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Guide to Developing Accurate Nutrient Values

Table of Contents

Appendix G: Reviewing Results of Laboratory Analysis

The laboratory analysis should be presented in a complete report, which includes unrounded values along with details of the sample tested and the methods used.

Every sampled unit should be accounted for in the report or results, whether with an individual result or as part of a composite. When describing the product, some details are only relevant to certain types of food products. You need to verify that the details you require for your application have been provided. For example, if the analysis is for a nationally representative food, the critical food description information may be different than that needed for a prepackaged food for labelling purposes. Thus, if your purpose is to include the values in a generic database, you will probably use a mean of values to represent a number of different products. However, if you are planning to create a Nutrition Facts table, the values will represent a single brand of product and will be rounded according to the Food and Drug Regulations.

You can use the checklist on the next page to guide your systematic review of nutrient values and results of calculations reported by the laboratory.

Checklist for Reviewing the Results of Laboratory Analysis

Content

Issue

Details

Unit treatment

Detailed food description

Name, source of units, state of processing, brand name, lot number, date of origin, weight of edible portion, weight of refuse components (if any)

Unit treatment

Detailed food description

Dates, storage times and conditions, name of technician(s) for all steps

Unit treatment

Compositing information

Were sample units analyzed separately or were composites formed?
If composites were formed, which units went into which composites?

Analysis

Method reference for each nutrient

AOAC-approved, CFIA-recommended, any deviations

Analysis

Are all of the nutrients requested included?

Moisture and ash should be included

Analysis

Any quality control results

You may or may not want to see these
(e.g. recoveries, calibration, reference material results)

Results should include:

All raw, untreated nutrient data for each unit or unit composite

Value per 100 g, units, measurement units
(including outliers)

Results should include:

For nutrients that are expressed eventually as an equivalent, the raw data components contributing the equivalent activity

e.g. for Vitamin A both the mg retinol and mg beta-carotene are provided in addition to the calculated RAE or RE (see Appendix B)

Results should include:

The number of sample units or composites

Were the composites formed as requested and are all sample units accounted for in the results?

Results should include:

Which values are obtained by laboratory analysis and which by calculation

For example, energy and carbohydrates are often determined by calculation.

Results should include:

The calculated mean of samples or composites per 100 g and per serving size if desired

Confirm that the correct serving size is used for the calculations.

Results should include:

Standard deviation or error

Which one is provided?
What calculation (formula) was used?

Results should include:

Factors used for calculations

For example: -nitrogen to protein
-calorie calculations

Are there:

Missing values, zeros, or values that are below detectable limits?

Are there any? What explanation is provided?
Are any of these significant in your product?

Are there:

Unusually large or small values?

Do the results make sense - are they plausible?
-Could use the reference database or similar products as a rough guide.
-Perform some basic verification as described in Section A of this Appendix.

Are there:

Rounded values?

Has some rounding already occurred (do the values end in 0, 2 or 5)?

Report format

Electronic is preferable

Some laboratories have automated systems that print results directly to reports. This avoids transcription errors, but may mean that you lose some of the raw data (see above) that it is advisable for you to have.

A. Verifying Laboratory Values

It is important to verify that the laboratory values are correct, as errors can occur during transcription of data and while performing calculations. There are several checks that are fairly easy to perform. Two of these are to check the proximate components, and to verify the energy calculation. An example of each is given here, based on the sample results below.

Sample Results of Laboratory Analysis
Nutrient	Laboratory Values
Nutrient	Per 40 g serving	Per 100 g
Ash (g)	0.796	1.99
Calories (kcal)	100.8	252
Calories from Fat (kcal)	2.8	7
Carbohydrates (g)	20.38	50.94
Dietary Fibre (g)	1.25	3.12
Fat (g)	0.33	0.83
Trans fatty acids (g)	0	0.0
Saturated Fatty acids (g)	0.08	0.2
Moisture (g)	14.37	35.93
Protein (g)	4.12	10.31
Sugars (g)	1.52	3.8
Vitamin A (RE):
Beta-carotene	ND	ND
Retinol	ND	ND
Total Vitamin A	ND	ND
Vitamin C (mg)	ND	ND
Cholesterol (mg)	0.2	0.5
Minerals: Sodium (mg)	208	519
Calcium (mg)	52	129
Iron (mg)	1.96	4.89

ND = Not detectable

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1. Check proximate components

Weight Check
Nutrients	Weight (g)
Water	35.93
Ash	1.99
Fat (total)	0.83
Protein	10.31
Carbohydrate	50.94
Total	100.00

Check that the proximate components (water, ash, fat, carbohydrate, protein) when expressed in terms of per 100 grams of the sample, add up to 100 (within 5%).

