Lee Seonmin, Jo Kyung, Jeong Seul-Ki-Chan, Choi Yun-Sang, Jung Samooel
Division of Animal and Dairy Science, Chungnam National University, Daejeon 34134, Republic of Korea.
Research Group of Food Processing, Korea Food Research Institute, Wanju 55365, Republic of Korea.
Food Chem. 2024 Feb 1;433:137419. doi: 10.1016/j.foodchem.2023.137419. Epub 2023 Sep 9.
This study investigated the effect of temperature control during freeze-drying of beef on the in vitro protein digestibility. Frozen (at - 50 °C for 2 days)-then-aged (at 4 °C for 26 days) beef was freeze-dried at 25 °C (FD1) and 2 °C (FD2) to obtain freeze-dried beef powder. Tryptophan fluorescence intensity and total free sulfhydryl groups of beef myofibrillar proteins decreased (P < 0.05) and increased (P < 0.05) after freeze-drying, respectively. In the myosin fraction of FD2, α-helix increased and β-sheet decreased (P < 0.05) compared to raw beef. In contrast, the actin fraction of FD1 showed a decrease in α-helix and increase in β-sheet (P < 0.05) compared to raw beef. The contents of α-amino group and proteins digested to<3 kDa in the in vitro digesta of beef were retained in FD2 while the α-amino group of FD1 decreased (P < 0.05). Therefore, freeze-drying at 2 °C can efficiently retain in vitro protein digestibility of beef.
本研究调查了牛肉冻干过程中的温度控制对其体外蛋白质消化率的影响。将冷冻（在-50°C下冷冻2天）然后熟化（在4°C下熟化26天）的牛肉分别在25°C（FD1）和2°C（FD2）下进行冻干，以获得牛肉冻干粉。牛肉肌原纤维蛋白的色氨酸荧光强度和总游离巯基在冻干后分别降低（P<0.05）和升高（P<0.05）。与生牛肉相比，FD2的肌球蛋白部分中α-螺旋增加，β-折叠减少（P<0.05）。相反，与生牛肉相比，FD1的肌动蛋白部分中α-螺旋减少，β-折叠增加（P<0.05）。牛肉体外消化物中α-氨基和消化至<3 kDa的蛋白质含量在FD2中得以保留，而FD1的α-氨基减少（P<0.05）。因此，在2°C下进行冻干能够有效保留牛肉的体外蛋白质消化率。
