Highlights
Ultrasound increases the DH of gelatin and antioxidant properties of hydrolysate.
Ultrasound facilitates the unfolding of protein structure.
Ultrasound accelerates the thermal degradation of the protein.
Ultrasound changes the morphology and interface characteristics of gelatin particles.
This study investigated the activity of adenosine monophosphate‐activated protein kinase (AMPK), glycolysis, and meat quality index in three altitude bovines during postmortem aging process. Local cattle (altitude:1,500 m), Gannan yak (3,000 m), and Yushu yak (4,500 m) postmortem Longissimus Dorsi (LD) muscle were used. Results indicated that CaCl2 significantly increased the AMPK activity by increasing the calcium‐regulated protein kinase kinase (CaMKKβ) activity. Besides, AMPK activation enhanced the activity of lactate dehydrogenase (LDH) and Ca2+‐ATPase and accelerated the rate of muscle maturation during postmortem aging. Moreover, the expression of HIF‐1, PRKAA2, and GLUT4 genes in high‐altitude Yushu yak was higher than that of low‐altitude bovines. CaCl2 activates AMPK by activating CaMKKβ cascade and accelerates postmortem glycolysis affecting the intramuscular environment, color, and muscle protein degradation to accelerate postmortem muscle maturation, suggesting that AMPK has essential effects on postmortem muscle glycolysis and quality, and can regulate muscle quality by regulating postmortem muscle AMPK activity.
Practical applications
Insufficient postmortem glycolysis usually leads to DFD (dark, firm, and dry) meat. Beef have relatively high incidences of DFD meat, which has an unattractive dark color and causes significant loss to the meat industry. Therefore, AMPK, which can regulate postmortem glycolysis to affect meat quality, is a valid research target.
In this study, the feasibility of preparing oxhide gelatin from cowhide scrap by high pressure assisted‐liquid extraction was verified. Different processing conditions, including high pressure time (15 to 25 min), pressure (250 to 350 MPa), and liquid‐to‐solid ratio (1:3 to 1:5), were optimized through response surface methodology. Under the optimum manufacturing conditions, when the high‐pressure processing (HPP) time was 22 min, the pressure was 289 MPa, and the liquid‐to‐solid ratio was 1:4, the highest extraction yield (36%) and gel strength (224 g) were achieved. Based on DSC, XRD, FTIR, SEM, gelling and melting temperatures, HPP led to the structural modification of the gelatinized collagen, which enhanced the rearrangement of the gel structure during the gelation process and made it have better gelling properties. In addition, compared with the commercial sample, they do not differ significantly in the relaxation time and peak area of prepared oxhide gelatin. These findings provide new insights into the practicability of HPP during the preparation of oxhide gelatin, which can noticeably reduce the processing time and be applied to industrial production.
Practical Application
Compared with traditional processing, a high pressure‐assisted extraction process can noticeably reduce the processing time while producing cowhide gelation with similar physicochemical and functional properties. Meanwhile, high pressure processing (HPP) led to the structural destruction of the cowhide and gelatinized collagen, which enhanced the rearrangement of the gelatin structure during the gelation process and made it have better gelling properties. Importantly, high pressure‐assisted extraction can facilitate the use of a low‐cost raw material and improve the preparation efficiency of oxhide gelatin, which shows great potential in large‐scale and efficient industrial production and the quality control of oxhide gelatin.
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