Mechanisms Underlying the Changes in the Digestive Properties of Chicken Breasts Induced by the Changes in Protein Structure During Frozen Storage

This study aimed to investigate the effects of different freezing temperatures and storage durations on the digestive and structural properties of chicken meat proteins. The texture, protein digestibility, particle size, and microstructure of the digested samples were used to characterize their digestive properties. Conformational changes in the digested samples were confirmed by infrared spectroscopy, circular dichroism, and endogenous tryptophan fluorescence spectra. The results revealed that the moisture and protein contents decreased with extended storage and increased temperature. Compared to fresh chicken breasts, protein digestibility decreased as the duration of frozen storage increased. Moreover, the samples stored at -40 °C had higher digestibility than those stored at -18 °C, and the protein structure of the samples stored at -18 °C exhibited more damage and was more likely to aggregate compared to the protein of samples stored at -40 °C. Therefore, a higher freezing temperature and an extended frozen storage duration result in greater structural damage to the protein and lower protein digestibility.