Saturday, July 12, 2008
the methods shown below can be used for detection of aflatoxins in milk thou grain was used as the main food for the mentioned methods.
Minicolumn
Finely ground grain is extracted with solvents, purified by a precipitation procedure, and the extract washed through a column containing two absorbents. Migration and long wave UV light are used for detection.
Rapid (9 to 15 min.), simple, and semi-qualitative; requires inexpensive equipment; can detect aflatoxins down to 4 ppb.
Quick but only qualitative. Can be used as a “go” or “no go” measurement above 4 ppb. The short minicolumn test is not suited for mixed feeds.
Enzyme Linked Immunosorbent Assay or “ELISA”
Grain is extracted in methanol and placed in plastic well. Addition of antibody-enzyme conjugate and chromagen results in color which is quantitative measure of alkaloid.
Test is specific for target alkaloid but may be crossreactive within members of an alkaloid group. Sensitive to 5 ppb (aflatoxin) and requires 10 minutes to complete.
ELISA requires a plate reader for accurate quantitation, but no other specialized equipment is necessary. ELISA is a good compromise of sensitivity, speed and expense.
Immunoaffinity column assay (ICA)
* similar to ELISA
http://diagnostics.montana.edu/GPDN/Mycotoxin/MYCOTOXINS.pdf
Applied Food Science And Nutrition.
11:26 PM
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Thursday, July 10, 2008
after some more researching,
these are the methods i've identified for aflatoxins:
Minicolumn, Immunoaffinity column assay (ICA), Enzyme-linked immunosorbent assay (ELISA), Thin-layer chromatography (TLC) and High-performance liquid chromatography (HPLC).
there are other methods for detection of aflatoxins.
but not all methods are applicable to our product.
and these are the methods for grayanotoxins:
TLC, HPLC, gas chromatography, liquid-chromatography–mass spectrometry/mass spectrometry (LC–MS/MS) and paper electrophoresis
Applied Food Science And Nutrition.
9:21 PM
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Tuesday, July 8, 2008
GRAYANOTOXINS
Name of Acute Disease: Honey Intoxication
- Formerly known as andromedotoxin, acetylandromedol, and rhodotoxin
- Caused by the consumption of honey produced from the nectar of rhododendrons
- The grayanotoxins cause the intoxication.
Nature of Disease: rarely fatal and generally lasts for no more than 24 hours
- Induces dizziness, weakness, excessive perspiration, nausea, and vomiting shortly after the toxic honey is ingested.
- Other symptoms that can occur are low blood pressure or shock, bradyarrhythima, sinus bradycardia, nodal rhythm, Wolff-Parkinson-White syndrome and complete atrioventricular block.
Associated Foods: most commonly results from the ingestion of grayanotoxin-contaminated honey, although it may result from the ingestion of the leaves, flowers, and nectar of rhododendrons
Relative Frequency of Disease: Grayanotoxin poisoning in humans is rare
- May be due to an increase consumption of imported honey or ingestion of unprocessed honey.
Target Population: Individuals who obtain honey from farmers who may have only a few hives are at increased risk. The pooling of massive quantities of honey during commercial processing generally dilutes any toxic substance.
Analysis in Foods: can be isolated from the suspect commodity by typical extraction procedures for naturally occurring terpenes. The toxins are identified by thin layer chromatography.
- Can also use Liquid Chromatography-Mass Spectrometry
• positive ion electrospray ionization
• ion trap tandem mass spectrometry
References
http://www.seafoodhaccp.com/SeafoodData/BadBugBook/CHAP44.HTML
http://www.ncbi.nlm.nih.gov/pubmed/11312909
http://niah.naro.affrc.go.jp/publication/seikajoho2/2001/niah01020-e.html
Applied Food Science And Nutrition.
11:39 PM
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Wednesday, July 2, 2008
AFLATOXINS
- Found in cereal, oilseeds, spices, tree nuts and milk.
- Members of aflatoxins found in our pdt are B1, B2, G1, G2, M1
- Legal limits
• B1 cannot exceed 2 parts per billion
• B1+B2+G1+G2 cannot exceed 4 parts per billion
• M1 cannot exceed 0.5 parts per billion
• Total aflatoxins in foods has to be less than 20 ppb
- Methods of Analysis:
• Solid-Phase Extraction
There are three steps involved in all analytical methods: extraction, purification, and determination. The solid-phase extraction is the purification step.
Test extracts are cleaned up before instrumental analysis to remove coextracted materials that often interfere with the determination of target analytes.
• Thin-Layer Chromatography
* most widely used separation techniques
* it has been considered the AOAC official method and the method of choice to identify and quantitate aflatoxins at levels as low as 1 ng/g.
• Liquid Chromatography
* similar to TLC in many respects
* use TLC for preliminary work to optimize LC separation conditions
* normal-phase LC (NPLC), reversed-phase LC (RPLC) with pre- or before-column derivatization (BCD), RPLC followed by postcolumn derivatization (PCD), and RPLC with electrochemical detection.
• Immunochemical Methods
* identify and measure aflatoxins in food in less than 10 minutes
* radioimmunoassay (RIA), enzyme-linked immunosorbent assay (ELISA), and immunoaffinity column assay (ICA)
* Thin layer chromatography and LC methods
> Laborious and time consuming
> require knowledge and experience of chromatographic techniques to solve separation and interference problems
• Confirmation of Identities of the Aflatoxins:
* Chemical derivatization * mass spectrometry (MS) - Aflatoxins and Human Health• difficult to avoid because fungal growth in foods is not easy to prevent • though heavily contaminated food supplies are not permitted in the market, concern still remains for the possible adverse effects resulting from long-term exposure to low levels of aflatoxins in the food supply. • Can cause occurrence of acute aflatoxicosis • Conditions increasing the likelihood of acute aflatoxicosis in humans include limited availability of food, environmental conditions that favor fungal development in crops and commodities, and lack of regulatory systems for aflatoxin monitoring and control. References http://www.commercialdiplomacy.org/case_study/egyption_peanuts.htmhttp://www.ansci.cornell.edu/plants/toxicagents/aflatoxin/aflatoxin.html#Aflatoxins
Applied Food Science And Nutrition.
8:00 PM
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Tuesday, July 1, 2008
For Package 2, fresa and i were tasked to find out stuff on:
(1) Legal permitted dosage
(2) Common analytical techniques used for detection of toxins
(3) Food safety concerns and awareness among food industries and regulatory bodies
For the toxins, we focused mainly on
aflatoxins and grayanotoxins.
Applied Food Science And Nutrition.
10:14 PM
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