SOP: Determination of Extraneous Material in Brined, Maraschino and Glacé Cherries
GIFSQ — Global Institute for Food Safety & Quality
1. Principle
This laboratory procedure applies to the sampling and examination of brined, maraschino and glacé cherries for insects, insect infestation, mites, mould, hairs, fibres, sand, soil, pits and pieces of pit, and other extraneous material. The cherries are boiled and washed through sieves to separate sieved filth, which is filtered and examined microscopically; cherries retained on the upper sieve are halved and examined for pits, pit pieces and defectives, and the results are recorded as pits per 50 cherries and percent defectives. The examination shows whether the food meets the requirements of Sections 4, 5 and 7 of the Food and Drugs Act. This method replaces ExFLP-04, dated February 2006.
2. Definition
- A lot is the amount (volume, weight, etc.) of the food produced, stored and/or shipped under conditions as nearly uniform as possible, preferably designated by a common container code or marking, and in any event consisting of not more than one variety, grade or type of product from a single identifiable source.
3. Apparatus and materials required
- Beakers (1.0 L)
- Stirrer hot plate
- U.S. standard sieves, No. 10 or No. 20 and No. 230
- Wash bottles
- Suction filtration apparatus, with either a Hirsch or Buchner funnel; the filter paper (S&S No. 8 ruled) is larger than the funnel plate so that the paper forms a cup in the funnel
- Petri dishes (10 cm diameter)
- Petri dish (14 cm diameter) or other suitably sized dish
- Sharp knife
- Magnifying lens (3-5×)
- Stereoscopic microscope (10-30×)
- Compound microscope (100×)
4. Reagents
- Filtered or distilled water
- Clearing agent — a glycerol-alcohol (95%) mixture (1:1)
- To prepare: mix equal volumes of glycerol and 95% ethanol (for example, 50 mL of each).
5. Collection of samples
- Scrutinize the lot for live infestation. If live infestation is found, do not sample until after fumigation or other effective treatment.
- Obtain three sample units, selected at random from the lot, of at least 500 g each, using appropriate sampling equipment and containers. Three sample units constitute a sample.
- Keep each sample unit separate and label them 1, 2 and 3. Record complete information respecting the lot size, country of origin, exporter, importer or domestic manufacturer, and product identification; this information accompanies the sample.
- If appropriate, freeze the samples before analysis to minimize the possibility of a live infestation of the laboratory.
6. Procedure
Weigh 250 g of cherries and a representative amount of liquid from a sample unit; this constitutes an analytical unit
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Repeat for each of the remaining two sample units
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Transfer the 250 g of cherries and liquid to a 1 L beaker and cover the cherries with approximately 500 mL of water
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Bring to a boil and simmer for ≥ 20 min
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Wash the cherries through a mesh of two sieves — the top sieve large enough to retain the cherries (a No. 10 or No. 20) and the bottom sieve a No. 230 — using a combination of water spray and rubbing to release material attached to the cherries
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Remove the upper sieve with the cherries and retain it for the determination of defectives
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Quantitatively transfer the residue (sieved filth) from the No. 230 sieve to a beaker with a stream of water from a wash bottle, and filter it through identified ruled paper using the suction filtration apparatus; moisten the filter paper first and check that its placement gives good suction
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Transfer the filter paper to a petri dish and moisten it with 1-2 mL of the clearing agent
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Transfer the cherries from the upper sieve to a suitably sized dish; determine the total number of cherries in the analytical unit
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Cut each cherry in half with a sharp knife and examine the external and internal surfaces with the magnifying lens (3-5×) for pits and pieces of pits ≥ 2 mm (longest dimension), insects and mites or their parts, tunnels, excreta, eggs or webbing, and mould
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Use the stereoscopic microscope (10-30×) only to confirm questionable areas; confirm mould filaments by transferring questionable particles to a glass slide and observing with the compound microscope (100×)
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Repeat the examination for the remaining two analytical units
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Classify each cherry into one of the following categories; if a cherry shows more than one defect, classify it only as a multiple defective:
- Insect Damaged — cherries containing insects, their parts, tunnels, excreta, eggs or webbing. Insects that may infest cherries include Diptera (flies), Coleoptera (beetles), Lepidoptera (moths) and Hemiptera (bugs). Report the kind and approximate number of insects and parts if present
- Mite Infested — cherries containing sufficient numbers of mites to be seen by examination of the whole cherry, i.e. > 20 mites per cherry. Mite contamination is often associated with a dusty, sugary or encrusted appearance and is confirmed microscopically by the presence of mite bodies
- Mouldy — cherries containing mouldy or rotten areas ≥ 2.5 mm in diameter, either singly or in aggregate
- Multiple Defectives — cherries showing more than one of the above defects
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Note cherries that show none of the above defects but may show other quality-related damage as acceptable cherries
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Examine each filter paper microscopically at 30× magnification for insects or their parts, mites or their parts, hairs, fibres, feather barbules, sand, soil and other extraneous material
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Record the number and the range in size for each type of extraneous material found on the filter paper, for each analytical unit separately
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Examine 50 cherries for pits and pieces of pit ≥ 2 mm (longest dimension)
7. Calculation
Number of pits and pieces of pit ≥ 2 mm per 50 cherries = (P × 50) ÷ N
- Where:
- P = number of pits and pieces of pit ≥ 2 mm (longest dimension) found
- N = number of cherries examined
Example: 3 pits found in 75 cherries examined → (3 × 50) ÷ 75 = 2 pits per 50 cherries
Percent of each defect category = (cherries in the category ÷ total cherries examined) × 100
- Record the percent by number of each category of defectives separately for each analytical unit, to the nearest 1%:
- Category (a) = % insect damaged defectives only
- Category (b) = % mite infested defectives only
- Category (c) = % mouldy defectives only
- Category (d) = % multiple defectives only
Total percent defectives = (a + b + c + d) %
- Combine the percent by number of each category to obtain the total percent defectives for each analytical unit separately.
8. Interpretation of results
- Determine the number of sample units falling in each of the following three ranges of percent defectives:
- 0-3 %
- 4-9 %
9 %
- These ranges are judged against Table 1 of the Guidelines for the General Cleanliness of Food — An Overview (Pietrzak, E., 2009, in Volume 1 of the Compendium of Analytical Methods).
9. Precautions
- If live infestation is found in the lot, do not sample until after fumigation or other effective treatment.
- If appropriate, freeze the samples before analysis to minimize the possibility of a live infestation of the laboratory.
References
Health Canada, Compendium of Analytical Methods, Volume 4 — Laboratory Procedure ExFLP-04, January 2019: “Determination of Extraneous Material in Brined Maraschino and Glacé Cherries.” (Prepared by the Extraneous Matter and Food Packaging Unit, Greater Toronto Area Laboratory, Canadian Food Inspection Agency.)
Pietrzak, E. 2009. Guidelines for the General Cleanliness of Food — An Overview. In: Volume 1. Compendium of Analytical Methods.