Noel A. McCarthy

Emulsification properties of pea protein isolate using homogenization, microfluidization and ultrasonication

Pea protein isolate (PPI) is used in many food formulations, due to its low cost, commercial availability and excellent amino acid profile. The objective of this study was to determine the emulsification properties of PPI. Particle size of PPI powders showed neither temperature (25-65°C) nor time (up to 24h) increased solubilisation of powder particles during mixing. Heating PPI dispersions (10%, w/w, protein) from 45 to 90°C led to an increase in storage modulus (G; Pa) at 71°C, indicating the onset of protein aggregation. Gel formation occurred at 79°C (G>1Pa). Pea protein-stabilised emulsions made using homogenization (15MPa; 1 pass) or microfluidization (50MPa; 1 pass) resulted in the formation of cold-set gels, with gel strength increasing with increasing oil concentration and fluidic pressure. Droplet size and viscosity of pea protein-stabilised emulsions decreased and increased, respectively, with increasing ultrasonication time. Overall, ultrasonication (<50°C) can create a uniform droplet size emulsion, while, homogenization and microfluidization can produce cold-set gels for use in a wide-range of food applications.

Effects of calcium chelating agents on the solubility of milk protein concentrate

The aim of this study was to determine the effects of calcium chelating agents on the dissolution and functionality of 10% (w/w) milk protein concentrate (MPC) powder. MPC powder dissolution rate and solubility significantly (Pxa0>xa00.05) increased with addition of sodium phosphate, trisodium citrate (TSC) and sodium hexametaphosphate (SHMP), compared to MPC dispersions alone. Trisodium citrate and SHMP addition increased viscosity as a result of micelle swelling. However, dispersions containing SHMP showed a decrease in viscosity after prolonged time due to micelle dissociation. Overall, MPC powder dissolution was aided by the addition of calcium chelating agents.

Whey Proteins in Infant Formula

Abstract One of the most common industrial applications for whey protein is in infant formula (IF) as a source of essential amino acids and other nutrients. While breast milk is considered the optimal source of nutrition for an infant, it is not always a viable option and IF can provide a suitable alternative. Whey protein is used to adjust the whey protein:casein level of bovine milk-based 1st stage formulas from a ratio of 20:80 to mimic that of human breast milk, i.e., 60:40. Human milk has many functions in addition to nutrition which include immune response, reduction in acute/chronic diseases, and allergic responses. IF manufacturers attempt to incorporate these biological functions into formulations through enriched whey ingredients, whereby the physiological characteristics of their constituents (e.g., major and minor proteins, enzymes, growth factors, cytokines, and oligosaccharides) determine the type and level used. Consequently, the inclusion of any whey protein ingredient (e.g., α-lactalbumin (α-La) and/or lactoferrin (Lf)) into IF requires understanding of complex interactions with other nutrients and ionic species to ensure in-process stability during heating, emulsification, concentration, and drying. It is clear that the thermal history of whey protein ingredients has a direct impact on the physicochemical behavior of liquid IF formulations during processing with β-lactoglobulin (β-Lg) having a modulating role. Ultimately, nutritional and functional properties of whey protein-based ingredients have an important function in ensuring the quality of an IF.

Dephosphorylation of caseins in milk protein concentrate alters their interactions with sodium hexametaphosphate

This study investigated the effects of dephosphorylation and sodium hexametaphosphate (SHMP) salt addition on the viscosity of milk protein concentrate (MPC) solutions. Dephosphorylation (DP) of casein was performed using bovine alkaline phosphatase. Nuclear magnetic resonance (NMR) spectra showed that dephosphorylation depleted the casein-bound phosphate region (CNP). SHMP addition (5u202fmM) had no impact on the 31P NMR spectra of DP-MPC; addition of 5u202fmM SHMP to control MPC (C-MPC) resulted in a shift in peaks associated with the CNP region, possibly caused by SHMP sequestering calcium, leading to swelling of micelles. DP-MPC exhibited a lower viscosity compared to C-MPC, with SHMP addition at 12.5 and 25u202fmM causing gelation of C-MPC and DP-MPC solutions. This work confirmed the role that phosphate residues have in maintaining micelle structural stability and provides new insights into controlling viscosity of MPC solutions.

Evaluation of Models for Temperature-Dependent Viscosity Changes in Dairy Protein Beverage Formulations During Thermal Processing: Modeling viscosity of dairy beverages…

Rheological modeling as a function of temperature is a useful tool for describing products undergoing thermal processing. The rheological behavior of a range of dairy-based (4%, w/w) protein beverages was investigated for applicability to semi-empirical temperature-dependent viscosity equations. The viscosity at 16.8 rad/s of the beverages was measured during heating, holding, and cooling over a temperature range of 25 to 90 o C using a rheometer with starch pasting cell geometry. Five established fitting methods were applied based on the Arrhenius and Williams-Landel-Ferry (WLF) equations using nonlinear regression analysis. A two-parameter WLF (WLF2 ) model, using viscosity at a reference temperature of 25 o C resulted in high R2 values (0.974 to 0.988) and a statistically superior fit compared to the Arrhenius, Generalized Arrhenius, and exponential equations (Pxa0<xa00.001). Deviation from the WLF2 modeled equation was used to describe and investigate the effect formulation had on the changes in viscosity during thermal heating. This study successfully applied the WLF equation to a liquid protein system, proving that a consistent and close fit can be achieved across a range of formulations. A rapid, quantitative method for viscosity-temperature profile evaluation is presented, which can ease product development and optimization of product processing stability.nnnPRACTICAL APPLICATIONnThis study validated the use of the Williams-Landel-Ferry equation to describe the behavior of dairy beverages during thermal processing, providing a better fit to rheological data than the widely used Arrhenius-based equations. In conjunction with the WLF equation, a method was presented which reduced the complex rheological data to a single value, which can aid in the comparison of formulations for product development and optimization in both research and industry.