How to store malting barley safely and maintain grain quality?

Storage conditions

Storing barley for later malting requires careful attention to ensure the grain remains viable and in good condition. For malting barley, a high germination rate is essential to ensure quality malt production. The required sprouting (germination) percentage required is typically 96% or higher. This is needed to effectively convert the barley starches into fermentable sugars during the malting process. This can only be achieved with attention on all the essential storage conditions. Just to make a brief overview these conditions are:

• Storage temperature should ideally be between 10-15°C (50-59°F). Lower temperatures help prevent insect infestation, but not necessarily mould and fungus growth.
• In hot climates this temperature range may not be possible to achieve, which increases the need for good monitoring.
• Barley moisture content should be about 12%. This is crucial for maintaining the viability of the barley for malting. A higher moisture content causes biochemical changes and loss of viability.
• Aeration control is necessary to prevent moisture buildup. Mind that moisture build up will occur if aeration control is not applied to “even out” natural moisture migration. The aeration control is critical to keep the moisture content around the target of 12%.
• Infestation control is critical. Insects and fungus spores are coming in with every single load of grain. That is why monitoring and aeration control is necessary to prevent infestation. Early detection and intervention are key to preventing infestations.

In conclusion safe barley storage requires all the above issues monitored and controlled.

Controlling stored barley

Barley is normally stored in either steel silos or flat stores. In any case the requirement the need for monitoring and control are the same.

Flat stores are more challenging to control during storage because grain in flat stores is more difficult to aerate (ventilate), and natural moisture migration often lead to “wet corners” that may kick-start infestation. Especially CO2 monitoring is therefore essential for safe storage (see below). It is strongly recommended to use aeration-channels in flat stores to have the ability to influence the barley moisture content.

Steel silos are a better option for barley storage because the temperature and grain moisture can easily be controlled with aeration. However, head-space humidity is critical, and a good aeration control system is required to make sure the dewpoint is not exceeded since this will wet the surface of the grain and kick-start fungus growth on the surface.

Best barley monitoring and aeration control practices

It is essential to maintain the viability of the barley, thus the approximately 12% moisture content must be monitors. Infestation control is also vital, so the following monitoring parameters are recommended:

• Grain moisture should be monitored to secure the grain is kept at target of 12%.
• Infestation monitoring is essential. The earliest detection of infestation is achieved with CO2 monitoring with sensors immersed in the grain.
• Temperature monitoring is required to assist aeration control and track temperature changes over time. This is especially required in hot climates.
• Aeration control is obviously the most important issue, because it is much too risky to let the aeration control be dependent on human factors. This is also important because most often the air quality needed to do the aeration is only available at night. Please mind, that aeration control requires a true EMC based control (grain Equilibrium Moisture Concentration control). The ambient weather condition (temperature and relative humidity) must be recalculated to storage silo grain temperature and the grain moisture concentration must be predicted in a real-time iteration process to safely start or stop the aeration fans. Moisture sensors in the grain must continuously monitor the aeration control process to keep the target of 12% barley moisture content. This helps ensure the barley remains in optimal condition for malting.

Data logging and reporting are important issues, and it is recommended to have a system with a real-time App to keep the operational staff informed about:

• Barley quality: moisture concentration, and grain temperature
• Infestation level via CO2 monitoring
• Aeration control progress toward a 12% moisture content and a target temperature of 12-14 °C

A good reporting will ideally be easily accessible information to operational staff on an APP based system, and a weekly report to top management. Barley is expensive, and only a good monitoring system and attention from top management gives both a transparent flow of information and awareness during the critical phase of storing the barley.

Best operational practises

The following best practices are recommended to ensure that stored barley remains in excellent condition for later malting, leading to high-quality malt and ultimately, better beer and whiskey production, etc.

• Moisture control to keep barley at target moisture for best viability.
• Infestation control with CO2 monitoring.
• Automatic aeration control to keep the barley safe and on target.
• Safe handling, handle barley with care to avoid physical damage. Broken or cracked grains are more susceptible to spoilage.
• Rotation of stock. Never use so-called “first in, first out” (FIFO) method. Always follow the principle: use “worst” grain first to avoid losses.
• Cleanliness and hygiene. Keep storage areas and containers clean and always sanitized.
• Handling and transport. Gentle handling during loading. Damaged seed reduce the overall germination rates.

Conclusion

Maintaining optimal storage conditions is essential to preserve the viability and germination potential of barley seeds. The key to avoid losses and have high germination rates are 3 essential issues:

1) Monitoring with focus on moisture content and infestation monitoring with CO2 monitoring, 2) Automatic aeration control that ensures target moisture and temperature, and 3) Reporting in an easy way for both operational staff and top management.

 

Author Peer Hansen, Biochemist, Denmark. ph@i-grain.net, published in Milling & Grain, September 2024