MPM: V-4. Chocolate, Sugars, and Related Products
Macroanalytical Procedures Manual (MPM) Main Page
A. Method for Cocoa Beans (V-18)
This method specifies procedures applicable to the analysis of raw cocoa beans to determine:
- Defects within individual beans due to insect infestation, molds, or other causes (these are expressed as percentages of reject beans by number and type of defect)
- General contamination of a lot by rodents, insects, molds, foreign matter from spillage and sweeps, or by other cause
(2) Applicable Documents
- CPG 7105.12 Defect Action Levels for Cocoa Beans
- CPG 7119.08 Coffee and Cocoa Bean Sweeps
- CPG 7103.01 Food Storage and Warehousing
- Insect Infestation and Damage -- Although a number of major insect pests (Families Aphididae, Miridae, Coccidae, etc.) infest cocoa in the field, insect damage in imported beans is primarily the result of insect attack in the stored product. Some of the most serious of these insect pests are the phycitid moths such as the tropical warehouse moth or almond moth [Cadra cautella (Walker)]; the tobacco moth [Ephestia elutella (Hübner)]; and the Indianmeal moth [Plodia interpunctella (Hübner)]. Important beetle pests are the coffee bean weevil [Araecerus fasciculatus (DeGeer)], the cigarette beetle [Lasioderma serricorne (Fabricius)], and some species of Dermestidae. Extensive internal damage to the beans may occur during the larval feeding stage of C. cautella, E. elutella and A. fasciculatus in the warehouses of producing countries. All of the pests of stored products mentioned, together with a number of secondary pests such as the foreign grain beetle [Ahasverus advena (Waltl)], the Mediterranean flour moth [Anagasta kuehniella (Zeller)] and driedfruit beetle [Carpophilus hemipterus (Linnaeus)] may infest the beans during drying (curing), transportation, and storage, producing variable degrees of damage.
- Moldiness of Fungal Decay -- Species of molds which appear in beans as a visible growth in the nibs (cotyledons) belong to three classes of fungi: Phycomycetes, Ascomycetes, and Fungi Imperfecti. Within the Phycomycetes, Mucor sp. and Circinella sp. produce a coarse weblike growth of mycelial strands scattered over the surface. Eurotium repens of the Ascomycetes is frequently found; it produces a thick matted mass of mycelial growth containing small, round yellowish bodies (the ascocarps) which are readily visible when the bean is cracked open. The ascocarps are scattered throughout the mycelium both on the surface of the cotyledons and between the folds. Among the Fungi Imperfecti, species of Aspergillus are most commonly found. A. flavus produces a dark grayish-green mass of mycelium and spores and, in cases of thick matted growth on the surface of the cotyledons, a dusty mass of spores arises when the bean is cracked open. A. tamarii produces a dark brown mass of mycelium and spores. A. niger occurs only occasionally and produces a dark-colored area on the bean caused by the production of a mass of blackish brown spores. These aspergilli are associated with cocoa beans having a high moisture content. Aspergilli contamination indicates poor drying and storage practices. The extent of mold damage to individual beans can vary widely. In some beans a few hyphal strands may be present, while in extreme cases the inside of the bean may be completely covered with a thick matted mass of mold filaments and masses of spores accompanied by visually apparent disintegration of the cocoa bean tissue. Between these extremes, defective beans may exhibit any gradation of contamination by invading molds.
(4) Procedure: Determination of Insect-Damaged and Moldy Cocoa Beans
- Sample Preparation -- A sample consists of a representative number of subsamples from the lot. Each subsample should contain about 1 lb of beans composited by taking about 1/3 lb from each of 3 bags or other containers in the lot. Mix each subsample and count out 100 beans. If subsamples are composited for analysis, take equal amounts from each subsample and mix thoroughly.
- Visual Examination -- Crack open each bean and break into small pieces (nibs) along the natural folds of the cotyledons to expose the internal surfaces of the nibs.1 Examine each bean in a good light without the aid of a magnifier2 and classify according to (4)c.
Classification of Reject Beans -- Beans should be classified as follows:
(i) Moldy -- Any bean showing extensive mold affecting 1/4 or more of the exposed nib material. Do not classify as moldy any beans with:
- Small, localized areas of mold, usually in the germ (broader) end of the bean
- Localized spots of spores around the germ or radicle
- Light, feathery mold
- Exterior mold only, limited to the removable shell or seed coat
- Grayish-blue (slate-colored) appearance but no mold filaments
Figure V-4 illustrates cocoa bean rejects due to mold.
COCOA BEAN REJECTS DUE TO MOLD
1Examination of beans can be accomplished with facility by using a cracking board made from a 15 in. square sheet of 1/4 in. aluminum or plywood drilled with one hundred 7/8 in. holes, equally spaced in 10 rows of 10 holes each. Place the board on a large sheet of paper on a hard surface. Scatter the beans on the board to fill the holes. Sweep the excess beans off with the hand and adjust any empty or double-filled holes so that each of the 100 holes contains one bean. Crack open each bean by placing an iron bolt (about in. in diameter and about 3 in. long) on the bean and gently tapping the head of the bolt with a hammer.
