Partial substitution of whey protein concentrate by zein in high‐protein nutrition bars: An effective method to reduce hardening during storage.

Whey protein concentrate‐based high‐protein nutrition bars (WPC‐based HPN bars) are prone to hardening during storage, which limits their shelf life. In this study, zein was introduced to partially substitute WPC in the WPC‐based HPN bars. The result of storage experiment revealed that the hardening of WPC‐based HPN bars was significantly reduced with increasing zein content from 0% to 20% (mass ratio, zein:WPC‐based HPN bar). Subsequently, the possible anti‐hardening mechanism of zein substitution was studied in detail by determining the change in microstructure, patterns, free sulfhydryl group, color, free amino group, and Fourier transform infrared spectra of WPC‐based HPN bars during storage. The results showed that zein substitution significantly blocked protein aggregation by inhibiting cross‐linking, the Maillard reaction, and protein secondary structure transformation from α‐helix to β‐sheet, which reduced the hardening of WPC‐based HPN bars. This work provides insight into the potential utilization of zein substitution to improve the quality and shelf life of WPC‐based HPN bars. Practical Application: In the preparation of whey protein concentrate‐based high‐protein nutrition bars, the introduction of zein to partially replace WPC can effectively reduce the hardening of WPC‐based HPN bars during storage by preventing protein aggregation between WPC macromolecules. Therefore, zein could act as an agent to reduce the hardening of WPC‐based HPN bars. [ABSTRACT FROM AUTHOR]