Heliyon (May 2023)
Changes in beef protein digestibility in an in vitro infant digestion model with prefreezing temperatures and aging periods
Abstract
The protein digestibility of beef at three prefreezing temperatures (freezing at −20 °C, F20; freezing at −50 °C, F50; and freezing at −70 °C, F70) and aging periods (4, 14, and 28 days) was investigated using an in vitro infant digestion model. The increased cathepsin B activity in the frozen-then-aged treatments (P < 0.05) resulted in a higher content of 10% trichloroacetic acid-soluble α-amino groups than in the aged-only group on days 14 and 28 (P < 0.05). F50 had the most α-amino groups in the digesta and digested proteins under 3 kDa on day 28 (P < 0.05), with the disappearance of actin band in the digesta electrophoretogram. The secondary and tertiary structures of myofibrillar proteins revealed that F50 underwent irreversible denaturation (P < 0.05), especially in the myosin fraction, while F20 and F70 showed protein renaturation during aging (P < 0.05). In general, prefreezing at −50 °C then aging can improve the in vitro protein digestibility of beef through freezing-induced structural changes.