Based on the sample on the previous page, you would sum the values for water, ash, total fat, protein and carbohydrates. This total as shown in the chart to the right should be 100.00 (between 95 and 105).

2. Verify the energy calculation

The next step is to verify the energy calculation by using general Atwater factors of 4, 9, 4 and 7 kilocalories per gram as follows:

Energy in kcal = (4 x g protein) + (9 x g fat) + (4 x g carbohydrate) + (7 x g alcohol)

In the table below, you can see that good correlation exists between the value obtained by laboratory analysis and the calculated value for our hypothetical product.

Nutrients	Laboratory analysis		Calculated value
Nutrients	Measured value	Factor (kcal/g)	Calculated value
Fat (total)	0.83	9	7.47
Protein	10.31	4	41.24
Carbohydrate	50.94	4	203.76
Alcohol	0	7	0
Total Calories	252		252.47

Keep in mind that many databases and some labels will use specific Atwater factors in the energy calculation, which can differ somewhat from the general Atwater factors demonstrated in this example. In addition, you may need to use specific factors for such nutrients as sugar alcohols.

B. Significance of Outliers

Unusually large or small values (outliers) can be very informative and should be reviewed with the laboratory and those who selected the sample. They may actually reflect true variation in the product or result from outside influences.

Some typical causes of outliers are transcription or calculation errors; extraordinary events during collection, transportation, storage, composite formation and analysis; problems in a particular plant (e.g. incomplete mixing of product); and problems with an ingredient from a particular source.

Like missing values, unusual results should not be ignored and only should be removed from a data set if you are certain they do not reflect true variation in the product.

Appendix H: Critical Features of Databases and Software

The following table lists some important features to look for when choosing databases to store nutrient data and software to manipulate the data. A second table on the next page suggests some other useful features.

Critical Features of Databases and Software

Critical Features

Options Available

Optimal Conditions

Original source of the data is defined, and source is reputable.

Suppliers; other labels; CNF; USDA-SR; other

Analyzed supplier data according to quality guidelines described in Chapter III

Data are recent.

Date of submission to the software programmer; date of entry into the database; date of entry into the original source database

Date of entry into the original source database

Knowledgeable personnel review data.

Analytical data are used.

Analytical data; calculated; imputed; averages only

Analytical data according to quality guidelines described in Chapter III, with standard deviations

Contains all mandatory nutrients plus others of interest for claims.

Mandatory nutrients plus moisture, ash and any other nutrients you want to add voluntarily to the label

There are no missing records for mandatory nutrients. Zeros are not used when a record is missing.

No missing records; missing records flagged; missing records estimated

Comprehensive datasets for all of the mandatory nutrients, moisture and ash

Metric conversions are available.
Reference Amounts are provided as per Canadian regulations.

Imperial (US databases and software programs); metric; metric reference amounts; no conversion factors

Reference amounts and gram weight conversion to the Reference Amounts

User can add foods to database and/or build entirely separate database.

Some programs permit users to choose which databases are accessible at a given time

Program able to handle high nutrient variation appropriately.

Standard deviations additive; standard deviations used to treat ingredient data before calculations; no indicators of variation

Flexibility, with a number of choices

Provision is made for moisture and fat changes. Provides standard recipes with established moisture and fat loss figures that can be a reference point (rough guide).

Able to do this within the program; possible to do this manually but not always within the program

Program can automatically apply losses and gains of moisture and fat, either entered by user within the program or borrowed from similar standard recipe

Retention factors are considered.
The source of the retention factors should be noted.

Retention factors

Automatically accounts for retention factors for the vitamins and minerals, with ability to add additional factors for unique processes

Program can round nutrients as required for labelling after end product calculations.

Programmed with current Canadian Nutrition Facts rounding rules and Daily Values. Can choose whether to work with rounded or unrounded values.

User can select how nutrients are expressed.

Able to select the correct units (e.g. RE units for Vitamin A)

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Other Positive Features to Look for in Databases and Software

Feature

Notes

Permits addition of nutrient fields.

