28 Extraneous Matter Methods​

28-01.01 Apparatus or Materials for Extraneous Matter Methods

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28-02.01 Reagents for Extraneous Matter Methods

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28-03.02 Special Techniques for Extraneous Matter Methods

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28-06.01 Cinder and Sand Particles in Farina—Counting Method

To recover, count, and evaluate cinder and/or sand particles in farina. Product is decanted, leaving cinder, sand, and rock particles isolated. Particles are counted and expressed by sand or equivalent per pound.

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28-07.01 Cinder and Sand Particles in Farina—Gravimetric Method

To recover, weigh, and evaluate cinder and sand particles in farina.

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28-10.02 Macroscopic Examination of External Contamination in Whole Grains

To determine external contamination by rodent excreta, other filth, and extraneous material, and amount of external rodent and insect damage. Insect damage may include that from weevils, moths, lygus bugs, and aphids. This method is applicable to cereal grains, unpopped popcorn, and dried peas and beans.

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28-19.01 External Filth and Internal Insect Infestation in Whole Corn

To recover and evaluate external filth and internal insects from the same sample. This method is used to detect premilling infestation by stored product pests such as the weevil and lesser grain borer, among others.

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28-20.02 Microscopic Examination of External Contamination in Whole Grains

To isolate and record external insect and rodent contamination from cereal grains, unpopped popcorn, and dried peas and beans. Sample is boiled to saturate food product without affecting insect, hair, feathers, and other extraneous matter. In this method, heptane is mixed into solution, coating filth and insects. Filth is isolated and separated by attraction to the heptane phase of the mixture. Heptane is isolated in neck of flask with a rod and disk or equivalent. Filth is filtered onto ruled filter paper for microscopic examination.

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28-21.02 X-Ray Examination for Internal Insect Infestation

This method detects the presence of hidden infestation in grains by X-ray. This is the condition in which grain-infesting insects not detected by the human eye are present within the wheat berry. To best utilize the radiographic (X-ray) method, the analyst should be familiar with the general life cycle and morphology of the common grain pests. The method is applicable to cereal grains, unpopped popcorn, and dried peas and beans. See Note 1.

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28-22.02 Cracking-Flotation Test for Internal Insects in Whole Grains

Insects inside grains are difficult to remove by mill cleaning and thus become ground and incorporated into finished product. In this method, surface insects are removed from grain by brushing prior to cracking and release of internal insects. Subsequently, cracked grains are extracted and filtered, and internal insects are removed and evaluated. It is desired to recover whole insects, or equivalents. The method is applicable to whole grains, including cereals, unpopped popcorn, and dried peas and beans.

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28-30.02 Macroscopic Examination of Materials Hard to Hydrate

To detect and estimate postprocessing surface or external contamination resulting from exposure to contamination from rodents, birds, insects, molds, and other sources of filth and decomposition. This method is applicable to baked goods, ready-to-eat cereals, and alimentary pastes. It is not designed to detect microscopic, internal filth; particulate filth; or decomposition contributed by unfit ingredients. For internal filth, use Method 28-32.02. See Note.

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28-31.02 Pancreatin Sieving Method, for Insect and Rodent Filth in Materials Hard to Hydrate

To recover and evaluate light insect and rodent filth applicable to baked goods, ready-to-eat cereals, and alimentary pastes. See Note.

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28-32.02 Sieving Method, for Materials Hard to Hydrate

To recover and evaluate light insect and rodent filth. The method is applicable to baked goods, ready-to-eat cereals, and alimentary pastes. See Note.

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28-33.02 Pancreatin Nonsieving Method for Insect and Rodent Filth in Materials Easy to Hydrate

To recover and evaluate light and heavy filth (including extraneous, insect, and rodent matter). The method is applicable to all easy-to-hydrate baked materials except chocolate products and pie crust without filling.

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28-40.01 Acid Hydrolysis Method for Insect Fragments and Rodent Hairs—Wheat-Soy Blend

To recover, quantitate and evaluate rodent, insect, and other light filth elements in wheat-soy blends.

