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Operational procedure: Processed product grade verification

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1.0 Purpose

The purpose of this document is to provide guidance to Canadian Food Inspection Agency (CFIA) inspection staff on standard commodity inspection procedures related to grade verification for fruits and vegetables that have been processed and for which a grade applies.

The guidance outlined below may be used when verifying compliance of a food product, to support a preventive control inspection, or as part of a food safety investigation or follow-up to a complaint.

This document is intended to be used in conjunction with other guidance documents as referenced in Section 3.0

2.0 Authorities

The inspection powers, including the authorization to take samples, by the above legislation are identified and explained in the Operational guideline – Food regulatory response guidelines.

3.0 Reference documents

4.0 Definitions

Definitions are located in the glossary documents listed below or as a defined word where it is intended to supersede the definitions within the glossary documents:

5.0 Acronyms

Acronyms are spelled out the first time they are used in this document and are consolidated in the Food business line acronyms list.

6.0 Operational procedure

This operational procedure provides inspection guidance specific to grade verification for fruits and vegetables that have been processed and for which a grade applies. Grade verification assesses whether processed products meet applicable requirements prescribed in the Canadian Grade Compendium Volume 3 or Volume 9 and the Canadian Standards of Identity. The procedures are presented in a progression from measurements prior to destruction of the container through to analysing the contents. Where more specific guidance is required then what is provided in the SIP, these will be indicated in this section.

Commodity inspection OGs refer the inspector to the SIP for basic guidance on the 4 inspection steps. If the commodity inspection is being conducted to support a preventive control inspection (PCI) currently underway, some or parts of the inspection steps will have already been completed.

6.1 Prepare for inspection

Refer to SIP, section 3, step 1. In addition to the general guidance provided in SIP, the following applies.

Grade verification applies to products for which a grade is prescribed. The grade designation depends on the type of product (canned or frozen) and the place of packaging (in Canada or in a foreign country). Refer to the Canadian Grade Compendium Volume 3 and Volume 9 for the grade designation requirements.

There are 3 scenarios that the inspector may encounter:

  1. Grade is not declared on the label: if a Grade is prescribed for that product, this constitutes a labelling non-compliance
  2. Canada Grade or an equivalent Grade is declared on the label: Verify that the product meets the declared grade according to the applicable requirements set out in the Canadian Grade Compendium Volume 3 and Volume 9
  3. Foreign Grade is declared on the label of an imported product sold in its original container:
Table 1. Recording inspection data in Digital Service Delivery Platform (DSDP)
Trigger

Choose one of the following triggers as appropriate:

  • Preventive Control Inspection Plan
  • Sample Collection Plan
  • Commodity Inspection Plan
  • Incident Response
  • Domestic Permission
  • Export Permission
  • Import Permission
Inspection task type Commodity Inspection
Inspection level 1 task Perform test
Inspection level 2 task Grade Verification

6.1.1 Prepare the toolkit

In addition to the list of equipment found in section 3.5 of the SIP, the equipment listed below is needed to complete the grade verification:

List of equipment for grade verification

The following items are required in addition to the equipment found in the Inspector Toolkit (accessible only on the Government of Canada network – RDIMS 11289973).

6.2 Conduct the Inspection

Refer to SIP, section 4, step 2. In addition to the general guidance provided in the SIP, the following applies.

6.2.1 Locate and identify the lots

The sample size used to conduct grade verification is based on a single sampling plan or a multiple sampling plan as outlined in Appendix 1.

6.2.2 Thawing of product (as needed)

  1. Frozen fruits

    Allow the product to thaw so that it is free from ice crystals and the individual units can be easily separated and handled. Many fruits will discolour after thawing (for example oxidation in sour pitted cherries) therefore the colour should be assessed while the product is still frozen. Refer to Canadian Grade Compendium Volume 3 Part 2 subsection 56(a).

