Pulse Fibres

Pulse Fibre Content

Pulses are a rich source of dietary fibre, ranging from 14 – 32%, the majority of which is insoluble. Incorporating fibres can serve to improve the overall nutritional profile of the product, as well as adding a number of functional advantages.

Dietary fibre content of pulses

^{Adapted from Toh and Yada. Food Research International 2010. 43. 450-460.}

Pulses also contain another form of dietary fibre known as resistant starch which is unable to be digested in the body. In pulses, resistant starch is primarily raw or ungelatinized starch granules (RS2) or retrograded starch (RS3). Resistant starch levels in cooked pulses have been reported at approximately 4%.

Formats

The majority of fibre is found concentrated in the seed coat (or hull), representing approximately 10% of the seed weight.  Hull fibre is largely composed of insoluble fibre, high in cellulose, however it also contains hemicelluloses, pectins and oligosaccharides¹. Prior to processing, the hull can be physically removed from the cotyledon and ground to produce a fibre ingredient with relatively high purity of 80% or higher. As a non-digestible carbohydrate that has been isolated from food, pulse fibres can be added to foods as a novel source of dietary fibre along those considered intrinsic (naturally occurring) and intact (not isolated from within food [JC1] ).

An additional fibre product can also be isolated from within the seed (the cotyledon), and is known as cell wall or inner fiber. Pulse cell wall fibre contains higher amounts of soluble fibres than the hull, however will not produce as pure of a product due to the presence of other seed components such as protein and starch. Hull and cell wall fibre will vary from each other in terms of their composition and functionality, thus it is important to clearly distinguish between the two.

Functionality

Processing history, physical characteristics of the fibre such as particle size, porosity and surface area, as well as the food’s chemical environment will have an effect on the properties of the ingredient.

^{1. Toh, S.M., Yada, D., (2010) Dietary fibres in pulse seeds and fractions: characterization, functional attributes and applications. Food Research International, 43: 450-460. https://doi.org/10.1016/j.foodres.2009.09.005}