By Dale Risula, P.Ag., Provincial Specialist, Special Crops
Temperatures have been steady around 30 C in August, bringing about rapid maturation of lentils and significant harvest progress. Some excellent yields and good quality have been reported. Proper storage and handling are crucial in preserving the quality and maintaining the value and marketability of lentils.
Oxidation of tannin precursors in the seed coat causes lentils to turn brown with age, reducing the quality. High temperature, moisture and sunlight can speed up this process. These conditions could also increase humidity in the bin, leading to growth of fungi and development of toxins associated with mould. Properly conditioned lentils can store well for up to two years; however, green lentils will discolour with age, reducing the grade. Avoid mixing harvested grain from one year to another to avoid downgrading.
During hot days, lentils should be stored in bins protecting them from sunlight and they should be cooled immediately after binning. Cool the lentils to approximately 15 C as soon as possible in aeration bins (Photo 1). They should also be dried to 14 per cent moisture content for green lentil and 13 per cent for red lentil. Foreign material can hold moisture, so it should be cleaned from the sample to reduce the possibility of increasing humidity within the bin. Other particles such as fine-grind material that make up dockage in the sample, will reduce the aeration system's airflow.
On the other hand, if you encounter cool, wet conditions during harvest, lentils should be dried in phases to not dry them too quickly. If using a grain dryer, a decrease of more than four or five per cent moisture content using a grain dryer can create problems. Lentils should be tempered between passes to allow them to cool and allow moisture to migrate. If lentils are dried too quickly, the seed may develop tiny cracks, which also affects their quality.
Aeration bins used to dry wheat will work well for lentils and even dry more efficiently than wheat. The drying or cooling rate is influenced by the seed size, bin dimensions, fan performance and weather conditions. Monitor regularly for hot spots and changes in moisture and temperature. Various manual and automated systems can be used to help keep track of changes in the bin.
The following is a guideline showing the number of weeks’ lentils will store safely for when conditioned properly:
Table 1 Number of weeks for safe storage of lentils at the specified grain moisture content and storage temperature
|Moisture Content of Seed (per cent)
||Maximum Safe Storage (Weeks)
|Source: Protection of Farm-Stored Grains, Oilseeds and Pulses from Insects, Mites and Moulds. Agriculture and Agri-Food Canada, 1851/E (revised)