Proper lentil storage management is important to prevent a grade decrease.
Green lentils are considered to be dry at <14% seed moisture content, while red lentils are considered to be dry at <13% seed moisture.
Lentils should be stored between 12% and 14% seed moisture, and at cool temperatures. A temperature of 5°C and 12% moisture content maximizes the safe storage of lentils to 370 weeks. Whereas a moisture content of 14% and a temperature of 20°C reduces safe storage time to 23 weeks. See Long-Term Storage of Lentils, Peas, and Chickpeas.
Lentil seed at 14% moisture or less and 15°C or less can be stored safely for up to 40 weeks.
The current recommendation for green lentils is that they should not be stored through a second summer season, in order to avoid excessive discoloration and downgrading.
Lentil seed coats turn brown over time due to the oxidation of tannins within the seed coat itself. Oxidation occurs quickly in conditions of high temperature, high humidity, and exposure to sunlight.
To prevent discolouration lentils should be stored in dry, dark conditions.
Regular bin probing and monitoring is required not only for moisture and temperature, but also the presence of insects.
Seed from different years should not be mixed because of the risk of grade loss due to seed coat browning.
Lentil seed that has browned may still be used for seed if germination and vigour are acceptable.
If pulses require handling, they should be moved as little as possible, and handled gently to reduce chipping and splits. Use belt conveyors instead of augers. If using augurs, run the auger full and at a reduce speeds. Use bean ladders on equipment to minimize the dropping of seed from more than a few feet.
Lentil seed should not be cleaned or handled below –20˚ C because of the increased risk of chipping and peeling.
Latest research: Improved Management of Stored Pulses, Research Update, August 2019, PAMI
DRYING OR AERATING DOWN
Green lentil is considered dry at <14% moisture content, tough at 14.1% – 16% seed moisture, and damp at >16% moisture content.
Red lentil is considered dry at <13% moisture content, tough at 13.1% – 16% seed moisture, and damp at >16% moisture content.
Using air for temperature control is known as aeration while using ambient air for drying is know as natural air drying (NAD).
Blowing air through grain is the most common method to control temperature in the bin. If the lentil is tough but not wet, then blowing ambient air through grain can also result in moisture removal.
When drying lentils, the time to run your fans will depend on airflow rate, starting moisture content, and ambient conditions.
Run the fans when the average ambient temperature is cooler than the grain.
If pulses require handling, they should be moved as little as possible, and handled gently to reduce chipping and splits. Use belt conveyors instead of augers. If using augers, run the auger full and at a reduce speed. Use ladders on equipment to minimize the dropping of seed from more than a few feet.
Lentil seed should not be cleaned or handled below –20˚ C because of the increased risk of chipping and peeling.
Seed moisture higher than 18% results in longer drying times and as lentil moisture approaches 20%, the crop is difficult to thresh without smashing the seed.
Lentil seed containing green weed seeds and other high moisture materials should be cleaned as soon as possible to prevent heating.
If heated grain drying is needed, air temperatures should not exceed 45°C to preserve germination and to ensure that the grain is not downgraded due to heat damage.
Excessive seed damage will occur when seed over 24% seed moisture is dried at temperatures over 38˚C.
The sample should not be dried more than 4% to 5% per pass through the dryer. Lentil seed can be easily damaged in the drying process, so caution is needed.
A cooling or steeping period of up to 8 hours should occur between every pass.
Producers using hot air dryers should have buyers test samples of lentil dried at different temperatures to establish a safe drying temperature.
Cooling lentil seed from a hot air dryer with aeration bins will help prevent damage during further handling.
Belt conveyors are preferred over conventional augers.
MAKING THE GRADE
Grading is done by the Canadian Grain Commission. Through the harvest sample program, farmers have the opportunity to send in harvested samples to the Grain Commission for grading. This grade can be compared with local buyer grades and may assist in marketing.
Colour and uniformity of size is an important factor in assessing the standard of quality or degree of soundness.
