Storage of quality malting barley in hermetic plastic bags

Abstract

The main destination of barley grown in Argentina is malt production. The main standard quality parameter for the malting industry is to maintain at least 98% germination percentage (GP). A typical operation is to harvest dry barley (around 12%) and store it in hermetic plastic bags, a temporary storage system of modified atmosphere, until end use in the malting industry. The objective of this study was to determine whether the typical Argentinean storage condition of malting barley in hermetic plastic bags produces a deleterious effect in its commercial and industrial quality. Two plastic bags filled each with 180 tonnes of malting barley were used for this experiment, one with 11% moisture content (m.c.) and the other with a range between 11 and 11.5% m.c. The experiment began immediately after harvest on December 27th (early summer) and lasted for five months. Carbon dioxide (CO₂) concentration, grain temperature, m.c., protein and GP were evaluated every 2 wk. GP did not substantially decrease during the entire storage period for both bags, but samples with higher m.c. had the lowest GP. The protein percentage remained stable throughout the entire evaluation period for both bags. The maximum value of CO₂ in the bag with 11% m.c. was 4.4%. The bag with the higher range of m.c. had a maximum CO₂ value of 13%, and this high concentration was associated to a small portion of spoiled grain, presumably due to rain water entering the bag through perforations in the plastic cover at the bottom of the bag. It was concluded that it is safe to store quality malting barley with 12% m.c. or less in hermetic plastic bags for five months.

Keywords: Silobag, Grain, CO₂, Germination