Twin-Screw Extrusion Puffing of Nonfat Dry Milk and Starch - The Effects of Acid Addition, Fluid Addition Rate and Nonfat Dry Milk Concentration on Extruded Products

Abstract

Nonfat dry milk (NDM) and a modified cornstarch were extruded at three NDM concentrations (45, 65, 85%), three lactic acid concentrations (0, 33 and 50% of the added fluid) and two fluid addition rates (6.5, 7.3 kg/h) to alter extrudate characteristics. Process responses (die temperature, die pressure, motor torque and specific mechanical energy) and product responses (color, solubility, expansion ratio, bulk density and peak viscosity) were analyzed statistically and response surface plots were generated using the results to graphically illustrate relationships present. It was demonstrated that NDM provided structural integrity to the extrudates, and formula conditions altered product characteristics such as density and color to change its fitness for use in extruded products. The response surfaces generated allow for the selection of formula conditions to produce desired product attributes. Practical Applications Protein fortification of extruded products is popular, but NDM is not typically used because protein–protein interactions between caseins are difficult to induce during extrusion, and high lactose contents lead to excessive browning. Understanding formula and extrusion conditions to alter its functionality in puffed ingredients will benefit the industry and allow for the expanded use of this ingredient in extruded products.

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

“…MPC80 (80% protein w/w dry‐basis, Milk Specialties Global, Eden Prairie, Minn., U.S.A.) was fed (25 kg/h) into a corotating twin‐screw extruder (DNDL 44, Bühler AG, Uzwil, Switzerland) at the Joseph J. Warthesen Food Processing Center (Univ. of Minnesota, St. Paul, Minn., U.S.A.) using systems previously described (Tremaine and Schoenfuss ). Screw speed (350 rpm), MPC80 feed rate, and set barrel temperature (50 °C) were fixed.…”

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

“…expansion index, hardness). Direct food applications include expanded snacks, textural crisps and meat analogs, although they are limited overall . A lesser‐studied use of extrusion is production of novel protein ingredients by simultaneously applying heat, shear force and pressure to modify the physiochemical properties of protein concentrates and isolates.…”

“…Table S1. Protein powder water holding capacity, and water droplet contact angle, volume, and angular and volumetric rates of change during dynamic contact angle analysis…”