Testing services for nutrition labelling provided by local laboratories

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Testing services for nutrition labelling provided
by local laboratories by Dominic Lam Hong
Kong Association for Testing, Inspection and
Certification Limited ????????????
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Background Hong Kong Association for Testing,
Inspection and Certification Limited is an
independent and non-profit making organization,
founded by a group of testing laboratories,
inspection companies and certification bodies

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Background (continuous) One of our major
objectives is to enhance the standard and quality
of testing, calibration, inspection and
certification for the furtherance of
international trade and consumer satisfaction.

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Presently there are about 164 laboratories with
HOKLAS accreditation. About 7 of them are
commercial laboratories accredited for nutrition
labelling testing services. (information provided
by CFS) Centre for Food Safety (CFS) recommends
the selection of laboratories that are accredited
to ISO/17025 standard under HOKLAS. However,
ISO/17025 accredited laboratories from other
countries can also be used.
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Nutrition labelling testing services
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General steps of food analysis
sample
homogenisation
extraction
concentration
detection
reporting
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• Method used (????)
• Suitable methods suggested as below
• Most recent edition of AOAC international
  (???????????)
• Manuals of Food Quality Control of Food and
  Agricultrue Organization of United Nation.
  (??????????)
• ISO or BS EN(?????? ? ??
• ??)
• Other national standard methods

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• Protein ??? (AOAC 928.08 or AOAC 992.15)
• Based on nitrogen content obtained by Kjeldahl
  method or combustion method.
• Apply nitrogen conversion factor to give the food
  protein content.
• For general food, multiply nitrogen content by a
  factor of 6.25 but for milk it is 6.38 (milk),
  soybean 5.70 etc.

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• Total fat ???? (AOAC 992.06)
• Sum of triglycerides (?????), phospholipids, wax
  ester, sterols and minor amount of non-fatty
  material.
• Acid hydrolysis followed by extraction and then
  by gravimetric method to measure the total fat
  content.
• Not to use the amount of triglycerides to
• measure the total fat content.

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• Saturated fatty acid ????? (AOAC 996.06)
• Refers to the sum of fatty acids that without
  double bonds.
• The fatty acids are

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• Saturated fatty acid ????? (AOAC 996.06)
• Determine the fatty acids by use of Gas
  Chromatographic method (?????).

?????/????????
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• Trans fatty acid ????? (AOAC 996.06)
• It is the sum of all unsaturated fatty acids
• (??????) which contains at least one
  nonconjugated and trans double bond.

saturated fatty acid
cis unsaturated fatty acid
trans unsaturated fatty acid
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• Trans fatty acid ????? (AOAC 996.06)
• The trans fats are referred as
• Determine the fatty acids by use of Gas
  Chromatographic method (?????).

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• Sodium ? (AOAC 969.23 or AOAC 985.35)
• Salted food contains large amount of Sodium as
  salt is sodium chloride.
• Sample is acid digested and followed by
  instrument ICP-OES measurement.

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• Sugar ? (AOAC 980.13)
• Means all monosaccharides (??) and disaccharides
  (??)
• present in food.
• Monosaccharides Fructose, Galactose, Glucose
• Disaccharides Lactose, Maltose, Sucrose

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• Sugar ? (AOAC 980.13)
• Sample is extracted in solvent followed by
  HPLC-RI analysis.
• Traditionally method of reducing sugar is used,
  but it is not applicable to food with high
  sucrose content (because sucrose is not a
  reducing sugar). The sugar content will be
  underestimated.

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• Dietary fiber ?????? (AOAC 985.29)
• Only AOAC methods can be used since dietary fiber
  is method dependent.
• Sample is firstly defatted, protein and
  carbohydrates will be hydrolysed by enzyme,
  finally dietary fiber is measured by gravimetric
  method (???).

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• Alcohol (ethanol) ??
• Measurement of alcohol is necessary for food
  significantly contains alcohol.
• Examples are alcoholic beverages, desserts with
  alcohol etc.
• It can be accurately measured by Gas
  chromatographic method.

Chocolate with wine inside
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• Organic acids ??? (AOAC 986.13)
• Codex (???????) does not provide a definition.
• Some prepackaged foods contain significant amount
  of organic acids.
• Eg fruit juice (citric acid), milk (lactic acid).
• Liquid chromatographic method (?????) is
  preferred.

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• Water content ?? (ISO14421997)
• Weigh the sample after it is dried at 105oC.
• Total Ash ???? (ISO 9361998)
• Weigh the sample after it is incinerated
• at 550oC.

Furnace
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• Carbohydrates ???????
• It is by calculation not by tests.
• I. Total carbohydrates
• available carbohydrates dietary fiber
• II. Available carbohydrates
• 100 - protein(g) fat(g) water(g)
  ash(g) alcohol(g) dietary fiber(g)/100g of
  food

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• Energy ??
• It is by calculation not by tests.
• Energy value kcal/100g available carbohydrates
  x 4 total fat x 9 protein x 4 alcohol x 7
  organic acid x 3
• Energy value KJ/100g Energy value kcal/100g x
  4.2
• (1kJ 4.2kcal)

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• Case studies ???? (????????)
• 1. If some products are packed in liquid, should
  the water be analysed?
• Case by case
• If the solid part is usually consumed with the
  liquid, the whole package should be analysed.

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• Case studies ???? (????????)
• 2. For health foods packed in the form of
  capsule, should the capsule be analysed
  together?
• As the capusle is usually consumed together, the
  content of the whole capsule should be analysed.
  Unless it is clearly specified that the content
  in the capsule should be removed for consumption.
  

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• Case studies ???? (????????)
• 3. If some products contain shell, should the
  shell be included in the calculation of nutrient
  content?
• If the shell is usually removed before processing
  or direct consumption eg. Peanut, crab etc., the
  shell should be removed before analysis for the
  nutrient content.

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• Case studies ???? (????????)
• 4. Does Shiitake mushroom needs to remove stem
  before analyse?
• Mushroom or fungi belongs to vegetable, and
  therefore it is exempted if no other ingredient
  is added or packed.

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• 5. Tea and coffee are quite similar, can coffee
  bean or powder be exempted?
• Case by case
• If brewed coffee does not have any energy value
  or contain any contents of core nutrients, the
  prepackaged product could be exempted.
• For espresso, both the energy value and protein
  content are unlikely able to meet the definition
  of zero.

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• Reasons for deviated test results of food
  nutritional test
• 1. Sampling tested sample randomly selected
  from production line. Batch to batch variation
  exists.
• Test samples are not homogeneous.
• 3. Raw material is different.
• 4. Different test methods are used in analysis.

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• Price and time to do nutritional label
• Generally, the price of 71 is HK4500 include
  alcohol and organic acid.
• It is about HK3500 if alcohol and organic acid
  are excluded.
• It takes about 15 working days to finish the
  71 tests.

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Thank You ! CONTACT Secretariat1/F, CMA
Building,64-66 Connaught Road Central,     Hong
Kong Tel [phone] Fax [phone]
http//www.hktic.org/