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Yak meat jerky, a traditional high-protein food commonly consumed in high-altitude regions, is often produced via air-drying, which may adversely affect its nutritional quality and digestibility. This study systematically compared the gastrointestinal digestion profiles of air-dried yak meat (ADM) and vacuum freeze-dried yak meat (VFDM) using a dynamic in vitro human stomach–intestine (DHSI-IV) system. Key digestive parameters, including gastric emptying kinetics, particle size distribution, and protein hydrolysis, were evaluated under physiologically relevant conditions. VFDM exhibited superior hydration capacity, contributing to delayed gastric emptying of the mixed solid–liquid phase (t_1/2 = 85.1 ± 1.0 min) compared to ADM (t_1/2 = 80.4 ± 1.2 min), indicating increased gastric satiety. Conversely, VFDM showed a faster solid-phase gastric emptying (t_1/2 = 107.2 ± 0.8 min) relative to ADM (t_1/2 = 113.1 ± 2.7 min), likely due to improved texture and rehydration. Both jerky types exhibited progressive particle disintegration; by 180 min, large particles (>2.0 mm) decreased to 16.88% ± 2.63% in ADM and 20.04% ± 0.64% in VFDM (p > 0.05). Protein digestibility, measured by SDS-PAGE and the degree of hydrolysis (DH), was significantly higher in VFDM (38.5 ± 3.6%) than in ADM (34.0 ± 0.1%, p < 0.05), with VFDM demonstrating more rapid and extensive protein degradation across gastric and intestinal phases. These improvements may be attributed to the porous microstructure and reduced processing-induced protein cross-linking in VFDM, facilitating enhanced enzyme access. Overall, vacuum freeze-drying substantially improved yak jerky protein digestibility, offering the potential for the development of meat-based functional foods targeted at individuals with compromised gastrointestinal function. Full article

It is well known that different muscles of yak exhibit distinctive characteristics, such as muscle fibers and metabolomic profiles. We hypothesized that different muscles could alter the flavor profile of yak jerky. Therefore, the objective of this study was to investigate the differences in flavor profiles of yak jerky produced by longissimus thoracis (LT), triceps brachii (TB) and biceps femoris (BF) through electronic nose (E-nose), electronic tongue (E-tongue), gas chromatography–mass spectrometry (GC-MS) and gas chromatography–ion mobility spectrometry (GC-IMS). The results indicated that different muscles played an important role on the flavor profile of yak jerky. And E-nose and E-tongue could effectively discriminate between yak jerky produced by LT, TB and BF from aroma and taste points of view, respectively. In particular, the LT group exhibited significantly higher response values for ANS (sweetness) and NMS (umami) compared to the BF and TB groups. A total of 65 and 47 volatile compounds were characterized in yak jerky by GC-MS and GC-IMS, respectively. A principal component analysis (PCA) model and robust principal component analysis (rPCA) model could effectively discriminate between the aroma profiles of the LT, TB and BF groups. Ten molecules could be considered potential markers for yak jerky produced by different muscles, filtered based on the criteria of relative odor activity values (ROAV) > 1, p < 0.05, and VIP > 1, namely 1-octen-3-ol, eucalyptol, isovaleraldehyde, 3-carene, D-limonene, γ-terpinene, hexanal-D, hexanal-M, 3-hydroxy-2-butanone-M and ethyl formate. Sensory evaluation demonstrated that the yak jerky produced by LT exhibited superior quality in comparison to that produced by BF and TB, mainly pertaining to lower levels of tenderness and higher color, taste and aroma levels. This study could help to understand the specific contribution of different muscles to the aroma profile of yak jerky and provide a scientific basis for improving the quality of yak jerky. Full article