It is well known that high-protein nutrition bars tend to harden to unpalatable levels during storage. A study published in the Journal of Food Science shows that adding ground extruded milk protein concentrates may enhance the texture and other sensory attributes of high-protein nutrition bars.
Previous instrumental study of high-protein nutrition (HPN) bars formulated with extruded milk protein concentrates (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 (milk protein concentrate with 80% protein w/w dry-basis) was extruded at two 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.
The researchers found that 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 researchers concluded that extruding milk protein concentrate with 80% protein produced a functional ingredient that, when incorporated in high-protein nutrition bars, resulted in favorable texture attributes, for example, reduced firmness and improved cohesiveness, when compared to the unmodified control.