  2. Frozen vegetables

    Unless otherwise prescribed in regulations (for example frozen spinach, frozen Ffrench fried potatoes), allow the product to thaw so that it is free from ice crystals and the individual units can be easily separated and handled. Immediately determine factors such as colour, uniformity of size, condition and absence of defects. To assess factors such as flavour, tenderness, freedom from fibre, etc., the product will need to be cooked according to package directions. If the cooking instructions call for boiling the vegetables in water, use only unsalted water for boiling. Refer to Canadian Grade Compendium Volume 3 Part 2 subsection 56(a).

6.2.3 Measure drained weight of canned fruits and vegetables

This task applies to canned fruits and vegetables except for canned tomatoes which are subject to drained weight requirements in the document Minimum drained weights and average drained weights for processed fruit or vegetable products in a hermetically sealed package.

Equipment
Procedure
  1. Place the sieve in a clean drip tray, place both on the scale and tare the scale.
  2. Remove the sieve from the drip tray and place into the empty dish. Gently pour the contents of the opened container evenly over the screen of the sieve, then:
    1. Turn fruits having concave surfaces (such as halves of peaches, pears or other fruits) so that the concave surfaces face downward on the screen to facilitate draining
    2. Allow the container and its contents to drain into the dish for 30 seconds
    3. Place the sieve with the drained product in the drip tray and weigh to determine the net drained weight
    4. Do not discard the drained product or the liquid, as they may be required for other measurements
  3. Repeat the procedure for each sample
  4. Calculate the average drained weight of all samples
Acceptance criteria

The lot meets the drained weight requirements if the calculated average meets or exceeds the regulatory minimum.

Note: For canned fruits listed in Table 1A of the document Minimum drained weights and average drained weights for processed fruit or vegetable products in a hermetically sealed package that are packed in unsweetened juice, use the drained weight requirements listed for fruits packed in water.

Note: One of the corrective action options for the regulated party is to label the product as "Contents (x) Per Cent Slack Filled" or as "Contents (x) Per Cent Short Weight" where (x) is the calculated percent "shortage" found. [SFCR 272(1)(e)]

6.2.4 Verify drained solids of canned tomatoes

The percentage of drained solids is one of the grade requirements of canned tomatoes in Section 47 of the Canadian Grade Compendium Volume 3 Part 1.

Equipment
Procedure
  1. Weigh each unopened container and record the gross weight as it will be used to calculate the drained solids
  2. Determine the net weight of the drained solids
    1. Place an empty dish and the circular sieve on the scale and press the "tare" button
    2. Remove the circular sieve, place it over the other dish and gently pour the contents of the opened container evenly over the screen of the sieve
    3. Without shifting the tomatoes, incline the sieve to facilitate draining of the juice
    4. Allow the container and the tomatoes to drain into the dish for 30 seconds
    5. Remove the sieve containing the tomatoes and place it back on the scale in the empty dish
      Note: Do not discard the drained product or the liquid, as they may be required for other measurements.
  3. Wash and dry the empty container, weigh it (along with the lid and label) and record the weight
  4. Calculate the percent drained solids (or use the worksheet for Percent drained solids (accessible only on the Government of Canada network – RDIMS 2031865)
  5. Repeat the procedure for each sample
  6. Record the average percent drained solids of all the samples
Acceptance criteria

The lot meets the drained solids requirement if the average percent (%) drained solids meets or exceeds the regulatory minimum Canadian Grade Compendium, Volume 3 section 47.

Note: One of the corrective action options for the regulated party is to label the product as "Contents (x) Per Cent Slack Filled" or as "Contents (x) Per Cent Short Weight" where (x) is the calculated percent "shortage" found. [SFCR 272(1)(e)]

6.2.5 Assess the quality factors for grade

This task applies to the products for which quality factors are part of the Grade prescribed in the Canadian Grade Compendium. For products that were packed in liquid, the quality factors are assessed on the solid portion only For products on which a drained weight or drained solids evaluation has already been done, place only the solid portion of the product on the tray. For all other products, drain the liquid (if any), reserve the liquid for evaluation and pour the solid portion of the product onto a tray.

For each sample taken, evaluate the recorded quality factors for compliance as defined in Volume 3 of the Canadian Grade Compendium.

