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  1. Laboratory Methods (Food)

Macroanalytical Procedures Manual (MPM) Main Page

Analytical Unit

The portion of the sample or subsample actually used for examination or analysis. It may be:

  • The entire contents of a container
  • A portion of the contents of a container
  • A combination of the contents of two or more containers
  • A portion of unpacked product

In some cases, the analytical unit is the same as a subsample.


A phylum consisting of invertebrate animals. In the adult form, arthropods are characterized by paired, segmented legs, an exoskeleton, and segmented bodies. Certain immature and/or parasitic forms lack some or all of these characteristics.

Authentic Specimen

A specimen unequivocally diagnosed as belonging to a certain species or a specimen known to contain specific quantities of materials. Used as a reference standard to confirm type of contamination or extent of adulteration by foreign ingredients.

Cast Skins

The exoskeletons of insect larvae which are shed when the larvae molt; each larva produces several cast skins throughout its development. Also called exuviae.


A silken case which the larvae of many insects form about themselves before changing to a pupa.

Coefficient of Variation

A measure of relative precision calculated as the standard deviation of a series of values divided by their mean. It is usually multiplied by 100 and expressed as a percentage.

Composite Sample

A single sample which is prepared by combining numerous small portions of product material from throughout the lot.

Defect Action Level (DAL)

Tolerance established by FDA for natural or unavoidable defects in a food produced under good manufacturing practice. The DALs are limits established by FDA for regulatory purposes.


The genus of flies commonly called vinegar flies or drosophilid fruit flies.

Drupelet Berry

A berry composed of a group of a very small, fleshy, one-celled, one-seeded fruits, such as the blackberry or raspberry.


Hard body produced by the fungus Claviceps purpurea; also the name of a disease of rye and other grasses caused by fungi of the genus Claviceps.


An artificial taxon ranking between genus and order, and composed of one or more genera.


The transformation of carbohydrate material that yields such products as alcohols, acids, and carbon dioxide and typically involves decomposition without participation of oxygen. Fruits sour when damaged by fermentation.

Field Fungi

Molds that infest growing crops.


Debris remaining after insect feeding, including insect excrement.


A low form of plant life which, lacking chlorophyll and being incapable of manufacturing its own food, lives off dead or living plant or animal matter.


A taxonomic category ranking between family and species. The genus comprises a group of structurally or phylogenetically related species and is designated by a capitalized Latin noun which constitutes the first word of the technical name of a species.


The rudimentary plant or embryo within the seed; in cereal grains, the small structure at the base of the seed.


A scar on the seed, marking the place where the seed was attached to the seed stalk.


One of the thread-like strands or filaments that constitute the mycelium of a fungus.


The immature form of insects which emerges from the egg stage (in those insects which undergo complete metamorphosis). Also the immature form of mites which emerges from the egg stage. Larvae have numerous vernacular names, e.g., maggots (muscoid flies), grubs (beetles), caterpillars (butterflies and moths), and wrigglers (mosquitoes).


Any identified amount of a particular commodity selected for inspection and/or sampling and analysis.


A worm-like larva, which is legless and without a distinct head capsule. Maggot refers to the immature form of flies which belong to the insect order Diptera.

Magnifying Power

A measure of the ability of a lens or combination of lenses to make an object appear larger. Magnifying power is expressed as "times" or "X" and represents the number of times the image seen through the instrument is larger than the object appears to the unaided eye.


The thallus, or vegetative body of a fungus; an aggregate of many filaments (hyphae) commonly interwoven into a more or less felt-like mass.


An organism that lives on or in another living organism (the host) from which the parasite derives nourishment and in which the parasite may cause varying degrees of injury or disease.


The stage between larva and adult in insects which undergo complete metamorphosis. It is a non-feeding and usually inactive stage.


Part of the seed embryo below the cotyledons, constituting the rudimentary root; in the cocoa bean, a hard, slender stalk about one-third the length of the bean (seed) situated at the hilum (broader) end.

Random Sampling

A selection process whereby each element in the population has an equal probability of being drawn.

Representative Sampling

An objective sampling technique used when the material drawn for testing is to be representative of the entire lot. Representative samples are always drawn at random and in sufficient size to permit valid inferences about the entire lot based on the sample.


The portion of the product drawn from a lot or shipment for further testing. A sample is usually drawn by the field inspector and consists of subsamples drawn from different portions of the lot.


A compact mass of hardened mycelium stored with reserve food material in various true fungi. When mature, the sclerotium becomes detached and remains dormant until a favorable opportunity for growth occurs. At that time the sclerotium sends out hyphae or produces spore fruits.

Selective Sampling

A subjective sampling technique used when the material to be examined is to be drawn from the portion of the lot suspected to contain defective material (e.g., where the inspector wants to confirm evidence of water damage or insect infestation). Selective sampling is useful in identifying deliberate attempts to mask defects.

Sequential Analysis

A sampling plan whereby units of a sample are examined sequentially in groups and a decision is made to pass, reject, or continue analysis based on the cumulative findings for the sample after each group is examined. A high percentage of rejects leads to early rejection, and a low percentage to early acceptance.


A taxonomic category ranking which is beneath genus. Individuals of the same species are genetically, morphologically, and physiologically differentiated from any other population. The specific name is designated by an uncapitalized Latin noun or adjective, and it constitutes the second term in a scientific name.

Storage Fungi

Fungi that live off stored products; generally associated with molds capable of growing on food products at a relatively low moisture level, e.g., Aspergillus and Penicillium.


(See definitions at Analytical Unit and Sample)
Webbing Fibrous material secreted by certain larval insects and arachnids during feeding and development. Typically associated with larval infestations of certain stored-product moths.

Whole Insects and Equivalent

A unit of measurement used in determining the total number of insects present in a sample or subsample by counting only essentially whole insects (heads and head parts) exclusive of fragments. The count generally provides an expeditious tally of insect infestation (e.g., the head count of fig paste) by eliminating the time-consuming counting of numerous fragments from these insects.

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