Structuring camellia seed-derived oleosomes for the fabrication of meat analogs using transglutaminase: Structural, functional, and rheological properties
Shahzad Farooq, Muhammad Ijaz Ahmad, Shijie Zheng, Usman Ali, Yipeng Zhang, Jiawen Xue, Yang Li, Cui Shixiu, Hui Zhang
Abstract
Presently, protein-based meat analogs fabricated via the extrusion process still cannot fully meet consumers' requirements, particularly in terms of replicating the real meat fiber that contains solid fat. This study introduced a facile approach to fabricating real meat analogs using plant-derived oleosomes (0–40 wt%) as lipid droplets, which were crosslinked with texturized soy-wheat gluten proteins (50 wt%) through a transglutaminase-induced reaction (0–50 U/g). FTIR and SDS-PAGE analyses confirmed that transglutaminase induction enabled oleosome-associated proteins to crosslink with texturized proteins through covalent bonds rather than non-covalent interactions. Microstructural analyses indicated that uncross-linked meat analogs contained an evenly distributed array of isolated oleosomes, whereas those with higher transglutaminase contents exhibited a compact and homogeneous 3D network of aggregated oleosomes and proteins. Analysis of appearance and colorimetry showed that color changes in meat analogs depended on oleosomes, which increased lightness and decreased redness, effectively changing the rough and uneven appearance of meat analogs into a smoother and more homogeneous one. Compared to control sample, elevated concentrations of oleosomes (0–40 wt%) and transglutaminase (0–50 U/g) led to increased critical strain (1.02–100.4 %), storage modulus (310–820 kPa), and structure-recovery ability (56.62–89.38 %), while decreased activation energy (16.16–7.12 kJ/mol). This indicated that oleosomes, which are integrated and assembled with proteins by enzymatic action, acted as “active fillers”, effectively strengthening the gel matrices. Additionally, Lissajous-Bowditch analysis best described the influence of filler/protein interactions on the gel matrices, showing a transition of meat analogs from viscoelastic to strongly elastic gels, resisting structural breakdown due to intensified covalent interactions and interconnected networks.