Optimization of salt morphology and oral perception of salt with CFD and CFD- DEM techniques

High sodium consumption is one of the major factors in increasing the risk of high blood pressure and cardiovascular
disease. The World Health Organization (WHO) recommends that adults should not consume more than 5 g/day NaCl [1].
However, in the US, UK, and Asian countries, the average intake of salt is 12, 8.8, and 9.4 g/day, respectively [2]. Salt is
largely obtained from processed foods (75%), and decreasing the amount of NaCl in these products is an effective way to
improve public health. Nevertheless, reducing NaCl content because of its role in controlling fermentation rate,
preservative properties, and adding flavour is difficult [3]. In snacks and other processed foods, salt enhances the taste,
and removing salt will change consumer perception and acceptance which should be considered in any salt reduction
strategy.
Direct reduction will affect the saltiness perception among consumers and, in the long run, there is a possibility that they
will choose alternative products with higher salt content or add salt to their favourite product themselves [4]. Thus, food
industries seek strategies that give the same saltiness perception to consumers with a lower amount of salt such as, salt
substitution and modification of salt particles to increase sodium availability and dissolution rate in saliva. It may also be
possible to alter the taste preference of consumers by gradually reducing the sodium content of all food products which is
not feasible and is not a timely solution for an ongoing threat to the public health. Recently, some replacers like potassium
chloride are used in order to substitute sodium in salt [2]. However, due to the undesirable metallic and bitter flavour this
replacement has some limitations.
A better way of reducing the salt content of the product without compromising the taste is to design optimized salt particles
that will be perceived better as a result of faster dissolution and absorption by the receptors. Salt crystals with higher
surface area dissolve faster and lead to higher saltiness perception. Therefore, crystals with a smaller size or hollow
structure are preferred. Furthermore, non-cubic and agglomerated crystals dissolve faster and internal cracks and cavities
allow crystal disintegration in saliva [1]. Hurst et al. [5] tested different salt morphologies and SODA-LO salt with fine
particles, soft pseudospherical structure with internal voids and higher surface area had the highest dissolution rate and
lower time to be perceived by consumers. Rios-Mera et al. [6] and Galvao et al. [7] used micronized salt crystals in turkey
ham and burgers, respectively and concluded that the salt consumption can be reduced by up to 30% without compromising
the taste. Freire et al. [8] showed that for shoestring potato this can be reached up to 50% by using smaller salt crystals.
Chokumnoyporn et al. [9] and Moncada et al. [10] obtained the same result for roasted peanuts and cheese crackers,
respectively. Therefore, designing new salt particles with maximum dissolution rate and lower intake is of paramount
importance.
In this project, we aim to design optimised salt grains through high fidelity computer simulations. First, we will start by
simulating the dissolution of salt particles with different morphologies. At this stage dissolution curves can be obtained
using CFD simulation and optimized particles that have maximum absorption and higher transport of ions to the receptors
will be found. Then, more complicated models will be added to model flow patterns and the static geometry of the oral
cavity.