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MPM: V-2. Bakery Products, Cereals, and Alimentary Pastes

Macroanalytical Procedures Manual (MPM) Main Page


  1. Method for Bakery Products, Cooked Cereals and Alimentary Pastes
  2. Method for Modified Whole Grains

A. Method for Bakery Products, Cooked Cereals and Alimentary Pastes

(1) Scope

This method covers procedures for the visual examination of bakery products, ready-to-eat cooked breakfast cereals, and alimentary pastes. The procedures are intended to detect and estimate post-processing surface or external contamination resulting from exposure of the processed product to contamination from rodents, birds, insects, molds and other sources of filth and decomposition.

It is not designed to detect microscopic, internal particulate filth or decomposition contributed by unfit ingredients that are agglomerated in the product. AOAC digestion methods are designed for determination of the latter. See Section 2.B. for uncooked cereal products.

(2) Applicable Documents

(3) Defects

These products may be exposed to insanitary conditions during manufacture, distribution, and storage, which may result in contamination or product damage detectable by macroscopic examination. Holes, tears, or other damage to the packaging material in which the food product is contained may occur from infestation by insects and other animals. Molds may develop on the product from association with such damage or from improper storage conditions. Other signs may include excrement from insects or other animals, insect cast skins, chewing, and webbing or other evidence of defilement.

(4) Procedure: Determination by Visual Examination of Extraneous Material, Including Contaminants From Molds and Insect, Rodent, and Other Animal Infestation

  1. Sample Preparation -- Sample a representative or selective number of units of the product, depending on the history of the lot.
  2. Visual Examination -- Examine the wrapper or packaging material of each unit for signs of holes, tears or other damage indicative of infestation (AOAC 973.63). Describe any damage found. Remove contents and examine for defects described above in (3). Note presence of any live insects.
  3. Report -- Classify defective units according to type of defect and determine percent of each. Enumerate defects in each unit according to format in AOAC 970.66B(i), using applicable categories.


(1) Brickey, P.M. Jr., J.S. Gecan, and A. Rothschild, "Method for Determining Direction of Insect Boring Through Food Packaging Materials," JAOAC 56: 640-642, 1973.

(2) Hummel, Charles, Macaroni Products Manufacture, Processing and Packing, 2nd Ed. Food Trade Press Ltd., London, 1966.

B. Method for Modified Whole Grains (V-13)

(1) Scope

This method describes a procedure for the visual examination of coarsely comminuted or shaped uncooked cereal products, which is applicable to rolled oats, flattened groats, rolled wheat, barley malt, and similar products derived from cereal grains and other food seeds.

Groats are the hulled kernels of oats, barley, or buckwheat and are usually in the form of large fragments of broken grains. Rolling or flattening a grain or seed to form a flake is done to decrease cooking time and to modify the texture of the cooked cereal.

Barley malt consists of barley grains which have been steeped in water and allowed to germinate. After germination the grains are dried, processed to remove rootlets, and finally flattened into flakes.

(2) Applicable Documents

(3) Defects

Whole rolled oats, flattened groats, rolled wheat, barley malt, and similar material may contain gross evidence of insect or rodent contamination which is difficult to evaluate by examining individual pieces and which may be obscured if the material is soaked and floated. In many of these examinations, a size separation serves to recover animal excreta, urine-wetted lumps, mats of insect webbing, lumps of moldy material, or loose insects. The presence of such material is usually due to improper storage and failure to take effective measures to protect the material against contamination.

(4) Procedure: Determination of Extraneous Material in Modified Whole Grains Caused by Mold, Insect, Rodent, or Other Animal Contamination

  1. Sample Preparation -- Sample a representative or selective number of analytical units of the product, depending on the history of the lot.
  2. Visual Examination

    1. (i) Weigh 225 g sample and sift a small portion through single or nested Nos. 6, 8, or 10 sieves (or other size as appropriate), depending on product size and type(s) of contamination found. Indicate sieve size and method of use in report. Set aside clumped material on sieve(s) for further examination. Repeat as necessary until entire sample has been sifted and all clumped material has been separated.
    2. (ii) Examine clumped material for presence of insect matter, molds, or other defects with such magnification as may be necessary. If the magnification exceeds 10X, this should be stated in the method section of the report. Check for presence of urine as indicated by fluorescence under ultraviolet light and verify by testing for presence of urine (AOAC Fig. 945.88). Classify clumped material as to type of defect and weigh the quantity in each category.
    3. (iii) After removing the clumped material, sift the remaining sample (both the "throughs" and "overs") separately or in combination, as appropriate, on a No. 20 sieve. Transfer material on the No. 20 sieve in portions to a white tray and examine for insect and rodent filth. Examine the sample material passing through the No. 20 sieve for insect excreta. Determine weight of insect excreta present by weighing screenings directly or calculate by removing excreta from an aliquot and weighing.
  3. Report -- Tabulate results as follows; add additional categories as necessary:
      Subsample No.
    1 2 3 etc.
    Weight Examined (g)        
    Clumped Defectsa (g)        
    Whole Insects or Equivalentb        
    Mammalian Excreta (mg)        
    Insect Excreta (mg)        
    a Describe clumping as due to molds, insects, etc.
    b Identify
    c Substitute appropriate heading
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