2Magnifiers may be used by analysts to confirm the identification of conditions initially observed by the unaided eye. Magnifiers may also be used for familiarization with the range of damage characterizing specific lots.)
- (ii) Insect Infested or Insect Damaged - any bean showing insects (fragments or whole insects), insect excreta, webbing, or tunneling. Describe kind and extent of insects present in subsample under "Remarks" in (4)d.
- (iii) Moldy and Insect Infested or Insect Damaged -- any bean that is both moldy and insect infested or insect damaged.
- Report -- Record results of examination as follows:
Code or Lot No. ____ Subsample No. 1 2 3 etc. No. of insect-infested beans No. of moldy beans No. of moldy and insect-infested beans Total Rejects
(5) Procedure: Determination of Extraneous Material in Cocoa Beans
- Sample Preparation and Visual Examination -- Weigh the sample or subsamples as submitted. Screen entire contents of each on a No. 3 sieve to sift out live or dead insects and other foreign matter from the cocoa beans. Examine siftings for presence of insects, rodent excreta, and other extraneous material. Classify any filth or extraneous material into suitable descriptive categories and record by number or weight, as appropriate. Record number and kind of insects, noting whether alive or dead, number and weight of rodent and other animal excreta, and give a suitable description of other extraneous contaminants.
- Report -- Tabulate and report amounts of each category of filth and extraneous matter per weight of sample or subsamples.
(1) Chadd, Eileen M., Cocoa -- Cultivation, Processing and Analysis, Interscience Publishers, Inc., New York, 1953.
(2) Gecan, J. S., and P. M. Brickey, Jr. "Cocoa Bean Histology and Comparative Micromorphology of Internal Bean Infesting Insects," , U.S. Food and Drug Administration, Internal Bulletin, Washington, DC, 1967.
(3) Cocoa Bean Import Survey 1959-1960, U.S. Department of Health, Education, and Welfare, Food and Drug Administration, Washington, DC.
B. Method For Candy (V-22)
This method describes a general macroscopic procedure applicable to most candy products for determination of relatively obvious extraneous contamination. The term "candy" includes a wide variety of products manufactured from diverse ingredients. The type and extent of contamination in a finished product may vary substantially, depending on the ingredients used. Each ingredient introduces the potential for contamination due to distinct sources associated with its production, transport, and storage prior to incorporation into the candy product. Selection of a suitable method for analysis of any specific product material should therefore take into account the ingredients in the product as well as the techniques used in its production and storage. Additional methods for utilizing various selective digestion techniques to recover microscopic particulate and extraneous contaminants from candy are available in AOAC.
(2) Applicable Documents
Because each raw material and processing method has unique contamination problems, it is essential to review the establishment inspection report and relevant defect profiles of product ingredients in order to identify likely routes of contamination and to determine suitable analytical procedures. Ingredients which are incorporated into a candy product with only slight changes in physical character may be easily separated from the product for selective analysis to detect visible moldy or insect-damaged portions. In some cases the external coating, such as chocolate, may be the suspect ingredient; in other cases it might be the starch-molded centers or whole nuts contained in the product. If the layers carry varying amounts and types of contaminants, they should be analyzed separately.
Where the finished candy may have become contaminated during the processing or in storage, a thorough macroscopic examination of the exterior is most important. Holes, tears, or other damage to the packaging material in which the candy is contained may occur from infestation by insects or other pests during storage. Molds may develop on the product from improper storage conditions. Other signs of contamination may include excrement from insects or rodents, insect cast skins, chewing and webbing, or other evidence of defilement.
(4) Procedure: Determination of Extraneous Contamination
- Sample Preparation -- The sample may consist of a number of selective subsamples from suspect portions of the lot together with exhibits indicating apparent damage. Alternately, the sample may contain representative subsamples of the lot. Count and/or weigh the subsamples to be examined.
- Visual Examination -- Before opening bulk or individually packaged candy, carefully examine the packaging material for any signs of damage by rodents, insects, or other causes. If insect-bored holes were detected, determine, if useful, whether holes were made by entrance or exit of the insects (AOAC 973.63). Examine macroscopically the entire contents of consumer size packages where portions will be selected later for microscopic analysis. For assorted candies, examine each variety separately, as appropriate. Examine the surface of the candy for gross contamination with the naked eye or by using a low-power magnifier. Cut open, as appropriate, to determine any internal damage. Describe any damage found. Note the presence of any live insects.
- Report -- For each subsample, report defective product units or pieces according to the type of defect and determine the percent of each.
Brickey, P.M., J.S. Gecan, and A. Rothschild, "Method for Determining Direction of Insect Boring through Food Packaging Materials," JAOAC 56: 640-642, 1973.