Lycopene, a potent antioxidant, has been widely used in the fields of pharmaceuticals, nutraceuticals, and cosmetics. However, the production of lycopene extracted from natural sources is far from meeting the demand. Consequently, synthetic biology and metabolic engineering have been employed to develop microbial cell factories for lycopene production. Due to the advantages of rapid growth, complete genetic background, and a reliable genetic operation technique, Escherichia coli has become the preferred host cell for microbial biochemicals production. In this review, the recent advances in biological lycopene production using engineered E. coli strains are summarized: First, modification of the endogenous MEP pathway and introduction of the heterogeneous MVA pathway for lycopene production are outlined. Second, the common challenges and strategies for lycopene biosynthesis are also presented, such as the optimization of other metabolic pathways, modulation of regulatory networks, and optimization of auxiliary carbon sources and the fermentation process. Finally, the future prospects for the improvement of lycopene biosynthesis are also discussed.

Currently, the conventional atmospheric pressure-based and vacuum-based tumbling processes have a limited improvement on the chicken characteristic attributes during the marination process. In view of this, through a breathing (pressure change) tumbling strategy, ultrasonication (40 kHz, 140 W) was applied to improve tenderness, taste, and microstructure of chicken by a redesigned tumbler. The results showed that the tumbling with the breathing action and ultrasonication significantly enhanced the marinating absorptivity, tenderness and taste, and accelerated the degradation of myosin light chain. Free peptides (from 1465.9 ± 34.6 to 4725.7 ± 43.2 μg/mL) and amino acids (from 1.503 ± 0.096 to 2.593 ± 0.109 mg/mL) rose evidently for the control and the breathing tumbling treatment assisted by ultrasound respectively. Raman analysis revealed that strength of disulfide bonds declined from 0.731 ± 0.006 to 0.607 ± 0.011 a.u. and the conversion from α-helix (decreased by 67.23%) into β-fold (increased by 1573%) conformation occurred. Low field NMR analysis indicated that the content of immobilized water increased from 77385 ± 14 to 137011 ± 106 au·ms by integral calculus. Scanning and transmission electron microscopies clearly showed a prospective rupture of myofibers, myofibrils, and lysosomes. Overall, as a potential alternative, the breathing ultrasonic tumbling means improved the marinating efficiency and characteristics of marinated chicken breast.

The quality changes of duck meat during thermal sterilization using microwave, stepwise retort and general retort heating were evaluated. Results showed that compared with stepwise retort and general retort, duck meat subjected to microwave showed significantly higher gumminess, chewiness, cohesiveness and resilience as well as glutamic acid, lysine and total amino acids. Low-field NMR revealed that the relative content of immobilized water after microwave and stepwise retort treatment was significantly higher than that after general retort treatment. The relative content of 1-octen-3-ol with characteristic mushroom aroma was significantly higher with microwave and stepwise retort heating than with general retort heating, while 2-pentyl-furan with poor taste was only detected with general retort heating. The muscle bundles subjected to microwave were neatly arranged, similar to those with no thermal sterilization. Overall, the meat quality after three thermal sterilization treatment was microwave > stepwise retort > general retort.