be predicted.
• Validate predictions of model by chemical deposit analysis

• Development and Initial Testing of R&D Potato Store Scale Model
• Validation of R&D Potato Store Flow Characteristics
• Validation of Commercial Potato Store against Model Scale Flow Characteristics
• Redefine application techniques to establish current practice for CIPC optimum distribution
• Complete analysis of CIPC residues

Objective 2. Further develop CIPC vapour as a potential sprout control method

Technical & scientific aims:

• Develop the use of vapour CIPC as an effective and viable sprout suppressant option.
• Model vapour desorption, adsorption and flow

• Testing of vapour release formulations
• Assessment of modelling vapour CIPC distribution
• Validate model in semi-commercial stores
• Complete analysis of CIPC residues

Objective 3. To develop an alternative or complementary sprout suppression technology based on a physical control

Objective 4. Develop alternative chemical treatments to replace or complement CIPC

Technical & scientific aims:

As part of an integrated management strategy for sprout suppression in stored potatoes, assess likely alternatives to CIPC and their potential for use in place of, or in combination with, CIPC to provide enhanced control and/or reduced chemical usage and associated residues.

Project Documents
• FRP - Final Report : FO0217 Report DEFRA   (532k)
• ANX - Annex : AnnexB1-Obj1 Report   (1505k)
• ANX - Annex : AnnexB2-Obj2 Report   (965k)
• ANX - Annex : AnnexB3-Obj3 Report   (2392k)
• ANX - Annex : AnnexB4-Obj4 2010-11 Report Year1   (239k)
• ANX - Annex : AnnexB5-Obj4 R438 2011-12 Report Year2   (128k)
Time-Scale and Cost
From: 2010

To: 2012

Cost: £299,418
Contractor / Funded Organisations
Sutton Bridge Experimental Unit, University - Cranfield
Food Chain              
Food Waste              
Resource efficient and resilient food chain              
Sustainable Farming and Food Science              
Fields of Study
Resource Efficient and Resilient Food Chain