Phytohemagglutinin content in fresh kidney bean in China

Abstract

Fresh kidney beans (Phaseolus vulgaris L.) are common green vegetable that are widely cultured and consumed worldwide. The benefits of fresh kidney beans are highly substantial, but at the same time, toxicity caused by phytohemagglutinin (PHA) has raised concerns. PHA from fresh kidney beans accounted for 40% of poisoning events induced by poisonous plants in China from 2004 to 2013. However, an understanding of PHA levels in fresh kidney beans remains elusive. An analysis method for PHA based on agglutination of PHA to erythrocyte cell was established. We investigated the effect of cultivar, bean part, maturity, and cooking method on PHA content in fresh kidney beans. We demonstrated significant differences in the distribution of PHA among various predominant, fresh Chinese kidney bean cultivars and parts. One major Chinese strain, Zihuayoudou, was found to contain the highest amount of PHA, which was abundant in fresh kidney bean seeds. Moreover, PHA concentrations were found to decrease with the maturity of the fresh product. Further, cooking methods had a significant effect on PHA levels in fresh kidney beans. PHA could be effectively removed when stir-frying for more than 18 min, or braising for more than 10 min. These findings provide insight into the PHA content of fresh kidney beans in China and will be helpful to guide food safety measures.