Soft matter characterisation of whey protein powder systems

The Influence of the Syrup Type on Rheology, Color Differences, Water Activity, and Nutritional and Sensory Aspects of High-Protein Bars for Sportsmen

Most often, high-protein bars consist of a protein preparation in the form of a loose powder, stuck together with a syrup mixture, ensuring a stable mass. According to the legal regulations in force, at least 20% of the energy value must come from protein for the product to be called high-protein. The objective of this study was to evaluate the impact of different syrup sources (oligofructose, maltitol, tapioca fiber, and chickpea-maize fiber) on rheology, water activity, color, and nutritional and sensorial properties of high-protein bars. Texture has changed depending on the type of syrup used. A significant increase of the hardness parameter referring to the control sample was noted for bars containing chickpea-maize liquid fiber in chocolate (311.65 N), with low adhesiveness simultaneously (54.71 N). Samples without chocolate made with the use of oligofructose syrup had apparently higher dynamic viscosities than other bars (226.67 mPas · g/cm3). The water activity of all tested bars indicated the high stability of samples over time (<0.80), except for samples without chocolate made of PM syrup. The color of the tested bars was from light cream to Earth yellow. Bars obtained with tapioca liquid fiber had the lowest nutritional value. Results presented in this study suggest that selecting the correct type of syrup may significantly influence the functional properties of high-protein bars.

Development, Validation and Application of an ICP-SFMS Method for the Determination of Metals in Protein Powder Samples, Sourced in Ireland, with Risk Assessment for Irish Consumers

A method has been developed, optimised and validated to analyse protein powder supplements on an inductively coupled plasma-sector field mass spectrometer (ICP-SFMS), with reference to ICH Guideline Q2 Validation of Analytical Procedures: Text and Methodology. This method was used in the assessment of twenty-one (n = 21) elements (Al, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Pb, Pt, Sn, Ti, Tl, V) to evaluate the safety of thirty-six (n = 36) protein powder samples that were commercially available in the Irish marketplace in 2016/2017. Using the determined concentrations of elements in samples (µg·kg-1), a human health risk assessment was carried out to evaluate the potential carcinogenic and other risks to consumers of these products. While the concentrations of potentially toxic elements were found to be at acceptable levels, the results suggest that excessive and prolonged use of some of these products may place consumers at a slightly elevated risk for developing cancer or other negative health impacts throughout their lifetimes. Thus, the excessive use of these products is to be cautioned, and consumers are encouraged to follow manufacturer serving recommendations.

Understanding How High-Protein Bar Formulations Impact Their Mechanical and Wear Behaviors Using Response Surface Analysis

High-protein bars are popular snack items that can have significant processing issues like sticking, clogging, and cold flow. These issues are primarily problematic during formulation development because current predictive testing is reliant on highly empirical bench tests or pilot plant testing, which is expensive and time-consuming. Wear testing, which has been used in the medical field to evaluate the lifetime of soft materials used in joint replacements, may have promise in evaluating food processing ability. Wear and rheological testing were used to better understand high-protein bar processing ability. The objective of this study was to determine bench-level instrumental tests that would be able to predict processing ability for a given formulation. Two response surface designs were used for formulations of model bar systems comprising whey protein isolate (WPI), high fructose corn syrup (HFCS), and either canola oil or vegetable shortening. Ingredient formulation affected processing ability, wear behaviors, and rheological behaviors. Formulations with high ratios of WPI to HFCS and either shortening or oil exhibited good processing ability, lower wear rates, and increased elastic-type behavior, indicating that processing ability is related to formulation. The results of this study indicated that material mechanical and wear behaviors were related to processing ability; both were controlled by formulation. Because it was shown to be a good indicator of high-protein bar processing ability, wear testing of food has potential significance in benchtop testing. PRACTICAL APPLICATION: Understanding of how high-protein bar formulations impact their mechanical behaviors can help streamline their formulation development and scaling from bench to industrial production. Processing ability may be predicted with a quick wear test, providing a rapid testing method that requires little sample for evaluating bar formulations.

Extrusion modifies some physicochemical properties of milk protein concentrate for improved performance in high-protein nutrition bars

BACKGROUND

Extruded and ground milk protein concentrate powders, specifically those with 800 g kg^-1 protein (i.e. MPC80), imparted softness, cohesion and textural stability to high-protein nutrition (HPN) bars. The present study evaluated some physicochemical properties of extruded and conventionally produced (i.e. spray-dried) MPC80 to explain these improvements. Protein chemical changes and aggregations within MPC80-formulated HPN bars during storage were characterized.

RESULTS

Extruded MPC80 powders had broader particle size distribution (P < 0.05) and smaller volume-weighted mean diameter (P < 0.05) than the spray-dried control. Loose, tapped and particle densities increased (P < 0.05) and correspondingly occluded and interstitial air volumes decreased (P < 0.05) after extruding and milling MPC80. Extrusion decreased water holding capacity (P < 0.05) and solubility (P < 0.05), yet improved the wettability (P < 0.05) of MPC80. MPC80 free sulfhydryl (P < 0.05) and free amine (P < 0.05) concentrations decreased after extrusion. Sulfhydryl and amine concentrations changed (P < 0.05) and disulfide-linked and, more prominently, Maillard-induced aggregates developed during HPN bar storage.

CONCLUSION

Extrusion and milling together changed the physicochemical properties of MPC80. Chemical changes and protein aggregations occurred in HPN bars prepared with either type of MPC80. Thus, the physicochemical properties of the formulating powder require consideration for desired HPN bar texture and stability. © 2017 Society of Chemical Industry.

Particle Size of Milk Protein Concentrate Powder Affects the Texture of High-Protein Nutrition Bars During Storage

Milk protein concentrate powder with 85% protein (MPC85) was jet-milled to give 2 particle size distributions (that is, JM-Coarse and JM-Fine) or freeze-dried (FD), in order to improve the functional properties of MPC85 for use in high-protein nutrition (HPN) bars. Volume-weighted mean diameter decreased from 86 μm to 49, 22, and 8 μm in FD, JM-Coarse, and JM-Fine, respectively (P < 0.05). The MPC85 powders modified by jet-milling and freeze-drying were significantly denser than the control MPC85 (P < 0.05). Volume of occluded air in the modified powders decreased (P < 0.05) by an order of magnitude, yet only FD possessed a lower volume of interstitial air (P < 0.05). Particle size reduction and freeze-drying MPC85 decreased its water holding capacity and improved its dispersibility by at least 20%. Contact angle measurements showed that these modifications increased initial hydrophobicity and did not improve wettability. HPN bars made from JM-Fine or FD were firmer by 40 or 17 N, respectively, than the control on day 0 (P < 0.05). HPN bar maximum compressive force increased by 38%, 33%, and 242% after 42 d at 32 °C when formulated with JM-Fine, FD, or control MPC85, respectively. HPN bars prepared with JM-Fine were less crumbly than those formulated with control or FD MPC85. Physically altering the particle structure of MPC85 improved its ability to plasticize within HPN bars and this improved their cohesiveness and textural stability.