Abstract: In order to investigate the effect of fermentation with Penicillium chrysogenum on the eating quality, microstructure and physicochemical properties of duck meat, duck meat was sterilized by autoclaving and inoculated with Penicillium chrysogenum for fermentation for 7 days at (27 ± 1) ℃, and ripening for 14 days at 30 ℃. A texture analyzer, a scanning electron microscope (SEM), a transmission electron microscope (TEM), Raman spectroscopy, low-field nuclear magnetic resonance (LF-NMR) and gas chromatograph (GC)-mass spectrometry (MS) were used to evaluate changes in the texture, microstructure, protein conformation, water distribution and volatile components of duck meat. The results obtained showed that the hardness and springiness of duck meat fermented with Penicillium chrysogenum decreased, and the gumminess increased. SEM and TEM results indicated that fermented duck meat had no intact myofibrils with disorderly arrangement and adhesion in the form of particles. Raman spectroscopy showed that the relative content of α-helix in the protein secondary structure of fermented duck meat decreased and the relative content of β-sheet increased, while the relative contents of β-turn and random coil did not reveal any changes. The micro-environmental hydrophobicity of tryptophan and tyrosine residues was significantly enhanced (P < 0.05). LF-NMR showed that the relative contents of bound water and immobilized water were significantly reduced (P < 0.05). GC-MS analysis identified 29 volatile compounds in unfermented duck meat, and 48 volatile compounds in fermented duck meat. Ketones, esters and acids were newly produced volatile compounds. Therefore, Penicillium chrysogenum can be used to produce fermented meat products with specific flavor and texture, which will provide a new idea for the development of fermented duck meat products that are safe to consume.

Key words: Penicillium chrysogenum; fermented duck meat; texture; Raman spectroscopy; low-field nuclear magnetic resonance; volatile compounds