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Lentil Post-harvest

Drying, storing and handling lentil seed are important parts of harvest, since these operations can affect the quality of this food product. 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.

The objective of a drying operation is to condition lentil seed to 14 per cent moisture content at 15˚ C. In this condition, discolouration and degradation due to mold growth will be minimized.

Aeration Systems

  • in an aeration operation, lentil provides about the same airflow resistance as wheat per unit depth, so aeration systems that perform well with cereals should perform well with lentil
  • aeration fans should be able to provide 1 to 2 cfm/bu.
  • drying will occur more quickly with higher air flow rates
  • floors can be either partially or fully perforated, although fully perforated is preferred
  • aeration systems will dry lentil at least as quickly as for the same amount of wheat
  • the effectiveness of natural air drying systems is extremely weather-dependent, so these systems must be carefully monitored

Hot Air Dryers

  • when using hot air dryers, lentil should not be dried more than 4 to 5 percentage points with every pass
  • 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:
    • lentil seed germination will be reduced if dryer temperatures over 45˚ C are used – downgrading due to heat damage is also possible
    • for food grades, recent research suggests drying temperatures as high as 70˚ C may be possible
    • excessive seed damage will occur when seed over 24 per cent seed moisture is dried at temperatures over 38˚ C
  • 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

Drying & Storage

Drying, storing and handling lentil seed are important parts of harvest, since these operations can affect the quality of this food product.

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.

The objective of a drying operation is to condition lentil seed to 14 per cent moisture content at 15˚ C. In this condition, discolouration and degradation due to mold growth will be minimized.

Aeration Systems

  • In an aeration operation, lentil provides about the same airflow resistance as wheat per unit depth, so aeration systems that perform well with cereals should perform well with lentil.
  • Aeration fans should be able to provide 1 to 2 cfm/bu.
  • Drying will occur more quickly with higher air flow rates.
  • Floors can be either partially or fully perforated, although fully perforated is preferred.
  • Aeration systems will dry lentil at least as quickly as for the same amount of wheat.
  • The effectiveness of natural air drying systems is extremely weather-dependent, so these systems must be carefully monitored.

Hot Air Dryers

  • When using hot air dryers, lentil should not be dried more than 4 to 5 percentage points with every pass.
  • 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.
  • Lentil seed germination will be reduced if dryer temperatures over 45˚ C are used; downgrading due to heat damage is also possible.
  • For food grades, recent research suggests drying temperatures as high as 70˚ C may be possible.
  • Excessive seed damage will occur when seed over 24 per cent seed moisture is dried at temperatures over 38˚ C.
  • 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.

Storage

  • Lentil seed should be stored in tight bins and sold within two years of harvest.
  • 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.
  • Lentil seed should not be cleaned or handled when ambient temperatures drop below –20˚ C because of the increased risk of seed splitting and cracking.