VitalityDuring prolonged storage, barley grain will slowly lose its vitality, causing a slower germination and even grain death, and will therefore be of less value for the maltster. The rate at which barley loses its vitality is dependent on the storage conditions. When stored at very low temperatures and low moisture content, barley may keep its vitality for centuries, but with increasing temperature and moisture the deterioration process is faster and barley can lose its germination ability in a very short time. Malting barley stored for 1 – 1½ year, should be kept at a moisture content of below 12 % and at temperatures below 12 °C. More information about the influence of temperature and moisture on vitality can be seen in the table below.
Fungal contamination during storageBarley with a moisture content of above 14 % may be attacked by fungi during storage especially by species Aspergillus and Penicillium. Most fungi produce secondary metabolites, some of which cause gushing in beer, where the beer spontaneously gushes from a bottle on opening. It is therefore important that malting barley is stored under conditions which prevent fungal growth. |
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Maximal length of storage for maintaining malting barley quality under different storage conditions.
Temperature |
Seed moisture content |
||||
10% |
12% |
14% |
16% |
18% |
|
0 °C |
16 years |
6 years |
2 years |
1 year |
190 days |
2 °C |
14 years |
5 years |
1.8 year |
315 days |
160 days |
4 °C |
11 years |
4 years |
1.5 year |
260 days |
130 days |
6 °C |
9 years |
3 years |
1.3 year |
210 days |
105 days |
8 °C |
7.5 years |
2.5 years |
1 year |
170 days |
89 days |
10 °C |
6 years |
2 years |
300 days |
140 days |
70 days |
12 °C |
5 years |
1.6 year |
240 days |
110 days |
55 days |
14 °C |
3.8 years |
1.3 year |
190 days |
85 days |
45 days |
16 °C |
3 years |
1 year |
150 days |
65 days |
35 days |
18 °C |
2.3 years |
290 days |
115 days |
50 days |
25 days |
20 °C |
1.8 year |
220 days |
90 days |
40 days |
20 days |
22 °C |
1.4 year |
170 days |
70 days |
30 days |
15 days |
24 °C |
1 year |
130 days |
55 days |
25 days |
12 days |
26 °C |
290 days |
100 days |
40 days |
18 days |
9 days |
28 °C |
210 days |
70 days |
30 days |
13 days |
7 days |
30 °C |
160 days |
55 days |
22 days |
10 days |
5 days |
At the Carlsberg Research Laboratory loss of seed vigour has been studied intensively (EBC 1989 and 1991). Barley seeds lose both their ability to germinate fast and evenly as a consequence of storage. The rate at which seed vigour is lost is dependent on the storage conditions. It is our experience that malting barley can be stored safely for the maximal length of time indicated in the table.
Publications:
- Aastrup, S., Riis, P. & Hansen, J.R. Proceedings of the European Brewery Convention Congress, Zurich 1989, 171-178
- Riis, P. & Bang-Olesen, K. Proceedings of the European Brewery Convention Congress, Lisbon 1991, 101-108