Food Biochemistry and Food Processing

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Table 31.5.

Comparison between Immunoassay Methods to Detect Foodborne Pathogens

Method

Advantages

Disadvantages

Detection Limit

a

ELISA

• Simplicity


• Large quantities of sample required

10

3 –10

5

cfu/mL

• Detection within a few hours


• Background levels can be high

Sandwich ELISA

• Concentrates the antigen


• Must have a second primary

in the well

antibody for a different

• Gives a stronger signal

portion of the antigen

• More time required than basic ELISA

Competitive ELISA

• Less false positives


• Must have pure antigen
  
  
  • Allows for quantitative results
  
  
  
  

available

Fluorescently labeled

• Less time required to


• More expensive than ELISA

immunoassay

measure signal

• Specialized equipment required

to analyze results

Fluorescent

• 30–40 minutes for


• Expensive chemicals required

500 cfu/mL

immunoassay with

detection after enrichment

• Trained personnel required

(Dunbar et al.

microsphere sorting

• Sensitive


• Computer sorter is

2003)

• Multiple pathogens can be

specialized and expensive

detected simultaneously

Immunomagnetic assay

• Time—no enrichment of


• Expense

1–2 cfu/g

pathogen required

• Trained personnel required

(Hudson et al.

for assay and conjugation of

2001)

antibody to beads

Latex agglutination

• No skilled help required


• Qualitative results only

0.3–222 cfu/g

assay

for assay

• Enrichment culturing required

(Matar et al.

• Inexpensive

1997)

• No specialized equipment

aDetection limits are for

L. monocytogenes