Protein Fraction-Dependent Antioxidant Responses to Thermal Processing in Korean Native Black Goat Extracts: A...

Korean native black goat is commonly consumed as thermally processed extracts and is widely perceived to exhibit health-promoting properties; however, the contribution of intrinsic muscle proteins to these functional characteristics remains unclear. This study evaluated the effects of thermal processing on the antioxidant activity of myofibrillar and sarcoplasmic protein fractions using a screening-based approach. Protein fractions were extracted and subjected to various thermal conditions (60-121 °C), followed by analyses of extractable protein, α-amino group content, and antioxidant activities, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, hydroxyl radical scavenging, iron-chelating ability, and ferric reducing antioxidant power (FRAP). Thermal processing increased α-amino group content, particularly in the myofibrillar fraction, indicating enhanced protein degradation. Antioxidant activities improved with increasing temperature, with myofibrillar proteins showing stronger activity than sarcoplasmic proteins. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated fragmentation in myofibrillar proteins and aggregation in sarcoplasmic proteins. Cluster analysis supported fraction-dependent differences in antioxidant responses. These findings suggest that thermal processing enhances antioxidant activity in a protein fraction-dependent manner and provide practical insights for optimizing processing conditions of Korean native black goat extracts.