Evaluation of the Hemagglutinating Activity of Low‐temperature Cooked Kidney Beans

Methodology was developed that allowed sensitive measurement of phytohemagglutinin (PHA), the lectin of kidney beans. Trypsinated porcine red blood cells were treated with saline extracts of kidney beans, incubated, and the nonagglutinated cells were quantitated using a Coulter Counter. This hemagglutination activity (HA) assay was then used to monitor the PHA in cooked kidney beans. The thermal treatment (minutes @°C) required to reduce HA by 1 log cvcle was: 12 @ 100°C: 62 @ 93°C: 136 @ 88°C: 160 @ 82°C. Beans were prepared in commercially available low‐temperature cookers and evaluated for tenderness and residual hemagglutinating activity.