Acceptance criteria for the inspection lot

If the number of non-compliant samples is:

< the acceptance number prescribed for the sample size in Appendix 1, the lot meets the requirements of the grade declared

> the acceptance number prescribed for the sample size in Appendix 1, the lot does not meet the requirements of the grade declared

6.2.6 Measure percent soluble solids content (° Brix)

Soluble solids are a measurement of the quantity of solids, mainly sugars, dissolved in packing media. As light passes from one medium to another (for example from air to water), the change in density causes the light to bend (refraction). A refractive index is calculated using the angles before and after the bend. As the concentration of dissolved solids in a solution increases, the refractive index changes in a predictable way and the two can be related using a scale called percent soluble solids.

Degrees Brix (° Brix) is the concentration of sucrose in a liquid. Fruit products contain a variety of sugars, acids and other substances, but for the purpose of this operational procedure, ° Brix and percent soluble solids are used interchangeably.

1 % soluble solids = 1 g of solids in 99 g of water
1 ° Brix = 1 g of sucrose in 99 g of water
1 % soluble solids = 1 ° Brix (for this operational procedure)

A refractometer measures the refractive index of a sample. Most refractometers convert the refractive index directly into a percent soluble solids or ° Brix value.

When canned fruits, frozen fruits and canned sweet potatoes are packed in juice or syrup, the juice or syrup strength (percent soluble solids) must fall within the ranges specified in the regulations.

6.2.6.1 Juice or syrup in canned fruits and canned sweet potatoes
Equipment
Procedure
  1. Allow the product to come to room temperature
  2. Calibrate the refractometer, following the manufacturer's instructions. Correct readings to 20°C, if necessary, do not correct for acidity
  3. Determine the production date
    1. Products 15 days or older are considered to have reached an equilibrium between the liquid and solids portions
      1. Stir the contents to homogenize the syrup
      2. Transfer a few drops of syrup to the refractometer and measure the percent soluble solids
      3. Clean the refractometer with distilled water and soft, non-abrasive wipes
      4. Repeat the steps for all samples taken
    2. For products packed for less than 15 days in containers of 540 mL (19 fl oz) or less:
      1. inspect the contents for extraneous material (for example, pits, rocks). If any extraneous material is found, remove it (to avoid damaging the blender blades). Refer to Appendix 4 of the Operational guideline: General principles of sampling and the Operational Procedure: Food Extraneous Matter Verification (under development) for guidance on how to inspect for extraneous materials.
      2. homogenize the contents in a blender
      3. transfer a few drops of slurry to the refractometer and measure the percent soluble solids (°Brix). Clean the refractometer with distilled water and soft, non-abrasive wipes
      4. repeat the steps for all samples taken
    3. For products packed for less than 15 days in containers larger than 540 mL (19 fl oz):
      1. use only 540 mL (19 fl oz) of the product. Ensure that the proportions of solids to liquids corresponds to the net and drained weight proportions prescribed in the Minimum drained weights and average drained weights for processed fruit or vegetable products in a hermetically sealed package Table 1A for canned fruits and Table 3 for canned sweet potatoes
      2. follow steps i) to iv) as described above for containers of 540 mL (19 fl oz) or less
  4. Calculate the average percent soluble solids of all the samples
Acceptance criteria

The lot meets the requirements if all three conditions are met:

Note: For products declaring "Packed in (name of the Fruit or Fruits) Juice (or Juice from Concentrate)", there is no prescribed maximum limit for soluble solids. This applies only when unsweetened juice or unsweetened juice from concentrate is used.

