Research on mixed meals using the INFOGEST protocol has often focused on individual foods, leaving co-ingested matrix associations less well characterized. To address this gap, this study investigated bidirectional associations between steaks cooked to three doneness levels (medium, SM; medium-well, SW; well-done, SD) and red wine during simulated gastrointestinal digestion, focusing on protein oxidation, apparent digestibility, secondary structure, and the apparent bioaccessibility of selected phenolic compounds. Results showed that co-digestion with red wine was associated with lower accumulation of protein oxidation markers across all doneness levels. In the gastrointestinal phase, carbonyl content was 44.5–46.8% lower and free sulfhydryl content was 53.4–59.1% higher than in steak digested alone. SW steak co-digested with wine exhibited the highest mean gastric apparent digestibility (37.7%), and FTIR indicated differences in protein secondary-structure distribution. Furthermore, mixed digests showed higher radical-scavenging activity than when wine was digested alone (an average ABTS increase of 61.4% in the gastrointestinal phase), while the steak matrix altered the digestive recovery and gastric apparent bioaccessibility of several target phenolic compounds. Overall, these findings indicate that steak doneness and red-wine co-digestion are associated with distinct matrix-dependent changes in both protein digestion and apparent phenolic bioaccessibility.

Thermal processing facilitates the transformation of major ginsenosides into rare ginsenosides, thereby enhancing the bioactive molecular profile of American ginseng. This study examined the impact of 1–4 cycles of high-temperature and high-pressure steaming (HTHPS) on ginsenoside composition, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity in American ginseng. HTHPS significantly decreased major ginsenoside levels while increasing the content of rare ginsenosides. Following three cycles (HTHPS-3), the concentrations of Rg3, Rk1, Rg5, Rh1, F4, and Rg6 reached 8.68, 6.02, 20.07, 1.92, 3.72, and 2.57 mg/g, respectively, in contrast to their absence in the untreated control. TPC exhibited a 6.74-fold increase after HTHPS-2, whereas TFC showed a 4.27-fold increase following HTHPS-3. Pearson correlation analysis revealed strong positive correlations between rare ginsenosides, TPC, TFC, and antioxidant activity. In summary, HTHPS treatment significantly altered the bioactive profile of American ginseng. HTHPS-2 was more suitable for maximizing TPC and DPPH/ABTS⁺ radical-scavenging activities, whereas HTHPS-3 favored rare ginsenoside accumulation, particularly Rg3, Rk1, and Rg5, and exhibited a stronger ·OH radical-scavenging capacity. These findings indicate that the preferred number of HTHPS cycles depends on the target bioactive components and functional properties.