Production and characterisation of resistant starch and its utilisation as food ingredient: a review

Starch is the storage carbohydrate in plants and also the largest source of carbohydrates in human food. Starch and starchy food products can be classified according to their digestibility as rapidly digestible starch, slowly digestible starch, and resistant starch (RS). Starch source, processing treatments, and chemical modification of starch are the main factors that influence the extent of starch digestion. RS has been defined as the sum of starch and starch degradation products not absorbed in the small intestine of healthy individuals by EURESTA (European Food- Linked Agro-Industrial Research-Concerted Action on Resistant Starch). There are four types of RS: physically inaccessible starch locked within cell walls (RS1), native granular starch (RS2), retrograded or crystalline starch (RS3) and chemically modified starch (RS4). The manufacture of RS involves acid/enzyme hydrolysis and hydrothermal treatments, retrogradation, extrusion and cross-linking. Extensive studies have shown that RS has physiological functions similar to those of dietary fibres such as protecting against colonic carcinogenesis and reducing the risk of diabetes, obesity, high cholesterol and other chronic diseases. RS offers an exciting new potential as a food ingredient since it is generally stable to heat treatments and survives in most food processes. The main use of RS has been as a functional ingredient in low-moisture food products particularly in bakery products such as bread and muffins, and in breakfast cereals.