Improved physical and structural properties of high-protein powders by fluidized-bed agglomeration.

High-protein powders (milk protein isolate (MPI) and soybean protein isolate (SPI)) were treated with maltodextrin solution (10% or 20%) or water as a binder and then subjected to fluidized-bed agglomeration. The MPI agglomerates were compared with the SPI agglomerates as a function of maltodextrin (MD) concentration. The particle size, wettability, and porosity values of SPI agglomerates were much higher than those of the raw powder when compared to the MPI agglomerates. The agglomerated protein powders with MD binder showed significantly higher solubility values than the raw powders. These tendencies were discernible in the morphological examination via SEM analysis. The dynamic modulus values of SPI agglomerates decreased with an increase in MD concentration from 10 to 20% whereas those of MPI agglomerates increased. These findings indicate that the physical, structural, and rheological properties of agglomerated high-protein powders are greatly influenced by the type of protein and the addition of MD binder.

Physical, Morphological, and Rheological Properties of Agglomerated Milk Protein Isolate Powders: Effect of Binder Type and Concentration.

Milk protein isolate powder (MPIP), a high protein-based powder, is a common dietary ingredient but has poor physical properties due to its cohesive nature. Powder agglomeration is one of the most widely used methods to improve and modify the quality of MPIP structures. In this study, the physical, morphological, and rheological properties of MPIPs agglomerated in a fluidized-bed agglomeration process were investigated as a function of sugar binder type and concentration. The physical properties of MPIP were evaluated by their flowability, cohesiveness, porosity, particle size distribution (PSD), and water-holding properties (wettability, solubility, and water-binding capacity). The density values of the agglomerated MPIPs decreased with increasing the binder concentration, whereas the porosity, wettability, and solubility values increased. Such trends were consistent with SEM observations. The MPIP agglomerated with 10% sorbitol had the largest particle diameter (D50) and showed better physical properties compared to the other sugar binders. The viscosity values (ηa,50) of the MPIPs agglomerated with sugar binders showed lower values than the control (no sugar binder). The agglomeration process enhanced the viscoelasticity of the MPIP, but the viscoelasticity decreased with increasing the sugar binder concentration. These observations suggested that the physical, morphological, and rheological properties of MPIP can be greatly affected by the binder type and concentration in the agglomeration process.

Rheological Information of Pudding-Thick Liquids Prepared Using Commercial Food Thickeners Marketed in Korea for Dysphagic Patients According to the Manufacturers' Guidelines.

Food thickeners are commonly used to prepare thickened liquids for the management of dysphagia. The National Dysphagia Diet (NDD) thickness levels of thickened liquids prepared with commercial food thickeners are known to vary depending on the thickener type, recommended amount of thickener, thickener brand, and preparation instructions. Particularly, detailed preparation instructions must be provided by the manufacturers to achieve the correct thickness levels. However, the rheological information on product labels provided by manufacturers is typically not accurate. Here, various pudding-thick liquids were prepared by mixing commercial xanthan gum (XG)-based thickeners based on the manufacturers' guidelines, and their rheological properties were characterized. Several thickened liquids prepared with four different XG-based thickeners (A-D) marketed in Korea did not meet the pudding-like criterion (> 1,750 mPa·s) based on the NDD guidelines. Significant differences in rheological parameter values (ηa,50, n, and G') were also identified among the various thickened liquids. Only one thickener (thickener A) manufactured in Korea showed optimal results, which satisfied the pudding-thick viscosity range for various food liquids and also showed lower stickiness and enhanced bolus formation ability for easy and safe swallowing when compared to other thickeners (B, C, and D).

Relationship between Syringe Flow Measurements and Viscosity of Nectar-Thick Beverages for Dysphagia Management.

Commercial cold beverages thickened with a xanthan gum (XG)-based food thickener were examined at different thickness levels by using the simple, cost-effective syringe flow test (SFT) developed by the International Dysphagia Diet Standardization Initiative (IDDSI). We prepared cold thickened beverage (CTB) samples with different thickener concentrations and measured them by extrapolating the viscosity range (51-350 mPa·s) for nectar-like consistency. CTBs were also measured via the line-spread test (LST), and the flow distance value (cm) by LST and the volume remaining (mL) in the syringe by SFT was correlated with the apparent viscosity (ηa,50). Plots comparing ηa,50 with SFT or LST values showed good exponential relationships between the measurements. The SFT showed a better relationship (R2 = 0.928) than LST (R2 = 0.825), indicating that the former can predict the viscosity better in the range for nectar-like consistency. In particular, the SFT showed a significant difference (R2 = 0.964) compared to the LST (R2 = 0.709) for thickened protein-based beverages. These results suggest that the SFT using the IDDSI methodology is a more suitable instrument than the LST for accurately evaluating the viscosity of XG-based CTBs with nectar-like consistency.