6.2.6.2 Juice or syrup in frozen fruit
Equipment
Procedure
  1. Thaw the product to room temperature in its original container
  2. For containers:
    1. of 500 g or less, blend the entire contents of the container in a blender
    2. larger than 500 g, stir the contents to obtain a uniform distribution, take a 500 g sample and blend the sample in a blender
  3. Calibrate the refractometer, following the manufacturer's instructions
  4. Transfer a few drops of the slurry to the refractometer and measure the percent soluble solids. Be sure to correct readings to 20°C, if necessary for refractometer (follow the manufacturer's instructions). Do not correct for acidity
  5. Clean the refractometer with distilled water and soft, non-abrasive wipes
  6. Repeat steps 4 and 5 for all samples taken
  7. Calculate the average percent soluble solids of all the samples
Acceptance criteria

The lot meets the requirements if all three conditions are met:

Note: For products declaring "Packed in (name of the Fruit or Fruits) Juice (or Juice from Concentrate)", there is no prescribed maximum. This applies only when unsweetened juice or unsweetened juice from concentrate is used. If sweetened juice or sweetened juice from concentrate is used, one of the other syrup names must be applied.

6.2.6.3 Jams, jellies, juices and other products
Equipment
Procedure
  1. Allow the product to come to room temperature
  2. Calibrate the refractometer, following the manufacturer's instructions
  3. Stir the contents to homogenize the product (blend if necessary).
    For containers:
    1. 500 g or less, use the entire container; or
    2. larger than 500 g, stir the contents to obtain a uniform distribution and take a 500 g sample
  4. Transfer the a few drops of the product to the refractometer and measure the percent soluble solids. Be sure to correct the readings to 20°C, if necessary for the refractometer (follow the manufacturer's instructions). Do not correct for acidity
  5. Clean the refractometer with distilled water and soft, non-abrasive wipes
  6. Repeat steps 4 and 5 for all samples taken
  7. Calculate the average percent soluble solids of all the samples
Acceptance criteria

The lot meets the soluble solids requirements if the average percent soluble solids meets or exceeds the regulatory minimum.

6.2.7 Measure percent titratable acidity

This task applies to:

Titratable acidity is a measurement of all the acids in a food. In food products, like any other solution, acids exist in two forms: "free" as ions or "in use" by buffering systems. Titration involves adding a strong base to the sample, to deplete the free ions. To compensate and maintain a certain pH, the buffering system frees up more hydrogen ions. As the titration continues, all of the acid in the product reacts with the strong base and the buffering ability is depleted. The total titratable acidity (total amount of acid in the product) can be calculated using the known strength of the base and the amount of base added.

Note: This activity does not replace pH verification for sauerkraut. pH is a critical factor for microbial stability in sauerkraut and should always be verified.

In processed products, titratable acidity is generally an indication of quality rather than safety. In apple juice, the amount of acid balances the sweetness, without being excessively tart. In sauerkraut, a lack of acidity makes the product bland, while too much makes it unpalatable.

6.2.7.1 Malic acid in apple juice

The inspector may choose to perform this procedure or collect a sample and submit it to the lab for analysis using the appropriate sample plan (adulteration apple juice).

Equipment and materials

Note: Check the expiry date of solutions and discard if expired.

Procedure
  1. Transfer 5 mL of apple juice to an Erlenmeyer flask, dilute to the 50 mL graduation with distilled water and add 2 drops of phenolphthalein
  2. Note the starting volume of NaOH in the buret
  3. Add NaOH to the apple juice, a drop at a time, gently swirling the contents of the flask. When the pink colour stays for 30 seconds, stop titrating. Hold the flask up against a white background (piece of paper) to be certain the pink colour remains
  4. Record the end volume of NaOH in the buret and subtract it from the start volume to find the volume used
  5. To convert to % malic acid, multiply the volume of NaOH used by 0.134

    (volume used)(0.134) = % Titratable Acidity as malic acid

  6. Repeat steps 2 to 5 for all samples taken
  7. Calculate the average percent malic acid of all samples
Acceptance criteria

The lot meets the malic acid requirements if the average percent malic acid is within the regulatory requirements.

6.2.8 Verify size classification for certain vegetables

This task applies to the vegetables with prescribed size classifications, and when the label contains one of the size designation statements prescribed in the Canadian Grade Compendium Volume 3 Part 3.

As specified in SFCR 322, the size classification declaration must be indicated on the label in one of the following manners:

It is unnecessary to verify size classification for products with a label that:

Note: Size classification is not related to the grade requirements for size and shape uniformity.