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28-41.03 Acid Hydrolysis Method for Extracting Insect Fragments and Rodent Hairs—Light Filth in White Flour

To extract insect and hair fragments for microscopic count and defect action level evaluation. See Note 1. Flour is hydrolyzed to reduce starch and saturate non-oleophilic food products without affecting insect hair, feathers, and other oleophilic extraneous matter. Oil is mixed into solution, coating oleophilic filth particles. Filth is isolated and separated by attraction to the oil phase of the oil/aqueous mixture. The aqueous phase is drained away and discarded, isolating the oil phase in the extraction vessel with filth elements. The oil phase is drained and filtered onto ruled filter paper for microscopic examination.

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28-43.01 Glass Plate Method, for Insect Excreta

To recover and evaluate amount of insect excreta. This method is applicable to flour (white, wheat, and corn).

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28-44.01 Iodine Method, for Insect Eggs in Flour

To isolate and record insect eggs. This method is used to detect possible "carryover" infestation in finished goods or when possible contact with stored product pests is suspected. It is applicable to flour (white, wheat, and corn).

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28-50.01 Decantation Method, for Rodent Excreta

To extract and evaluate rodent excreta in degerminated cornmeal, corn grits, brewer's grits, flour, rye meal, wheat meal, whole-wheat flour, farina, and semolina.

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28-51.02 Flotation Method, for Insect and Rodent Filth

To extract, quantitate and evaluate insect fragments, rodent hair and other light filth elements. The method is applicable to whole and degerminated cornmeal, corn grits, brewer's grits, rye meal, wheat meal, flour, whole-wheat flour, farina, and semolina.

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28-60.02 Tween-Versene Method, for Insect Fragments and Rodent Hairs in Rye Flour

To extract, quantitate, and evaluate insect fragments, rodent hair, and other light filth elements from rye flour.

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28-70.01 Defatting-Digestion Method, for Insect Fragments and Rodent Hairs

To remove fat and oils that may interfere with filth extraction. The method is applicable to full-fat soy flour.

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28-75.02 Sieving Method, for Light Filth in Starch

Starch may be contaminated with dirt, sand, insect fragments, hairs, feathers, wood fibers, splinters, etc., depending on the method of manufacture and/or storage conditions. This method is intended for use in removing particles of solid extraneous matter.

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28-80.01 Flotation Method, for Insect and Rodent Filth in Popped Popcorn

To recover light filth from popcorn. Sample is saturated with water by boiling. Heptane is mixed into sample after boiling and cooling in order to coat unsaturated filth. Filth is isolated by attraction to the heptane phase and extracted by flotation

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28-85.01 Ultraviolet Light Examination, for Rodent Urine

Presence of rodent urine on bags and other packaging materials can be detected by examination for fluorescence under ultraviolet (UV) light. Stained spots and areas usually fluoresce with blue-white color, but color may vary, depending on background color of packaging material, type of lamp, and type of filter used. Other materials give similar fluorescence. Lubricating oils often leave fluorescence along seams or elsewhere on cloth bags. Fluorine materials and floor waxes also fluoresce and may impart fluorescence when bags are dragged across these materials or when they are spilled on bags. Urine fluoresces on grain seeds, but it is difficult to separate this fluorescence from natural fluorescence of certain seed tissues. Thus, the presence of UV fluorescence is a valuable means of locating areas that may be urine-stained, but positive identification can be made only by performing specific identification tests.

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28-86.01 Xanthydrol Test, for Urea

This method, which is applicable to cloth bags and other packaging materials, is most commonly used to detect urea. It confirms suspected contamination or "staining" on bags and boxes, etc., by rodent urine

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28-87.01 Urease-Bromthymol Blue Test Paper, for Urea

This method is used to detect urea, as an indication of rodent urine. The method is applicable to cloth or sack fibers, whole or ground cereal grains, whole or chopped nuts, spices, etc.

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28-93.01 Direction of Insect Penetration into Food Packaging

This method determines characteristics of insect chewing on food packaging materials to differentiate between exit and entrance holes. (Note that, in mature infestations with multiple stages, insects often enlarge entry holes for exit and reentry.) The method is applicable to various types of packaging materials.

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28-95.01 Insect, Rodent Hair, and Radiographic Illustrations

Cereal grains and grain products are susceptible to infestation and contamination by many species of insects, causing both internal and external infestation. This method describes the structural fragments of several common insects and also describes rodent hair infestation.

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