Particle agglomeration of gum mixture thickeners used for dysphagia diets

Highlights

• Physical and rheological properties of agglomerated gum mixture powders were examined.

• Addition of GG and CMC to XG for agglomeration had a major influence on powder flow characteristics.

• GG and CMC addition had a synergistic effect on the elastic properties of agglomerated XG powder.

• Physical and rheological properties of agglomerated XG are affected by the gum addition and type.

• Results could be useful in developing the XG-based food thickener for dysphagic patients.

Abstract

Among various food gums, xanthan gum (XG), guar gum (GG), and carboxymethyl cellulose (CMC) are commonly used as main ingredients of commercial food thickeners for the management of dysphagia. In this study, the physical and rheological properties of XG and gum mixture powders (XG/GG and XG/GG/CMC) agglomerated by a fluidized bed agglomerator were investigated. Agglomerated XG/GG mixture showed the lower Carr index and Hausner ratio, indicating a better flowability and lower cohesiveness than the other samples. The viscosity values of thickened beverages, except for thickened water, prepared with the agglomerated XG/GG mixture were higher than those prepared with the agglomerated XG alone and XG/GG/CMC mixture. Storage modulus (G′) values of thickened milk prepared with XG alone were significantly higher than those of gum mixtures. However, the loss tangent values of the thickened liquids prepared with XG alone were considerably lower than those of the liquids prepared with gum mixtures, demonstrating that the elastic property of thickened liquids decreased with the addition of GG and CMC. These results suggest that the physical and rheological properties of agglomerated gum powders were strongly influenced by the type of gum comprising the food thickener and the type of dispersing medium characterizing the thickened liquids.

Introduction

Dysphagia is a congenital or acquired swallowing disease that can be caused by anatomical or physiological abnormalities such as motor neuropathy, a stroke, and Parkinson's disease (Logemann, 2007). Patients with dysphagia struggle to control the flow of fluids, resulting in the risk of liquid aspiration. Dysphagia can lead to various negative health symptoms: nutritional deficiency, dehydration, aspiration, pneumonia, and other problems (Sura et al., 2012). In general, it is known that adding food thickeners to liquid foods is a popular management strategy for dysphagia (Kim et al., 2018). Thin liquids are difficult for these patients to consume because too low a viscosity may mean that the material travels faster into the pharynx and may be more likely to enter the airway before the protective mechanisms of the swallow can be initiated (Kim and Yoo, 2015). Patients with dysphagia can be treated with food thickeners which control the speed of thickened-fluid movement by engaging in the swallowing process and promote safe food intake via slow fluids movement through the oropharynx (Garin et al., 2014). Therefore, the rheological characteristics of food thickener are essential for the treatment of dysphagia. The main ingredients of commercial food thickeners are referred to as gums (e.g., xanthan gum (XG), guar gum (GG) and carboxymethyl cellulose (CMC)). These thickeners play a major role in various food processes, including thickening, gelation, dispersion, stabilization, and film formation (Funami, 2011). However, these gums are fine particles and suffer from low flowability and poor dispersion, leading to lumping. To avoid these problems, commercial food thickeners are manufactured by means of fluidized bed agglomeration process.

In the fluidized bed agglomeration process, the fine powders are agglomerated by spraying a binder solution directly onto the fluidized powder bed, resulting in liquid bridges associated with an increase in size of the agglomerates. The agglomerated powders are characterized by improved physical and morphological characteristics (such as size, density, surface and porosity) relative to those of the initial powders. In this fluidized bed agglomeration process, the physical and morphological characteristics as well as rheological characteristics can vary depending on the type of powder, binder solution, and process condition employed (Bellocq et al., 2018, Jeong et al., 2019, Szulc and Lenart, 2013). Recently, Jeong et al. (2019) and Kim et al. (2017) reported that the rheological properties of agglomerated XG can be significantly influenced by the binder type and the concentration of the binder solution.

The physical and morphological properties of agglomerates associated with food powders such as dairy products, beverage, starch-based powders, and tea powder have been extensively investigated (Bellocq et al., 2018, Ji et al., 2015, Jinapong et al., 2008, Sakurai et al., 2017). In contrast, the food thickeners used for dysphagic patients have rarely been studied. Several studies have considered the rheological properties of various thickened liquids prepared with commercial food thickeners (Cho and Yoo, 2015, Garin et al., 2014, Moret-Tatay et al., 2015; C. W. Seo and Yoo, 2013, Sopade et al., 2007, Yoon and Yoo, 2017). However, no analysis has been conducted on the rheological properties of thickened liquids prepared with agglomerated gum powders manufactured by a lab-scale fluidized bed agglomerator under the same agglomeration conditions. Therefore, in this study, the physical (density, flowability, cohesiveness, and particle size distribution) and morphological properties of agglomerated XG and gum mixture powders (XG/GG and XG/GG/CMC) were investigated. The flow and dynamic rheological properties of four different thickened liquids (water, milk, orange juice, and sports drink) prepared with different agglomerated gum powders were also examined. During this evaluation, the synergistic effect of the GG and CMC on XG, and the rheological differences between XG/GG and XG/GG/CMC mixtures were assessed.