Storing the potato perfectly

Nora Olsen Adrian Cunnington

Head, Sutton Bridge CSR,

AHDB Potato Council,

Spalding, UK

Potato Specialist,

University of Idaho,

Kimberly, Idaho, USA

WORKSHOPWORKSHOP 11

Differing perspectives?NORTH AMERICA EUROPE

Never increase quality in

storage…only help maintain and

minimize reductions

Physical and physiological changes

and disease development occur with

time in storage

Storing the potato perfectly

KEY TOPICS

• Storage systems and management

• Storage control

• Sprout suppression

• Low cost options for developing markets

SUSTAINABLE, EFFICIENT, COST-EFFECTIVE SOLUTIONS

Storage systems & management

NORTH AMERICA

Storage systems & management

TRENDS – North America

Quality expectations

Storage at 3 – 7°C for fresh; 7 – 12°C for processing

Increase in cultivar integration

Variable frequency drive (VFD) adaptation

Insulation, refrigeration, ventilation, humidification

sophistication and control

Data collection and interpretation

Sustainable, effective and efficient management

Storage systems & management

EUROPE

Storage systems & management

TRENDS - EUROPE

Climate > move to refrigeration but cost is concern

Storage at 2 – 6°C for fresh; 6 – 12°C for processing

Varieties increasingly dictated by markets

Insulation increasing in response to energy costs

Store sizes reduced > better control?

Sophisticated control options available

More focus on sustainable solutions

Dedicated staff resource for storage in decline

Storage control

TECHNOLOGY – NORTH AMERICA

Supply air temperature control = +/- 0.05°C (or 0.1°F)

Automation

– Outside air requirements to mix with return air to

maintain temperature

– Sensors – differential between pile top and

bottom (ΔT); within pile; reliability

– Use of refrigeration, if necessary (portable/fixed)

– CO2 control (purge)

Remote monitoring and alarms

(email, text messages)

Collect, interpret and use data to manage store

Storage control

TECHNOLOGY- EUROPE

• Automated control is crucial for storage success

• Simple control remains popular

• Computers/technology offer much more but many

systems don’t interface well with users at present

• Knowledge-based controllers remain in their

infancy: eg weather prediction for energy saving

• Decision support potential is huge to bring expertise

to the user in the store, wherever that store is

located

Storage control

VENTILATION

• Key is air distribution:

positive ventilation �

• Flexibility:

variable air volumes

improve efficiency

High rates: drying,

field heat removal

Lower rates: CIPC,

temperature stability

Storage control

VENTILATION

Conditions/location dictate airflow

– North America = maximum 25 cfm/ton

– Europe = higher airflows (75 cfm/t or 150 m3/h/t)

– Dry versus wet conditions at harvest; field heat

removal; cooling air available

Variable frequency drive fans

– Energy savings

– Minimise over-ventilation

– Holding periods: can be 30-40% of maximum airflow

AIR DISTRIBUTION SYSTEMS

Above-floor ducts (soil floors)

Under-floor concrete duct system

Storage control

Photo courtesy of Bob Hesse, Suberizer, Inc.

Storage control

CONDENSATION MANAGEMENT

Critical: free moisture is

the enemy!

Moisture encourages

disease and sprouting

Insulation is key -

to minimize temperature

gradients

Air movement and

roof space heat can help

Storage control

HUMIDIFICATION

Maritime areas, eg NW Europe: more difficult to justify

Can help to mitigate against weight loss

Evaporative cooling offers scope to reduce costs

Must be closely controlled to avoid condensation

Storage control

HUMIDIFICATION

Dry, cold climates, eg Pacific Northwest USA:

Humidify fresh air: 1 or 2 systems used

– Evaporative cooling pads (additional cooling benefit)

– Spinner or centrifugal humidifier (pulsating or continuous)

