Fibrous cellulose improves the strength and water retention of heat-induced myofibrillar protein gel by microstructure enhancement

In this study, four kinds of cellulose were prepared by mechanical grinding and/or acidolysis methods, including fibrous microfibrillated cellulose (MFC), fibrous nanofibrillated cellulose (CNF), rod-like microcrystalline cellulose (MCC) and acicular nanocrystalline cellulose (CNC). Subsequently, the effects of different amounts of these celluloses (0.1, 0.3, 0.5, 0.7 and 1.0 wt%) on properties of chicken myofibrillar protein (MP) gel were investigated. The results showed that the addition of all celluloses induced the compact and uniform gel microstructure, which significantly improved the gel hardness and water holding capacity (p < 0.05), stabilized the internal water content of gel and improved its viscoelasticity. Compared with MCC and CNC, CNF and MFC with 0.5 wt% significantly improved the gel performance (p < 0.05), indicating that the enhancement of MP gel by cellulose was largely dependent on the shape and length-diameter ratio rather than the size. In addition, the filling of cellulose had percolation threshold, in other words, excessive filling was not conducive to the strengthening effect of cellulose. Finally, two mechanical models (Halpin-Kardos and Ouali) were introduced to explain the enhancement mechanism of MP gel by cellulose, it was found that the formation of CNF filler network in MP matrix was the main reason for the enhancement of MP gel.