Colour, Lentils other than Red:
Colour is evaluated after the removal of stained and damaged lentils using approved lentil standard prints.
Good natural colour: Lentils that are sound, well matured and have a good natural colour.
Reasonably good colour: Lentils with light amounts of adhered soil or lightly discoloured from storage or other natural causes.
Fairly good colour: lentils with moderate amounts of adhered soil or otherwise moderately discoloured from natural causes.
Poor colour: Lentils that do not meet the definition of fair colour, but are without severely adhered soil or are severely discoloured (dark brown).
Stained lentils only apply to lentils, other than red and include mottled seeds (distinct spots on seed coat); water spot (brown discolorations on seed coat); ascochyta (dark-colored lesions on the seed coat); and blue-black (green lentils with significant blue-black discoloration of the seed coat).
Colour, Lentils Red:
Good natural colour: 1% copper; 3% total bleached including copper %; and light amounts of adhered soil.
Reasonably good colour: 3% copper; 10% total bleached including copper %; and moderate amounts of adhered soil.
Fairly good colour: 10% copper; 25% total bleached including copper %; and heavy amounts of adhered soil
Poor colour: lentils that do not meet the definition of fair colour.
Copper seeds have a rust colour covering both sides of seed and the entire seed coat. The rust colour is in distinct contract with the natural red colour of sound lentils.
Bleached seeds have a whitened seed coat that is distinctly faded from the natural red colour of sound lentils. The discolouration must affect the entire seed coat. Lentils having a lighter pink shade that are contrasting with the overall sample are considered sound.
Sunburned or oxidized is used to describe the discolouration of the seed coat which occurs during storage. The colour may vary from light tan to brown or very dark brown, depending on the duration and conditions of storage.
Contrasting colours ranked separately from colour. Contrasting colors refers to cotyledon color and a significantly different seed coat colour. For example, red Cotyledons contrasted with yellow cotyledons, and seed coats where dark-green speckled lentils contrast with green lentils. If greater than 3%, lentils are then graded “Lentils, Sample Canada Account Contrasting Colours”.
Damaged lentils may include:
Peeled, split, broken, sprouted, distinctly green, frost damaged, distinctly deteriorated or discoloured by weather or disease, insect damaged, heat damaged or otherwise damaged in a way which materially affects quality.
Lentils with cracked or clipped seed coats are considered sound when the cotyledons are firmly held together.
For green cotyledon varieties, do not assess distinctly green cotyledons as damage.
Frost damage is normally indicated by a combination of wrinkling and close adherence of the seed coat to the cotyledon. Seed coat may be translucent and cotyledons brittle.
Sprouted is when the primary sprout emerges from between the cotyledons or the primary sprout has been broken off but there is clear evidence of sprouting.
Adhered soil: unprocessed lentil densely covered with adhered soil (often referred to as mud balls) that will ultimately be removed in processing are assessed as dockage; in processed samples, lentil is considered damaged.
Ascochyta: Ascochyta is a fungal disease that attacks the lentil plant and seed. Any degree of white fungal growth on the seed is considered damaged.
Heat damaged: Heated lentils are usually dark tan to black in appearance. If the lentils have tan-coloured cotyledons and a distinct heated odour, then the grading factor is “Heated”. Lentils with tan-coloured cotyledons and no odour are graded “Damage”.
Odour: There is no numeric tolerance for odour. Consider the basic quality of the sample; the type and degree of the odour, and the presence of visible residue causing the odour.
An excessive objectionable odour not associated with the quality of the grain, but not heated or fireburnt – graded as “Lentils, Sample Canada Account Odour”.
Heated odour: An excessive heated odour, graded as “Lentils, Sample Canada Account Heated”.
Fireburnt: An excessive fireburnt odour, graded as “Lentils, Sample Canada Fireburnt”. Fireburnt seeds are seeds charred or scorched by fire. A cross-section of a fireburnt seed resembles charcoal with numerous air holes. The air holes result in a low weight seed which crumbles easily under pressure.