– High pressure nozzles

Limit free moisture

Control to maintain set point

Human decision on when to limit humidity due to

disease concern

Sprout suppression

Sprout suppression

TRENDS – CIPC USE IN N. AMERICA:

Temperature of application

Timing of application: typically one application (16-25 ppm);

second application only if necessary

Solid and liquid

Combination or mixtures with other sprout inhibitors,

carriers or surfactants

Applied thermally, after curing, before pile settles

MRL (USA) = 30 ppm

Sprout suppression

TRENDS – CIPC USE IN UNITED KINGDOM :

Now applied as soon as possible after loading

Rates limited according to market: 36 g/t, 63.75 g/t

Stewardship in place to ensure high standards

Applied in bulk using speed-controlled fans: this

has reduced usage by up to 50%

Box storage (without positive ventilation) remains

most difficult to treat uniformly – ongoing R&D

Most CIPC applied as liquid + methanol solvent

MRL (EU) = 10 ppm

ALTERNATIVE SPROUT INHIBITORS

Maleic hydrazide (applied in field; timing important)

Substituted napthalenes

– 1,4-dimethylnapthalene (DMN)

– Diisopropylnapthalene (DIPN)

Ethylene (UK fresh market)

Clove oil; spearmint and peppermint oils; caraway oil

Others in development

– 3-decen-2-one

– Hydrogen peroxide

Sprout suppression

3-decen-2-one applied thermally

Low cost storage for developing markets

FOCUS FOR SUCCESS

Use basic fundamentals of storage management

– Ventilation, temperature, humidity

– Variety selection

– Sound potatoes into storage

– Limit variability in crop

– Adapt basics to climate

Sprout control options

Quality expectations and market needs

Low cost storage in developing markets

FUTURE REQUIREMENTS?

Best practice guidance to produce

crops better suited to storage

Education in storage practices to

minimize wastage/maximize return

Effective, environmentally-friendly

and sustainable solutions

Acknowledgements

North America:

Todd Forbush, Techmark, Inc.

Bob Hesse, Suberizer, Inc.

Joel Micka, JMC Ventilation Refrigeration, LLC

Dale Nelson, Nelson’s Vegetable Storage Systems, Inc.

Nathan Oberg, Agri-Stor Company

Tim Pearson, BTU, Agri-Control Technologies

Europe:

SBCSR research team, AHDB Potato Council, UK

Ray Andrews, Crop Systems, UK

Paul Kok, Omnivent, Netherlands

Rolf Peters, KTBL, Dethlingen, Germany

Storage systems and management

STORAGE FUNDAMENTALS

In dark and protected

Store only sound potatoes

Store proper maturity of potatoes with set skin

Maintain constant temperature

Maintain %RH and temperature at desired level

Aerate and remove carbon dioxide regularly

Adequate and well distributed air flow

Easy to clean

Storage systems & management

CONSIDERATIONS

Impact of location

– Environmental conditions

– Field agronomics

– Type and proximity to markets

Bulk versus bin/box

Size of storage

Quality expectations

Store control

CONDENSATION MANAGEMENT

Appropriate quality of insulation for area

Continuous air movement along ceiling to mix air

Increase temperature of air above potatoes

Live airflow walls and other storage designs

CONSIDERATIONS

Maintain quality

Minimize weight loss and sugar development

Variety selection

Use of coolest temperature appropriate to

market use

Proximity to markets

Sprout inhibitors

Sprout suppression

ALTERNATIVE SPROUT INHIBITORS

0

10

20

30

40

50

60

70

80

CIPC Carvone Clove oil Spearmint Untreated

leng

th (

mm

)

4 month 6C

8 month 6C

4 month 9C

8 month 9C

Sprout suppression

Comparison trials (PCL R438) at SBCSR, UK - 2010/11

Spearmint Peppermint Untreated CIPC

Russet Burbank after 9 months in 7.2°C (45°F) storage (8 applications of oils) – Univ of Idaho

Sprout suppression