You will be able to add voluntary nutrients.

User can include notes pertaining to items added to database.

Allows documentation of data sources and other information within the database.

Added database items are protected from overwriting when software and/or its associated database are updated.

User can duplicate an existing database item and save it with a new name.

This feature is especially useful when adding copies of ingredients in which some of the nutrients have been modified to reflect processing.

Ingredient name field is large enough to permit meaningful descriptions.

Food naming conventions and abbreviations should be established at the outset.

Software vendor's database is supplemented with other manufacturer's ingredients.

Useful for comparison with ingredient suppliers' information.

User can insert notes in product calculations.

For example, it can be useful for noting manufacturing process and revisions to formulas.

Data can be exported easily to spreadsheet program.

Facilitates supplementary calculations and preparation of custom reports.

References

AOAC INTERNATIONAL: Official Methods of Analysis of AOAC INTERNATIONAL, 18th Edition Revision 1, 2006
https://my.aoac.org/source/Orders/index.cfm?section=unknown&activesection=Orders

Canadian Food Inspection Agency: Nutrition Labelling Compliance Test-Nutrition Labelling, Nutrient Content Claims and Health Claims: CFIA Compliance Test to Assess the Accuracy of Nutrient Values, 2003
www.inspection.gc.ca/english/fssa/labeti/nutricon/nutricone.shtml

Ibid: 2003 Guide to Food Labelling and Advertising, Draft Document. Fair Labelling Practices Program, Bureau of Food Safety and Consumer Protection, December 2003
www.inspection.gc.ca/english/fssa/labeti/guide/toce.shtml

Health Canada: Canadian Nutrient File, Food Program, 2005
www.healthcanada.ca/cnf
Note: If you click on "Search online for foods..." that page also includes links to:

USDA National Nutrient Database for Standard Reference, Release 17
Nutrient Value of Some Common Foods
International food composition tables
Nutrition Labelling - Regulations
Nutrition Labelling - Compliance testing
Food and Drug Act and Regulations

Ibid: Food and Drugs Act and Food and Drug Regulations
www.hc-sc.gc.ca/food-aliment/friia-raaii/food_drugs-aliments_drogues/act-loi/index-eng.html Ibid: Nutrient Value of Some Common Foods. Health Protection Branch in cooperation with Health Promotion and Programs Branch, 1999 (reprinted 2002) www.hc-sc.gc.ca/food-aliment/ns-sc/nr-rn/surveillance/e_nutrient_value_of_some_common-eng.html Ibid: Nutrition Labelling Regulations www.hc-sc.gc.ca/hpfb-dgpsa/onpp-bppn/labelling-etiquetage/regulations-eng.php

National Academy of Sciences, Institute of Medicine: Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc, National Academies Pr, 2000
www.nap.edu/catalog/10026.html

National Academy of Sciences, Institute of Medicine: Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium and Carotenoids, National Academies Pr, 2000
www.nap.edu/catalog/9810.html

National Nutrient Databank Conference Steering Committee: International Nutrient Databank Directory. Produced for the 28th National Nutrient Databank Conference, University of Iowa, Iowa City, Iowa, USA, 2004
www.medicine.uiowa.edu/gcrc/nndc/NDB%20survey%20final%20version%2011-04.pdf

Standards Council of Canada: Guidelines for the Accreditation of Agricultural and Food Products Testing Laboratories. CAN-P-1587, 2003
www.scc.ca/en/publications/criteria/labs/agriculture.shtml

US Department of Agriculture, Agricultural Research Service, Nutrient Data Laboratory: USDA National Nutrient Database for Standard Reference, Release 17, 2004
www.nal.usda.gov/fnic/foodcomp/Data/SR17/sr17.html

Ibid: USDA Table of Nutrient Retention Factors, Release 5, 2003
www.nal.usda.gov/fnic/foodcomp/Data/index.html#retention

US Food and Drug Administration, Center for Food Safety and Applied Nutrition: FDA Nutrition Labeling Manual -A Guide for Developing and Using Data Bases, 1998
http://vm.cfsan.fda.gov/~dms/nutrguid.html

US Food and Drug Administration, Department of Health and Human Services:Code of Federal Regulations Title 21, Part 101.108, Appendices C and D
www.access.gpo.gov/nara/cfr/waisidx_04/21cfr101_04.html

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