For each sample taken, measure the size of the vegetable pieces using a caliper, an aggregate area chart, a sizing ring or a mesh sizing screen. Refer to Footnotes in the Canadian Grade Compendium, Volume 3, Part 3 which contains procedures specific to some products. In general, the easiest way to evaluate size is to find and measure the largest and the smallest vegetable pieces in each can or package.

Acceptance criteria for the inspection lot

If the number of non-compliant samples is:

the acceptance number prescribed for the sample size in Appendix 1, the lot meets the size classification requirements.

> the acceptance number prescribed for the sample size in Appendix 1, the lot does not meet the size classification requirements.

6.2.9 Measure acidity

This task applies to the following foods when packed in hermetically sealed containers and stored at room temperature, including:

6.2.9.1 pH strips

For quick screening purposes, use pH strips to determine if the pH is below or above 4.0:

  1. Select samples at least 24 hours old to ensure they have reached their final equilibrium pH. At equilibrium, the pH of the brine and the solids are equal
  2. For each sample, dip the pH strip a few seconds in the liquid portion of the sample. When the strip changes colour, compare the colour with the standard colour chart
Acceptance criteria for the samples and the inspection lot
6.2.9.2 pH meter

For a more precise screening, use a pH meter:

  1. Select samples at least 24 hours old to ensure they have reached their final equilibrium pH
  2. Measure the temperature of the samples to make sure they are at room temperature
  3. Calibrate the pH meter according to the manufacturer's instructions
  4. Measure the pH of the brine for each sample and record the result
Acceptance criteria for the samples and the inspection lot

If all samples have a pH ≤ 4.6, the samples are compliant and the lot meets the pH requirements.

If one or more samples have a pH > 4.6, consult the manufacturer or importer to determine if pH is a critical factor in the manufacturing process:

6.2.10 Categorize non-compliance

If a non-compliance is identified related to food labelling and advertising, consult the Operational guideline: Guidelines on categorizing labelling and advertising non-compliance and timeframes for correction (accessible only on the Government of Canada network – RDIMS 9912657) and the Operational guideline: food regulatory response guidelines.

6.2.11 Capturing notes related to commodity inspection in DSDP

For information on capturing notes relating to commodity inspections in the DSDP, refer to Appendix A section 5.4.1 of the SIP and section 3.5.1 of the DSDP SOP INS – conducting an inspection (accessible only on the Government of Canada network – RDIMS 9839405).

In addition to capturing an accurate description (brand name, common name, net quantity, lot number) of the commodity inspected in the "Commodity Description" field in DSDP, enter the same commodity description in the "objective evidence" field along with the non-compliances found so that it appears in the final inspection report.

Worksheets used as tools to aid in the compliance decision of the grade verification should be saved as an RDIMS file and referenced in the "Notes" section of the document record of the inspection task record in DSDP. Upon request, the worksheet may be given to the licence holder.

6.3 Communicate the results

Refer to SIP, section 5, step 3.

6.4 Conduct follow-up

Refer to SIP, section 6, step 4.

For general inquiries related to this OG, follow established communication channels, including submitting an electronic Request for Action Form (e-RAF) (accessible only on the Government of Canada network).

7.0 Appendice

Appendix 1: Sample sizes and acceptance numbers for grade verification

For general inquiries related to this Operational Guidance Document, please follow established communication channels, including submitting an electronic Request for Action Form (e-RAF).

