Instrumental and Sensory Texture Attributes of High‐Protein Nutrition Bars Formulated with Extruded Milk Protein Concentrate

Abstract

Previous instrumental study of high-protein nutrition (HPN) bars formulated with extruded milk protein concentrate (MPC) indicated slower hardening compared to bars formulated with unmodified MPC. However, hardness, and its change during storage, insufficiently characterizes HPN bar texture. In this study, MPC80 was extruded at 2 different conditions and model HPN bars were prepared. A trained sensory panel and instrumental techniques were used to measure HPN bar firmness, crumbliness, fracturability, hardness, cohesiveness, and other attributes to characterize texture change during storage. Extrusion modification, storage temperature, and storage time significantly affected the instrumental and sensory panel measured texture attributes. The HPN bars became firmer and less cohesive during storage. When evaluated at the same storage conditions, the texture attributes of the HPN bars formulated with the different extrudates did not differ significantly from each other. However, textural differences were noted most of the time between the control and the HPN bars formulated with extruded MPC80. An adapted HPN bar crumbliness measurement technique produced results that were correlated with sensory panel measured crumbliness (r = 0.85) and cohesiveness (r = -0.84). Overall, the HPN bars formulated with extruded MPC80 were significantly softer, less crumbly, and more cohesive than the control during storage.

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

“…Moisture content was determined ( n = 3) by mass difference after drying for 16 h at 102 °C. Particle size D ‐values and distribution span were measured ( n = 2) by laser diffraction (Mastersizer 2000, Malvern Inc., Worcestershire, U.K.; Banach and others ). Loose ( ρ loose ), tapped ( ρ 100X ), and extremely tapped ( ρ 1250X ) densities were calculated ( n = 3) after mechanically tapping (Autotap™, Quantachrome Instruments, Boynton Beach, Fla., U.S.A.) 30 g powder in a 100‐mL graduated glass cylinder 0, 100, and 1,250 times, respectively.…”

“…HPN bars (700 g) were prepared at 30% protein (w/w) using either control, JM‐Fine, or FD MPC85. HFCS (39.6 g), glycerol (146.1 g), maltitol syrup (72.5 g), and distilled water (50.2 g) were heated to 60 °C and were then combined with melted palm oil (105.1 g) and lecithin (3.5 g; Banach and others ). Protein powder (248 g) blended with maltodextrin (35.1 g) was intermittently added to the lipid/polyol blend over 4.5 min of low‐speed mixing with the paddle attachment using a stand mixer (K5SS, Kitchen Aid, St. Joseph, Mich., U.S.A.).…”

“…HPN bar samples ( n = 6) from each powder, temperature, time, and preparation combination were twice compressed to 60% strain at 2 mm/s using the TA‐XT2 Texture Analyzer (Texture Technologies, Scarsdale, N.Y., U.S.A.; Banach and others ). Hardness (N) was the force at maximum strain.…”

“…Following compression, the samples were sieved three at a time by mechanical shaking for 30 s on speed 3 (Shaker #18480, CSC Scientific Sieve, Fairfax, Va., U.S.A.). Crumbliness was the mass percent passing the top mesh with 5.6 mm aperture (Banach and others ). Water activity ( a w ) was measured ( n = 3) using the Aqua Lab 4TE Duo (Decagon Devices Inc., Pullman, Wa., U.S.A.).…”

“…Formulating HPN bars with 20% to 50% protein (w/w) is a challenge as inclusion at these levels adversely affects texture and shortens sensory shelf life. High‐protein (that is, ≥ 80% protein w/w) milk protein concentrate (MPC) powders produce HPN bars that quickly harden during storage and lack cohesion (Loveday and others ; Imtiaz and others ; Banach and others ). Whey protein concentrate (WPC) or isolate (WPI), specifically their hydrolysates, produce texturally stable HPN bars (McMahon and others ).…”