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The Complete GAP Manual
GAP e-learning module

Ensure that your almonds are dry before being picked up

Moisture leads to the proliferation of microorganisms, including molds that produce aflatoxin in almonds. Be sure that the almonds in windrows are dry before they are picked up. Also, be sure the orchard floor is dry, thereby discouraging the warm, moist environment favored by microorganisms for growth and proliferation. More information regarding moisture can be found in the orchard floor management section.

Cross contamination

If your almond orchard is adjacent to other nut trees (walnuts, pistachios, etc), care must be taken to ensure that almonds being harvested are not mixed with any other nut type. If necessary, hand rake to ensure separation of almonds from other nuts before harvest operations occur.

Keep a clean pick-up machine

    • Know how the pick-up machine has previously been used. Be sure it was not previously used in an orchard where manure or compost was applied after January 1.
    • Make every effort to be sure the pick-up machine was cleaned and sanitized prior to picking up your almonds. At minimum, harvesting equipment should be cleaned and sanitized between orchards. 
    • Pick your almonds up as cleanly as possible, keeping excessive soil, rocks and other foreign materials out of the pick-up machine wherever possible. Soil is loaded with microorganisms you don’t want to deliver to the huller/sheller.

Transport of harvest

Inspect trailers/containers to ensure they are:

    • Clean of all visible debris, dirt, and other nutmeat
    • Free of odors
    • Dry

Verify that the trailers and cargo containers have not previously been used to transport materials from animal operations such as dairy or poultry farms, and specifically that they have not been used to haul waste or manure. In addition, if trailers have been used to haul other nuts they will need to be cleaned to ensure there isn’t cross-contamination with respect to allergen concerns. A form follows for your use when inspecting trailers and/or containers.

Do not permit employees or transport workers to walk on or make direct contact with almonds in trailers when tarping or any other time.

Have a policy in place for trailers or cargo containers that fail to meet your satisfactory loading guide-lines, and tell your huller/sheller and handler about your policy. Document any shipments not loaded because of an unsatisfactory condition of the trailer or cargo container.

Work with the huller/sheller

    • Inspect the delivery area at the huller/sheller to ensure the area is free of signs of rodents and birds. Especially check eaves of the delivery area roof for possible bird and rodent nesting areas.
    • Ask your huller/sheller or handler about their company’s traceback procedure. Understand the product flow within the huller/sheller’s plant and have the company provide you with a copy of their traceback policy/procedure.

Stockpile Management and Aflatoxin Potential

Recent studies supported by the Almond Board show there are clearly stockpile conditions under which Aspergillus can grow with resulting aflatoxin contamination. This work is being led by Bruce Lampinen (UC Davis Extension Specialist) and was initiated in 2007.  This summarizes guidelines developed by this work to date.

Stockpiling, Moisture Content and Aflatoxin

  • Stockpiling at a “total fruit” (in-hull almond) moisture content  greater than  7% is problematic.  This leads to an rH of  greater than 65% within the pile  -- which is the maximum rH for almond storage. 
      • Most critical is the outer portion of piles where there can be significant temperature fluctuation, condensation on tarps, and moisture accumulation.
      • Of particular concern in these outer portions are the “green molds”, which include the Aspergillus mold that produces aflatoxin.
      • This is not a uniform problem throughout high moisture content piles because the equilibrium rH  within the piles comes to a steady state below maximum limits recommended for storage
  • A practical guideline: Do not stockpile if either the hull moisture content exceeds 13% or the kernel moisture content exceeds 6%.

Orchard Sampling Prior to Stockpiling

There is variability in drying on the orchard floor and in windrows and sampling should take this variability into account.  Variability depends on light / temperature and canopy cover.

  • Sampling prior to sweeping
      • Representative sample: Across the orchard floor (from trunk to middle of drive row) and along the tree row.
      • “Worst case” sampling: North  side of canopy adjacent to trunk
  • Windrow sampling
      • There is more moisture on bottom.

Managing Piles

  • Orientation and shape of pile both can play an important role in minimizing mold growth potential.
      • Orienting the long axis of piles north/south is preferable. Condensation and mold growth tends to be worse on north side of piles with long axis oriented east/west.
      • Smooth tops on pile helps minimize concentration of condensate and resulting mold growth.
  • Results show tarp type/color can play an important role in minimizing temperature fluctuations  and condensation.
      • White-on-black is best at minimizing temperature fluctuations and the resulting condensation and problems.  Consider using this for piles having higher moisture content in-hull product.
      • Clear produces the highest temperature fluctuations, but is fine for dry in-hull product.
      • White is intermediate between clear and white-on-black. 
  • If piles are stacked too wet, it is important to open them up in the daytime when the relative humidity is lower and close them at night when the relative humidity is higher.
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