Table 1: Determining factors for requesting a health risk opinion
Container size
(Net volume)
Inspection lot size (number of containers)
Group 1:
≤ 398 mL
(≤ 14 fl oz)
3,600
or less
3,601 to 14,400 14,401 to 48,000 48,001 to 96,000 96,001 to 156,000 156,001 to 228,000 228,001 to 300,000 300,001 to 420,000 Over 420,000
Group 2:
> 398 mL and
≤ 1.36 L
(>14 fl oz and ≤ 48 fl oz)
2,400
or less
2,401 to 12,000 12,001 to 24,000 24,001 to 48,000 48,001 to 72,000 72,001 to 108,000 108,001 to 168,000 168,001 to 240,000 Over 240,000
Group 3:
> 1.36 L and
≤ 3.58 L
(> 48 fl oz and ≤ 126 fl oz)
1,200
or less
1,201 to 7,200 7,201 to 15,000 15,001 to 24,000 24,001 to 36,000 36,001 to 60,000 60,001 to 84,000 84,001 to 120,000 Over 120,000
Group 4:
> 3.58 L and
≤ 22.75 L
(> 126 fl oz and ≤ 5 gal)
200
or less
201 to
800
801 to 1,600 1,601 to 2,400 2,401 to 3,600 3,601 to 8,000 8,001 to 16,000 16,001 to 28,000 Over 28,000
Group 5:
> 22.75 L
(> 5 gallons)
25
or less
26 to
80
81 to
200
201 to
400
401 to
800
801 to 1,200 1,201 to 2,000 2,001 to 3,200 Over 3,200
Single sampling plans
Sample size (n) 3 6 13 21 29 38 48 60 72
Acceptance number Table Note 3 0 1 2 3 4 5 6 7 8

The inspector shall assess, in the case of:

To decrease the sample sizes ranging between 6 and 72 samples, the multiple sampling plan may be used (see Table 4).

Table 2: Frozen processed products, sold by weight, consisting of readily separable pieces
Container size
(net weight)
Inspection lot size (number of containers)
Group 1:
≤ 454 g
(≤ 1 pound)
2,400 or less 2,401 to 12,000 12,001 to 24,000 24,001 to 48,000 48,001 to 72,000 72,001 to 108,000 108,001 to 168,000 168,001 to 240,000 Over 240,000
Group 2:
> 454 g and
≤ 1.81 kg
(> 1 lb and ≤ 4 lbs)
1,800
or less
1,801 to 8,400 8,401 to 18,000 18,001 to 36,000 36,001 to 60,000 60,001 to 96,000 96,001 to 132,000 132,001 to 168,000 Over 168,000
Group 3:
> 1.81 kg and
≤ 4.54 kg
(> 4 lbs and ≤ 10 lbs)
900
or less
901 to 3,600 3,601 to 10,800 10,801 to 18,000 18,001 to 36,000 36,001 to 60,000 60,001 to 84,000 84,001 to 120,000 Over 120,000
Group 4:
> 4.54 kg and
≤ 45.36 kg
(> 10 lbs and ≤ 100 lbs)
200
or less
201 to 800 801 to 1,600 1,601 to 2,400 2,401 to 3,600 3,601 to 8,000 8,001 to 16,000 16,001 to 28,000 Over 28,000
Group 5:
> 45.36 kg
(> 100 lbs)
25
or less
26 to 80 81 to 200 201 to 400 401 to 800 801 to 1,200 1,201 to 2,000 2,001 to 3,200 Over 3,200
Single sampling plans
Sample size (n) 3 6 13 21 29 38 48 60 72
Acceptance number Table Note 4 0 1 2 3 4 5 6 7 8

The inspector shall assess, in the case of:

To decrease the sample sizes ranging between 6 and 72 samples, the multiple sampling plan may be used (see Table 4).

