Kapor was my mother’s secret ingredient for ensuring that her achar vegetables remained crunchy. It is similarly used as a stir-fry ingredient in Thai cooking to keep vegetables crunchy. Its chemical name is calcium hydroxide, and it has many industrial uses which make it questionable for cooking due to health concerns.
In the past, kapor, areca nut, betel leaf and gambier were hand rolled together to form the addictive sireh which Nonyas used to chew and spit as a leisurely pastime.