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.

Summary As an efficient strategy to promote human health, diet regulations are gaining increasing attention on the intake of high‐quality oils and proteins. In this study, we developed reconstituted milk using natural soybean diglyceride‐milk fat globule membrane (DAG‐MFGM) and investigated its stability, in‐vitro digestion, and sterilisation safety. Results showed that the smallest droplet size (250 nm) of DAG‐MFGM reconstituted milk was obtained under 0.1% MFGM addition, demonstrating high stability. The in‐vitro digestion revealed that the fatty acid release of DAG‐MFGM reconstituted milk was 85.6% within 120 min, significantly higher than milk‐fat reconstituted milk (67.2%) and soybean triglycerides‐MFGM reconstituted milk (55%). This indicated that the DAG‐MFGM reconstituted milk was digested easily. After sterilisation, the levels of 3‐chloropropanol ester and glycidyl ester were 1.109 μg kg−1 and 4.292 μg kg−1, respectively, well below the European Union (EU)2020/1322. This work provided a promising guide for preparing new reconstituted milk with DAG.