Food Biochemistry and Food Processing (2 edition)

BLBS102-c42 BLBS102-Simpson March 21, 2012 14:27 Trim: 276mm X 219mm Printer Name: Yet to Come

42 Food Allergens 811

Table 42.4.Commonly Used Food Allergen Detection Methods

Principle

Limit of

Detection Advantages/Disadvantages References

Protein-based methods

Rocket immunoelec-

trophoresis

(RIE)

Binding of allergen to human

IgE or antibodies raised in

animal followed by

observation in gel

2.5 mg/kg Not widely used due to the

laborious procedure.

Semi-quantitative.

Besler et al.

2002b

EAST inhibition Binding of specific IgE

antibodies to food allergens

bound to a solid phase

followed by measurement

1 mg/kg Mainly used for clinical

diagnosis.

Limited commercial products

available due to reliance on

human sera.

Quantitative.

Nordlee and

Taylor

1995

SDS-PAGE and

immunoblotting

Proteins are denatured and

separated according to their

molecular mass. The proteins

are then transferred onto a

membrane and detected with

labelled human IgE or

antibody raised in animals.

5 mg/kg Complex and time-consuming

procedure.

Reliance on human sera.

Scheibe et al.

2001

Dot immunoblotting Reaction between sample

protein extracts and

enzyme-labelled specific

antibodies on a nitrocellulose

membrane.

Intensity of dot

is proportional

to the amount

of allergen.

Semi-quantitative but simple

and inexpensive.

Blais and

Phillippe

2000

ELISA Detects allergens by

colourimetric reaction formed

by the binding of allergen and

specific enzyme-labelled

antibody.

0.05–10 mg/kg Most widely used method.

High specificity and sensitivity.

Rapid ELISA kits for major

allergens are commercially

available.

Schubert-

Ullrich

et al. 2009

Flow-through

Microarray

Immobilised allergen specific

antibodies on a microarray

chip react with allergens.

1.3 ng/mL for

ovalbumin

Powerful tool but still in

infancy stage for food

allergen detection.

Shriver-Lake

et al. 2004

Optical biosensors,

e.g., surface plasmon

resonance (SPR)

Interaction of immobilised

molecules (e.g.

allergen-specific antibodies)

on a sensor surface and a

target molecule (e.g.

allergens) in solution.

1–12.5 mg/kg Interaction is measured by

either a resonance angle or

refractive index value.

No need to use labelled

molecules.

Yman et al.

2006

DNA-based methods

PCR with gel

electrophoresis

Amplification of a specific DNA

fragment followed by agarose

gel electrophoresis and

visualisation by staining or

southern blotting.

<10 mg/kg Qualitative.

Target DNA is less affected

than protein during

processing and extraction

from food matrices.

Results do not truly represent

actual allergen exposure.

Poms et al.

2001

Real-time PCR Uses a target-specific

oligonucleotide probe with a

reporter dye and a quencher

dye attached.

<10mg/kg Requires costly laboratory

equipments.

Allows for gel-free detection.

RT-PCR kits are available for

various food allergens.

Oliver and

Vieths 2004

DNA-ELISA Amplified product of specific

DNA fragment is linked with

a specific protein labelled

DNA probe coupled with a

specific enzyme-labelled

antibody.

<10mg/kg Semi-quantitative. Poms et al.

2004

Source: Adapted from Poms et al. 2004.