Investigating the impact of boiling and pressure cooking on resistant starch levels in food

Abstract

SummaryResistant starch (RS) has been shown to manipulate food digestion and nutrient metabolism as well as being important in promoting gut health. However, the presence of RS varies across diverse food systems depending upon process conditions. To investigate this, chickpeas, potatoes, arrowroots, unripe bananas and oats were subjected to boiling and pressure cooking at various cooking durations and the RS% was determined. After 45 min of boiling and 15 min of pressure cooking, RS% of chickpeas increased by ~29% and ~41%, respectively. Increasing the cooking time, together with boiling and pressure cooking, led to higher RS% in chickpeas, mainly due to the retrogradation of starch after gelatinisation. In contrast, boiling and pressure cooking led to a reduction in RS% for potatoes, arrowroots, unripe bananas and oats, while a further decrease was encountered with the increase in processing time. After 45 min of boiling, RS% of potatoes, arrowroots, unripe bananas, and oats were reduced by 58%, 22%, 80% and 70%, respectively. After 15 min of pressure cooking, RS% of potatoes, arrowroots and unripe bananas were reduced by 41%, 22% and 83%, respectively. This was mainly due to the disruption of the ordered structure of starch molecules during thermal processing in the presence of water. This study clearly elucidates the impact of boiling and pressure cooking on RS% as a function of processing time and type of RS source.