Table 3: Canned or frozen processed products, sold by weight or volume, in a comminuted, fluid, or homogeneous state
Container size
(net weight or volume)
Inspection lot size (number of containers)
Group 1:
≤ 340 g (≤ 12 oz)
≤ 341 mL (≤ 12 fl oz)
5,400 or less 5,401 to 21,600 21,601 to 62,400 62,401 to 112,000 112,001 to 174,000 174,001 to 240,000 240,001 to 360,000 360,001 to 480,000 Over 480,000
Group 2:
> 340 g and ≤ 1.70 kg
(> 12 oz and ≤ 60 oz) > 341 mL and ≤ 1.70 L (> 12 fl oz and ≤ 60 fl oz)
3,600 or less 3,601 to 14,400 14,401 to 48,000 48,001 to 96,000 96,001 to 156,000 156,001 to 228,000 228,001 to 300,000 300,001 to 420,000 Over 420,000
Group 3:
> 1.70 kg and ≤ 4.54 kg
(> 60 oz and ≤ 160 oz)
> 1.70 L and ≤ 4.54 L (> 60 fl oz and ≤ 160 fl oz)
1,800 or less 1,801 to 8,400 8,401 to 18,000 18,001 to 36,000 36,001 to 60,000 60,001 to 96,000 96,001 to 132,000 132,001 to 168,000 Over 168,000
Group 4:
> 4.54 kg and ≤ 45.36 kg
(> 160 oz and ≤ 100 lbs)
> 4.54 L and ≤ 45.5 L (> 160 fl oz and ≤ 10 gal)
200
or less
201 to 800 801 to 1,600 1,601 to 3,200 3,201 to 8,000 8,001 to 16,000 16,001 to 24,000 24,001 to 32,000 Over 32,000
Group 5:
> 45.36 Kg (100 lbs)
> 45.5 L (10 gallons)
25 or less 26 to 80 81 to 200 201 to 400 401 to 800 801 to 1,200 1,201 to 2,000 2,001 to 3,200 Over 3,200
Single sampling plans
Sample size (n) 3 6 13 21 29 38 48 60 72
Acceptance number Table Note 5 0 1 2 3 4 5 6 7 8

The inspector shall assess, in the case of:

To decrease the sample sizes ranging between 6 and 72 samples, the multiple sampling plan may be used (see Table 4).

Table 4: Multiple sampling plan
Multiple sampling plan based on sample size, n from single sampling plan
n = 6 n = 13 n = 21 n = 29 n = 38 n = 48 n = 60 n = 72
nc c r nc c r nc c r nc c r nc c r nc c r nc c r nc c r
4 0 2 8 0 3 10 0 3 12 0 4 14 0 4 16 0 4 18 0 5 22 0 5
6 0 2 10 0 3 14 1 4 16 0 4 20 0 5 24 1 5 28 1 6 32 1 7
8 1 2 12 1 3 18 1 4 20 1 5 26 1 6 32 2 6 38 2 7 42 2 8
      14 2 3 22 2 5 24 2 5 32 2 6 40 3 8 48 3 8 52 3 9
            26 4 5 28 3 6 38 3 7 40 4 8 58 4 8 62 5 10
                  32 3 6 44 6 7 56 8 8 68 8 9 72 6 10
                  36 5 6                   82 9 10

Legend:

nc: Cumulative sample sizes
c: Acceptance numbers
r: Rejection numbers

Acceptance Criteria for the Multiple Sampling Plan: If the number of non-compliant samples is:

  1. ≤ the acceptance number (c) prescribed for the cumulative sample size (nc), the lot is accepted.
  2. ≥ the rejection number (r) prescribed for the cumulative sample size (nc), the lot is rejected.
  3. between the acceptance number (c) and rejection number (r) prescribed for the cumulative sample size (nc), take additional samples so that the cumulative sample size (nc) is equal to the next largest cumulative sample size in the plan. Determine if the lot is accepted or rejected by applying the procedures outlined in (i) and (ii). Increase the cumulative sample size until lots are determined accepted or rejected.

The multiple sampling plan allows for fewer samples as compared to the single sampling plan, while remaining statistically valid. Refer to Table 4 and select the smallest cumulative sample size (nc) that corresponds to the number of samples (n) prescribed by the applicable single sampling plan.

Example:

If the simple sampling plan prescribes 6 samples (n = 6) but you decide to take less, you must take 4 samples (nc 4), as prescribed by the multiple sampling plan:

nc = 4 (c = 0; r = 2)

If the number of non-compliant samples is:

nc = 6 (c = 0; r = 2)

In this case, analyze 2 additional samples (4+ 2 = 6). If the total number of non-compliant samples:

nc = 8 (c = 1; r = 2)

In this case, analyze 2 more additional samples (6 + 2 = 8). If the total number of non-compliant samples:

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