Phytohaemagglutinin Quantification

Phytohaemagglutinin, is a lectin and naturally occurring food toxin that can be found in many species of legumes plants in significant quantities.

Figure 1. Examples of foods associated with food toxin phytohaemagglutinin

Phytohaemagglutinin can be found in a variety of fresh legumes such as white or red kidney beans with high concentration and green beans as well as other common beans with relatively lower quantities. Phytohaemagglutinin has a variety of different properties on the cell metabolism such as the ability to affect membrane transportation and permeability to proteins and agglutination of red blood cells and can be applied for different medical uses.

Fresh beans have good benefits to human health, while toxicity caused by phytohaemagglutinin also has raised concerns. Phytohaemagglutinin is usually sensitive to the high temperature. The level of phytohaemagglutinin in fully cooked beans are significantly reduced. Phytohaemagglutinin can be reduced to the safe level after cooking at 100℃ for at least half an hour. The insufficient cooking of beans is a major contribution to the foodborne outbreaks associated with beans. The consumption of raw or uncooked beans can cause foodborne illnesses. Even as few as four or five raw beans can trigger symptoms. There have been several foodborne outbreaks that were caused by a slower cooker with internal cooking temperature not reaching high enough to destroy phytohaemagglutinin in the beans.

As a food toxin, phytohaemagglutinin can cause poisoning symptoms to humans including extreme nausea and possible severe vomiting in a short period. Then diarrheal symptoms can develop later with abdominal pain. The diseases caused by phytohaemagglutinin usually happen rapid and last for several hours. All symptoms caused by phytohaemagglutinin typically can resolve within several hours.

There are currently no established regulations or guidelines of FDA to restrict the presence of lectins in foods. The raw kidney beans contain from 20,000 to 70,000 hemagglutinating unit (hau) and fully cooked beans contain from 200 to 400 hau. FDA has provided recommendations on bean cooking practices prior to the consumption of legumes.

The procedure for the analysis of phytohaemagglutinin in foods includes the sample preparation and extraction, and detection/quantification. We control sample preparation factors and we have expertise in the sample preparation of a variety types of food matrices. The sample preparation has significant effect on the accuracy of the level measured in the food samples.

We offer accurate and validated analytical methods that have been widely applied in the determination of phytohaemagglutinin in food samples to meet customers' needs.

Immunoassay (enzyme linked immune sorbent assay, ELISA)

ELISA method has high specificity binding ability to active lectin with relatively simple sample preparation steps. The method also showed good repeatability. It typically has a limit of quantification of 15 ng of phytohaemagglutinin. The sensitivity of the method corresponds to 30 ppm, permitting the measurement of traces of active phytohaemagglutinin even in diluted samples. The results can also be converted to HAU if needed.

We also maintain high quality assurance for the analysis. The recovery of internal standard, the use of blanks and spikes is monitored for each batch of analysis.