Exploring in vitro gastrointestinal digestion of myofibrillar proteins at different heating temperatures

The effects of different heating temperatures (40-115 °C) on the structure, oxidation, and digestibility of beef myofibrillar protein were investigated. Reductions in the number of sulfhydryl groups were observed, together with gradual increases in the number of carbonyl groups, indicating oxidation of the protein by the increased temperatures. At temperatures between 40 °C and 85 °C, β-sheets were converted to α-helices, and increased surface hydrophobicity showed that the protein expanded as the temperature approached 85 °C. These changes were reversed at temperatures over 85 °C, indicative of aggregation induced by thermal oxidation. Between 40 °C and 85 °C, the digestibility of the myofibrillar protein was increased, reaching a maximum of 59.5 % at 85 °C, after which it began to decrease. These results indicated that moderate heating and oxidation-induced protein expansion were beneficial to digestion while protein aggregation resulting from excessive heating is not conducive to digestion.