Magnesium spot is a black spot penetrating the cotyledon, most commonly found in cranberry beans. Affected beans are considered damaged.
Rime is the adhered lining of the seed pot and is included in the general tolerance for damage and is considered in the general appearance of the sample.
If the rime is completely and densely covers the lentils, it is graded as “Damaged”.
If the rime is sparse enough to expose the soundness of the lentil, it is graded to “Sound”.
Wrinkled only applies to red lentil. Wrinkled seeds have sharp ridges and pronounced depressions that could also be described as seed coat folds and indents. Wrinkles may be evident only one side. Lentils that only have dimpled seed coat or folds restricted to the outside ring of the seed are considered sound.
Foreign material includes anything that is not a lentil or part of a lentil.
These materials could include adhered soils, earth pellets (soft), earth pellets (hard) are considered stones, shale, or similar material, ergot and sclerotia not removed in cleaning.
Hard earth pellets are pellets or stones that do not crumble under light pressure.
Soft earth pellets are pellets that crumble under light pressure.
Stones are hard shale, coal, hard earth pellets, and any other non-toxic materials of similar consistency. Fertilizer pellets are assessed as stones when constituting 1.0% or less of the net sample weight. Stones are handpicked from a representative portion of the cleaned sample, and the stone concentration is determined in the net sample.
Stones of 0.1 and 0.2 can be graded in the regular grades;
samples up to 2.5% are graded Lentils, Rejected “basic grade” Account Stones in Western Canada, and “Lentils, Sample Canada Account Stones”; and
above 2.5% stones is graded Lentils, Sample Savage.
Excreta is excrement from any animal including mammals, birds, and insects.
Ergot is a plant disease producing elongated fungal bodies with purplish-black exterior, a purplish-white to off-white interior, and a relatively smooth surface texture.
Insect parts refer to pieces of insects such as grasshoppers and lady bugs that remain in the sample after cleaning or processing.
Samples are analysed for the percentage of insect fragments and graded according to established tolerances.
Insects may also result in seed staining and earth adhering to the seed and may result in samples having an objectionable odour.
Samples containing staining of this nature will be considered to be earth tagged and grading according to colour definitions.
Sclerotinia sclerotiorum is a fungus producing hard masses of fungal tissue, called sclerotia. The sclerotia vary in size and shape, have a coarse surface texture, vary in exterior colour from dark black to gray to white and have a pure white interior.
Contaminated is defined in the Canada Grain Act as; “Contaminated means, in respect of grain, containing any substance in sufficient quantity that the grain is unfit for consumption by persons or animals or is adulterated within the meaning of the regulations made pursuant to sections B.01.046(1), B.15.001 and B.15.002(1) of the Food and Drugs Act.”
Samples deemed to be contaminated by the Grain Research Laboratory in consultation with the Chief Grain Inspector for Canada are graded “Lentils, Sample Condemned”.
EARTH TAG MANAGEMENT
Earth-tag seed (soil stains on seeds that cannot be removed) are very undesirable for marketing.
Soil adhered to the seed is called earth tag and is a common factor in downgrading lentil. Earth tag may occur during combining when moisture from weeds or heavy dew causes soil or dust to stick to the seed.
To reduce earth tag in lentil, follow these management tips:
Select a variety with a good harvest rating.
Ideally roll lentil fields soon after seeding and when the soil surface is dry. Rolling can also be done after emergence, however, be mindful of crop staging as damage to stems and branches can seriously reduce yields. Refer to Seeding, for other rolling considerations or consult Government of Alberta resource Land Rolling Guidelines for Pulse Crops in Western Canada
Since lentil is harvested close to the ground, smooth soil surfaces and stone-free conditions are desirable. Rolling will eliminate ridges and an uneven seed bed, and this approach will minimize dirt entering the combine (normal plant dust will not adhere to a dry lentil seed coat, but combined soil will).
Use a desiccant at 30% grain moisture content to even out crop drydown and eliminate green weed material. Green material is either green weeds or green dry bean plant material that will increase the level of earth tag on the seed.