Gastrointestinal digestion characteristics and bioactive peptide production of tsampa proteins

Tsampa (Zanba), a roasted highland barley flour staple in Chinese Tibetan diets, contains higher protein and lysine content than most cereals. Despite its nutritional significance, the digestion kinetics of tsampa proteins and bioactivity of resultant peptides remain incompletely characterized. This study systematically compared the in vitro protein digestive characteristics and peptide release profiles between black and white tsampa varieties. The results show that black tsampa contained significantly higher protein and proanthocyanidin, which was associated with higher in vitro radical-scavenging capacity. Prolonged gastric emptying half-time (t_1/2) (66.89 ± 1.40 min vs. 54.65 ± 2.79 min; p < 0.001) indicated slower digestion of black tsampa. Conversely, white tsampa demonstrated higher apparent soluble protein digestibility (95.07 ± 2.53% vs. 81.41 ± 14.01%), reduced protein band intensity, and higher intestinal total essential amino acid concentration (1422.73 ± 22.05 vs. 1252.03 ± 13.23 μg/mL, p < 0.001). 252 endpoint peptides were identified, from which 28 unique candidate bioactive peptide sequences were predicted, including 15 detected in black tsampa and 19 detected in white tsampa, with 6 shared sequences. The digesta antioxidant study revealed fluctuating activity in black tsampa versus stable release in white. These findings characterize proteolytic dynamics during tsampa digestion and identify functionally active peptides, enhancing the understanding of health benefits derived from tsampa protein digestion products.