LeapZipBlog: jessica's blog: A Comparison of Rapid Test Methods for Ochratoxin A in Food

A Comparison of Rapid Test Methods for Ochratoxin A in Food

February 20, 2020 by jessica  

Ochratoxins are a series of chemical structural analogues produced by Aspergillus or Penicillium verrucous in food and feed. A large number of animal experiments have been conducted on ochratoxin A toxicity. Toxicological studies have shown that ochratoxin A has strong liver and kidney toxicity, and has teratogenic, mutagenic and carcinogenic effects. Ochratoxin A is recognized as one of the strongest carcinogenic natural substances, and it has a wide range of distributions, which have different degrees of harm to most food raw materials and manufactured products worldwide. In some parts of the world, ochratoxin A has been suspected to be associated with porcine mycotoxin nephropathy, and the toxin has been detected in human blood in endemic areas. The relationship between dietary intake of ochratoxin A and human health has drawn increasing attention and attention.

As ochratoxin A-producing bacteria are widely distributed in nature, including cereals, dried fruits, grapes and wines, coffee, cocoa and chocolate, Chinese herbs, seasonings, canned foods, oils, olives, soy products, beer, tea, etc. And many crops and food can be contaminated with ochratoxin A. Contamination of ochratoxin A in animal feed is also very serious. In countries where food is the main ingredient of animal feed, such as Europe, ochratoxin A accumulates in animals after they eat feed contaminated with ochratoxin A. As ochratoxin A is very stable in animals, it is not easy to be metabolized and degraded. Ochratoxin A is often detected in animal foods, especially pig kidneys, liver, muscles, blood, milk and dairy products. Humans are exposed to ochratoxin A by eating crops and animal tissues contaminated with ochratoxin A, and are harmed by ochratoxin A. The most widely investigated research on ochratoxin A contamination substrates in the world is cereals (wheat, barley, corn , Rice, etc.), coffee, wine and beer, seasonings, etc.

During 1996 and 1997, Croatia tested the levels of ochratoxin A in 105 local corn crops, and the results showed that the average levels of ochratoxin A were 3.61 μg / kg and 19.8 μg / kg, respectively, the highest pollution levels were 224 μg / kg / and 614 μg / kg;

During 1995 to 1999, European countries conducted a comprehensive survey of ochratoxin A contamination in coffee. Among them, 30 were roasted coffee beans on the market in Germany, and ochratoxin A was detected in 20, with concentrations ranging from 0.3 μg / kg to 7.5 μg. Ochratoxin A (0.1-8 μg / kg) was detected in 64 of 80 British instant coffees, with a positive rate of 80%.

In Denmark, where swine mycotoxin nephropathy is endemic, analysis of 300 pig kidneys showed that 237 were positive for ochratoxin A, with a positive rate of 79% and a maximum of 14.72 μg / kg. Germany also tested 61 pig kidneys, of which 27 were positive, the positive rate was 44.26%, and the highest content was 9.33 μg / kg.

In Australia, France, Spain and many other countries, the presence of ochratoxin A in wine have been reported. The content of ochratoxin A in wine is generally 0.01-3.4μg / kg, the content of ochratoxin A pair in sweet wine is 1-3.9μg / kg, and the content of ochratoxin in grape juice is 1.16-2.32μg / kg. The content of ochratoxin A in raisins is relatively high, generally exceeding 40 μg / kg.

A comparison of existing detection methods for ochratoxin A

As the content of ochratoxin A in grain is very low, the detection methods are very demanding. Relevant scholars from various countries in the world have conducted a lot of research on ochratoxin A. The current detection methods are mainly divided into two categories: confirmation methods and rapid methods. The verification method is mainly based on physical and chemical equipment, such as thin layer chromatography (TLC), gas chromatography (GC), high pressure liquid chromatography (HPLC), and various combined technologies such as gas-mass spectrometry (GC-MS), liquid chromatography HPLC-MS, etc.; rapid methods are mainly based on immunochemical methods such as immunoaffinity column-fluorescence detection (IAC-FLD), enzyme-linked immunosorbent assay (ELlSA), and colloidal gold immunochromatography Law, etc.

TLC is the most common detection method in the early research of ochratoxin A. It has been widely used because of its simple operation. However, this method is time-consuming (about 48 hours) and has poor sensitivity and specificity. There are many kinds and large amounts of organic solvents required in the process.

The HPLC method has high sensitivity and can accurately and quantitatively analyze ochratoxin A in samples, but this method is not suitable for the detection of non-batch samples.

Enzyme-linked immunosorbent assay ELISA method and colloidal gold rapid detection card are commonly used in enterprises for rapid detection methods, but they also have their own advantages and disadvantages: ELISA method can be relatively high sensitivity and quantitative detection, but the operation process is relatively complicated. High environmental and personnel requirements, complex environmental interference factors, and poor repeatability; colloidal gold test cards can meet the rapid requirements of the scene, can be quickly measured within 5-10min, but can only be qualitative, and the sensitivity is low.

Creative Diagnostics provides a wide range of ochratoxin rapid test products.